Since the spreading operation and error correction must share the bandwidth available in a CDMA system, it is appropriate to approach these problems jointly. Several papers have addressed this problem with promising results. Hui (1984) has shown that under certain assumptions, the system performs better when more bandwidth is devoted to error correction. Giallorenzi (see PhD thesis, Univ. of Virginia, Charlottesville, VA, 1994) shows that combining error correction decoding and multiuser detection significantly improves system performance. We extend this research by considering not only simultaneous despreading and decoding, but also the simultaneous encoding and spreading. We consider a coded asynchronous CDMA system over an AWGN channel with constant information rate, R/sub I/. Each user's transmission rate is R/sub tx/=R/sub I//spl middot/Q/spl middot/N where 1/Q is the convolutional code rate and N is the spreading factor. The receiver matches to each signature sequence and performs maximum likelihood sequence detection.
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机译：由于扩频操作和纠错必须共享CDMA系统中可用的带宽，因此适当地共同解决这些问题是适当的。几篇论文已经解决了这个问题，并取得了可喜的结果。 Hui（1984）表明，在某些假设下，当更多带宽用于纠错时，系统性能会更好。 Giallorenzi（请参阅弗吉尼亚大学的博士学位论文，弗吉尼亚州夏洛茨维尔，1994年）表明，将纠错解码和多用户检测相结合可以显着提高系统性能。我们不仅考虑同时解扩和解码，还考虑同时进行编码和扩展，从而扩展了这项研究。我们考虑具有恒定信息速率R / sub I /的AWGN信道上的编码异步CDMA系统。每个用户的传输速率为R / sub tx / = R / sub I // spl middot / Q / spl middot / N，其中1 / Q是卷积码率，N是扩频因子。接收机匹配每个签名序列并执行最大似然序列检测。
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