Dispensers are provided of the type which include a flow path through which liquid must pass to leave the dispenser. After the dispenser has been actuated to dispense, the flow path then receives reverse flow as the dispenser recovers ready for the next dispensing. This reverse flow limits the possibility of dripping from the dispensing outlet. A flow controller in the flow path automatically adjusts to have little or no interference to the flow of liquid leaving the dispenser and then positions itself to slow down the rate of reverse flow into the dispenser. The dispenser is suitable for more viscous liquids.

Dispensers have been developed which consist of an inverted container for receiving the liquid and having a bottom outlet positioned inside a reservoir. A pool of the liquid accumulates under atmospheric pressure in the reservoir around the bottom outlet to thereby trap the liquid in the container with a negative pressure above the liquid. Various structures have been provided to disturb the balance of the liquid and the negative pressure in the container to thereby cause controlled flow from the dispenser through an outlet associated with the reservoir and then, after dispensing to cause suck-back to clear liquid from the dispensing outlet. Such dispensers can be seen in applicant's prior patents, namely U.S. Pat. Nos. 4,324,349, 4,635,828, 4,645,097, 5,033,653, and 5,217,147.
The principles of operation of the dispensers are described in some detail in U.S. Pat. No. 5,033,653 which includes diagrams illustrating the conflicting parameters associated with providing temperature compensation. As demonstrated in that patent, the liquid must not flow from the dispenser when temperature rises, and yet the dispenser must have a response rate which will allow the user to dispense almost instantaneously upon applying a force to the dispenser. U.S. Pat. No. 5,033,653 also provides structures which overcome these disadvantages satisfactorily by separating the two parameters so that response rate will not be so dependent on the amount of temperature compensation provided in the structure. However it has been found that when liquids of higher viscosities are used, there is a disadvantage in all of the prior structures which was not apparent earlier. It has now been found that when the dispenser recovers from dispensing by receiving air from outside, instead of liquid returning into the container from the reservoir, air will tunnel directly through the viscous liquid and find its way into the container. This results in excessive build up of liquid in the reservoir and eventual dripping and improper dispensing.
A second cause of the same difficulty results from the rate of recovery of the dispenser after squeezing the container to dispense. The initial force driving the recovery rate is greatest when the container is at its maximum deflection where the most energy is available to drive the recovery. As a result, air will initially be inspired into the dispenser at a high rate and this will cause the air to tunnel through the liquid and into the container.
These disadvantages are exacerbated in smaller structures such as those used to contain hand soap or shampoo. Inherently with these structures the distances and dimensions are such that both of these disadvantages take place at the same time.
It has now been found that different approaches to the relationship between temperature compensation and response rate have to be considered if higher viscosity liquids are to be dispensed, particularly from small dispensers.


A clip assembly 20 for concealed fixing of cladding sheets 50, of the type having re-entrant longitudinal ribs 51, 52 has a retaining element 29 for engaging inside a rib of the sheet. The retaining elements includes a fixing portion 31 disposed in a plane transverse to the rib and shaped for snap-fit engagement with a re-entrant portion 59 of the rib. The retaining formations may be disposed along a strap 21 in opposed pairs, with fastening apertures 40 in the strap centrally disposed below each rib. An improved cladding sheet 50 having interlocking male and female end regions 61, 62 is also disclosed.

The present invention relates generally to a cladding system for the concealed fixing of roofing or other cladding sheets and to a clip and cladding sheet for use in such a system.
Throughout the specification, the invention is described with reference to the orientation for use in roof cladding where the plane of the sheets is generally horizontal. This, however, should not be construed as limiting the invention to that orientation, as the cladding may be laid in other orientations. Accordingly, references to a particular orientation is to be construed to encompass these other orientations.
Cladding sheets for concealed fixing have a plurality of longitudinal, re-entrant ribs, with pan sections between the ribs. The edges of the sheets are adapted for interengagement with the adjacent sheets, so that an end rib of one sheet fits over the end portion of the adjacent sheet.
The sheets are typically secured to the roof structure by elongated clips which secure the trailing edge end portion of the previously laid sheet and the end rib and intermediate ribs of the sheet to be laid. The clip has retaining formations spaced along the length thereof to coincide with the rib spacing. An endmost retaining formation of the clip is engaged with the trailing edge portion of the previously laid sheet, with the remainder of the clip extending in the direction of progress, and is fixed to the roof structure. The next sheet is then pressed onto the clip so that the leading edge rib and intermediate ribs are engaged with the retaining formations and the leading edge rib also locks over the trailing edge portion of the previous sheet.
The prior art clips are formed as a strap, which is folded to form a series of humps. The humps have detents for engagement with re-entrant portions of the ribs of the sheet.


An electronic component is equipped with a pad. The pad includes a lower transparent electric conductive layer formed on an insulating substrate. An insulating layer is formed on the lower transparent electric conductive layer. A contact hole is formed in the insulating layer for exposing the lower layer transparent electric conductive layer. A metal layer is formed on the lower transparent electric conductive layer and covered with the insulating layer so as to surround the contact hole. An upper transparent electric conductive layer is formed on the insulating layer and connected with the lower transparent electric conductive layer through the contact hole.

Needs of a touch panel as an input interface in mobile terminals, such as a mobile phone, have been expanding by optical feature that haze is small and transmissivity is high, and wide application such as multi-touch correspondence. There is a capacitive sensor as one of position detection methods of the touch panel.
The touch panel using the electric capacitive sensor, for example, is attached to a display surface of a liquid crystal display panel. The touch panel is equipped with a glass substrate, a detection electrode formed of ITO (Indium Tin Oxide) and a pad on the glass substrate. The glass substrate of the touch panel is attached on the display surface of the liquid crystal display panel by adhesives. A detection electrode side of the touch panel is covered with a decorative plate. The decorative plate is attached on the touch panel by adhesives.
In the touch panel, when operator's fingers, etc., contact on the surface of the decorative plate to input data, the electrostatic capacitance of the detection electrode changes near the input position. For this reason, the detection electrode can detect the input data by detecting the change of electrostatic capacitance as voltage change. The inputted information is transmitted to the pad.
The above-mentioned pad is formed with electric conductive composite layers. However, ohmic contact may not be formed between the electric conductive layers.

Electronic component and electronic device using the same


A plasma cell for destroying hazardous gases. An electric-discharge cell having an electrically conducting electrode onto which an alternating high-voltage waveform is impressed and a dielectric barrier adjacent thereto, together forming a high-voltage electrode, generates self-terminating discharges throughout a volume formed between this electrode and a grounded conducting liquid electrode. The gas to be transformed is passed through this volume. The liquid may be flowed, generating thereby a renewable surface. Moreover, since hydrochloric and hydrofluoric acids may be formed from destruction of various chlorofluorocarbons in the presence of water, a conducting liquid may be selected which will neutralize these corrosive compounds. The gases exiting the discharge region may be further scrubbed if additional purification is required.

The present invention relates generally to destruction of hazardous gaseous materials, and more particularly to the destruction of hazardous gases using an electric-discharge plasma cell having one liquid electrode.
Electric-discharge "plasma cells" are dielectric barrier discharge cells often referred to as ozonizer cells, since they are widely used in the industrial generation of ozone. See, e.g., T. C. Manley, "The Electric Characteristics of the Ozonator Discharge," Trans. Electrochem. Soc. 84, 83 (1943). Multiple, self-terminating microdischarges occur throughout the discharge volume as a result of the application of an alternating high-voltage waveform to one of the two electrodes. The feed gas typically contains oxygen and/or water vapor; highly reactive O and OH radicals being produced therefrom in the microdischarges, which species react with and convert the hazardous components of the feed gas into less hazardous forms such as water and carbon dioxide, or possibly carbon monoxide.
Two difficulties are encountered in the use of currently available plasma cells in the destruction of hazardous components of the feed gas. Hydrochloric acid forms within the plasma cell from the destruction of chlorocarbon compounds in the feed gas. Additionally, the discharge volume may become blocked by reactions therein and from wall-reaction products.
Accordingly, it is an object of the present invention to provide an electric-discharge plasma cell for destruction of hazardous gases, where the electrode in contact with hostile gases, either in the feed stream or formed in the plasma does not corrode.
Another object of the invention is to provide an electric-discharge plasma cell for destruction of hazardous gases, where reaction products may be readily removed, thereby eliminating cell blockage.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.

Apparatus for the plasma destruction of hazardous gases

The United States of America as represented by the United States Department of Energy


An apparatus includes a media handler which is capable of processing a supply of media sheets which can take the form of plates, aluminum or plastic used in lithographic printing presses or the like, or can be film which is advanced to a drum and scanned by a scanning process and thereafter removed from the drum surface by appropriate handling means.

This invention relates to a system for positioning a photosensitive media sheet on an exposure platen in registration with a given datum from which datum a scanning operation is conducted on the media sheet and deals more particularly with a media handling system wherein conformable media is capable of being handled from a supply of such media in flat form and configured by the system to take the shape of the drum support surface and further deals with an improvement in laser scanners wherein motion controls of the spinner assembly are directly dependent upon the desired print resolution of the image.
Exposing of media by scanning is made more efficient through the use of drum plotters which employ a rapidly spinning projection mirror which directs a light beam from a laser source downwardly onto the photosensitive material which is supported on the drum support surface. Media which is supported on the drum surface must be flexible enough to conform to the arcuate contour of this surface, but made of a strong enough material to be used, for example, directly in a lithographic printing press. Media consists of a photographically sensitive coating, e.g. emulsion, on a base material of polyester or aluminum. Such media sheets are usually provided in a supply of such sheets layered onto each other in a flat orientation and contained in a cassette. As such, any handling device which is used to automatically load the media sheets into drum plotters must be capable of handling a somewhat mechanically unstable element between this supply station and the scanning station, and thereafter to any subsequent handling station, such as one wherein the media is developed.
Media of the type of which the present invention is concerned has a photosensitive layer or emulsion formed on it which is sensitive to radiant energy in a given wavelength to expose areas of the emulsion where a positive or negative image is to be made. In some instances, the emulsion used is sensitive to room light, and it is therefore necessary that loading and scanning operations be done in "dark rooms". Operating in dark rooms is not advantageous from a production standpoint because the workers involved in the handling process must operate in a dimly light room, usually under red light and must always be conscious about the exposure of media to stray room light, such as when a door opens.
Accordingly, it is an object of the invention to provide a media handling system whereby media is taken from a supply of media loaded into the system in a light-tight condition and is thereafter scanned within the light-tight confines of a scanning apparatus.
It is yet a further object of the invention to provide a media handling device for a plotter wherein the media handled is one which is flexible and the handling device is capable of picking and placing an individual media sheet and conforming it to a given configuration so that it can be supported on the partial cylindric support surface of a drum plotter.
Still a further object of the invention is to provide a highly accurate scanning system which is capable of scanning on a media sheet with different pixel densities and light spot diameters in accordance with graphic information inputted as code into the plotter.
Yet a further object of the invention is to provide a scanner in which vibrations otherwise acting on the scanner components are insulated therefrom by structure which negates the effects of such vibrations.
Still a further object of the invention is to provide a scanner of the aforementioned type wherein scan speed and spinner axis axial movement are related to the maximum resolution capabilities of the system.

Apparatus and method of positioning photosensitive media on an exposure platen


An impact-type printing device includes a printer for printing characters with a plurality of impression pressures including a high impression pressure sufficient for printing on all of the sheets of a set of copy sheets. The device also include a keyboard having a key for selecting one of the plurality of impression pressures when the device operates in a normal operation mode. The device further includes a switch for switching the device between the normal operation mode and a copy mode of operation. In the normal mode the printer is capable of printing in any of the plurality of impression pressures selected by the operator at the keyboard. In the copy mode the printer prints only with a high pressure, sufficient for printing on all of the sheets of the set of copy sheets. The device also erases a previously printed character when in the normal mode and overstrikes the previously printed character in the copy mode.

1. Field of the Invention
The invention relates to a character printing device and more particularly, to an impact printer for printing with a plurality of impression pressures and for erasing or overstriking misprinted characters.
2. Description of Pertinent Information
Impact-type typing devices such as electronic typewriters can be used to type characters on a set of carbon copy forms 10, as shown in FIG. 1(b). The set is composed of a top form 2, shown in FIG. 1(a), and two sheets of carbon paper 4, 4, positioned between the top form and a middle form 6, and between the middle form and a bottom form 8. The middle and bottom forms 6 and 8 are identical to the top form 2.
Unlike typing on a single form, care must be taken by the operator when performing printing or correcting on a set of carbon copy forms. Otherwise, the carbon copies will not be legible, or the correction will not be completely made. This is due to several reasons.
First, the force with which the typing elements must be impressed on a set of carbon forms is greater than the force with which the typing element must be impressed on a single sheet of paper. Therefore, if the operator forgets to check or change the impression force when typing on a set of carbon copy forms, a clear overstrike may not be made on the bottom-most sheet of the set. This situation is shown in FIG. 2(a). Thus, the operator must make sure that the impression force is increased when typing on a carbon copy form in order to leave a clear overstrike on all of the sheets of the set, as shown in FIG. 2(b).
Second, performing the correction operation is complicated. Correcting an incorrectly typed character is typically performed by striking over the incorrectly typed characters with another character, as shown in FIG. 3(a). In this example, numbers "1,2,3,4,5, and 6" are struck over with an "X". However, before this can be done, the typing portion of the typewriter must be backed up to the position of the incorrectly printed characters. In addition, a typing element must strike over the exact number of characters that are incorrectly printed. Any character may be used for such an overstriking operation, as shown in FIG. 3(b), which shows overstriking of an "X", an equal sign, and a Roman Numeral. However, the operator must usually use the same character for the overstrike operation as the printed character to be erased in order to ensure complete erasure.
Consequently, performing printing and correcting operations on sets of carbon copy forms is complicated for the operator and requires a complex typewriter.

Character printing device with pressure impact control


A shock-absorbing fence comprises: a guard net provided in a stretched state between main posts provided to stand at a predetermined interval; a safety net attached between a skirt of the guard net and a ground; and a member joining an upper rim of the safety net to the skirt of the guard net as well as securing a lower rim of the safety net to the ground, the member including a horizontal support rope member provided along the lower rim of the safety net and a plurality of hillside support rope members connecting between a plurality of points of the horizontal support rope member and a plurality of hillside anchors, the safety net being allowed to deform in an extended manner following deflection and deformation of the guard net, while maintaining a gap below the guard net in a closed state, in case of rockfall.

1. Technical Field
The present invention relates to a shock-absorbing fence that absorbs impacts of falling objects such as falling rocks and soil, and in particular relates to a shock-absorbing fence that has the improved capability to capture falling rocks.
2. Description of the Related Art
In Japanese Patent Application Laid-Open Publication No. H7-197423, there is disclosed a shock-absorbing fence that includes: tubular main posts built in vertical holes bored at intervals on a hillside slope to be provided in a standing state; and a net formed of metallic mesh provided in a stretched state on each of the tubular main posts along with cables at a plurality of stages.
There is also proposed a shock-absorbing fence for absorbing impacts of falling rocks and the like by converting the impact energy into the friction energy, which includes as the basic configuration: main posts provided to stand at predetermined intervals; horizontal rope members anchored between the main posts in a horizontally slidable manner and secured at both ends thereof; and a wire net retained on the horizontal rope members to cover a space between the main posts. In addition to the basic configuration, the proposed shock-absorbing fence further includes as an absorbing section: an extra length section formed by overlapping rope members in the middle of the horizontal rope members; and a clump that clumps the extra length section with a certain strength. In case a tensile force beyond the predetermined level is applied to the horizontal rope members, the extra length section can extend to absorb the tensile force while a certain friction force is maintained on the horizontal rope members (see for example, Japanese Patent Application Laid-Open Publication No. H6-173221, and Japanese Patent Application Laid-Open Publication No. H6-336709).
(1) This is a type of shock-absorbing fence configured to stop falling rocks and the like in a band-shaped net stretched across main posts. When such a shock-absorbing fence catches falling rocks, the midsection of the net deflects and deforms by a large amount toward the foot of a slope, and at the same time, the height (effective height) of the fence changes by a large amount.
In other words, the net deflects and deforms by a large amount in and around the region hit by falling rocks, and due to such deformation, the length between the upper and lower rims of the net (net width in its height direction) becomes shorter.
As a result, in case that rockfalls occur in a repetitive manner, rocks from subsequent rockfalls can slip through a gap wide open between the bottom end of the net and the ground, and the rocks may jump over the net, posing problems in its capability to trap falling rocks.
(2) If cost is not taken into account, it is possible to enhance capability to trap falling rocks by reducing the amount of deformation by utilizing a large quantity of absorbers, increasing the number of ropes, and installing a multiple layer of shock-absorbing fences.
However, in light of the current severe economic environment, it is difficult to implement costly countermeasures as mentioned above, and for this reason, it is much needed to propose a shock-absorbing fence whose installation costs can be lowered without sacrificing the protection performance.


A device and method for detecting and suppressing double-talk in a cellular mobile unit employ a cellular transceiver; a receive signal path; a transmit signal path; and a double-talk detector. The double-talk detector determines a receive slope of a receive signal, and determines a transmit slope of a transmit signal. The double-talk detector further determines a difference slope of a difference signal that is determined by evaluating differences between the receive signal and the transmit signal. Finally, the double-talk detector generates a double-talk flag signal in the event the transmit slope indicates an increasing transmit speech power, and the receive slope and the difference slope indicate a prescribed relationship between the changes in the receive speech power and the difference power.

The present invention relates double-talk detection in transceivers, and more particularly to double-talk detection in hands-free wireless transceivers. Even more particularly, the present invention relates to robust double-talk detection in hands-free cellular telephone transceivers.
Cellular telecommunication systems in North America are evolving from their current analog frequency modulated (FM) form towards digital systems. Digital systems must encode speech for transmission and then, at the receiver, synthesize speech from the received encoded transmission. For the system to be commercially acceptable, the synthesized speech must not only be intelligible, it should be as close to the original speech as possible.
Codebook Excited Linear Prediction (CELP) is a technique for speech encoding. The basic technique consists of searching a codebook of randomly distributed excitation vectors for that vector which produces an output sequence (when filtered through pitch and linear predictive coding (LPC) short-term synthesis filters) that is closest to the input sequence. To accomplish this task, all of the candidate excitation vectors in the codebook must be filtered with both the pitch and LPC synthesis filters to produce a candidate output sequence that can then be compared to the input sequence. This makes CELP a very computationally-intensive algorithm, with typical codebooks consisting of 1024 entries, each 40 samples long. In addition, a perceptual error weighing filter is usually employed, which adds to the computational load.
A number of techniques have been considered to mitigate the computational load of CELP encoders. Fast digital signal processors have helped to implement very complex algorithms, such as CELP, in real-time. Another strategy is a variation of the CELP algorithm called Vector-Sum Excited Linear Predictive (VSELP) Coding. An EIA/TIA IS-54 standard that uses a full rate 8.0 Kbps VSELP speech coder, convolutional coding for error protection, differential quadrature phase shift keying (QPSK) modulation, and a time division, multiple access (TDMA) scheme has been adopted by the Telecommunications Industry Association (TIA). See EIA/TIA IS-54B. The Electronic Industries Association (EIA) published EIA/TIA IS-55 for the dual-mode mobile station, base station cellular telephone system compatibility standard. This standard incorporates a VSELP codebook search method that is disclosed in U.S. Pat. No. 4,817,157 by Gerson.
The CELP-based coders, which use LPC coefficients to model input speech, are adequate for clean signals, however, when background noise is present in the input signal, the CELP-based coders inadequately model the signal. This results in some artifacts at the receiver after decoding. These artifacts, referred to a swirl artifacts, considerably degrade the perceived quality of the transmitted speech. U.S. patent application Ser. No. 08/169,789 of Ganesen et al., entitled REMOVAL OF SWIRL ARTIFACTS FROM CELP BASED SPEECH CODERS and filed Dec. 20, 1993, commonly assigned with the present patent document, and incorporated herein by reference, improves upon conventional CELP-based speech coders, and removes the swirl artifacts through the use of a voice activity detector (VAD).
In hands-free telecommunication, a high-sensitivity microphone and a high-volume, i.e., loud, speaker are employed, which allow a mobile user to hear incoming (or far-end) communications, and to transmit outgoing (or near-end) communications without the need for the mobile user to hold a handset to his or her ear and mouth.
Problematically, hands-free transceivers are susceptible to local acoustic echo (or a false double talk condition), which is caused by far-end audible signals, e.g., voice signals from a remote unit, being sounded through the mobile unit's speaker and simultaneously received (or fed back) into the mobile unit's microphone. As a result, the audible signals are retransmitted to the remote user causing an echo of the far-end audible signals. This problem arises because near-end speech, i.e., speech received through the microphone, can be caused by the mobile (or near-end) user or by the mobile unit's speaker, i.e., by the far-end user. Conventional hands-free mobile units are unable to distinguish between signals originating at the near end and signals originating at the far end, and, in order to make such a distinction, very complex processor-intensive processing would need to be performed.
In one type of conventional hands-free mobile unit, the microphone is "turned off," i.e., acoustic signals received into the mobile unit's microphone are not transmitted, whenever incoming voice signals are detected by a receive speech detector. This prevents the mobile unit from re-transmitting (or echoing) the incoming (far-end) voice signals after they are sounded by the mobile unit's speaker. As a result, echo, or feedback of the far-end user's transmission, is prevented. Unfortunately however, in such an implementation, the mobile (or near-end) user is unable to "interrupt" the remote (or far-end) user, because the mobile user's microphone is "turned off" whenever the far-end voice signals are received, i.e., whenever the remote user is transmitting. Thus, the mobile user must wait to transmit until the remote user stops transmitting.
Such an implementation becomes particularly problematic when the mobile user is attempting to communicate with another mobile user who is using a similarly configured hands-free cellular transceiver, because both cellular transceivers will occasionally "turn off" their microphones in response to detected double talk, i.e., in response to each detecting an incoming signal. In this case, communication will "lock up" until one or the other of the cellular transceivers ceases echo suppression, i.e., turns its microphone back on. Problematically, such "lock up" may not be readily detectable by either mobile user, because both users may be talking and assume that their signals are being heard through the opposite mobile user's speaker.
Thus, improvements are needed in double-talk detection and echo suppression for hands-free cellular telephone transceivers, and other communications transceivers that exhibit local acoustic echo and/or false double talk conditions.


Devices and methods for the prognosis of intradialytic parameters such as a blood pressure are described, wherein at least one learning algorithm and/or at least one neural network is/are provided. A memory device stores patient-individual intradialytic parameters, laboratory parameters, and/or machine parameters, which can be used in the prognosis of patient-specific parameter progress during a dialysis treatment.

Hitherto, problems in medical treatment, such as intradialytic hypotensive situations for example, have been reduced or corrected by retrospective control. Thus, an intervention such as the reduction of the ultrafiltration rate (UF rate) has only been performed in the event of a hypotensive episode.
Symptomatic, intradialytic hypotensive situations pertain to the most common complications during dialysis treatment. One of the main causes of these hypotensive situations is the imbalance between the UF rate and the refill process, i.e. the subsequent flow of water from the intracellular space and the interstitium into the intravasal space. For the purpose of reducing and avoiding such hypotensive situations, various techniques have been developed, which are based on biofeedback systems. Possible control parameters for stabilizing the hemodynamic circulation of the patient are e.g. the blood pressure (BD) and the relative blood volume (RBV). Candidates for adjustable parameters are the temperature (DT) of the dialysis liquid, the ultrafiltration rate (UFR or UF rate), and the conductivity (LF) of the dialysis liquid. All these control parameters or adjustment parameters coalesce in different combinations and with various reciprocal effects.

Device and method for predicting intradialytic parameters


A multiple antenna system including a mobile station and a base station are operable to perform a method for transmitting control information for interference mitigation. A Mobile Station (MS) can transmit control information for interference mitigation. The MS determines a first Precoding Matrix Index (PMI) and a second PMI for interference from an adjacent Base Station (BS). Based on a correlation level from correlation values between one of the first PMI and second PMI and the remaining PMIs in the codebook, the MS determines a level of a subset of PMIs, and feeds back information indicating the correlation level.

Orthogonal Frequency Division Multiplexing (OFDM) and multiple antenna (i.e., Multiple Input Multiple Output (MIMO)) techniques have attracted extensive attention for its high spectral efficiency in Long Term Evolution (LTE) and Institute of Electrical and Electronics Engineers (IEEE) 802.16 standards.
OFDM based systems do not suffer from interference among multiplexed users within a cell given perfect frequency synchronization. However, when it comes to a multi-cell environment, InterCell Interferences (ICIs) between adjacent cells are induced which seriously degrade cell edge user performance.
Intercell interference mitigation techniques are generally classified as three types: interference randomization, interference cancellation, and interference coordination. The interference randomization is aimed at randomizing interference and allowing interference mitigation through processing gain. The interference cancellation techniques are proposed to cancel interference at receivers by using multiple antenna techniques or Interleaved Division Multiple Access (IDMA) schemes. The interference coordination is based on the concept that a well-designed coordination of resource among Mobile Stations (MSs) in adjacent cells can reduce interference and improve user capacity and coverage at cell edge.
FIG. 1 illustrates intercell interference experienced by a cell edge MS in a MIMO system according to the conventional art.
Referring to FIG. 1, it is assumed that a serving BS 100 and an interfering BS 120 use the same codebook for precoding, and are connected with each other through a backbone network. In addition, in an environment in which the serving BS 100 and the interfering BS 120 transmit data using the same frequency band, an MS 110 located at a cell edge of the serving BS 100 suffers from interference from the interfering BS 120, which is an adjacent BS. H1 105 is a channel matrix between the serving BS 100 and the MS 110, and H2 115 is a channel matrix between the interfering BS 120 and the MS 110.
In order to mitigate interference, the MS 110 searches a reference signal for a Precoding Matrix Index (PMI) (hereinafter, referred to as 'the worst PMI') causing high interference or a PMI (hereinafter, referred to as 'the best PMI') causing low interference. The MS 110 can feed back the searched worst or best PMI to the serving BS 100 and then, the serving BS 100 informs the interfering BS 120 of the worst or best PMI fed back from the MS 110. The interfering BS 120 restricts the fed back worst PMI among its using PMIs (hereinafter, referred to as 'PMI restriction') or uses the fed back best PMI among its using PMIs (hereinafter, referred to as 'PMI recommendation'), thereby being able to mitigate the interference of the MS 110.
However, the feedback of only the worst or best PMI to mitigate the interference is not enough because other PMIs besides the worst PMI may also cause interference in the MS 110, and other PMIs besides the best PMI may also work well for interference mitigation. Therefore, it is preferred if multiple PMIs can be fed back for either PMI restriction or recommendation. However, the difficulty is that a feedback of a PMI subset from the MS 110 to the serving BS 100 will incur too much overhead.
Thus, there is a need for a method and apparatus for efficient PMI feedback for interference cancellation in a multiple antenna system.

Method and apparatus for transmitting control information for interference mitigation in multiple antenna system