发明授权
- 专利标题: Rate detection in direct sequence code division multiple access systems
- 专利标题(中): 直接序列码分多址系统中的速率检测
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申请号: US09343647申请日: 1999-06-29
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公开(公告)号: US06687233B1公开(公告)日: 2004-02-03
- 发明人: Albert Chen , Ingolf Held
- 申请人: Albert Chen , Ingolf Held
- 主分类号: H04L1226
- IPC分类号: H04L1226
摘要:
A method of rate detection at a receiving end of a code division multiple access (CDMA) system, in which system the effective data rate is variably selected at the transmitting end from an applicable rate set including a full rate and lower rates, each lower rate being the full rate divided by a different integer, and encoded symbols are repeated for the lower rates to maintain a constant apparent symbol transmission rate, includes the formation of scaled correlations between data entering a Viterbi decoder, after any required de-repetition, and re-encoded data at each of the possible data rates in the applicable rate set. Rate decision logic sequentially considers the full and lower candidate data rates in descending order, choosing the considered candidate data rate to be the actual data rate if certain conditions are met. A first of the conditions is whether the scaled correlation for the considered data rate plus a predetermined biasing threshold associated therewith is greater than or equal to the largest of the scaled correlations for the other data rates, and a second condition depends on whether CRC checking if available for the considered data rate. If CRC checking is available for the considered data rate, the second condition is satisfied if CRC checking has not failed. If CRC checking is not available, it is determined as the second condition whether the scaled correlation for the considered data rate is equal to or greater than a further predetermined threshold associated therewith.
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