A NOVEL CDMA MULTIUSER INTERFERENCE CANCELLATION RECEIVER WITH REFERENCE SYMBOL AIDED ESTIMATION OF CHANNEL PARAMETERS

A novel multistage successive interference cancellation scheme is prop osed which operates on the reverse code-division multiple-access (CDMA ) link using binary phase shift keying (BPSK) modulation, coherent det ection and reference symbols to obtain channel estimates. The results of a single cell multiuser investigation demonstrate increased traffic capacity. However, this increase is initially very moderate due to co rruption of the channel estimates by interference from symbols not get demodulated and cancelled. A modification in the transmitted signal s tructure addressing this problem is proposed. The results of a single cell analysis of the modified cancellation scheme demonstrate that the system's traffic capacity reaches approximately 80% of that of a mult istage successive interference cancelling receiver operating with the perfect knowledge of channel parameters. Subsequent multicell investig ation shows that for hexagonal cell geometry with path loss exponent o f four and without any forward error correction (FEC) coding or cell s ectorization, capacity of the system compares very favorably with that of the IS-95 system, which employs powerful error control coding. Cap acities with other path loss exponents and cell geometries are also in vestigated. The results show substantial traffic capacity increase ove r that of a comparable receiver without interference cancellation.