The present invention relates to a method for encrypting a short message in mobile communication. According to the present invention, a user first inputs short-message content and a short-message password to a first communication electronic device. Then the first communication electronic device writes the short-message content to a short-message packet according to a short-message protocol, configures a set of unused parameters of the short-message packet as a set of encryption parameters according to the short-message protocol, and configures the short-message password to the set of encryption parameters for transmitting the short-message packet containing the set of encryption parameters to a second communication electronic device. Thereby, according to the present invention, the short message is encrypted. After the user of the second communication electronic device receives the short message, he cannot read the received short message unless he inputs the correct password to the second communication electronic device.

In recent years, the communication technologies adopted by communication electronic devices have developed from the first generation (1G) mobile communication technology to the fourth generation (4G) mobile communication technology for improving the quality of mobile communication, increasing the data transmission quantity of mobile communication, and providing more communication functions, and hence providing more convenience for users. In continuously improving and developing mobile communication technologies, short message service is still indispensable because it provides the users of communication electronic devices with an alternative communication method when they cannot contact the others real-timely through phone calls. In addition, short message service keeps improving as well, enriching the content of short messages. For example, based on short message service, multimedia message service (MMS) improves and provides another kind of short message service so that the users of communication electronic devices can transmit not only text but also multimedia files, such as photos, voice, or video, to remote users.
Accordingly, all current communication electronic devices have short message functions for enabling users to transmit communication content to remote users through short message service under the circumstance of inconvenience in using phone calls. No matter whether short messages having commercial confidentiality or personal privacy, people usually need to transmit such short messages in situations when using phone calls is not convenient. For example, two users of communication electronic devices are situated in the environment where noise is not allowed. Alternatively, users in a noisy environment, in which the listener cannot recognize the speech content clearly, and their conversation can only proceed using the text of short messages. In addition, the content of the conversation between two users, such as technical content or private account and password, can even be inappropriate to be disclosed in the public. For avoiding divulgence through spoken language, the conversation can only be performed using the text of short messages.
There are many communication technologies in our lives include encryption mechanism for ensuring the security of data transmission and prevent data from misappropriation. The most common encryption method is to set a password during the usage activation process of communication electronic devices. In the process, the user first enters a preset page, in which he has to input the password before using the communication electronic device. For example, in commercial mobile phones, a serial code corresponding to a subscriber identity module card (SIM card) is set as the activation code at start. The user has to input the serial code before he can activate the mobile phone. If the user inputs the incorrect serial code, the mobile phone will not be activated. Beside, a general communication electronic device can further let the user set a self-defined password as the activation code of the communication electronic device.
The encryption method described above can only protect communication electronic devices against activation by others but not protecting the short messages. If a user lends his communication electronic device to another after activation for using its functions, such as making phone calls, sending short messages, using the movie playback function of multimedia functions, browsing or accessing emails via mobile network by using communication electronic devices, and playing the games downloaded in communication electronic devices. At this time, if the communication electronic devices receive a short message, the short message may be opened and read by the other person owing to lack of protection measures during the reading process of short message in the communication electronic device. Consequently, private short messages, particularly those concerning account and password or other important information, might be read.
Although an encryption method has been developed presently for protecting short messages, a hardware circuit is required in the communication electronic device. In addition, when the communication electronic device reads short messages, it has to restore the short-message content, and hence increase its computational complexity, which burdens the computational circuitry and reduces the operational performance of the communication electronic device.
Accordingly, the present invention provides a method for encrypting a short message of mobile communication, which improves the problems of message being stolen owing to inability in encrypting the short message and avoids increase in computational complexity of a communication electronic device.

Method for encrypting short message of mobile communication


A system and method for an auxiliary network for a peer-to-peer overlay network using landmark numbering. Using information available through the auxiliary network, expressway connections are established amongst expressway nodes and ordinary connections are established between ordinary and expressway nodes. The connections established is unconstrained and arbitrary. After the connections are established, efficient routing of information may take place.

Providing scalable and efficient content delivery is becoming more important as the demand for applications such as streaming media grows at an incredible rate. Content distribution Network ("CDN") and network service providers advocate using network overlays for providing scalable and robust Internet based applications. Typical overlays are administrator configured, and due to the centralized nature of the overlay construction process, it is not feasible to construct large overlays
Recent application-level overlay networks, such as CAN, eCAN, Chord and PAST, are scalable and self-organizing in nature. Nodes in these networks collectively contribute towards a fault-tolerant and administration-free storage space. The basic functionality these systems provide is a distributed hash table ("DHT"). In these systems, an object is associated with a key. Every node in the system is responsible for storing objects whose keys map to the ID of the node (via hashing). Retrieving an object amounts to routing to a node that is responsible for storing that object. The routing path on these overlay networks is at the application-level rather than the IP level.
While elegant from a theoretical perspective, these systems suffer from two major limitations. First, they rely on application-level routing that largely ignores the characteristics of the underlying physical networks. Because the underlying physical characteristics are not taken into consideration, excessive routing delays typically result. Second, they construct a homogeneous structured overlay network, while in reality, the nodes usually have different constraints such as storage, load, packet forwarding capacities, and network connections.
In addition, the typical overlay networks are constrained. In other words, the number of connections for a node is fixed or limited. Because of the constraint, the ability to accurately model the underlying physical characteristics is limited as well. Further, the earlier auxiliary networks do not handle the dynamic nature of the nature of the underlying network well, for example, when nodes exit and new nodes enter the network.

Landmark numbering based auxiliary network for peer-to-peer overlay network

Hewlett-Packard Development Company, L.P.


A film of an epitaxial layer that allows the reduction in both the height of a bunching step and crystal defects caused by a failure in migration of reactive species on a terrace is formed on a SiC semiconductor substrate having an off angle of 5 degrees or less. A film of a first-layer epitaxial layer is formed on and in contact with a surface of the SiC semiconductor substrate having an off angle of 5 degrees or less. Subsequently, the temperature in a reactor is lowered. A second-layer epitaxial layer is caused to epitaxially grow on and in contact with a surface of the first-layer epitaxial layer. In the above-described manner, the epitaxial layer is structured with two layers, and the growth temperature for the second epitaxial layer is set lower than the growth temperature for the first epitaxial layer.

In order to form a SiC semiconductor device, it is necessary that an epitaxial layer serving as an active region of a semiconductor element is caused to grow on a SiC substrate. The epitaxial layer is formed through step-flow growth. A crystal surface of the SiC substrate has a fine unevenness, and an uneven portion is called a "step" while a surface having no uneven portion is called a "terrace". In the step-flow growth, a wafer is inclined so that reactive species adhering to the crystal surface diffuse over the terrace, and the reactive species are sequentially incorporated from the one having reached the step. Thus, a flat surface morphology is obtained. Generally, the inclination of the wafer is formed in the [11-20] direction from a (0001) plane. An angle of the inclination is called an "off angle". Currently, the general off angle is 8 degrees in a case of a 4H-SiC substrate, and 3.5 degrees in a case of a 6H-SiC.
Patent Document 1 proposes to cause an epitaxial growth on a 4H-SiC substrate having an off angle of 8 degrees from a (0001) plane of the substrate in the [11-20] direction, to thereby form an epitaxial layer on which an epitaxial growth is further caused at a raised growth temperature, thus reducing the Basal Plane Dislocation density that is taken over from the SiC substrate.

Method for manufacturing silicon carbide semiconductor device


Embodiments of the present invention described herein, discloses a method and a system for segment protection system in an Ethernet communication network. In one embodiment herein, a ‘periodic integrity check’ message frame being created at the source-node and is multicasted to the destination-node directly and via the peer node(s) within a segment protection domain. A Σ1 receiver is configured at the destination-node for receiving the multicasted message frames. The Σ1 receiver ‘selects’ only single message frame from the multicasted message frames being received at all maintenance points, for maintaining at least one fault-less path between the source-node and the destination-node.

In a typical computer network, the network peers send and receive data packets. Each packet of data follows a particular path from source peer to the destination peer. A fault in a segment or failure of path will disturb the data traffic. A segment generally consists of plurality of nodes linearly connected with links. A typical example of a segment would be a link connecting two nodes or an entire end-to-end service path.
Presently, local segment based protection switching is done when the segment is under fault connection. To monitor the connectivity fault of end-to-end service there are a standard based mechanism: IEEE 802.1ag (CFM OAM), IEE802.3ah (EFM OAM), ITU-T Y.1731 (ETHOAM), ITU-T G.8031 (ELPS) and ITU-T G.8032 (ERPS). Essentially it involves exchanging of periodic frames between end nodes of service or segment. Despite there being many standards for connectivity monitoring, there are cases where a service could be working but segment could be reported to be in fault due to forwarding database error or mis-configuration within a segment. There are also cases where forwarding database of service is faulty or a service is misconfigured within the segment even while the segment is in order. The above mentioned problem may be overcome by a method using a unicast CCM (periodic integrity check message), where unicast CCM was provisioned between the end-points of an Infrastructure Segment to monitor the connectivity of the same. The method using a unicast CCM do not solve the issues of reduced bandwidth utilization within the infrastructure segment protection domain per service, coordination needed between inner infrastructure segment protection domain and outer infrastructure segment protection domain, and more numbers of frame processing per service within nested infrastructure segment protection domain.
Therefore, there is a need in the art for a method and system for segment protection domain in an Ethernet communication network to overcome the above restrictions and limitations.
Before describing the novel solution in detail, it would be important to first understand the following terminologies.
Segment Protection Domain—It basically consists of multiple infrastructure segments between the end points such that if one infrastructure segment fails then other infrastructure segment will protect the traffic flowing over failed infrastructure segment.
Infrastructure Segment—It is the linear chain of nodes and links. Two or more infrastructure segment form one infrastructure segment protection domain or segment protection domain

System and method of segment protection in a communication network


Provided is a device, including: a first terminal which receives an external clock signal; a clock generation circuit connected to the first terminal to generate an internal clock signal based on the external clock signal; word lines and bit lines; amplifier circuits connected to the bit lines, respectively; and a control unit. The control unit controls, in a test operation, at least one of the word lines to repeat a selected state and an unselected state in accordance with the internal clock signal during a first period, and maintains the amplifier circuits in an active state during the first period. The control unit further controls, in a normal operation, the amplifier circuits to switch between the active state and an inactive state depending on switching between the selected state and the unselected state of the at least one of the word lines.

1. Field of the Invention
This invention relates to a semiconductor device, and more specifically, to a semiconductor storage device including a plurality of memory cells.
2. Description of the Related Art
A semiconductor storage device such as a dynamic random access memory (DRAM) includes a plurality of memory cells arranged so as to correspond to intersections between a plurality of word lines and a plurality of bit lines. The memory cells may be accessed for each row by selectively activating one corresponding word line. Further, an access for each memory cell may be controlled by a combination of a word line and a bit line.
However, as a result of a progress in reducing the size and increasing the integration of semiconductor devices, a potential change in each word line now affects other surrounding word lines. In other words, due to the parasitic capacitance and other such effects, when a word line is selectively activated, momentary electric potential change to other word lines now occurs. As a result, there now occurs a phenomenon that electric charges held in a memory cell connected to a different word line than the activated word line flow out to a bit line. Such outflow of the electric charges may cause loss of data written in the memory cell. Therefore, there has conventionally been conducted an electrical test called "disturb test" for examining whether such outflow of electric charges is equal to or less than a permissible value.
The disturb test involves performing an operation of sequentially selecting a plurality of word lines or an operation of repetitively selecting one or a plurality of word lines. A related semiconductor storage device is configured so that, in order to perform such operation of selecting the word lines at high speed, an internal row address strobe (RAS) signal φRAS is generated in synchronization with a clock signal generated in an internal period setting circuit, and so that a RAS-system control circuit is operated in accordance with the internal RAS signal φRAS. Examples of such semiconductor storage device include a semiconductor storage device described in Japanese Unexamined Patent Application Publication (JP-A) No. 8-227598.


A portfolio of components and a method for creating an embellishment for an orthopedic cast comprising a shrink-film in a sleeve like configuration that conforms to the cast in a substantially circumferential relationship and the shrink-film having at least one decoration.

Packagers have used shrink-film polymers for many years to wrap products. Common films use polyolefin polymer, such as, polypropylene or polyethylene, or polyvinyl chloride (PVC) polymer. Other shrink-film polymers include polystyrene and glycol-modified polyester. Recently, packagers have begun to consider biodegradable polymers, such as film based on polylactic acid. The shrink-film helps protect products from damage and contamination during handling and shipment, prevent loss of bundled components from theft, or to indicate product tampering. A distinguishing characteristic of shrink-film is its ability upon exposure to a level of heat energy to shrink or create shrink-tension within the film if it is restrained. Examples of wrapped items include: cans, jars, bottles, compact disk recordings, toys, food products, gift baskets, household items, hardware components, and the like.
Containers, such as bottles and jars, generally have a closure that seals contents within the container. Applying an adhesive, such as a pressure sensitive rubberized adhesive, to one side of the shrink-film creates a heat shrinkable film tape that packagers wrap around the closure and then shrink to make a secondary closure. Similarly, packagers make the secondary closure by creating a pre-made heat shrinkable sleeve, some open only at one end, which slides over the closure and then is heat-shrunk. This secondary closure can provide indication of product tampering and helps keep the closure and adjacent areas of the bottle or jar substantially free of contamination.
Packagers pre-decorate shrink-films as means for labeling the bottle or jar. A shrink-film label is generally made of a special shrink-film polymer material that shrinks mostly in a transverse direction than in an axial direction of the bottle or jar.
For decades, medical professionals have treated injured bones, joints, and surrounding soft tissue using the orthopedic cast made in part of plaster based structural materials and more recent fiberglass based structural materials that harden to thereby substantially immobilize and support the injured area. Typically, medical professionals apply casts to limbs and torsos. Depending on the injury, injury treatment and use of the cast can take a period of a few weeks to several months. On average, these professionals will treat over 9.8 million U.S. residents each year; many are children or animals important to children.
In practice, medical professionals apply a padding covering the injured area before applying the structural material. The padding is usually white in color and traditionally the structural material is white in color, but occasionally has a pigment in one of a few other select colors.
Because these casts are temporary, often replaced during the period of treatment, patients and their friends, relatives, and other individuals often decorate the cast with any number of drawings, sketches, slogans, hieroglyphics, phrases, comments, poetry, symbols, and the like. Children are particularly interested in decorating their casts and parents usually encourage this interest in that it creates an activity that is fun for them and may partly distract them from otherwise often traumatic issues associated with treatment. Psychologically, the decorations can become a badge of honor.
Until this invention, individuals apply decorations directly to the cast's structural material using felt-pens, ballpoint pens, brushes, or other similar marking means that use ink, paint, or pencil lead. Once applied, the decoration remains until cast removal. Sometimes decorations applied later become inappropriate. Sometimes the cast becomes soiled. Other times cast decorations may become a memento.
Accordingly, an intention of the invention is to decorate orthopedic casts in a novel manner that creates applied decorations that can partially distort in interesting ways during application of heat energy and subsequent contraction of shrink-film.
Another intention of the invention is to enable individuals to readily alter, remove, or hide at will cast color and/or previously applied decorations.
Another intention of the invention is to help enable individuals to maintain a fresher and cleaner cast appearance.
Another intention of the invention is to provide means that may enable parents and medical professionals to help children ease, often traumatic, issues associated with treatment.
Another intention of the invention is to enable individuals to transfer decoration applied to a previous cast if medical professionals determine treatment requires a replacement cast.
Another intention of the invention is to provide a portfolio of selected components that will enable individuals to apply initial cast decorations and to readily exchange previously applied decorations.
From description, appended claims, and accompanying drawings that follow, additional benefits and advantages of the present invention will become apparent to those skilled in art to which this invention relates.


A computer implemented method for identifying and removing similar examination items in a digital examination includes obtaining, with an examination evaluation server, a digital examination with a plurality of examination items, tokenizing a first examination item of the plurality of examination items into a first set of n-grams, tokenizing a second examination item of the plurality of examination items into a second set of n-grams, generating a first item vector from the first set of n-grams, generating a second item vector from the second set of n-grams, generating multiple item congruence values for corresponding similarity dimensions by comparing the first item vector with the second item vector, and identifying that the first and second examination items are a potential enemy item pair if one or more of the item congruence values exceed corresponding threshold values.

Digitized examinations may be generated by compiling multiple examination items. For example, an item may be a question or problem statement. Items may be compiled from a repository, e.g., a relational database or other electronic storage medium or data store. Items may be categorized by different characteristics, such as field, topic, and/or difficulty of the content. Many times, digitized examinations may be limited or fixed in length, i.e., the number of items presented to a test subject. Nevertheless, in many cases, it is a goal to present a test subject with a broad range of non-cumulative items for the purpose of assessing a sufficient breadth and scope of the test subject's skill and/or knowledge. Accordingly, it is desirable to exclude repeated, cumulative, duplicative, and/or highly similar items in any given digitized examination form. Undesirably similar questions may be referred to as "enemy items." For example, pairs of enemy items may be linguistically similar, lexically similar, syntactically similar, and/or semantically similar. However, identifying enemy items, when done manually, may be relatively subjective in nature and time consuming, such that resulting digital examination forms may be relatively non-uniform, and difficult to create.
Traditional technology does not provide an automated and/or objective mechanism for identifying enemy items for removal from digitized examination forms. For example, checking for the presence of enemy items on a newly assembled fixed-length test form has been a labor-intensive process. For a complete check, a human content expert would need to compare every item to every other item on the test form. For a 60-item form, this involves
      (                            60                                      2                      )    =      1    ,    770  pairwise item comparisons. The problem of finding all enemy item pairs in a larger pool of items is far more daunting. A pool of 1,000 items contains
      (                                        1            ,            000                                                2                      )    =      499    ,    500  distinct pairs of items, and it's impossible to humanly check every pair for the degree of item similarity between the two. As assessment increasingly evolves from fixed-length forms to computer-adaptive administrations (items being selected from the pool "on the fly" in response to ongoing examinee performance), it becomes not just desirable but essential to find a way to automatically, quickly, and objectively (at the time of administration) determine the degree of similarity between any two given items drawn from an item pool.

Automated determination of degree of item similarity in the generation of digitized examinations


It is intended to establish a technology of controlling Gramineous plant seed-borne disease that avoids the danger of development of resistant pathogeus, being highly safe to environment and stable. There is provided a fungus having activity of controlling fungal disease and bacterial disease occurring during the raising of rice plant seedling, and are further provided, using the fungus as an active ingredient, a controlling agent, method of controlling and biological material.

As the damages caused by diseases during the raising of Gramineous plant seedlings, diseases caused by fungi such as Gibberella fujikuroi, Cochliobolus miyabeanus, and Pyricularia oryzae; and bacterial diseases caused by bacteria such as Burkholderia glumae, Burkholderia plantarii, and Acidodovorax avenae can be given. To control those diseases, a seed disinfectant, a soil drenching agent, a soil treatment agent, and a foliage spraying agent after greening are considered as effective, and a chemical pesticide is used alone or chemical pesticides are used in combination. For the diseases caused by fungi, highly effective EBI fungicides are used. For the diseases caused by a bacterium, an oxolinic acid or a copper (II) hydroxide is used. However, there arise some cases where stable effects may not be expected because of the appearance of resistant bacteria each having reduced sensitivity against those fungicides. Moreover, waste water of chemical pesticides has to be processed after the use thereof, resulting in problems such as burden on workers and costs required therein.
From said viewpoint, studies on biocontrol utilizing microorganisms, which are assumed to exhibit lower environmental burden than a chemical pesticide, have been progressed in recent years, and parts of them have been put into practical use. For controlling the above-mentioned seed-borne diseases, Patent Document 1 discloses a non-pathogenic Pseudomonas glumae, which is effective for the disease caused by Burkholderia glumae, and Patent Document 2 discloses that Erwinia carotovora having lost its pathogenicity is effective for controlling the disease caused by Burkholderia plantarii. Meanwhile, Patent Document 3 describes Pseudomonas sp. which is effective for diseases caused by Burkholderia glumae, Burkholderia plantarii, and Gibberella fujikuroi, and Non-patent Document 1 describes Pseudomonas aureofaciens which is effective for diseases caused by Burkholderia glumae and Burkholderia plantarii.
Meanwhile, Patent Document 4 discloses a microorganism belonging to the genus Trichoderma, which is effective for fungal disease caused by Gibberella fujikuroi, Pyricularia oryzae, or the like, and Patent Document 5 discloses a microorganism belonging to the genus Trichoderma, which is effective for a bacterial disease caused by Burkholderia plantarii.
While biocontrol generally utilizing a microorganism has been realized, however, controlling agents which are effective with a low administration amount, and which exhibit less environmental burden have been desired. However, even for the biological pesticides utilizing those microorganisms, it was difficult to control the damages caused by diseases such as fungi disease and bacteria disease and attain stable effects comparable to chemical pesticides.
Patent Document 1: JP-A-04-295407
Patent Document 2: JP-A-06-087716
Patent Document 3: JP-A-09-124427
Patent Document 4: JP-A-11-225745
Patent Document 5: JP-A-11-253151
Non-patent Document 1: "Biological Pesticide Test Score in 1999" (Japan Plant Protection Association, January 2000)

Fungus having activity of controlling disease of gramineous plant, controlling agent using the same, method of controlling and biological material


The present invention provides a method and a system for the display of customized pages with Double WebView. The method includes: determining a template type to generate a customized page based on loaded information of an original web page, wherein the original web page is loaded via a mobile Internet; creating a new WebView associated with a primary web page based on the template type, wherein the primary web page is the original web page or a web page evolved from operating on the original web page; loading a template corresponding to the template type of the new WebView; creating a built-in JavaScript object within the new WebView; obtaining data of the primary web page through the built-in JavaScript object; generating a customized page within the new WebView based on the data of the primary web page; and displaying the customized page. The present invention can realize the customization of web pages without the support of a customization server and the modification to the primary web page. They can also make possible the switch between the primary web page and the customized page seamlessly, almost instantaneously. At the same time, they are able to screen and block advertisements on the web page.

Along with the development of mobile Internet technology, more and more people prefer browsing web pages through mobile terminal devices, enjoying the convenience of having the Internet in the pocket. However, due to the limit of hardware of mobile devices, the browsing effect of the browsers on mobile terminal devices falls far behind that of PC browsers. Furthermore, moving the web pages viewed on PC browsers to the browsers on mobile terminal devices will consume huge data traffic. Therefore, many browsers on mobile terminal devices have realized customization of web pages.
Generally, there are two major ways of customization of web pages by browsers:
1. Forward the request for a web page from a user's browser to the server of the browser's manufacturer, which in turn will obtain the data of the web page from the actual address of the web page, and customize the web page; and
2. Obtain the data of the web page in the normal way rather than through the transit and customization by the manufacturer's server; however, after obtaining the data of the web page, the browser will modify HTML Document Object Model (DOM) tree by inputting JavaScript (JS), JS language or through other means, so as to modify the display effect and functions of the web page, thus realizing the purpose of customization.
However, both methods for the purpose of customization have serious limitations and shortcomings. First of all, for the customization of web page through the manufacturer's server, some background servers must be established to maintain the function of customizing web pages, which will increase the cost of maintenance; moreover, the function of customizing web pages will be affected when the server breaks down. In addition, this mode of transit will also reduce the speed of opening web pages. Second, the modification of DOM tree through inputting JS or otherwise will damage the structure of DOM tree of the original web page, as a result of which the functions of web page, such as caching and saving the source code of the web page will be affected. Because the original web page has been modified, the DOM tree that has already been cached cannot be used when the web page is re-opened. As the process of saving the source code of the web page is actually a process of re-resolving the DOM tree into a character string, as a consequence of which the original functions of caching and saving the source code of the web page will no longer be effective. In addition, this mode of inputting JS or otherwise modifying DOM tree will be unable to block the advertisements controlled by web page JS after the customization. Finally, neither of the two methods of customizing web pages described above can realize seamless switch between entering and exiting from the mode of customization.

Method and system for displaying customized webpage on double webview


A seat track assembly is disclosed. An illustrative embodiment of the seat track assembly includes a seat track having an elongated track plate and a pair of generally elongated, parallel, spaced-apart track flanges extending from the track plate. Each of the track flanges is variable in depth. A method of fabricating a seat track assembly is also disclosed.

Seat tracks are used in passenger aircraft to anchor passenger seats to the airframe of the aircraft. Conventional seat tracks typically have a "hat" design (a pair of outwardly-extending top flanges and a pair of outwardly-extending middle flanges which together form a top cord and a pair of outwardly-extending bottom flanges which form a bottom cord). The middle flanges are used to attach the track to the airframe.
One of the limitations of the conventional aircraft seat tracks is that the top, middle and bottom flanges are thick to overcome load instability. This renders excessive weight of about 400 lbs. to the tracks, resulting in loss of about $120,000 in revenue for each aircraft per year. Moreover, seat tracks are typically extruded. Extrusion is optimal for objects which have a constant or uniform cross-sectional geometry; because an optimized seat track would be thicker at the middle than at the ends of the track since loads are greater at the middle, fabrication of an optimized extruded track would require extensive machining of a large block of metal such as titanium.


A radio communications method includes carrying out, by a transmitter: providing a digital time signal carrying digital symbols to be transmitted; and transmitting a radio frequency signal carrying the digital time signal. The method further includes carrying out, by a receiver: receiving the radio frequency signal transmitted by the transmitter; processing the received radio frequency signal to obtain a corresponding incoming digital signal; and extracting, from the incoming digital signal, the digital symbols carried by the incoming digital signal. The digital time signal carrying the digital symbols to be transmitted results from an approximation of the Hilbert transform in frequency domain, which approximation is based on a frequency main mode and one or more frequency twisted modes, wherein the frequency main and twisted modes carry, each, respective digital symbols to be transmitted.

In consideration of Orbital Angular Momentum (OAM) potentialities of increasing transmission capacity and since RF spectrum shortage problem is deeply felt in radio communications sector, recently a lot of experimental studies have been carried out on the use of OAM states, or modes, at RF (also known as radio vortices) in order to try to enhance RF spectrum reuse.
In this connection, reference may, for example, be made to:                Mohammadi S. M. et al., "Orbital Angular Momentum in Radio—A System Study", IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, IEEE SERVICE CENTER, PISCATAWAY, N.J., US, vol. 58, no. 2, 1 Feb. 2010, pages 565-572, which shows that standard antennas arranged in circular arrays can be used to generate RF beams carrying OAM;        Tamburini F. et al., "Encoding many channels in the same frequency through radio Vorticity: first experimental test", arXiv.org, 12 Jul. 2011, Ithaca, N.Y., USA, which experimentally shows that it is possible to propagate and use the properties of twisted non-monochromatic incoherent radio waves to simultaneously transmit several radio channels on one and the same frequency by encoding them in different (and, thence, orthogonal) OAM states (even without using polarization or dense coding techniques);        GB 2 410 130 A, which discloses a planar phased array antenna for transmitting and receiving OAM radio vortex modes, which antenna comprises a circular array of cavity backed axial mode spiral antenna elements whose phase is controlled such that the phase of each antenna element changes sequentially about the array; and        WO 2012/084039 A1, which discloses a transmit antenna arrangement comprising N antenna elements arranged along a circumference with an angular separation of a degrees between neighboring antenna elements, the antenna arrangement comprising an OAM encoder arranged to receive N input signals for transmission, indexed from M=−(N−1)/2 up to M=(N−1)/2 for odd N and from M=−(N−2)/2 up to N/2 for even N; the OAM encoder connecting each input signal to each antenna element and giving each input signal M at each antenna element a phase shift of M*α relative to the phase of the same input signal M at an adjacent antenna element; wherein two or more antenna elements are directional, have their directivity in the same direction, and have an antenna aperture higher than, or equal to, 5λ, where λ is the wavelength of the N input signals.
From a mathematical perspective, the transmission of an OAM mode (or state) at a single RF (i.e., by using a pure tone) implies that the electrical field on the radiating aperture can be represented as:F(ρ,φ)=F(ρ)ejkφ,where ρ and φ are the cylindrical coordinates on the radiating aperture, j is the imaginary unit, and k is a positive or negative integer.
The radiated field can be represented in the far zone as:
            E                    (                  ϑ          ,          φ                )              =                  1        R                          ∫                              ∫            S                                                        F                                            (                                  ρ                  ,                  ϕ                                )                                                                e                                                -                  j                                                                                2                                π                                                  ρ                  λ                                                                  sin                                                        (                    ϑ                    )                                                                                cos                                                        (                                          φ                      -                      ϕ                                        )                                                                                ρ                                                                          d                                                                          ρ                                                                          d                                                                          ϕ                                ,where θ and φ are the spherical coordinates in the far field, R denotes the radius of the sphere centered on the radiating aperture, S denotes the integration surface used at reception side, and λ denotes the wavelength used.
As is known, due to intrinsic characteristics of OAM, an OAM mode transmitted at a single RF (i.e., by using a pure tone) is affected by a phase singularity which creates a null at the bore-sight direction, thereby resulting thatE(0,0)=0.
In order for said phase singularity to be compensated, the integration surface S used at reception side should be sized so as to include the crown peak generated by the OAM mode.
In particular, the integration surface S used at reception side should be different for each OAM mode and, considering the sampling theorem applied to the radiating antenna, should have an area given by:
            Δ                                      S        =                  ΔΩ                                                            R          2                    =              2                                      (                                          λ                D                                          R                        )                    2                      ,where D denotes the diameter of the radiating antenna.
Therefore, the price to be paid with pure OAM modes transmitted by using pure tones (i.e., single radiofrequencies) is that the dimensions of the equivalent receiving antenna depend on the distance R from, and on the diameter D of, the transmitting antenna.
This solution is impractical for satellite communications, where the aperture efficiency and the size of the antennas are very critical issues. For example, in geostationary-satellite-based communications in Ka band, for a ground antenna having a diameter D of about 9 m, the diameter of the receiving ring on board the geostationary satellite should be of the order of 50 Km, thereby resulting impractical.
Thence, in view of the foregoing, the main criticality in using radio vorticity in practical systems is that the orthogonality between OAM modes depends on the size of antennas, on the distance between the transmitting and receiving antennas, and on the need for the receiving antenna to operate as an interferometer basis (as, for example, disclosed in the aforesaid papers "Orbital Angular Momentum in Radio—A System Study" and "Encoding many channels in the same frequency through radio Vorticity: first experimental test", in GB 2 410 130 A and in WO 2012/084039 A1). These constraints result in OAM-based radio communication systems which are inefficient and unusable for very long distances such as the ones involved in satellite communications.
Moreover, further criticalities in the use of radio vorticity for satellite communications are represented by the need of an extremely accurate mutual pointing of the transmitting and receiving antennas, and by the unfeasibility of the geometry for Earth-satellite configurations due to the criticality of the positioning of the receiving antennas (or the receiving antenna elements).
A solution to the aforesaid technical problems is provided in the International Application No. PCT/IB2012/056804 filed on 28 Nov. 2012 in the name of EUTELSAT S. A. and concerning a multidimensional space modulation technique for transmitting and/or receiving radio vortices at frequencies ranging from a few KHz to hundreds of GHz. Specifically, the multidimensional space modulation technique according to the International Application PCT/IB2012/056804 allows to transmit and/or receive orthogonal RF OAM modes in one and the same direction (i.e., the bore-sight direction) and to overcome, at the same time, the aforesaid technical problems caused by OAM phase singularity at the bore-sight direction, thereby allowing the use of radio vortices also for long-distance radio communications, such as satellite communications.
In particular, the multidimensional space modulation according to the International Application PCT/IB2012/056804 is actually a phase modulation applied to signals to be transmitted at RF such that to result in orthogonal radio vortices along the bore-sight direction. Therefore, the modulation according to the International Application PCT/IB2012/056804 is called multidimensional space modulation because it allows orthogonal RF OAM modes to be transmitted and/or received in one and the same direction, namely the bore-sight direction, wherein each OAM mode represents a specific space channel along the bore-sight direction, which specific space channel is orthogonal to all the other space channels represented by the other OAM modes.
In order for the multidimensional space modulation according to the International Application PCT/IB2012/056804 to be understood, attention is drawn, by way of example, to the fact that, as is known, a twisted RF signal having, or carrying, the OAM mode m=+1 is characterized by only one clockwise rotation of 360° of the Poynting vector around the propagation axis per period T and, thence, it can be generated by transmitting, for example by means of four ring-arranged transmitting antenna elements, RF signals associated with phases of 0°, 90°, 180°, and 270° clockwise distributed among said four ring-arranged transmitting antenna elements. Instead, the International Application PCT/IB2012/056804 proves that it is possible and convenient, in order to transmit at RF the OAM mode m=+1 and, at the same time, to solve the problem caused by OAM phase singularity at the bore-sight direction, to exploit only one antenna transmitting the four different phases 0°, 90°, 180°, and 270° at different times (or at different frequencies) with a time step of T′=T/4. This possibility increases the efficiency of the transmitting and receiving configuration, which can work regardless of the elementary antenna element spacing in an antenna array.
From a conceptual perspective, according to the International Application PCT/IB2012/056804, in order to manage OAM rotation, namely in order to control the speed of rotation of an RF OAM mode about the bore-sight direction, a supplementary phase modulation is introduced, which leaves only a residue of the OAM twist and keeps the OAM signature in a limited bandwidth. This residual rotation achieved by means of the supplementary phase modulation allows a signal having a proper bandwidth to be orthogonal to another signal having a different rotation (multiple of the minimum one). Therefore, an RF twisted wave can be transmitted by means of a modulated waveform and can be received by an antenna operating in the complex conjugate mode. The received signal is equal to the transmitted one, apart from standard attenuation and transmission and reception gains in a time period Tmod. The bandwidth increase does not prevent the transmission of plane waves (i.e., the OAM mode m=0), but limits the number of OAM modes at different central frequencies in the available bandwidth. The multidimensional space modulation according to PCT/IB2012/056804 allows to use a standard antenna in place of a phased array antenna, since the used signals are native orthogonal.
It is important to underline the fact that the generation of RF OAM modes by means of the multidimensional space modulation according to PCT/IB2012/056804 allows to drastically simplify the antenna design. In fact, the antenna does not need to take memory at the period of the carrier frequency of the phase between elements f0=1/T0. This duty is performed by the sampling frequency of the twisted waves, which is at least 3 times the signal bandwidth; therefore the phase shift assigned to the sampling is already orthogonal in time; it follows that the antenna can be a standard one without the need of using a phased array configuration on either the antenna aperture, or, in case of a reflector antenna, the focal plane. Therefore, the multidimensional space modulation according to PCT/IB2012/056804 can be exploited in satellite communications by using already existing satellite and ground antennas.
In order for the multidimensional space modulation according to PCT/IB2012/056804 to be better understood, reference is made to FIG. 1, which shows a functional block diagram of a transmitting system (denoted as whole by 1), which is disclosed in PCT/IB2012/056804 and which exploits the aforesaid multidimensional space modulation for transmitting radio vortices at frequencies ranging from a few KHz to hundreds of GHz.
In particular, the transmitting system 1 comprises:                a signal generation section 10 designed to generate                    a first digital signal s0(t) carrying an information stream, having a given sampling period T0 and occupying a given frequency bandwidth W centered on a predefined frequency f0, and            up to 2N second digital signals sm(t), with −N≤m≤+N and N≥1 (for the sake of illustration simplicity in FIG. 1 only signals s+1(t), s−1(t), s+N(t) and s−N(t) are shown), each carrying a respective information stream, having a respective sampling period Tm=4|m|T0 (or Tm=3|m|T0) and occupying a respective frequency bandwidth W/4|m| (or W/3|m|) centered on said predefined frequency f0 (which can, conveniently, be an Intermediate Frequency (IF) thereby resulting that the first and second digital signals are IF digital signals);                        a device 100 for generating OAM modes, which is coupled with said signal generation section 10 to receive the first and second digital signals generated by the latter, and which is designed to                    apply, to each second digital signal sm(t) received from the signal generation section 10, a respective space modulation associated with a respective OAM mode m so as to generate a corresponding modulated digital signal carrying said respective OAM mode m, having the given sampling period T0, and occupying the given frequency bandwidth W, and            provide an output digital signal sout(t) based on the modulated digital signals and on the first digital signal s0(t) received from the signal generation section 10; and                        an RF transmission section 1000, which is coupled with the device 100 to receive therefrom the output digital signal sout(t), and which is designed to transmit at predefined radio frequencies the output digital signal sout(t) by means of a single antenna (which is not shown in FIG. 1 for the sake of illustration simplicity and which can be also a reflector antenna with a single feed) or an antenna array (which is not shown in FIG. 1 for the sake of illustration simplicity and which can be also a multi-feed reflector antenna), thereby transmitting an overall RF signal carrying                    said first digital signal s0(t) by means of a plane wave, and            said second digital signals sm(t), each by means of a corresponding radio vortex having the respective OAM mode m.
The aforesaid predefined radio frequencies can conveniently range from a few KHz to hundreds of GHz depending on the specific application for which the overall transmitting system 1 is designed.
Conveniently, the signal generation section 10 can be a signal generation section of a transmitting system for satellite communications (such as a transmitting system of a feeder link Earth station, of a satellite, or of a ground apparatus for satellite communications), or of a device for wireless communications, such as LTE-based communications.
Accordingly, the RF transmission section 1000 can conveniently be an RF transmission section of a transmitting system for satellite communications (such as a transmitting system of a feeder link Earth station, of a satellite, or of a ground apparatus for satellite communications), or of a device for wireless communications, such as LTE-based communications.
Additionally, FIG. 2 shows in greater detail the device 100 for generating OAM modes, which device 100 comprises 2N OAM mode generation modules. In particular, FIG. 2 shows, for the sake of illustration simplicity, only:                an OAM mode generation module 110 for generating OAM mode m=+1;        an OAM mode generation module 120 for generating OAM mode m=−1;        an OAM mode generation module 130 for generating OAM mode m=+N; and        an OAM mode generation module 140 for generating OAM mode m=−N.
In detail, a generic OAM mode generation module for generating OAM mode m is operable to apply to a respective second digital signal sm(t) received from the signal generation section 10 a respective space modulation associated with said OAM mode m so as to generate a corresponding space-modulated digital signal smsm(t) carrying said OAM mode m, having the given sampling period T0, and occupying the whole given frequency bandwidth W centered on said predefined frequency f0.
More in detail, the generic OAM mode generation module for generating the OAM mode m is operable to:                receive a synchronization signal synchm (not shown in FIG. 2 for the sake of illustration clarity) indicating the given sampling period T0 and, conveniently, also the sampling period Tm of the respective second digital signal sm(t) received from the signal generation section 10; and        apply the respective space modulation to said respective digital signal sm(t) by                    digitally interpolating said respective second digital signal sm(t) on the basis of the received synchronization signal synchm so as to generate a corresponding digitally-interpolated signal having the given sampling period T0;            applying to the digitally-interpolated signal a respective digital phase modulation associated with said OAM mode m such that to generate a corresponding phase-modulated signal carrying said OAM mode m with a predefined OAM mode rotation speed; and            digitally filtering the phase-modulated signal thereby obtaining a filtered signal which represents the aforesaid space-modulated digital signal smsm(t).
For example, the OAM mode generation module 110 is conveniently configured to:                receive, from the signal generation section 10, the second digital signal s+1(t) and a synchronization signal synch+1 indicating the given sampling period T0 and, conveniently, also the sampling period T+1=4T0 (or T+1=3T0) of the second digital signal s+1(t);        digitally interpolate the second digital signal s+1(t) by outputting, for each digital sample of said second digital signal s+1(t), four corresponding digital samples with time step (i.e., time distance) T0, thereby generating a corresponding digitally-interpolated signal having the given sampling period T0;        apply to each set of four digital samples obtained by means of the digital interpolation digital phase shifts related to the OAM mode +1 with the predefined OAM mode rotation speed (namely, digital phase shifts related to phase values 0, π/2, π and 3π/2) so as to generate a corresponding set of four phase-shifted digital samples, which corresponding set of four phase-shifted digital samples carries said OAM mode +1 with the predefined OAM mode rotation speed;        digitally filter each set of four phase-shifted digital samples obtained by means of the digital phase shifting so as to output a corresponding set of four filtered digital samples; and        combine the sets of four filtered digital samples obtained by means of the digital filtering into a single filtered signal which represents the space-modulated digital signal sms+1(t).
Accordingly, the OAM mode generation module 120 is conveniently configured to:                receive, from the signal generation section 10, the second digital signal s−1(t) and a synchronization signal synch−1 indicating the given sampling period T0 and, conveniently, also the sampling period T−1=4T0 (or T−1=3T0) of the second digital signal s−1(t);        digitally interpolate the second digital signal s−1(t) by outputting, for each digital sample of said second digital signal s−1(t), four corresponding digital samples with time step (i.e., time distance) T0, thereby generating a corresponding digitally-interpolated signal having the given sampling period T0;        apply to each set of four digital samples obtained by means of the digital interpolation digital phase shifts related to the OAM mode −1 with the predefined OAM mode rotation speed (namely, digital phase shifts related to phase values 0, 3π/2, π and π/2) so as to generate a corresponding set of four phase-shifted digital samples, which corresponding set of four phase-shifted digital samples carries said OAM mode −1 with the predefined OAM mode rotation speed;        digitally filter each set of four phase-shifted digital samples obtained by means of the digital phase shifting so as to output a corresponding set of four filtered digital samples; and        combine the sets of four filtered digital samples obtained by means of the digital filtering into a single filtered signal which represents the space-modulated digital signal sms−1(t).
The OAM mode generation modules for generating higher-order OAM modes (i.e., with |m|>1) operate, mutatis mutandis, conceptually in the same way as the OAM mode generation modules 110 and 120.
Moreover, again with reference to FIG. 2, the device 100 further comprises:                a combining module 150 operable to combine the first digital signal s0(t) received from the signal generation section 10 and all the space-modulated digital signals smsm(t) generated by the OAM mode generation modules into a corresponding combined digital signal sc(t); and        a transmission filtering module 160, which is operable to digitally filter the combined digital signal sc(t) by means of a predefined transmission filter such that to adjust the signal bandwidth to the bandwidth of transmission radio channel (i.e., the specific radio channel used in transmission) so as to reduce Inter-Symbol Interference (ISI), thereby obtaining a corresponding output digital signal sout(t); wherein the transmission filtering module 160 is coupled with the RF transmission section 1000 to provide the latter with the output digital signal sout(t).
For example, in case of (free-space) satellite communications on a radio channel having the given frequency bandwidth W, the transmission filter can be a predefined root raised cosine filter adapted to said given frequency bandwidth W.
As far as reception is concerned, reference is made to FIG. 3, which shows a functional block diagram of a receiving system (denoted as whole by 2), which is disclosed in PCT/IB2012/056804 and which exploits the aforesaid multidimensional space modulation for receiving radio vortices at frequencies ranging from a few KHz to hundreds of GHz.
In particular, the receiving system 2 comprises:                an RF reception section 2000, which is designed to receive signals at predefined radio frequencies by means of a single antenna (which is not shown in FIG. 3 for the sake of illustration simplicity and which can be also a reflector antenna with a single feed) or an antenna array (which is not shown in FIG. 3 for the sake of illustration simplicity and which can be also a multi-feed reflector antenna), and which is designed to obtain an incoming digital signal uin(t) on the basis of the received signals;        a device 200 for demodulating OAM modes, which is coupled with said RF reception section 2000 to receive the incoming digital signal uin(t) therefrom, and which is designed to process said incoming digital signal uin(t) so as to output useful signals (in FIG. 3 useful signals u0(t), u+1(t), u−1(t), u+N(t) and u−N(t) outputted by the device 200 are shown); and        a signal processing section 20, which is coupled with said device 200 to receive the useful signals outputted by the latter and which is designed to process said useful signals.
The aforesaid predefined radio frequencies can conveniently range from a few KHz to hundreds of GHz depending on the specific application for which the overall receiving system 2 is designed.
Conveniently, the RF reception section 2000 can be an RF reception section of a receiving system for satellite communications (such as a receiving system of a feeder link Earth station, of a satellite, or of a ground apparatus for satellite communications), of a device for wireless communications (such as LTE-based communications), of a radar system, of a Synthetic Aperture Radar (SAR) system, or of a radio astronomy receiving system.
Accordingly, the signal processing section 20 can conveniently be a signal processing section of a receiving system for satellite communications (such as a receiving system of a feeder link Earth station, of a satellite, or of a ground apparatus for satellite communications), of a device for wireless communications (such as LTE-based communications), of a radar system, of a SAR system, or of a radio astronomy receiving system.
Additionally, FIG. 4 shows in greater detail the device 200 for demodulating CAM modes. In particular, as shown in FIG. 4, the device 200 comprises a reception filtering module 210, which is operable to digitally filter the incoming digital signal uin(t) by means of a predefined reception filter such that to equalize the incoming digital signal uin(t) with respect to reception radio channel (i.e., the specific radio channel used in reception) and, conveniently, also with respect to transmission filter (i.e., the specific filter used in transmission), thereby obtaining a corresponding filtered incoming digital signal uf(t).
For example, in case of (free-space) satellite communications on a radio channel having the given frequency bandwidth W, wherein the transmission filter is a predefined root raised cosine filter adapted to said given frequency bandwidth W, the reception filter can be the complex conjugate of said predefined root raised cosine filter so as to reduce ISI.
Additionally, again with reference to FIG. 4, the device 200 further comprises a digital oversampling module 220 operable to digitally oversample the filtered incoming digital signal uf(t) on the basis of a predefined oversampling period Tover, thereby outputting a corresponding set of digital samples.
For example, in case the receiving system 2 is configured to receive the RF signals transmitted by the transmission system 1, the predefined oversampling period Tover can conveniently be equal to T0/Q, wherein T0 is the given sampling period previously introduced in connection with the transmission system 1, and Q denotes an integer higher than one.
Furthermore, again with reference to FIG. 4, the device 200 comprises also a processing module 230 configured to:                provide a linear system of M equations (where M denotes an integer higher than one) relating                    the set of digital samples outputted by the digital oversampling module 220            to X unknown digital values (where X denotes an integer higher than one and lower than M) of useful signals associated, each, with a respective predefined OAM mode m with a predefined OAM mode rotation speed;            wherein said linear system of M equations relates the set of digital samples outputted by the digital oversampling module 220 to the X unknown digital values through                            first predefined parameters related to the predefined OAM modes with the predefined OAM mode rotation speed, and                second predefined parameters related to the predefined reception filter, to the reception radio channel and, conveniently, also to the transmission filter;                                                compute the X digital values by solving the linear system of M equations; and        digitally generate and output the useful signals (for example the useful signals u0(t), u+1(t), u−1(t), u+N(t) and u−N(t) shown in FIG. 4) on the basis of the corresponding digital values computed.
In this connection, it is important to underline the fact that, in order to extract the useful signals (i.e., in order to solve the linear system of M equations thereby computing the X digital values, and, thence, to generate and output the useful signals), the processing module 230 is conveniently configured to operate as a generalized matched filter which exploits one or more mathematical processing techniques, such as the pseudo-inverse technique.
Moreover, it is also important to underline the fact that the oversampling operation performed by the digital oversampling module 220 allows to increase redundancy of the linear system of M equations (i.e., it allows to obtain a number M of independent equations higher and higher than the number X of the unknown digital values), thereby allowing to find more robust solutions to said linear system of M equations.
Furthermore, the better the characterization of the OAM modes and of the radio channel in the linear system of M equations, the more robust the resolution of said linear system of M equations. Specifically, an increase of the number of first and second predefined parameters used in the linear system of M equations allows to increase redundancy of said linear system of M equations (i.e., it allows to obtain a number M of independent equations higher and higher than the number X of the unknown digital values), thereby allowing to optimize the resolution of, i.e., to find optimum solutions to, said linear system of M equations in terms of energy per bit to noise power spectral density ratio Eb/N0.
In case the receiving system 2 is configured to receive the RF signals transmitted by the transmission system 1, the first predefined parameters are related to the sampling periods T0 and Tm previously introduced in connection with the device 100, and to the digital phase shifts applied by the OAM mode generation modules of the device 100 to the digital samples of the digitally-interpolated signals.
Moreover, again in case the receiving system 2 is configured to receive the RF signals transmitted by the transmission system 1, the useful signals generated and outputted by the processing module 230 (such as the signals u0(t), u+1(t), u−1(t), u+N(t) and u−N(t) shown in FIG. 4) are the digital signals transmitted by said transmission system 1 by means of the plane wave and the several radio vortices (namely the signals s0(t), s+1(t), s−1(t), s+N(t) and s−N(t) shown in FIGS. 1 and 2).
Preferably, the device 100 for generating OAM modes and the device 200 for demodulating OAM modes are implemented by means of Field-Programmable Gate Array (FPGA), Application-Specific Integrated Circuit (ASIC), and Software Defined Radio (SDR) technologies.
Finally, according to a further aspect of to the International Application PCT/IB2012/056804, an overall radio communication system including both the transmission system 1 and the receiving system 2 is preferably designed to:                monitor interference experienced by the radio vortices transmitted; and,        if the interference experienced by a radio vortex carrying a given digital signal sm(t) by means of a given OAM mode m meets a given interference-related condition (for example, if it exceeds a given interference level),                    start using an OAM mode m* different from the given OAM mode m for transmitting the information stream previously carried by said given digital signal sm(t) by means of said given OAM mode m, and            stop using said given OAM mode m.
In case said further aspect of PCT/IB2012/056804 is used for satellite communications, it is possible to mitigate jammer, since said further aspect of PCT/IB2012/056804 allows to reject a jammed OAM mode. Moreover, said further aspect of PCT/IB2012/056804 can be used also in combination with other anti-jamming capabilities of the receiving system.

This patent is subject to a terminal disclaimer.

Radio communications system and method with increased transmission capacity


A system includes determination of a plurality of backup jobs based on a backup catalog, the backup catalog comprising a plurality of records, each of the plurality of records associated with one of the plurality of backup jobs, reception of a first instruction to delete a first backup job of the plurality of backup jobs, and, in response to the first instruction, addition of a first record associated with the first backup job to the backup catalog, wherein the first record indicates that the first instruction to delete the first backup job was received.

Modern database systems provide processes for generating database backup files and for using such backup files to recover from database crashes. Some systems utilize a backup catalog to specify information regarding previously-generated backup files, such as ID, host, service, location, size, etc. The backup catalog itself may be stored in the data area of a database and may therefore be backed-up during each data backup. Both the backup catalog and its corresponding backup files may become large and cumbersome over time, and systems are desired to efficiently manage these entities.


A method renders a volume data set including a plurality of voxels. A sampling rate for each voxel in a volume data set is determined. Each voxel is filtered according to the sampling rate and pixels for an output image are generated from the filtered voxels.

Hardware-accelerated volume rendering methods for rectilinear grids include ray casting, texture slicing, shear-warp and shear-image rendering, and splatting, see, Roettger et al. "Smart hardware-accelerated volume rendering," Eurographics/IEEE TCVG Symposium on Visualization, 2003, texture slicing, see, Rezk-Salama, et al., "Interactive volume on standard pc graphics hardware using multi-textures and multi-stage rasterization," Proceedings of the ACM SIGGRAPH/EUROGRAPHICS workshop on Graphics hardware, pages 109-118, ACM Press, 2000, Engel, et al., "High-quality pre-integrated volume rendering using hardware-accelerated pixel shading," Proceedings of the 2001 ACM SIGGRAPH/Eurographics Workshop on Graphics hardware, pages 9-16. ACM Press, 2001, Pfister et al., "The VolumePro real-time ray-casting system," Proceedings of ACM SIGGRAPH 1999, pages 251-260. ACM Press, 1999, Wu, et al., "Shear-image order ray casting volume rendering," ACM Symposium on Interactive 3D Graphics, pages 152-162, June, 2003, and Pfister, "The Visualization Handbook," chapter Hardware-Accelerated Volume Rendering, Chris Johnson and Chuck Hansen (Editors), Academic Press, 2004.
Splatting reconstructs a continuous function by sampling a scalar field of values using 3D reconstruction kernels associated with each scalar value. For volume rendering, the continuous function is mapped to screen space as a superposition of pre-integrated 3D kernels, which are called 2D footprints, see, Westover, "Footprint evaluation for volume rendering," Proceedings of ACM SIGGRAPH 1990, pages 367-376, August 1990. Splatting offers flexibility in terms of volume grids, including non-rectilinear, and mixing with point-sampled geometry, see Mao, "Splatting of non rectilinear volumes through stochastic resampling," IEEE Transactions on Visualization and Computer Graphics, 2(2):156-170, 1996, and Zwicker, et al., "Ewa volume splatting," IEEE Visualization 2001, pages 29-36, 2001.
Zwicker et al. describe a method for aliasing-free splatting. However, achieving interactive high quality EWA splatting is still difficult due to the computational complexity of EWA filtering.
Splatting benefits from the use of pre-integrated reconstruction kernels. Since Westover's original work, see above, and Westover, "Interactive volume rendering," C. Upson, editor, Proceedings of the Chapel Hill Workshop on Volume Visualization, pages 9-16, May 1989, most volume splatting methods focus on improving image quality, including ray-driven perspective splatting, edge preservation, eliminating popping and blur, and image-aligned splatting, see, Mueller, et al., "Fast perspective volume rendering with splatting by utilizing a ray driven approach," Proceedings of the 1996 IEEE Visualization Conference, pages 65-72, October 1996, Huang et al, "Edge preservation in volume rendering using splatting," Proceedings of the 1998 IEEE symposium on Volume visualization, pages 63-69, 1998, Mueller et al., "Eliminating popping artifacts in sheet buffer-based splatting," Proceedings of the 1998 IEEE Visualization Conference, pages 239-246, October 1998, Mueller et al., "Splatting without the blur," Proceedings of the 1999 IEEE Visualization Conference, pages 363-370, October 1999, and Mueller et al., "High-quality splatting on rectilinear grids with efficient culling of occluded voxels," IEEE Transactions on Visualization and Computer Graphics, 5(2):116-134, 1999.
With splatting, the volume data are interpreted according to 3D reconstruction kernels, one kernel for each particle, discrete sample point, or voxel. Each 3D reconstruction kernel has the effect of absorbing and emitting light. Integrals are predetermined separately across each 3D kernel, resulting in 'footprint' functions. Each footprint function 'spreads' the contribution of each point over nearby pixels in an output image. Typically, the span of the footprint is in the order of two to five pixels. The 'smeared' contributions of each voxel in the 3D volume are composited, i.e., accumulated, in a front-to-back or back-to-front order to produce the pixels of the output image.
Aliasing problems in volume splatting is described by Swan et al., "An anti-aliasing technique for splatting," Proceedings of the 1997 IEEE Visualization Conference, pages 197-204, October, 1997, and Mueller, et al., "Splatting errors and antialiasing," IEEE Transactions on Visualization and Computer Graphics, 4(2):178-191, April-June 1998. There, a distance-dependent stretch of the footprints was used to make the footprints act as low-pass filters.
Heckbert, in "Fundamentals in Texture Mapping and Image Warping" Master's Thesis, University of California at Berkeley, Department of Electrical Engineering and Computer Science, 1989, describes a rendering method that uses elliptical weighted average (EWA) filters to avoid aliasing of surface textures. However, that method only operates on regularly sampled 2D texture. In other words, that method cannot be used directly with irregular point samples or volume data sets.
Zwicker et al., extended Heckbert's method to represent and render texture functions on irregularly point-sampled surfaces, and to volume splatting, see Zwicker et al., "Surface splatting," Proceedings of A CM SIGGRAPH 2001, pages 371-378, July 2001, Zwicker et al., "Ewa splatting," IEEE Transactions on Visualization and Computer Graphics, 8(3):223-238, 2002, and Zwicker et al., "Ewa volume splatting," IEEE Visualization 2001, pages 29-36, 2001.
Point-based models have been successfully rendered on a graphics processing unit (GPU), see, Rusinkiewicz et al., "Qsplat: A multiresolution point rendering system for large meshes," Proceedings of ACM SIGGRAPH 2000, pages 343-352, July 2000, Botsch et al., "High-quality point-based rendering on modern GPUs," Proceedings of the 2003 Pacific Graphics Conference, pages 335-343, 2003, and Guennebaud et al., "Efficient screen space approach for hardware accelerated surfel rendering," Proceedings of the 2003 Vision, Modeling and Visualization Conference, pages 1-10, November 2003.
Ren, et al., in "Object-space ewa surface splatting: A hardware accelerated approach to high quality point rendering," Proceedings of Eurographics 2002, pages 461-470, September 2002, described an object space formulation for EWA surface splats and an efficient implementation of the formulation on graphics hardware. For each point in object space, quadrilaterals, which were texture-mapped with a Gaussian texture, were deformed to result in a correct screen-space EWA splat after projection.
Other prior art method includes opacity-based culling, fast splat rasterization, hierarchical splatting, object and image space coherence, shell splatting, 3D adjacency data structure, and post-convolved splatting, see, Mueller et al., "High-quality splatting on rectilinear grids with efficient culling of occluded voxels," IEEE Transactions on Visualization and Computer Graphics, 5(2):116-134, 1999, Huang et al., "Fastsplats: Optimized splatting on rectilinear grids," Proceedings of the 2000 IEEE Visualization Conference, pages 219-227, October 2000, Laur et al., "Hierarchical splatting: A progressive refinement algorithm for volume rendering," Proceedings of ACM SIGGRAPH 1991, pages 285-288, August 1991, Ihm et al., "On enhancing the speed of splatting with indexing," Proceedings of the 1995 IEEE Visualization Conference, pages 69-76, 1995, Botha et al., "Shellsplatting: Interactive rendering of anisotropic volumes," Proceedings of 2003 Joint Eurographics—IEEE TCVG Symposium on Visualization, May 2003, Orchard et al., "Accelerated splatting using a 3d adjacency data structure," Proceedings of Graphics Interface 2001, pages 191-200, September 2001, and Neophytou et al., "Post-convolved splatting," Proceedings of the symposium on Data visualisation 2003, pages 223-230, Eurographics Association, 2003.
Lippert et al., in "Fast wavelet based volume rendering by accumulation of transparent texture maps," Proceedings of Eurographics 1995, pages 431-443, September 1995, described a splatting method that directly uses a wavelet representation of the volume data. A hierarchical and frequency sensitive splatting method is based on wavelet transformations and pre-computed splat primitives, which accomplished view-dependent and transfer function-dependent splatting, Welsh, et al., in "A frequency-sensitive point hierarchy for images and volumes," Proceedings of the 2003 IEEE Visualization Conference, Seattle, USA, October 2003. None of those methods have been implemented completely on a GPU.
Some GPU-accelerated splatting methods use texture mapping hardware for the projection and scan-conversion of footprints, see Crawfis et al., "Texture splats for 3d scalar and vector field visualization," Proceedings of the 1993 IEEE Visualization Conference, pages 261-266, 1993, and Botha, et al., above.
EWA Volume Splatting
Volume splatting interprets volume data as a set of particles that are absorbing and emitting light. To render the data, line integrals are precomputed separately across each particle, resulting in 2D footprint functions or splats in the image plane. The splats are composited back-to-front to determine the output image. Particles are represented by 3D reconstruction kernels A common choice is 3D elliptical Gaussian kernels. The notation Gv(t−p) represents an elliptical Gaussian kernel centered at a 3D point p with a 3×3 variance matrix V:
                                          G            V                                          (                          t              -              p                        )                          =                              1                                                            (                                      2                                        π                                    )                                                  3                  /                  2                                                                                                  V                                                                    1                  /                  2                                                                                ⅇ                                                -                                      1                    2                                                                                (                                          t                      -                      p                                        )                                    T                                                                                V                                          -                      1                                                                                (                                          t                      -                      p                                        )                                                                        .                                              (        1        )
In theory, Gaussian kernels have infinite support. In practice, the kernels are truncated to a given cutoff radius r, i.e., the kernels are evaluated only in a range(t−p)TV−1(t−p)≦r2,  (2)where usually 1≦r≦3. Furthermore, the choice of Gaussians as 3D kernels guarantees a closed-form footprint function after integration along viewing rays.
However, during perspective rendering, the splatting process usually results in aliasing artifacts due to a changing of sampling rate along the viewing rays while rendering. EWA volume splatting minimizes the artifacts by convolving the footprint function with a 2D low-pass filter, which yields an aliasing-free footprint function called the EWA volume resampling filter.
Zwicker, et al., in "Ewa volume splatting," IEEE Visualization 2001, pages 29-36, 2001, described a closed-form representation of the EWA volume resampling filter that is based on the following two assumptions. First, the low-pass filter takes the form of a 2D Gaussian reconstruction kernel function. Second, a non-linear perspective transformation, which maps reconstruction kernels to image space, is linearly approximated using a Jacobian matrix.
To summarize the derivation of the EWA volume resampling filter, a rotational part of the viewing transformation that maps object space to camera space coordinates is given by a 3×3 matrix W. Denote camera space coordinates by u=(u0, u1, u2). Normalized, the origin of the camera space u=0 is at a center of projection and an image plane is a plane at a distance u2=1. Camera space coordinates of a voxel k are given by uk. Image space coordinates are denoted by x, and the image space position of voxel k is xk. Further, the Jacobian matrix of the perspective projection at a point uk in camera space to image space is a 3×3 matrix Juk:
                              J                      u            k                          =                              (                                                                                1                                          u                                              k                        2                                                                                0                                                                      -                                                                  u                                                  k                          0                                                                                u                                                  k                          2                                                2                                                                                0                                                                      1                                          u                                              k                        2                                                                                -                                                                  u                                                  k                          1                                                                                u                                                  k                          2                                                2                                                                                u                                              k                        0                                                                                                                              (                                                                              u                                                          k                              0                                                                                ,                                                      u                                                          k                              1                                                                                ,                                                      u                                                          k                              2                                                                                )                                                                                                                            u                                              k                        1                                                                                                                              (                                                                              u                                                          k                              0                                                                                ,                                                      u                                                          k                              1                                                                                ,                                                      u                                                          k                              2                                                                                )                                                                                                                            u                                              k                        2                                                                                                                              (                                                                              u                                                          k                              0                                                                                ,                                                      u                                                          k                              1                                                                                ,                                                      u                                                          k                              2                                                                                )                                                                                                                            )                    .                                    (        3        )
Given the 3×3 variance matrix Vk″ of a reconstruction kernel k in object space, its transformation through camera space to image space is Vk=JukWVk″WTJukT.
The EWA volume resampling filter ρk(x) is obtained by integrating the reconstruction kernel in image space along viewing rays. The reconstruction kernel is convolved with the Gaussian low-pass filter, which, as shown by Zwicker et al, above, yields the 2D footprint function
                                                        ρ              k                                                  (              x              )                                =                                    1                              2                                π                                                                                        J                                          u                      k                                                              -                      1                                                                                                                                                                W                                          -                      1                                                                                                                                                                                                                        V                          ^                                                k                                            +                                              V                        h                                                                                                                      1                    2                                                                                ⅇ                                                -                                      1                    2                                                                                (                                          x                      -                                              x                        k                                                              )                                    T                                                                                M                    k                                                                          (                                          x                      -                                              x                        k                                                              )                                                                                ,                                          where                            (        4        )                                          M          k                =                                            (                                                                    V                    ^                                    k                                +                                  V                  h                                            )                                      -              1                                .                                    (        5        )
There, Vh is a 2×2 variance matrix of the Gaussian low-pass filter, which is usually chosen to be the identity matrix. The 2×2 variance matrix {circumflex over (V)}k is obtained by skipping the third row and column of Vk1. A matrix with a hat symbol, '^', denotes the result of skipping its third row and column.
The problem with the prior art filtering is that after a particular filter is selected, the same filter is used for the entire volume data set, without considering how the volume voxels were generated, and without considering how the data set is sampled along the viewing rays during the generation of the output image.
It is desired to solve this problem.

Sample rate adaptive filtering for volume rendering

Mitsubishi Electric Research Laboratories, Inc.


In view of providing a network system enabling communication having passed fire walls (repeaters) and assuring high security and operation flexibility through access control based on users and applications, a user-held table indicating correspondence between repeaters and passwords, a repeater-held table indicating correspondence between users and passwords and a table indicating access regions are defined respectively for users, departments of users and official positions of users and a route control information storing table indicating correspondence between networks and next transmitting destination is also provided to execute the access control for each user. Moreover, the repeater is provided with the repeating route control table so that a repeater located in the course of route to the transmitting destination computer and allowing communication from the transmitting side computer is selected from the data repeating control table and the process for requesting the repeating operation of communication with the destination is executed to the selected repeater.

The present invention relates to security of a computer connected to a network system and particularly to a method of constituting a network system which executes access control and relays communications of applications through mutual cooperation of fire walls.
As a method of preventing invasion into a computer through a network, a repeater (fire wall) has been proposed to give restriction to the access from outside.
A typical fire wall has a function, as is described xe2x80x9cComputer Security Resource Clearinghousexe2x80x9d of NIST (National Institute of Standards and Technology), to control the accesses depending on IP (Internet Protocol) addresses of the transmitting side and receiving side and kinds of services and to the store access record.
Moreover, as a repeater for repeating communication between a client and a server, there is provided socks V5 proposed by RFC1928 in the environment where fire walls exists. In the socks, mutual identification between the client and the repeating server and socks protocol for realizing connection instruction for the repeating server are defined and thereby communication between the client and the server having passed one fire wall can be realized.
Moreover, there is a gateway protocol such as RIP (Routing Information Protocol: RFC 1058), OSPF (Open Shortest Path First: RFC 1131), etc. as a mechanism to realize dynamic exchange of repeating route information in the IP layer.
With rapid development of Internet system, a person can get various kinds of information generated in the world on the real-time basis but, on the other hand, a person is in turn threatened to external invasion. As effective measures for such external invasion, it has been proposed to (1) give limitation on IP address for making access to each service and to (2) provide a gateway (fire wall in narrow sense) to store the access record. Use of such fire wall in narrow sense has enabled reduction of threat for an external invader by acquiring matching property of the operating environment of the gateway itself and localizing the range of control by an administrator.
However, in the case of executing the access control utilizing the technique of the related art, since the access control object is based on the information incorporated to a computer such as class of service and IP address, there is a problem that the access control based on users cannot be realized. For example, desired access control becomes impossible for the computer to which the IP address is assigned dynamically and class of service is limited to particular users.
Moreover, in private network utilizing the Internet, a fire wall plays a very important role for security and an internal fire wall is increasingly installed in the private network in order to protect the sub-network. There are several problems to be solved for the communication in the environment where a plurality of fire walls exist. For example, when the communication having passed the internal fire wall for protecting the sub-network is to be attempted from a computer of an external network, the communication must be repeated between the external fire wall and the internal fire wall.
However, since the routing information for the internal fire wall provided for repeating is concealed to the external network, such routing information must be obtained with a certain method. FIG. 1 shows an example of the problem explained above. When a client ex101 attempts to make communication with a server accommodated in the network ex106 of A corporation, an external fire wall ex102 repeats the communication. Since the external fire wall ex102 can obtain the routing information to the server ex104 for communication with the server ex104 in the network ex106 of A corporation, communication can be repeated. However, since the server ex105 is concealed by the internal fire wall ex103 for the communication with the server ex105 accommodated in the sub-network ex107, the external fire wall ex102 cannot obtain the routing information to the server ex105 and thereby this communication cannot be repeated.
Moreover, in the case of the communication between two networks connected through the external network, this communication cannot be realized between respective internal fire walls, unless the routing information for identifying the internal fire wall is set for the external fire wall.
FIG. 2 shows an example of the problem explained above. A client ex201 accommodated in the network ex210 is capable of making communication with a server ex202 in the network ex211 by registering the fire wall ex206 as the route to the server ex202 in the fire wall ex205. However, when a server ex204 is provided in the internal sub-network ex214 of the network ex213, since the route is concealed by the fire wall ex208, the internal fire wall ex209 cannot be registered in the fire wall ex207.
It is therefore an object of the present invention to provide a large scale network system which enables communications having passed the fire wall and repeaters (fire walls) used in the same network by solving the problems explained above and offering a means for exchanging the repeating route information among a plurality of repeaters (fire walls).
Moreover, it is also an object of the present invention to provide a network system which enhances security and assures higher operation flexibility and repeaters used therein through the access control based on the computer users and applications.
The objects explained above will be achieved using following means.
(1) Access control based on computer users and applications
Executing access control as an object of access control on the basis of computer users and applications
(2) Identification of computer users and applications
Identifying, for executing access control, that the communication is requested by a person who has issued the request.
(3) Data transfer in the repeaters having the access control function
Providing transparency of communication in the communication between computers having the access control functions
The data transfer by the repeaters can be realized by providing, in the repeater, a repeating route control table storing correspondence between the address of the transmitting side computer and the address of the repeater provided to transfer the data to such address and executing the processing to select, from the data repeating route control table, the repeater provided in the course of the route to the target computer in the receiving side to enable the communication from the computer of the transmitting side and the processing to connect the repeating program of the repeater identified by the processing explained above to request the repeating of communication with the receiving side to the repeater.

Repeater and network system utililzing the same