# US 7,613,227 B2 · Reverse link correlation filter in wireless communication systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,613,227 B2 - Document ID: US7613227B2 - Status: Granted - Kind: B2 - Application number: 11/901,571 - Filed: 2007-09-17 - Published: 2008-03-27 - Granted: 2009-11-03 - Earliest claimed: 2000-02-23 - Assignees: IPR Licensing, Inc. - Inventors: Antoine J. Rouphael; John E. Hoffmann; George Rodney Nelson, Jr.; Samir K. Patel; James A. Proctor, Jr.; Daniel I. Riley - Web page: https://patentgrep.com/patent/US7613227B2 ## CPC - H04B 1/707: using direct sequence modulation - H04B 1/7105: Joint detection techniques, e.g. linear detectors - H04B 1/712: Weighting of fingers for combining, e.g. amplitude control or phase rotation using an inner loop - H04B 2201/70703: using multiple or variable rates - H04B 2201/70705: Rate detection - H04B 2201/7071: with dynamic control of receiver resources - H04B: TRANSMISSION ## Abstract A single, common correlation filter (CF) core is provided in a receiver for recovery of data from received code division multiple access (CDMA) signals. Signals are received over CDMA channels with different data rates, where the received signals include user information such as pilot and data symbols that have been spread according to different despreading rates including tier 1, tier 2 and tier 3 rates, where tier 1 is the smallest despreading rate. The received signal is correlated at the smallest despreading rate in the correlation filter (CF) by time multiplexing delayed versions of the pseudorandom noise (PN) code. The correlated information is then demultiplexed and pilot-aided QPSK demodulated. The demodulated information is summed at the proper integer multiple of the tier 1 rate to achieve tier 2 and tier 3 despreading rates. According to an embodiment, the three strongest multipaths components in terms of the received power are selected in a window or time period for optimal information recovery. ## Claims ### Claim 1 A method for use in wireless communication, the method comprising: receiving signals over a code division multiple access (CDMA) channel, each received signal having a user-unique code and an associated data rate; correlating the received signal with the user-unique code at a basic data rate using time multiplexing in a single correlation filter to produce one or more sets of correlated outputs; demultiplexing and demodulating the one or more sets of correlated outputs to generate demultiplexed and demodulated sets of correlated outputs; and on a condition that the associated data rate is a multiple of the basic data rate, summing the demultiplexed and demodulated sets of correlated outputs at the multiple of the basic data rate to recover user information from the received signal at the associated data rate. ### Claim 2 (depends on 1) The method of claim 1, wherein the demodulating includes quadrature phase shift keying (QPSK) demodulation. ### Claim 3 (depends on 2) The method of claim 2, wherein the demodulating includes pilot-aided QPSK demodulation. ### Claim 4 (depends on 1) The method of claim 1, wherein the user-unique code includes a pseudorandom noise (PN) code. ### Claim 5 (depends on 1) The method of claim 1, wherein the recovered user information includes pilot symbols and data symbols interleaved in a specified and known order. ### Claim 6 (depends on 5) The method of claim 5, further comprising: determining a channel estimate from the pilots symbols; and in response to the summing, selecting three strongest peaks in terms of received power in the recovered user information. ### Claim 7 (depends on 6) The method of claim 6, wherein the selected three strongest peaks are combined into one output for each data symbol. ### Claim 8 (depends on 7) The method of claim 7, wherein the selected three strongest peaks are combined into one output using maximum ratio combining (MRC). ### Claim 9 (depends on 1) The method of claim 1, wherein the CDMA channel is one of an access channel, a maintenance channel, or a traffic channel. ### Claim 10 (depends on 1) The method of claim 1, wherein the basic data rate is 8 chips per symbol and the multiple of the basic data rate is generated by a multiplying factor of one of 4 or 16. ### Claim 11 (depends on 1) The method of claim 1, wherein the basic data rate is 8 chips per symbol and the associated data rates is one of 8, 32 or 128 chips per symbol. ### Claim 12 An apparatus for use in wireless communications, the apparatus comprising: a receiver configured to receive signals over a code division multiple access (CDMA) channel, each received signal having a user-unique code and an associated data rate; a correlation filter configured to correlate the received signal with the user-unique code at a basic data rate using time multiplexing to produce one or more sets of correlated outputs; a demultiplexer configured to demultiplex the one or more sets of correlated outputs to generate demultiplexed sets of correlated outputs; and a data post processor configured to: demodulate the sets of demultiplexed outputs to generate demultiplexed and demodulated sets of correlated outputs; and on a condition that the associated data rate is a multiple of the basic data rate, sum the demultiplexed and demodulated sets of correlated outputs at the multiple of the basic data rate to recover user information from the received signal at the associated data rate. ### Claim 13 (depends on 12) The apparatus of claim 12, wherein the data post processor is configured to demodulate according to quadrature phase shift keying (QPSK) demodulation. ### Claim 14 (depends on 13) The apparatus of claim 13, wherein the data post processor is configured to demodulate according to pilot-aided QPSK demodulation. ### Claim 15 (depends on 12) The apparatus of claim 12, wherein the user-unique code includes a pseudorandom noise (PN) code. ### Claim 16 (depends on 12) The apparatus of claim 12, wherein the recovered user information includes pilot symbols and data symbols interleaved in a specified and known order. ### Claim 17 (depends on 16) The apparatus of claim 16, further comprising: a pilot post processor configured to determine a channel estimate from the pilots symbols, wherein the data post processor is further configured to select three strongest peaks in terms of received power in the recovered user information. ### Claim 18 (depends on 17) The apparatus of claim 17, wherein the data post processor is further configured to combine the selected three strongest peaks into one output for each data symbol. ### Claim 19 (depends on 18) The apparatus of claim 18, wherein the data post processor is further configured to combine the selected three strongest peaks into one output using maximum ratio combining (MRC). ### Claim 20 (depends on 12) The apparatus of claim 12, wherein the CDMA channel is one of an access channel, a maintenance channel, or a traffic channel. ### Claim 21 (depends on 12) The apparatus of claim 12, wherein the basic data rate is 8 chips per symbol and the multiple of the basic data rate is generated by a multiplying factor of one of 1, 4 or 16. ### Claim 22 (depends on 12) The of apparatus claim 12, wherein the basic data rate is 8 chips per symbol and the associated data rates is one of 8, 32 or 128 chips per symbol. ### Claim 23 (depends on 12) The apparatus of claim 12 further comprising a digital signal processor configured to provide instructions to the correlation filter and the data post processor. ### Claim 24 (depends on 12) A base station comprising the apparatus of claim 12. ### Claim 25 (depends on 12) A mobile station comprising the apparatus of claim 12.