1. Multi User Detection for CDMA Group Members: -Bhushan G. Jagyasi -Bhushan G. Jagyasi -Himanshu Soni -Himanshu Soni

2. Multiple Access Interference(MAI) Conventional Detector b 1 (.) b 2 (.) b n (.) g1 g2 gn Modula- tion AWGN Modula- tion b^ 1 (.) b^ 2 (.) b^ n (.) g1 g2 gn Decision Reciever / Detector Noisy Channel r(t) Received signal, r(t) = b1g1f1+ b2g2f2+ ……bngnfn + n(t) After detector y(t)=b^1(t) = b1.g1.g1. f1+ b2.g2.g1.f2+ ……bn.gn.g1.fn + n o.g1 y(t) = b1 f1 + MAI + z k

3. Actual Problem y(t) = b1. f1 + MAI + zk Total Interference (Includes interference due to other cells also) I = I MAI + f I MAI where f= Ratio of other cell MAI / I MAI Near Far Problem in CDMA Difficulty to implement more sophisticated algo at receiver because of limitations of size, cost, weight of handset. Solutions to all such problems is Multi-user detection 0

4. Genre of Multi-user detctors NonBlind Multiuser detection algorithm –Detectors Available Linear Detector (LMS based) Subtractive interference canceller –Requires following information Spreading waveform of desired signal Spreading waveform of interfering signal Timing (pd) of desired signal Timing (pd) of interfering signal Training data for every active user Drawback –More Computational complexity. –Requires much more information.

5. Genre of Multi-user detctors Blind multiuser detection algorithm –Detectors Available Kalman based –Requires following information Spreading waveform of desired signal Timing (pd) of desired signal Turbo MUD: –Joint channel decoding and MUD using iterative exchange of information between two processes.