Joint iterative decoding of serially concatenated error controlcoded CDMA

摘要

Joint iterative decoding of multiple forward error control (FEC)nencoded data streams is studied for linear multiple access channels,nsuch as code-division multiple access (CDMA). It is shown that suchnsystems can be viewed as serially concatenated coding systems, and thatniterative soft-decision decoding can be performed successfully Tonimprove power efficiency, powerful FEC codes are used. These FEC codesnare themselves serially concatenated. The overall transmission systemncan be viewed as the concatenation of two error control codes with thenlinear multiple access channel, and soft-decision decoders are used atneach stage. A variance transfer function approach applied to thenanalysis of this system captures the role of the component decoders innan overall iterative decoding system. We show that this approach forms anmethodology to study the effects of the component codes as well as thatnof the iteration schedule. Analysis and simulation examples arenpresented for transmission systems that operate close to the Shannonnlimit and illustrate the accuracy of the analysis