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Method and apparatus for generating a correction termRelated Patent Categories: Telecommunications, Transmitter And Receiver At Separate Stations, Having Measuring, Testing, Or Monitoring Of System Or PartMethod and apparatus for generating a correction term description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070173201, Method and apparatus for generating a correction term. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATION [0001] This application is a continuation of U.S. patent application Ser. No. 10/869,672 filed on Jun. 16, 2004, which claims the benefit of U.S. Provisional Application No. 60/482,809 filed on Jun. 26, 2003, which are incorporated by reference as if fully set forth. FIELD OF INVENTION [0002] This invention relates to generation of a channel quality indicator (CQI) in wireless communications, and more particularly to a method for adaptive biasing of the signal-to-interference ratio (SIR) for CQI generation. BACKGROUND [0003] Adaptive Coding and Modulation (ACM) is an effective technique for providing link adaptation in both Uplink (UL) and Downlink (DL) communications. ACM is typically accomplished by algorithms working together in both the receiver and the transmitter. The receiver makes an estimate of the channel quality by measuring the SIR of one or more transmissions from the transmitter. The measured SIR is then used to compute a CQI. [0004] Each CQI may correspond to a particular configuration of radio resources such as code rate and modulation type. After each SIR measurement is made, the CQI is computed. For example, the SIR is compared to a table of SIR-CQI pairs and the CQI value that yields the best performance, such as in terms of Packet Error Rate (PER) or throughput, is selected and sent back to the transmitter. The transmitter then selects a radio configuration that is no more aggressive than that indicated by the received CQI value. In an otherwise unpopulated cell, the transmitter would simply use a configuration consistent with the channel quality indicated by the CQI. [0005] However, SIR alone does not give complete information about the quality of the channel. For example, in order to maximize data throughput, a channel with a large delay spread and/or a large Doppler spread should not be assigned as high of a CQI value. Additionally, the CQI will depend on the receiver design. SUMMARY [0006] In one embodiment, the present invention is related to a method and apparatus for generating a correction term. The present invention is related to a method and apparatus for generating a correction term. A plurality of data packets are received from a transmitter. An acknowledgement (ACK) signal is generated for each data packet in which an error does not exist, and a negative-acknowledgement (NACK) signal is generated for each data packet in which an error exists. The generated signals are mapped into a binary signal. The binary signal is filtered to generate a filtered binary signal. A target PER is generated. An error signal is generated by subtracting the target PER from the filtered binary signal. The error signal is processed to generate at least one correction term. The at least one correction term may be used to bias a SIR estimate of a communication channel established between the transmitter and a receiver based on the received data packets. [0007] In another embodiment, the present invention provides a system and method for biasing the SIR value that is used for CQI generation in order to maintain a certain specified PER as a mechanism to maximize data throughput. In this way, the proper CQI values are selected regardless of the type of propagation channel. Furthermore, additional algorithms such as Doppler estimators, or other feed forward correction terms, are not required but may be used in conjunction with the invention to further improve throughput performance. [0008] In a preferred embodiment relating to Frequency Division Duplex High Speed Downlink Packet Access (FDD-HSDPA), a CQI table is specified such that each entry in the table corresponds to the code rate, modulation type, number of codes, and power offset that differ by 1 dB in required Common Pilot Channel (CPICH) SIR to the target PER. The CQI value is derived by adding a bias to the estimated CPICH SIR. [0009] In the prior art, the bias was fixed and was determined primarily by the design of the table, the signaled power ratio of the pilot signal and the data signal, and the desired performance over a large class of channel types. By employing the present invention, the need to select a compromised fixed bias is removed. This is accomplished by monitoring the performance in terms of PER and adjusting the SIR bias to maintain a desired long-term average PER performance. BRIEF DESCRIPTION OF THE DRAWING(S) [0010] FIG. 1 is a block diagram of a system for generating CQI in accordance with the present invention. [0011] FIG. 2 is a block diagram of a system for generating a CQI value by biasing SIR with a correction term created from an ACK/NACK signal according to a preferred embodiment of the present invention. [0012] FIG. 3 is a block diagram of a system for generating a CQI value with several channel-type correction terms and a SIR prediction term in accordance with an alternative embodiment of the present invention. [0013] FIG. 4 is a signal diagram of the result of simulation for long-term PER for ITU channels under various levels of inter-and intra-cell interference. [0014] FIG. 5 is a signal diagram of the results of simulation of the ACK/NACK signal and adaptive bias correction signal generated according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) [0015] The present invention will be described with reference to the drawing figures wherein like numerals represent like elements throughout. [0016] The present invention is generally applicable to all modes of the Third Generation (3G) standards including Time Division Duplex (TDD), Frequency Division Duplex (FDD), Time Division Synchronous Code Division Multiple Access (TDSCMA) and Code Division Multiple Access 2000 (CDMA 2000) scenarios, but is envisaged to be applicable to other scenarios as well. [0017] FIG. 1 is a block diagram of a system 8 for signal processing in accordance with the present invention. A data packet transmitted from a transmitter (not shown) is received by a receiver, only a portion of which is shown in FIG. 1. The system 8 includes a SIR estimator 20, an adaptive correction term generator 10, a combiner 21 and a SIR-CQI mapping unit 30. The received data packet is input into the SIR estimator 20 which calculates a SIR estimate of a communication channel established between the transmitter and the receiver based on the received data packet by a conventional method. The received data packet is also input into the adaptive correction term generator 10 and is processed for error detection. An ACK/NACK signal generated from the error detection process is used by the adaptive correction term generator 10 to generate a correction term to bias the SIR estimate. The SIR estimate and the correction term are combined at the combiner 21 to generate a corrected SIR. [0018] The corrected SIR is mapped to a CQI value by the SIR-CQI mapping unit 30. The CQI value is reported to the transmitter in order to adjust the configuration of the next transmitted data packet. The CQI value ensures desired throughput performance by maintaining a PER that is close to the target PER. The purpose of maintaining a PER that is close to the target PER is that it optimizes the utilization of radio resources and, therefore, the data throughput of the system. Continue reading about Method and apparatus for generating a correction term... Full patent description for Method and apparatus for generating a correction term Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method and apparatus for generating a correction term patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Method and apparatus for generating a correction term or other areas of interest. ### Previous Patent Application: Method and system for allocating resource in a communication system Next Patent Application: Method of selecting one of dual antennas Industry Class: Telecommunications ### FreshPatents.com Support Thank you for viewing the Method and apparatus for generating a correction term patent info. 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