טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentShai Waxman
SubjectIterative Multi User Detection of the IS-95 CDMA Uplink
Channel
DepartmentDepartment of Electrical Engineering
Supervisor ? 18? Shamai )Shitz( Shlomo


Abstract

A soft-parallel-multi-stage interference cancellation scheme combined with iterative decoding and channel parameters estimation is applied to the IS-95 uplink system. Simulations show that the number of active users can be significantly increased relative to conventional detection and interference cancellation schemes. For moderate load near-single-user performance is demonstrated in an additive white Gaussian noise (AWGN) channel and flat Rayleigh fading channel.

The interference cancellation scheme proposed increases the “capacity” (number of active users) by 66% in a worst case scenario where synchronous users with equal power and random rapidly varying carrier-phase are assumed. In other scenarios such as the unequal received power case where users amplitudes are Rayleigh distributed or where carrier-phase can be accurately tracked, number of active users is increased even further. In addition, the interference cancellation scheme low complexity, low latency and robustness in a variety of different types of channels, makes it attractive option for leveraging the IS-95 infrastructure and implementing it in other IS-95 based approaches such as CDMA2000.

Further investigation such be done to assess the performance in a multi-path environment where performance gain is expected to be similar.