An electrical connector (7) for surface mounting on a printed circuit board (PCB) includes an insulative housing (1); a number of terminals (5) disposed in the housing and having tails (51) extending beyond the housing, all the tails (51) defining a common mounting plane (52); at least one metallic mounting portion (42) assembled to the housing (1), the at least one metallic mounting portion (42) defining a bottom plane (421) for soldering to the PCB, the bottom plane (421) being located at a level higher than said the mounting plane (52) by a distance; and a solder ball (6) connected to the at least one metallic mounting portion (42), the solder ball (6) being able to be softened to fill said distance during soldering.

1. Field of the Invention
The present invention relates to an electrical connector, and more particularly to an electrical connector for surface mounting on a printed circuit board.
2. Description of Related Art
Generally, a conventional electrical connector for electrically connecting a chipset to a printed circuit board (PCB) is attached to the PCB by soldering terminals thereof to the PCB via Surface Mounting Technology (SMT). Before the electrical connector is attached to the PCB, solder tails of the terminals should be adjusted to perform a wonderful coplanarity so as to ensure that each of the terminals can be reliably soldered to the PCB.
CN. Pat. No. 200320103928.X discloses an electrical connector including a housing with a pair of cantilevered side walls in opposite ends of the housing, a plurality of terminals loaded in the housing and a pair of metallic latches assembled to the housing. Each said latch has a body, which assembled to the side wall, a securing arm downwardly extending from a distal end of the body, a mounting portion formed near a downmost distal end of the securing arm, and a flexing portion joining the securing arm and the mounting portion. The mounting portion includes two slips respectively positioned at frontside and rearside of the flexing portion. There is a cutout defined between the flexing portion and each of the slips. Since the mounting portion is soldered onto the PCB by SMT together with the solder tails of the terminals, it is required that the tails of the terminals and the mounting portion of the latch perform a good coplanarity, or else neither facility nor reliability of soldering operation can't be ensured. However, since the terminals and the latch are formed from different metal sheets and are assembled on the housing separately, it is difficult to ensure a wonderful coplanarity between said tails and said mounting portion. Thus the latches should adjust the position of a solder surface of the mounting portions thereof for gaining a coplanarity with the tails of the terminals. Therefore, the flexing portion should be compressed if the securing arm is too long to perform a coplanarity with the tails of the terminals, or should be drawn out if the securing arm is too short to perform a coplanarity with the tails of the terminals. However, such compression or drawing operation may causes the mounting portion to slant from the PCB, as a result of which the connecting area between the mounting portion and the PCB is reduced and the capability of connecting is weakened. Moreover, the solder tails of terminals are apt to be twisted by an unintentional and improper operation during adjusting of the latches so that some tails of the terminals may be deformed to destroy the coplanarity. Furtheremore, to adjust the mounting portion coplanarity with the solder tails of the terminals after the adjusting of the coplanarity between the tails increases an additional procedure.
Therefore, an improved electrical connector is desired to overcome the disadvantages of the prior arts.


Apparatus and methods for enhanced wireless determination of a position and direction of a smart device. Wireless transceivers controlled by the smart device communicate with reference point transceivers to generate data sufficient to determine relative positions of the wireless transceivers and a direction of interest. Operation of one or both of a magnetic force sensor and LIDAR may be operative to verify the position and direction of the Smart Device.

It is known for a geospatial position to be ascertained based upon triangulation techniques. Such triangulation techniques may be based upon artificial location references, such as satellites and/or cell towers. However, location determination within a structure is limited due to variations in communication signal strength within a structure. In addition, such positioning systems lack an accurate functionality for determining a direction of interest to a user.

This patent is subject to a terminal disclaimer.

Method and apparatus for enhanced position and orientation determination


A spoke including a metallic core covered, at least in its central portion, with a sheath of composite material comprised of an assembly of fibers embedded in a matrix, the core including an end portion adapted to be attached to the rim or the hub of a wheel, and a main body whose cross-sectional surface area is between 30% and 50% or, in a particular embodiment, between 35% and 45%, of the cross-sectional surface area of the aforementioned end portion. Furthermore, in the area of the main body, the sheath has a cross section between 150% and 500% or, in a particular embodiment, between 150% and 350%, of the cross section of the metallic core in the same area. The metal core includes two mechanical anchoring zones, positioned in the vicinity of its ends, on both sides of the main body.

1. Field of the Invention
The present invention relates to a cycle wheel spoke and a cycle wheel comprising such a spoke.
2. Background Information
Conventionally, the spokes of a cycle wheel are tensioned when the wheel is assembled because, due to their length and small cross section, they cannot work in compression. When the cycle is in use, the spokes are subject to fatigue development, as they undergo a load cycle with each turn of the wheel, thereby constantly varying their tension. Indeed, when a spoke is located between the ground and the wheel hub (such as positioned vertically in relation to the ground), its tension is reduced due to a slight deformation of the wheel caused by the cyclist's weight which provides a force countering tension; and when a spoke passes above the hub (again, such as positioned vertically in relation to the ground), it is re-tensioned by the pre-stressing and the load effect. The ends of the spokes, each having a fastening zone enabling them to be assembled to the rim or the hub of the wheel, are more affected by the fatigue phenomenon than the central portion of the spokes, due to the stress concentrations caused by the geometric variations of the fastening zones (thread, elbow, head, etc.), and therefore have a greater risk of breakage. Therefore, the ends of the spokes must have higher mechanical properties than those of the central portion of the spokes, which is why their cross section is conventionally greater than that of the central portion.
In addition to a very good tensile strength, the spokes must have a certain degree of flexural flexibility. A flexural flexibility of the spokes provides the entire wheel with greater resistance to side impacts, such as those encountered, for example, when a cyclist riding in a very compact group of riders inadvertently moves too close to another cyclist and the spokes of his front wheel engage the rear derailleur of the cyclist immediately ahead of him/her. Such engagement is capable of breaking a plurality of spokes, which can cause the front wheel to collapse and the cyclist to lose control of the bike, thereby resulting in a very serious fall. When a spoke has a certain flexibility, this type of engagement may damage the spoke without causing it to break.
Spokes made of a metallic material, such as steel, can combine good tensile strength and flexibility, but these spokes are heavy.
Spokes made of a composite material are, for equal strength, much lighter but more fragile. In particular, composite materials have exceptional tensile properties, but also very low shear properties, which does not make it possible to provide efficiently working threads on composite rods. Therefore, these materials are very well suited to the central zone which is subject to tensile stress, but it is very difficult to fasten these spokes to the rim and the hub without using a fastening metal piece specifically for adjusting their tension independently of one another, in order to ensure a balanced geometry in the wheel.
It is known to combine metallic and composite materials to make hybrid spokes.
For example, the document EP 1 930 146 describes a spoke comprising an aluminum core covered with a sheath formed of carbon fibers coated with polymerization-cured resin.
This spoke has the advantage of being very lightweight, due to its aluminum core. However, despite the use of a composite material, this spoke is not necessarily suitable for applications requiring very high rigidity, because the modulus of elasticity, and therefore the rigidity of the aluminum, is only on the order of 71,000 MPa. In addition, a spoke of this type requires specific and quite large fasteners on the rim and the hub, and such fasteners are not adaptable to all types of rims/hubs.
Another example of hybrid spoke is described in the document FR 2 915 710. In this case, the core is formed by a blade and two end pieces welded together. Given that welding locally deteriorates the properties of the metal, it is necessary to take such deterioration into account when sizing the core. Finally, obtaining a spoke that is adequately strong requires making a relatively heavy core. Moreover, a spoke having a core that requires three distinct elements assembled to one another is expensive to manufacture.
A third example of a hybrid spoke is provided in the document EP 1 420 963. The spoke illustrated in FIGS. 1 to 6 of this document comprises a metallic core having a constant cross section and a sheath made of composite material. The objective of the designer of such a spoke is to improve the aerodynamics, and he only provides a wing shape to the sheath.

Cycle wheel spoke and cycle wheel comprising such a spoke


A method and group of masks for manufacturing a device whereby illumination of a photoresist layer (4) takes place by subsequent illumination through partial masks (1) and 2). During these separate illuminations, complementary scales of grey are obtained in the connection region (7, 8) of the images (5, 6), the total illumination in the connection region (7, 8) being nevertheless complete. According to the invention, good results are obtained when the partial masks (1) and (2) have complementary transparency gradients in the ends (9, 10) corresponding to the scales of grey.

1. Field of the Invention
The invention relates to a method of manufacturing a device whereby in a photolithographic treatment subsequently at least two partial masks are aligned relative to the same substrate and a photoresist layer is illuminated through these partial masks in order to obtain connected images having an overlapping connection region, a first illumination through a first partial mask at the connection region forming first halves of details in the photoresist layer with increasing scales of grey towards their ends (decreasing illumination), and a second illumination through a second partial mask forming second halves of the details in the photoresist layer corresponding to the first halves with increasing scales of grey (decreasing illumination) towards their ends, which overlap the ends mentioned above, these scales of grey being complimentary to the scales of grey formed during the first illumination, so that in total a complete illumination of the details is obtained by the two illuminations.
The overlapping connection area is thus formed by ends of halves of details imaged in the photoresist layer.
2. Description of the Related Art
A method of the kind described in the opening paragraph is known from J. P. Rominger "Seamless Stitching for Large Area Integrated Circuit Manufacturing" Optical/Laser Microlithography, Burn J. Lin, Editor, proc. SPIE, 922, pp. 188-14 193 (1988).
Increasingly small details are required in the manufacture of integrated semiconductor circuits, for which imaging systems with high resolution are used, the so-called wafer steppers.
The imaging field of a stepper, however, is limited in size. Since increasingly large surface areas are required for the integrated circuits, it can happen that a semiconductor device no longer fits the imaging field. If such a device is to be manufactured nevertheless, the mask may be split up into various partial masks and the partial masks may subsequently be imaged on a slice of semiconductor material.
In order to let corresponding details of the circuit merge fluently into one another in the case of illumination through subsequent partial masks, the ends of details of adjoining images are given complementary scales of grey at the area of their connection region.
The publication mentioned above describes how the scales of grey are obtained by giving the mask used an extra mask which is not in the object plane of the imaging system, so that half-shadow is obtained in the image plane.
This last-mentioned manufacturing method has a number of disadvantages:
1. Extra process steps are required for manufacturing the masks. PA1 2. In the case of imaging systems which are not telecentric, the position of the half-shadow in the image plane relative to the connection region depends on the distance between the connection region and the optical axis of the imaging system. PA1 3. Corresponding ends of partial masks must end on a straight connection line. This limits the possibilities for circuit design. A connection line is a line which connects and divides into two the ends of adjoining details in a partial mask and which runs practically parallel to the nearby edge of the partial mask in these ends. PA1 4. Connections between ends of partial masks which run parallel to a connection line are not very well possible. PA1 5. A very wide connection region is required between adjoining images, i.e. in the order of 150-1000 .mu.m.

Method of manufacturing a device and group of masks for this method


A method for acquiring magnetic resonance (MR) data for a three-dimensional (3D) dynamic study includes partitioning a ky-kz plane with a plurality of views into an inner region and a plurality of outer regions. The inner region includes a set of views in a central region of the ky-kz plane and each outer region includes a plurality of views outside of the central region of the ky-kz plane. The method also includes partitioning each outer region into a plurality of radial fan beam segments, defining a first view ordering for the inner region and defining a second view ordering for each outer region. Once the ky-kz plane is partitioned and the view orderings are defined, MR data is acquired for the set of views in the inner region and for all of the views in each of the outer regions in an alternating acquisition order where the set of views in the inner region are acquired more frequently than the views in each of the outer regions. At least one MR image is generated based on the acquired MR data.

Magnetic resonance imaging (MRI) is a medical imaging modality that can create images of the inside of a human body without using x-rays or other ionizing radiation. MRI uses a powerful magnet to create a strong, uniform, static magnetic field (i.e., the "main magnetic field"). When a human body, or part of a human body, is placed in the main magnetic field, the nuclear spins that are associated with the hydrogen nuclei in tissue water become polarized. This means that the magnetic moments that are associated with these spins become preferentially aligned along the direction of the main magnetic field, resulting in a small net tissue magnetization along that axis (the "z axis," by convention). A MRI system also comprises components called gradient coils that produce smaller amplitude, spatially varying magnetic fields when current is applied to them. Typically, gradient coils are designed to produce a magnetic field component that is aligned along the z axis and that varies linearly in amplitude with position along one of the x, y or z axes. The effect of a gradient coil is to create a small ramp on the magnetic field strength, and concomitantly on the resonance frequency of the nuclear spins, along a single axis. Three gradient coils with orthogonal axes are used to "spatially encode" the MR signal by creating a signature resonance frequency at each location in the body. Radio frequency (RF) coils are used to create pulses of RF energy at or near the resonance frequency of the hydrogen nuclei. These coils are used to add energy to the nuclear spin system in a controlled fashion. As the nuclear spins then relax back to their rest energy state, they give up energy in the form of an RF signal. This signal is detected by the MRI system and is transformed into an image using a computer and known reconstruction algorithms.
MRI data may be acquired using a three-dimensional (3D) acquisition strategy, the most common of which is a rectilinear sampling that fills a 3D Cartesian grid with Fourier reciprocal space (i.e., "k-space") data. The data may be collected with Nyquist frequency sampling to provide unique location encoding of the MRI signals and thereby prevent aliasing in the reconstructed images. The 3D data is spatially encoded using phase encoding along two perpendicular spatial directions (the y and z directions) and frequency encoding along the third (the x direction). Usually, the secondary phase encoding is referred to as "slice encoding," to distinguish it from the primary phase-encoding. The resultant raw data fills a 3D k-space matrix which is then "reconstructed" using Fourier transformation techniques, resulting in a stack of two-dimensional images.
MRI data is typically collected in frames that are referred to as "views." For 3D imaging, each view corresponds to a single ky and kz value, but contains data for the full range of kx values that are required to reconstruct an image. Multiple view-ordering schemes are known in the art for determining how ky, kz encoding is performed for each view. For example, in a "nested" view-ordering scheme, all of the views corresponding to one phase-encoding axis (kz, for example) are acquired before incrementing the value on the other phase-encoding axis (ky, for example). An "elliptical centric" view-ordering scheme replaces the two nested loops with a single loop that steps through ky, kz pairs according to their distance from the origin in the ky-kz plane. The choice of a view-ordering scheme often depends on how the imaged object or its corresponding magnetization is expected to change during the data acquisition. Views near the center of k-space have the strongest effect on the overall image appearance, because most of the k-space information about an object is contained near the center of k-space.
Dynamic or time-resolved MR studies (or acquisitions) have been developed to image dynamic or time-varying processes (e.g., cardiac motion, multi-phase scans, contrast enhancement (e.g., vascular contrast), joint motion, catheter tracking, etc.) and typically involve repeatedly collecting the same data over time. View ordering techniques have been developed for encoding views in a dynamic or time-resolved acquisition, for example, keyhole techniques such as TRICKS (Time Resolved Imaging of Contrast Kinetics) and BRISK (Block Regional Interpolation Scheme for K-Space) that divide k-space into multiple regions and repeatedly update data in the center of k-space more frequently than other parts of k-space. Such techniques, however, can result in eddy current induced artifacts due to intra- and inter-region jumps in k-space during the acquisition. It would be desirable to provide a method and apparatus for acquiring MRI data for a dynamic or time-resolved acquisition that minimizes intra- and inter-region jumps and reduces eddy current induced artifacts.

Method and apparatus for view ordering of magnetic resonance imaging data for dynamic studies


The present invention concerns a wheel rim and a method for making a wheel rim of the type suited for use on an agricultural or construction vehicle. The new feature of the wheel rim according to the invention is that the central hub plate at the outer periphery includes a number of tabs extending away from the center of the central hub plate, where the second hub plate at its inner periphery also includes a number of tabs extending towards the center of the hub plate, where the tabs have a geometric shape such that the tabs fit between each other, where the tabs include holes arranged at the same pitch circle diameter and at right angles to the tabs. In connection with the making of the hub plate, the second hub plate and the central hub plate can be produced from a single piece of suitable material, preferably steel plate, as the mentioned tabs extend over each other when two parts are separated and turned such that the tabs come to lie upon each other. The two hub plate parts are then joined by bolts in the holes formed in the mentioned tabs.

1. Field of the Invention
The present invention concerns a wheel rim and a method for making a wheel rim of the type suitable for use on an agricultural or construction vehicle, wherein the rim includes a rim ring for mounting a tyre and further including an at least two-part hub plate extending inside the rim ring, where the at least two-part hub plate includes a central hub plate including a number of holes and a contact surface for mechanical and detachable securing to a hub on a vehicle, wherein the central hub plate includes holes on a contact surface at the outer periphery for joining with a second hub plate with an inner periphery and an outer periphery, wherein the second hub plate at the inner periphery includes a contact surface with corresponding holes for joining with the central hub plate, where the second hub plate at the outer periphery includes holes for direct or indirect joining with the rim ring.
2. Description of Related Art
It is commonly known that wheel rims suited for use on construction and agricultural machines are made of steel with a rim ring and a with a hub plate. A typical design is that the rim ring is rolled in the wanted diameter and made with rim edges and other geometric shapes such that a tyre can be fitted thereon. The hub plate typically consists of a steel plate, either plane or shaped with one or more depressions. These depressions have partly the purpose of stiffening the hub plate and partly for bevelling the contact surfaces which are secured to a hub on a vehicle and to the inner side of the rim ring. The hub plate can often be mounted on the rim ring at various positions such that the position of the rim ring relative to the hub on the vehicle can be adjusted. This may be necessary if a tractor and an implement are to be driven between rows of crops on a field. By moving the hub plate between the various positions and by possibly turning the hub plate around, a plurality of different possibilities for changed wheel gauges are attained.
Another known adjusting possibility on such rims is the central part of the hub plate itself which advantageously can be replaceable as not all vehicle hubs are made with the same dimensions. Frequently there is a recess on the hub on which the rim bears via a central hole in the hub plate, and furthermore there are a number of bolt holes in the hub plate which are to fit bolt holes or bolts on the hub. By making the hub plate in two parts, the central part of the hub plate—the central hub plate—can be selected depending on which hub the wheel rim is to the mounted. For example, the central hub plate may have a central hole with a diameter of 390 mm, and ten holes with a diameter of 16 mm are disposed on a pitch circle with a diameter of 430 mm, corresponding to the actual hub. At the outer periphery on the central hub plate there may be provided a standardised hole pattern which fits all current hub plates. Thus it becomes possible to use the same rim on a plurality of different hubs just by replacing the central hub plate to one having proper dimensions. Central hub plates of the said type is often made of steel plate and may be plane as well as pressed with a depth.
However, many rims are made with a welded hub plate and with a central hub plate that can be turned around and which furthermore can be moved from one side to another of the welded hub plate in order thereby to adjust the wheel gauge of the actual vehicle. Alternatively, the central hub plate can be replaced by another one where the pressing depth is different. Respective hub plates are joined to each other by means of bolts with washers and nuts.
When a tractor or a contractor's machine is to be provided with wheel rims which either are or can be adapted to the desired wheel gauges, it is very often a request from the customer that the rims are to be delivered with a certain colour. In order to meet this demand, it is often required that the rims and hub plate initially are to be painted. If a dealer of wheel rims wants to shorten the delivery time, he is actually required to have a disproportionately large stock of prefabricated rims of different dimensions and with different types of hub plates and not the least a plurality of different colours. By having this large stock, where part of or all rims may be painted in the most current colours, a reasonably short delivery time can be achieved. However, typically it appears that this large stock is not attractive for the supplier as orders for making wheel rims and/or hub plates that are not in stock frequently occur anyway.
Another drawback of the prior art solutions is that the hub plates are made with a central hole wherein along the periphery of the hole is located a plurality of holes corresponding to similar holes in the central hub plate made with a diameter about 60 to 100 mm greater than the central hole in the hub plate. In other words, there is a relatively large waste of material as the material in the central hole cannot be used but has to be discarded.
From U.S. Pat. No. 4,279,446 is known a solution to an adjustable wheel rim where between the rim ring and the hub there is arranged a multi-part hub plate which in principle consists of a plurality of uniform parts arranged releasably in continuation of each other between hub and rim ring on elevations adapted for the purpose on the rim ring itself. Thus it is so that a multi-part hub plate can be moved between various positions on a rim ring. In no way it is here envisaged how the design of the individual parts should be in relation to each other in order to achieve a minimal consumption of material and simultaneously achieve a minimal number of work processes. Furthermore, it is a rather cumbersome solution as it is not readily possible to change the pressing depth of a wheel rim into another, and not at all into a third value.
From US 2008/0054714 A1 it is known with another solution wherein a hub plate can be mounted at a first or a second side of a fitting on a rim ring. Also, the hub plate can be reversed, and hereby four different pressing depths are enabled on such a wheel. Not in this solution either there is thought about minimising material consumption or to achieve a minimum number of work processes, neither during production nor during use.


A technique for imaging an object with a coherent beam of electromagnetic radiation involves sequencing at least a portion of the coherent beam through a set of orthogonal transverse spatial modes and summing the output signals that result from set of orthogonal transverse spatial modes. To create an image of an object, the coherent beam is applied to multiple spots on the object and sequenced through the same set of orthogonal transverse spatial modes at each spot. The output signals generated from the sequencing are summed on a per-spot basis.

Imaging an object with a coherent beam of electromagnetic radiation is often plagued with the phenomenon of speckle, i.e., the randomly bright and dark grainy appearance of an image resulting from alternately constructive and destructive interferences over the aperture and the field of view. If the electromagnetic radiation source is perfectly coherent, the severity of the speckle will depend on three dimensionless parameters: the root-mean-square object roughness in terms of wavelengths, the average lateral spacing between surface features in wavelengths, and the number of features in the illumination area. Many kinds of laser illumination, particularly holography, invite the speckle problem because the number of features within the illumination area whose height deviates from the average height by approximately half an optical wavelength or more is enormous. In contrast to coherent imaging, incoherent imaging is immune to speckle since any set of optical paths from the source to the object to the detector (e.g., a retina, film, a CCD array) is only destructive for a fraction of the wavelengths involved.
Some techniques for dealing with speckle in coherent imaging systems utilize frequency diversity or angle diversity to reduce the occurrence of alternating constructive and destructive interference. Although these techniques can reduce speckle, the usefulness of frequency diversity is limited by a scarcity of spectrum in certain microwave regions of interest and the usefulness of angle diversity is limited by mechanical and cost considerations.
In view of this, what is needed is a coherent imaging technique that reduces speckle and that is efficient to implement.

Coherent imaging that utilizes orthogonal transverse mode diversity


The present invention relates to methods and compositions of a novel gene and the peptide encoded by the gene. Mutations in the gene, named atlastin, are factors in the disease Hereditary Spastic Paraplegia and related disorders. The present invention will be used for the in the research, diagnosis and treatment of these disabling diseases.

Hereditary spastic paraplegia (HSP) is characterized by insidiously progressive lower extremity weakness and spasticity that affects thousands of Americans and tens of thousands of individuals around the world. The disorder begins at any age. Wheelchairs are often required. HSP is classified as "uncomplicated" or "pure" if neurologic impairment is limited to progressive lower extremity spastic weakness, hypertonic urinary bladder disturbance, mild diminution of lower extremity vibration sensation and, occasionally, joint position sensation. HSP is classified as "complicated" if the impairments present in uncomplicated HSP are accompanied by other system involvement or other neurologic findings such as seizures, dementia, amyotrophy, extrapyramidal disturbance, or peripheral neuropathy, in the absence of other co-existing disorders such as diabetes mellitus.
Currently, the diagnosis of uncomplicated HSP is established by the presence of typical clinical features and the exclusion of alternative diagnostic possibilities. Clinical features of HSP include insidiously progressive, bilateral lower extremity weakness, and increased muscle tone that is maximal in the iliopsoas, hamstring, and tibialis anterior muscles; lower extremity hyperreflexia and extensor plantar responses, often accompanied by mildly impaired vibration sensation in the distal lower extremities; and family history of similarly affected individuals. Magnetic resonance imaging (MRI) of the brain and spinal cord may be normal or show thin corpus callosum and/or spinal cord atrophy. For the vast majority of subjects, hereditary spastic paraplegia is a diagnosis of exclusion. The differential diagnosis (including multiple sclerosis, structural abnormalities involving the spinal cord, B12 deficiency, adrenomyeloneuropathy and other leukodystrophies, and dopa-responsive dystonia) should be considered thoroughly.
Molecular genetic testing for mutations in the spastin and proteolipid protein (PLP) genes are available in a limited number of laboratories. Prenatal testing for other types of HSP is being investigated on a research basis.
As can be seen from the foregoing, at the present time, diagnosis of HSP is generally a process of exclusion of other disorders, and observation of family history. As with all types of exclusionary diagnosis, patients can and are misdiagnosed. What is needed is a test for the accurate diagnosis of HSP and new methods of treatment of this debilitating disease.

The Regents of the University of Michigan


A sensor device according to the present invention has a detection mode for detecting an object W, a first setting mode for changing the output duration of an output signal, and a second setting mode for changing a light-emission period of light emitted to the object W. These modes are switchable by a mode selector switch 12. If a rotary control knob 15 is operated in the detection mode, a CPU 30 changes a setting of a threshold value in response to the operation of the rotary control knob 15 and displays the changed setting of the threshold value on a digital indicator 20. This makes it possible to accurately change settings through relatively simple operations. The rate of change may correspond to the speed of operation of the knob.

1. Field of the Invention
The present invention relates to a sensor device with an improved method for setting a threshold value.
2. Description of the Prior Art
Conventionally, sensor devices are known that are capable of detecting the presence or absence of bodies, etc. They detect the presence or absence of a body, etc. by comparing a detection signal, outputted according to the detection state of an object, with a predetermined threshold value.
Such sensor devices are configured to allow changes in the settings, such as threshold values. As a setting change device, for example, some sensor devices are equipped with multiple buttons for use in changing the settings. Pressing the buttons can change a threshold displayed on a digital indicator. This allows an operator to accurately set the threshold value while looking at the digital indicator.
For example, as disclosed in Japanese Utility Model No. 4-76003, there is a sensor device that is equipped with a rotatable input element, such as a variable resistor. This element allows the operator to change a setting by rotating the variable resistor to a desired position while looking at a graduated scale. The rotatable input element makes it possible to set a threshold value through a simpler operation than the pushing of buttons.
Generally, sensor devices allow the operator to set not only the threshold value, which is the detection sensitivity, but also various values related to other various functions, including the timing and output duration of a signal outputted from the sensor device and the light-emission period of a photoelectric sensor. With a type of sensor in which settings are changed by pressing buttons, settings are made in each of these various functions by switching among the operation modes of the buttons. This makes it difficult for an operator to see at a glance how to change a desired setting, causing the inconvenience of having to operate the buttons while keeping an operations manual at hand.
Also, to change a threshold by 10 steps for example, a setting button must be pressed 10 times. This is troublesome. Generally, the operator tends to press a button faster corresponding to increases in the total number of times he/she must press the button. Consequently, the operator may often press a button for an incorrect number of times. If, for example, the button is mistakenly pressed for an additional 10 times, the threshold value is changed too much and must be returned to a predetermined value (in this case corresponding to 10 more button pressings). This complicates the task of setting the threshold value.
On the other hand, it is easy to understand the operating method (setting method) when changing a setting by rotating a variable resistor to a specific scale position. However, it is difficult to make an accurate setting because the visually determined scale position (setting) has an unavoidable difference from the actual setting.
The present invention has been made in view of the above circumstances and has as an object to provide a sensor device that allows settings to be accurately changed through relatively simple operations.


An assembly includes a mounting bracket; a member; a guide disposed in the member; and a slider, the slider configured to move between a first position and a second position relative to the member, the slider being configured to move within the guide. The slider has a first end and a second end, the first end opposite the second end. The first end includes a first portion and a second portion, the first portion configured to provide a contact for application of a force in a first direction and the second portion configured to provide a contact for application of a force in a second direction. The second direction is opposite the first direction.

A panelboard includes a panel or group of panel units designed for assembly in a form of a single panel that includes buses and automatic overcurrent devices, equipped with or without switches for control of light, heat, or other power circuits. The panelboard is generally placed in a cabinet or cutout box and placed in or against a wall, partition, or other support. A panelboard includes buses to which individual circuit breakers can be installed.

Device insertion and removal method for electrical equipment


An auxiliary drive unit (30) intended for driving a chain (11) in a horizontal track (12) is arranged to operate only when a forward end (33) of the chain passes a predetermined point. A drive sprocket (16) engages with the chain and initially freewheels until the forward end (33) of the chain contacts a switch (34), actuating a drive motor (13) of the auxiliary drive (30). The drive sprocket (16) is normally "parked" in a precisely orientated position so as to engage the forward end (33) of the chain (11) cleanly. The sprocket (16) has a plurality of circumferentially spaced alternating polarity magnetic poles (22, 23) which park the sprocket (16) precisely in position relative to opposite polarity magnetic poles (27) provided on a fixed member of the auxiliary drive unit. The auxiliary drive unit (30) is particularly designed for driving a rolling shutter (10) suspended from a chain (11) running in a horizontally extending track (12).

This invention relates to a drive for a rolling shutter of the type which is suspended beneath a generally horizontally extending track and which travels on a linear or non-linear path extending horizontally. Such a shutter may be for example of the type set out in our prior British patent number 2I84474.
In that patent, there is described and claimed a horizontally moving shutter which, when fully stowed away, is rolled about a vertical barrel. It is driven by a motor acting on a drive sprocket at the barrel and is pushed out from the barrel housing along the track. The shutter curtain is tensioned throughout its movement by a substantially constant tension spring arrangement which also assists in returning the shutter to the barrel when it is being stowed.
It has been found possible by this means to drive extremely large shutters, up to 30 meters in length.
However, there is a problem with driving a shutter of this type over a longer distance or with driving a shutter of substantial length around a very circuitous track which has a tendency to increase the friction met by the shutter. Clearly, it is undesirable to overstrain the drive motor. However, increasing the horsepower of the drive motor is not the answer to the problem of extending the shutter further.
It has been proposed to attach a motor to the far end of the track and, by means of cables to pull the shutter into its extended fully opened condition but this is most unsatisfactory because the cable needs to be guided around the track if there are any bends in the track and also tends to sag along its length, stretch in use and otherwise cause problems.
It would be desirable to provide an auxiliary drive such that, at a predetermined distance from the barrel housing, the leading end of the shutter is engaged by the auxiliary drive and is driven forwards in addition to the continuing operation of the main drive motor. Although this would be desirable, hitherto no means has been found of engaging an auxiliary drive motor with the leading end of the shutter in motion.
It will be appreciated that a metal rolling shutter of perhaps 30-40 meters in length has a very substantial mass and, even when moving at a relatively slow speed, has very substantial momentum. In an attempt to engage a drive with such a moving shutter, it is essential to ensure that the auxiliary drive engages the shutter cleanly at the appropriate position without obstructing its passage. Otherwise there is a danger of either jamming the shutter or damaging the auxiliary drive or both. It is also essential to synchronise the auxiliary and main drives.


A non-volatile memory device and method of manufacturing the same is provided. A substrate is provided and then a trench is formed in the substrate. Thereafter, a bottom oxide layer, a charge-trapping layer and a top oxide layer are sequentially formed over the substrate and the surface of the trench. A conductive layer is formed over the top oxide layer filling the trench. The conductive layer is patterned to form a gate over the trench. The top oxide layer, the charge-trapping layer and the bottom oxide layer outside the gate are removed. A source/drain doping process is carried out. Because the non-volatile memory device is manufactured within the trench, storage efficiency of the device is improved through an increase in the coupling ratio. Furthermore, more charges can be stored by increasing the depth of the trench.

1. Field of the Invention
The present invention relates to a memory device and manufacturing method thereof. More particularly, the present invention relates to a non-volatile memory device and method of manufacturing the same.
2. Description of the Related Art
Electrically erasable programmable read-only memory (EEPROM) is a non-volatile memory device that allows multiple data writing, reading, and erasing operations. In addition, the stored data will be retained even after power to the device is removed. With these advantages, it has been broadly applied in personal computer and electronic equipment. A typical EEPROM device has a floating gate and a control gate fabricated using doped polysilicon. During a programming operation, electrons injected into the floating gate will be evenly distributed over the entire polysilicon floating gate layer. Obviously, if the tunneling oxide layer underneath the polysilicon floating gate contains some defects, a leakage current will be produced and reliability of the device will be affected.
To resolve the leakage problem in an EEPROM device, the polysilicon floating gate of a conventional memory device is replaced by a charge-trapping layer. The charge-trapping layer is a silicon nitride layer with silicon oxide layers above and below the silicon nitride layer, thereby creating an oxide/nitride/oxide (ONO) composite stacked structure. An EEPROM having this stacked gate structure is often referred to as a silicon/oxide/nitride/oxide/silicon (SONOS) memory device.
FIG. 1 is a cross-sectional view of a conventional SONOS memory device. As shown in FIG. 1, an oxide/nitride/oxide (ONO) composite layer 102 is formed over a substrate 100. The ONO composite layer 102 includes a bottom oxide layer 104, a silicon nitride layer 106 and a top oxide layer 108. In addition, a polysilicon gate 112 is formed over the ONO composite layer 102 to serve as a word line. A source/drain region 118 is formed in the substrate 100 on each side of the ONO composite layer 102 to serve as a buried bit line. Spacers 116 are also formed on the sidewalls of the polysilicon gate 112. A lightly doped region 114 is formed in the substrate 100 underneath the spacers 116 to connect with the source/drain region 118 electrically.
In general, the SONOS memory device is programmed by injecting channel hot electrons (CHE) through the bottom oxide layer 104 and trapping the electrons within the ONO composite layer 102. Furthermore, data within the SONOS memory device is erased by injecting tunneling enhanced hot holes (TEHH) through the bottom oxide layer 104 and annulling the trapped electrons inside the ONO composite layer 102. The storage capacity of a SONOS memory device mainly depends on the coupling ratio. In other words, the contact area between the aforementioned top oxide layer 108 and the polysilicon gate 112.
Through the widespread miniaturization of semiconductor devices, line width of each device is shrunk correspondingly. When the contact area between the top oxide layer and the polysilicon gate inside the SONOS memory device is reduced, overall storage capacity is affected. Consequently, scientists and engineers are now working hard to find methods for increasing the coupling ratio and hence boosting the storage capacity of a SONOS memory device.

Non-volatile memory device and method of manufacturing the same


An anti-bogdown control system monitors and regulates operation of a turbine and a compressor to prevent underspeed trip of the turbine while avoiding surge of the compressor. A turbine speed controller receives a turbine speed signal and a turbine temperature signal, generates a surge margin setpoint, and regulates overfiring of the turbine. A surge margin controller associated with the compressor receives the surge margin setpoint from the turbine speed controller and receives a load signal from one or more sensors and modulates a compressor throttle valve so that the compressor operates at a surge margin that is approximately equal to the surge margin setpoint. In a system with multiple compressors driven by a single turbine, a surge margin controller is associated with each compressor.

1. Field of the Invention
The present invention relates to the field of compressor and turbine control systems. In one aspect, the invention concerns an anti-bogdown system for controlling a turbine/compressor system in a manner that avoids underspeed trip of the turbine and avoids surge of the compressor that is driven by the turbine.
2. Description of Prior Art
Gas turbines are commonly used to drive large compressor systems that are used, for example, in the refrigeration cycles of processes for liquefying natural gas. In order to maximize the efficiency of such turbine/compressor systems, the gas turbines are typically operated at or near their maximum rated speed and load. Various changes in the operating parameters of a turbine/compressor system may cause the turbine to slow down. A partial slowdown in the speed of the turbine tends to precipitate further slowdown until the turbine "bogs down" (i.e., automatically shuts down when it reaches a critically low operating speed).
Several factors can cause a gas turbine to slow down. First, if two compressors are running in parallel, a decrease in the output of a first compressor would increase the load on the second compressor, thereby causing the turbine driving the second compressor to slow down. Second, if a starter/helper motor shuts down, the loss in power provided by the starter/helper motor can result in a sudden increase in the train load and accompanying decrease in turbine speed. Third, the operating conditions of the gas turbine can cause it to slow down when, for example, hot gases from the turbine exhaust are blown into an air intake of the turbine.
The load of centrifugal compressors is determined primarily by the fluid flow rate through the compressor and the fluid pressure increase across the compressor. When the fluid flow rate through the compressor becomes too low, the compressor can enter an operating condition know as "surge." When a compressor enters surge, it is unable to maintain the pressure required at the discharge port. During surge, the direction of fluid flow is reversed as the higher pressure fluid at the discharge flows backward into the compressor.
Surge in centrifugal compressors can be understood to occur at low flow conditions below which the rotating impeller cannot impart sufficient momentum to the fluid to overcome the difference in pressure between the compressor inlet and compressor outlet. During surge, flow through a compressor becomes unstable and momentarily reverses direction—shock loading the compressor, disrupting system operations, and potentially damaging the compressor. Thus, centrifugal compressors that operate over a range of conditions should be protected from inadvertent entry into surge.
In order to avoid surge, compressors are typically operated at a flow rate above the surge flow rate (i.e., the flow rate at which surge is initiated). The difference between the operating flow rate of a compressor and its surge flow rate is known as the "surge margin." Surge margin is generally expressed as a percentage difference between the operating flow rate and the surge flow rate, with the flow rates being expressed on a volumetric basis. For example, if surge flow rate is 10 and operating flow rate is 12, the operating surge margin is 20 percent.
A conventional method of avoiding surge involves recirculating fluid from the compressor outlet to the compressor inlet to decrease the net flow rate through the compressor, a process often referred to as "recycle." The decrease in net flow rate interacts with the process system to limit the difference in pressure between the compressor inlet and compressor outlet. Although surge is avoided by initiating recycle, operating in recycle mode adversely affects the system efficiency and, therefore, the cost of operation.
The approach of a compressor to surge can be monitored by external measurement of flow rate and pressure to determine the compressor's condition relative to surge. Seeking an optimum operating surge margin is desired to avoid both surge and unnecessary inefficiency. Setting the operating surge margin too high can limit the efficiency of the system and result in wasted energy and an unnecessary loss of efficiency during low flow conditions because recycle is unnecessarily or prematurely initiated. Setting the operating surge margin too low can result in the compressor reaching surge and being damaged.
Accordingly, there is a need for an improved compressor/turbine monitoring and control system that does not suffer from the problems and limitations of the prior art.

Anti-bogdown control system for turbine/compressor systems


A method of fabricating a semiconductor device includes the steps of providing a hard mask cover using a patterned photoresist layer, wherein the patterned photoresist layer comprises at least four first holes arranged in two rows and two columns. Part of the hard mask is removed to form at least four second holes by taking the pattered photoresist layer as a mask. Next, each of the first holes is widened, and the widened first holes and the second holes are filled up by a filler. Later, the patterned photoresist layer is removed entirely. Part of the hard mask is removed to form at least a fourth hole by taking the filler as a mask. Finally, the filler is removed entirely.

1. Field of the Invention
The present invention relates generally to a method for increasing pattern density, and more particularly to a method of using a single photo mask and a single shot to form a dense pattern.
2. Description of the Prior Art
Many factors, including demand for increased portability, computing power, memory capacity and energy efficiency, have led to integrated circuits being continuously reduced in size.
This means that density of semiconductor elements on a wafer has increased with the advancements in the semiconductor industry. In particular, miniaturization of microelectronic elements has made the intervals between elements shorter and shorter, which increases the difficulty of a lithographic process.
The lithographic process is commonly used to pattern features. Due to factors such as optics and the wavelength of light used to pattern the features, lithographic techniques have a resolution limitation.
For current lithographic tools, it is impossible to create semiconductor elements with pitch lower than the resolution limitation in one exposure. The current solution is that the desired semiconductor elements are patterned by two exposures using two photo masks, respectively, on a photo resist layer. This process is then followed by one etching step. The current method incurs a high processing cost, however.

Hwa-Ya Technology Park Kueishan, Taoyuan


Methods and apparatuses for providing feedback by a UE. A method includes receiving a first set of CSI-RS and a second set of CSI-RS, calculating a CQI using a received power of the first set of CSI-RS and a channel matrix estimated based on the second set of CSI-RS, and sending feedback based on the calculated CQI. A method includes measuring signals received on a plurality of CSI-RS ports; calculating CQI values for each of applications of precoding matrixes to each of the selected combinations of CSI-RS ports; selecting a SPN, a SPI, a PMI, and a RI that yields a highest CQI from among the calculated CQI values; and sending feedback indicating the SPI, the highest CQI value, the PMI, and at least one of the SPN or the RI.

The following documents and standards descriptions are hereby incorporated into the present disclosure as if fully set forth herein: 1) 3GPP TS 36.211 v11.2.0; 2) 3GPP TS 36.212 v11.2.0; 3) 3GPP TS 36.213 v11.2.0; 4) 3GPP TS 36.331 v11.2.0; 5) R1-125402, 3GPP TS 36.211 CR; and 6) R1-125404, 3GPP TS 36.213 CR. Channel quality indicator (CQI) is defined in section 7.2.3 of 3GPP TS 36.213 v11.2.0. Differential CQI is described in section 7.2 of 3GPP TS 36.213 v11.2.0. A channel state information (CSI) process is described in 3GPP TS 36.331 v11.2.0. Physical uplink control channel (PUCCH) mode 1-1 is described in section 7.2.2 of 3GPP TS 36.213 v11.2.0. PUCCH mode 2-1 is also described in section 7.2.2 of 3GPP TS 36.213 v11.2.0.
In 3GPP LTE-Advanced standards, wide beam patterns are used for CSI-RS transmissions. The beam (virtualization) patterns of antenna ports are transparent to the user equipment (UEs). The UEs may not know or need to know the virtualization pattern for transmission/reception. A channel coefficient from each CSI reference signal (RS) port to a UE may correspond to a composite response of multiple paths, and is often frequency selective. The UE estimates channel coefficients relying on CSI-RS, and then using the estimated channels to calculate various parameters including precoding matrix indicator (PMI), rank indicator (RI) and CQI (for <=8 CSI-RS ports) or PMI, RI, precoding type indicator (PTI) and CQI (for 8 CSI-RS ports) according to enhanced Node B (eNB) (e.g., base station (BS)) configuration.
When all CSI-RS ports have wide beams, the average power of signals received from the CSI-RS ports is on a similar order. The similar power levels partially motivated constant-modulus precoding matrices/vectors in legacy LTE codebooks in 3GPP TS 36.211 and 36.213. When a vector/matrix is constant-modulus, all the elements of each vector/matrix have the same magnitude.
Accordingly, there is a need for improved communication techniques and standards in advanced wireless communication systems.

Channel state information feedback design in advanced wireless communication systems


A method, device and computer program product for the prediction of the stability of an electric power network, where the method is executed after a fault or contingency has occurred, and comprises the steps of (a) during a time interval in which the network is in a transient condition, determining for at least one load connected to the electric power network, at least one parameter describing an estimated steady state behavior of the load, (b) executing a load flow calculation for the electric power network using the least one parameter describing the estimated steady state behavior the at least one load, (c) determining, if the load flow calculation indicates stability has a solution, that a future stability of the electrical power network exists, or, if the load flow calculation indicates instability does not have a solution, that a future stability of the electrical power network does not exist.

An electric power transmission network comprises high-voltage tie lines and substations for transforming voltages and for switching connections between lines. Loads and power generating plants are connected to the network. An important issue when controlling power generation and load flow is to keep the network stable, i.e. to avoid voltage collapse and swings. Existing SCADA (Supervisory control and data acquisition) systems provide estimates about the stability of a network. However, such an estimate is based on the assumption that the network is in a steady state condition. Consequently, it is not valid if it is obtained during a transient condition, i.e. in the time after a fault or contingency has occurred and before the network is back in a seemingly steady state. It often happens that the network seems to be in a steady state after a contingency, however, an instability caused by the contingency develops unnoticed. The instability is detected by the SCADA system only when the network voltages are severely affected. At this point in time, remedial actions such as load shedding must be drastic, if complete collapse of the network is to be avoided. It therefore is desirable to obtain, after a contingency is detected, an early estimate of the future stability of a network, such that remedial actions can be executed before the effects of the instability become too large.
U.S. Pat. No. 5,638,297 shows a method of on-line transient stability assessment of an electrical power system. A computer model is used to simulate an effect of an artificially introduced study contingency. The simulation uses a step-by-step integration method and predicts future effects of the contingency on the network, in particular on network stability. However, the method requires a full model of dynamic behavior of the network and a significant computational effort for the simulation. The algorithm uses pre-calculations that are made before a given contingency occurs. If a contingency was not pre-calculated or if cascaded contingencies occur, the algorithm fails. If applied to voltage stability, the algorithm would fail as well for cascaded contingencies since an exhaustive pre-calculation of combinations of contingencies is not practicable.

Stability prediction for an electric power network


A polishing apparatus is used for polishing a workpiece such as a semiconductor wafer to a flat mirror finish. The polishing apparatus has an interlock function includes a turntable having a polishing surface thereon, a top ring for holding a workpiece to be polished and pressing the workpiece against the polishing surface on the turntable, a first motor for rotating the turntable, and a second motor for rotating the top ring. The polishing apparatus further comprises a first actuator for lifting and lowering the top ring, a second actuator for moving the top ring in a horizontal direction, and a control unit for controlling the motors and the actuators. The control unit controls the motors and the actuators in such a manner that when an abnormality is detected in at least one of the motors and the actuators, at least one of the motors and the actuators other than that of the abnormality performs a predetermined operation.

1. Field of the Invention
The present invention relates to a polishing apparatus for polishing a workpiece such as a semiconductor wafer to a flat mirror finish, and more particularly to a polishing apparatus having an interlock function which can perform a predetermined operation such as shutdown of a plurality of components in the overall apparatus when an abnormality is detected in at least one of motors and actuators of the apparatus by, for example, measuring magnitudes of the torques of the motors or measuring magnitude of vibration of a top ring.
2. Description of the Prior Art
Recent rapid progress in semiconductor device integration demands smaller and smaller wiring patterns or interconnections and also narrower spaces between interconnections which connect active areas. One of the processes available for forming such interconnections is photolithography. Though the photolithographic process can form interconnections that are at most 0.5 .mu.m wide, it requires that surfaces on which pattern images are to be focused by a stepper be as flat as possible because the depth of focus of the optical system is relatively small.
It is therefore necessary to make the surfaces of semiconductor wafers flat for photolithography. One customary way of flattening the surfaces of semiconductor wafers is to polish them with a polishing apparatus, and such a process is called Chemical Mechanical polishing.
Conventionally, a polishing apparatus has a turntable and a top ring which rotate at respective individual speeds. A polishing cloth is attached to the upper surface of the turntable. A semiconductor wafer to be polished is placed on the polishing cloth and clamped between the top ring and the turntable. An abrasive liquid containing abrasive grains is supplied onto the polishing cloth and retained on the polishing cloth. During operation, the top ring exerts a certain pressure on the turntable, and the surface of the semiconductor wafer held against the polishing cloth is therefore polished to a flat mirror finish while the top ring and the turntable are rotated.
In the conventional polishing apparatus, a motor for rotating the turntable, the motor for swinging a top ring, and a motor for rotating the top ring have such respective functions that the respective motors are stopped when an overcurrent occurs in the respective motors. In this case, the allowable overcurrent depends on the capacity of the respective motors.
However, in the method in which each of the motors is stopped by detecting an overcurrent of the respective motors, since the turntable and the top ring are rotated by the respective motors, even if one of the motors is stopped due to an overcurrent, the other motors continues to be rotated. In other words, even if one of the turntable and the top ring is stopped, the other continues to be rotated, and thus the stopping one is dragged by the other element which continues to be rotated. As a result, the semiconductor wafer held by the top ring is damaged, or the top ring or the associated component in a polishing unit is damaged.

Polishing apparatus having interlock function


Surrogate browsing techniques are disclosed. A request for a page is received, from a client, by a surrogate. The specified page is requested by the surrogate from a site. Data received from the site in response to the request is rendered at the surrogate. A representation of the page is transmitted to the client.

One way that nefarious individuals perpetrate computer attacks is by exploiting browser vulnerabilities. When an unsuspecting user visits a website hosting malicious content, that user's browser can by compromised and the compromise can further be extended to other resources on the user's computer. Exposure to known threats can sometimes be prevented by having users routinely apply patches or otherwise update their browsers. Unfortunately, many users lack the skill or knowledge to keep their browsers up to date (or run legacy browsers for which such patches/updates are not available) and thus remain vulnerable to preventable attacks. Approaches such as having patches automatically applied can reduce but not eliminate risk. For example, even browsers diligently kept up-to-date can be compromised by zero-day and/or other attacks that the browser is not capable of withstanding.


In a code division multiple access (CDMA) spread spectrum cellular communication system in which a mobile station user communicates with another system user via at least one base station, wherein each base station transmits a common pilot signal of a different PN offset with respect to other base stations in said system, a method for merging neighbor lists to account for false indications of signal strength due to topography. The merged list, included as part of the Neighbor List Update Message, is arrived at by first measuring pilot signal strengths and phase delays received by the mobile station and reporting this information to the mobile telephone switching office. At the mobile telephone switching office, pilots whose phase delay indicates a large round trip delay time are ignored in subsequent calculations. Then a neighbor list union is generated as the union of all predetermined neighbor lists corresponding to said received pilot signals. Each member, or base station, in the neighbor list union is operated on by a weighting function which takes into account how often each member is included in each received pilot's predetermined neighbor list and the signal strength of such pilots. The relative weights are then sorted and the highest ranking members form the Neighbor List Update Message, up to a predetermined number of members.

I. Field of the Invention
The present application relates to mobile communications systems. More specifically, the present invention relates to a novel and improved method and apparatus for merging predetermined neighbor lists to provide a single list of neighboring base stations to mobile communication units, used to identify possible handoff candidates in a code division multiple access (CDMA) cellular communications system.
II. Description of the Related Art
The use of code division multiple access (CDMA) modulation techniques is but one of several techniques for facilitating communications in which a large number of system users are present. The use of CDMA techniques in a multiple access communication system is disclosed in U.S. Pat. No. 4,901,307, (the '307 patent) entitled "SPREAD SPECTRUM MULTIPLE ACCESS COMMUNICATION SYSTEM USING SATELLITE OR TERRESTRIAL REPEATERS", and U.S. Pat. No. 5,103,459, (the '459 patent) entitled "SYSTEM AND METHOD FOR GENERATING SIGNAL WAVEFORMS IN A CDMA CELLULAR TELEPHONE SYSTEM", both of which are assigned to the assignee of the present invention and incorporated by reference herein.
In the '307 and '459 patents, a multiple access technique is disclosed wherein a large number of mobile telephone system users, each having a transceiver, communicate through satellite repeaters or terrestrial base stations (also known as base stations, or cell-sites) using code division multiple access (CDMA) spread spectrum communication signals. The use of CDMA techniques results in a much higher spectral efficiency than can be achieved using other multiple access techniques.
In the exemplary CDMA cellular communication system, each base station transmits a "pilot carrier" signal or, for short, pilot signal. The pilot signal is an unmodulated, direct sequence, spread spectrum signal transmitted at all times by each base station using a common pseudorandom noise (PN) spreading code. The pilot signal allows the mobile stations to obtain initial system synchronization, i.e. timing, in addition to providing a phase reference for coherent demodulation and a reference for signal strength comparisons between base stations for handoff determination.
The pilot signal is transmitted by each base station using the same PN spreading code but with a different PN offset. For example, in the present invention the pilot signal spreading code is of a PN code length of 2.sup.15. In this example there are 511 different offsets from the zero offset, where the offsets are in increments of 64 PN chips. It is this PN offset which allows the pilot signals to be distinguished from one another by the mobile station, resulting in a differentiation between base stations from which they originate. Use of the same pilot signal code allows the mobile station to find system timing synchronization by a single search through all pilot signal code phases. The strongest pilot signals, as determined by a correlation process for each PN offset, are readily identifiable. The identified pilot signal generally corresponds to the pilot signal transmitted by the nearest base station. However, due to topography, this may not always be true. This phenomenon causes problems with present methods of generating the Neighbor List Update Message, described below. Further details of pilot searching techniques are disclosed in U.S. Pat. No. 5,577,022 (the '022 patent) entitled "PILOT SIGNAL SEARCHING TECHNIQUE FOR A CELLULAR COMMUNICATIONS SYSTEM," assigned to the assignee of the present invention and incorporated by reference herein.
Each base station also transmits a sync channel signal which is a modulated, encoded, interleaved, direct sequence, spread spectrum signal used by the mobile stations to acquire additional synchronization, system time, and other overhead control information. Information such as system identification, network identification, a pilot PN sequence offset index, a long code state, current system time along with other time parameters and paging channel data rate are transmitted on the sync channel. It should be noted that the pilot PN sequence offset index identifies an offset value from a zero offset pilot PN sequence. The sync channel signal is despread using the same pilot PN sequence offset as the pilot channel.
Each base station also transmits a paging signal on one or more paging channels. The paging signals are modulated, interleaved, scrambled, direct sequence, spread spectrum signals, which contain control and overhead information. The paging channel is used as such to communicate global and mobile station specific orders, including pages. Overhead messages transmitted on the paging channel include a system parameters message, which contains general system and base station overhead information; an access parameters message, which contains information to be used by the mobile station on an access channel when accessing the system; and a Neighbor List Update Message which identifies to the mobile station the pilot signal PN sequence offsets of neighboring base stations. The sync channel transmitted long code state message is used by the mobile station to descramble the paging channel scrambled signal. Like the sync channel signals, the paging channel signals are spread and despread using the same pilot PN sequence offset as the pilot channel.
Each base station transmits user information to an intended mobile station on a selected one of a plurality of traffic channels. Each mobile station is thus assigned to a unique traffic channel for receiving the mobile station specific information. The traffic channel signals are modulated, interleaved, scrambled, direct sequence, spread spectrum signals transmitted to mobile stations on a respective traffic channel. Information received in the sync channel message is used by the mobile station to descramble the traffic channel scrambled signal.
Further details on the modulation scheme for the various channels of the base station are described in the '459 patent.
In present CDMA systems, the mobile station uses multiple receivers, or diversity reception, to combat the problem of multipath fading. Using a diversity receiver, a mobile station simultaneously demodulates a plurality of signals transmitted by a given base station but which have traveled along different propagation paths. The plurality of demodulated estimates are combined to provide an improved estimate of the data. An example of a diversity receiver is disclosed in U.S. Pat. No. 5,109,390 (the '390 patent) entitled "DIVERSITY RECEIVER IN A CDMA CELLULAR TELEPHONE SYSTEM", assigned to the assignee of the present invention and incorporated by reference herein. Diversity reception in the mobile station also allows it to communicate with more than one base station at a time, such as when the mobile station is transitioning between cells. This is an important concept for soft handoffs, discussed below.
Handoff is a general term used to describe the process whereby communications between a mobile station and a base station controller, also known as a Mobile Telephone Switching Office (MTSO), is continued as the mobile station travels through more than one coverage area or cell. In the conventional cellular telephone system, the handoff scheme implemented is intended to allow a call to continue when a mobile telephone crosses the boundary between two cells. The handoff from one cell to another is initiated when the receiver in the cell base station handling the call notices that the received signal strength from the mobile telephone falls below a predetermined threshold value. A low signal strength indication implies that the mobile telephone is near the cell border. When the signal level falls below the predetermined threshold value, the base station asks the system controller to determine whether a neighboring base station receives the mobile telephone signal with greater signal strength than the current base station.
The system controller in response to the current base station inquiry sends messages to the neighboring base stations with a handoff request. The base stations neighboring the current base station employ special scanning receivers which look for the signal from the mobile telephone on the specified channel. Should one of the neighboring base stations report an adequate signal level to the system controller, then a handoff will be attempted.
Handoff is then initiated when an idle channel from the channel set used in the new base station is selected. A control message is sent to the mobile telephone commanding it to switch from the current channel to the new channel. At the same time, the system controller switches the call from the first base station to the second base station. The above described handoff method is known as a "hard" handoff because there is no overlap in call continuation as the call is transferred from the first base station to the second base station. The switching function of the hard handoff can be considered a "break-before-make" connection.
In contrast is the soft handoff method used in modern CDMA system. Such methods are disclosed in U.S. Pat. No. 5,267,261 (the '261 patent) entitled "MOBILE STATION ASSISTED SOFT HANDOFF IN A CDMA CELLULAR COMMUNICATIONS SYSTEM" and U.S. Pat. No. 5,101,501 (the '501 patent) entitled "METHOD AND SYSTEM OF PROVIDING A SOFT HANDOFF IN COMMUNICATIONS IN A CDMA CELLULAR TELEPHONE SYSTEM", both of which are assigned to the assignee of the present invention and are incorporated by reference herein.
In a mobile assisted soft handoff, the mobile station constantly searches for strong pilot signals. To streamline the process of searching for pilots, four distinct sets of pilot offsets are defined: the Active Set, the Candidate Set, the Neighbor Set, and the Remaining Set. The Active Set identifies the base station(s) or sector(s) through which the mobile station is communicating. The Candidate Set identifies the base station(s) or sector(s) for which the pilots have been received at the mobile station with sufficient signal strength to make them members of the Active Set, but have not been placed in the Active Set by the base station(s). The Neighbor Set identifies the base station(s) or sector(s) which are likely candidates for the establishment of communication with the mobile station. The Remaining Set identifies the base station(s) or sector(s) having all other possible pilot offsets in the current system, excluding those pilot offsets currently in the Active, the Candidate and Neighbor sets.
In system communications between the mobile station and the MTSO, the mobile station is provided a Neighbor List Update Message comprising of PN offsets corresponding to base stations of neighboring cells. In addition, the mobile is provided with a message which identifies at least one pilot corresponding to a base station through which the mobile station is to communicate through. These lists are stored at the mobile station as a Neighbor Set and an Active Set of pilots respectively, and are updated as conditions change.
A search is conducted for determining the signal strength for each pilot identified in the Active, Candidate, Neighbor, and Remaining Set as follows. In one possible search technique, the signal strengths of all pilots in the Active and Candidate Sets are measured first, then the signal strength of the first pilot in the Neighbor Set is evaluated. Then the Active and Candidate Set pilots are re-evaluated, followed by the second pilot in the Neighbor Set. This continues until the last Neighbor pilot is evaluated, then the first pilot of the Remaining Set is evaluated. This cycle continues by a re-evaluation of the Active and Candidate pilots and so on. Further details of the searching process are disclosed in the aforementioned '022 patent.
When communications are established with the mobile station through a base station, the mobile station continues to monitor the signal strength of identifiable pilot signals transmitted from the various neighboring base stations. When a pilot signal exceeds a predetermined threshold level in signal strength, denoted as T.sub.-- ADD, the pilot is added to the Candidate Set at the mobile station and a message is sent to the MTSO identifying all Active and Candidate pilots, their respective signal strengths and phase delays. This message is called the Pilot Strength Measurement Message. The phase delay information is a measurement used by the MTSO to determine each pilot's Round Trip Delay time with respect to the mobile station. The MTSO, upon receipt of the Pilot Strength Measurement Message, places the pilot that has exceeded T.sub.-- ADD into the mobile station Active Set and sends a message to the mobile station containing all the pilots to be included in the Active Set through which the mobile station is to communicate. The MTSO also communicates information to the base station corresponding to the new pilot in the Active Set and instructs this base station to establish communications with the mobile station. The mobile station communications are thus routed through all base stations identified by pilots in the mobile station Active Set.
When the mobile station is communicating through multiple base stations, the pilot signal strength of these base stations along with other base stations is monitored by the mobile station as described above. Should a pilot signal corresponding to a pilot of the Active Set drop below a predetermined threshold, denoted as T.sub.-- DROP, for a predetermined period of time, denoted as T.sub.-- TDROP, the mobile station generates and transmits the Pilot Strength Measurement Message to report the event. The MTSO receives this message via at least one of the base stations through which the mobile station is communicating. The MTSO may then decide to terminate communications through the base station whose pilot signal strength as measured at the mobile station is below the threshold level.
The MTSO upon deciding to terminate communications through a base station generates a new message identifying the pilots of the Active Set to which the mobile station is to communicate through. In this message which identifies pilots of the Active Set, the pilot of the base station to which communications with the mobile station are to be terminated is not identified. The MTSO also communicates information to the base station not identified in the Active Set to terminate communications with the mobile station. The mobile station, upon receiving the message identifying pilots of the Active Set, discontinues processing signals from the base station whose pilot is no longer in the Active Set. The mobile station communications are thus routed only through base stations identified by pilots in the mobile station's Active Set. In the case where there were previously more than one pilot identified in the Active Set and now only one, the mobile station communicates only to the one base station corresponding to the pilot identified in the mobile station Active Set.
Since the mobile station is communicating with the MTSO via at least one base station at all times throughout the handoff, there is no interruption in communications between them. A soft handoff in communications provides significant benefits in its inherent "make before break" communication over conventional "break before make" techniques employed in other cellular communication systems.
Soft handoffs are far less likely to drop calls than are hard handoffs because a phenomenon referred to as "ping-ponging" is greatly reduced. "Ping-ponging" occurs when the mobile telephone is near the border between two cells. In this situation the signal level tends to fluctuate at both base stations. This signal level fluctuation results in a situation in which repeated requests are made to hand the call back and forth between the two base stations. Such additional unnecessary handoff requests increase the possibility of the mobile station incorrectly hearing the channel switch command or failing to hear the command at all. Furthermore, this situation raises the possibility that the call will be discontinued if it is inadvertently transferred to a cell in which all channels are currently in use and thus unavailable for accepting the handoff.
The soft handoff technique described above can also be used to provide continued communication as a mobile station traverses between different sectors of a single base station. Such a method is disclosed in U.S. patent application Ser. No. 08/405,611, filed Mar. 13, 1995 entitled "METHOD AND APPARATUS FOR PERFORMING HANDOFF BETWEEN SECTORS OF A COMMON BASE STATION," assigned to the assignee of the present invention and incorporated by reference herein.
Current methods of generating the Neighbor List Update Message, while reasonable for small systems, are often problematic when used in large metropolitan areas, because they generate a very large Neighbor Set. For example, the Neighbor List Update Message in some systems is generated from the union of neighbor lists for each pilot signal in the mobile station's Active Set. The Neighbor List Update Message is generated the same way whether the mobile station is in soft handoff or not. The union of neighbors from the Active pilots can yield a very large Neighbor Set which imposes a search burden on the mobile station. That is, the mobile station can only search a limited number of pilot signals within a given time frame. The number of pilots in the Neighbor List Update Message is limited to a predetermined number, such as twenty.
Another problem with present methods of generating the Neighbor List Update Message is false indications of pilot strength due to topography. For example, a mobile station may detect a strong pilot signal from a base station which is located many miles away only because that base station is located on top of a mountain. Or a mobile station may detect a weak pilot signal from a nearby base station only because the mobile station happens to be in a valley at the time the nearby base station pilot energy is measured. In some systems, the Neighbor List Update Message is generated by simply selecting the first pilot signal identified in the Pilot Signal Measurement Message and placing all of its corresponding neighbors into the Neighbor List Update Message first. Then the next pilot's neighbors are placed in the List and so on. Using this method, far away base stations may be included in the Neighbor List Update Message though unsuitable for handoff, while nearby base stations may be excluded, though more suitable for handoff.
What is needed is a better method to generate the Neighbor List Update Message in order to find the most likely candidates for handoff. The method should prioritize the list of neighboring base stations and solve the problem of false pilot signal strengths due to topography.

Method and apparatus for merging neighbor lists in a CDMA mobile telephone system