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Thursday, 12 July 2012

Multi User CDMA System Model

Let's have CDMA System with K Users indexed by j=1K. Let Each User Transmits BPSK Modulated Signal Simultaneously. Then the Transmitted Signal for one such User j can be Represented as:

Sj(t)=2Pjcj(t)bj(t)Cos(ωct+θj)
Where,

cj(t)=n=c(n)jpTc(tnTc)
is the jth User Signature Waveform, with the Signature bits

c(n)j1,+1


bj(t)=n=b(n)jpT(tnT)
 
is the BPSK Modulated Signal for User j


b(n)j1,+1
and

T=NTc
Where N is the Spreading Factor or Processing Gain. The Received Signal at the Receiver can be Represented as

r(t)=Kj=12Pjcj(tτj)bj(tτj)Cos(ωct+ϕj)+η(t)
Where τj is Relative Time offset and τj[0T]
ϕj is Phase Offset such that ϕj[02π]
and ϕj=θjωcτj
η(t) is Zero Mean AWGN Process with PSD N0



1 comment:

  1. Performance Analysis can be Obtained Using matched Filter Detection of Each User.Lets do the Detection for User 1.

    z1=T0r(t)c1(t)Cos(ωct)dt

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