FPGA Central

I am looking for the Cramer Rao lower bound(CRLB) of a CDMA system.

I have got a single user system with multipath and I want to estimate th
number of multipath components (L) and its propagation delays (tau_l).

The System model is the following:
The input of the unknown channel h[n] is a known PN Sequence u[n]. Th
channel makes the convolution of u and h and some white Gaussian noise i
added. Finally the signal is passed through a matched filte
(h_m[n]=u*[n]).

u[n] ... known PN sequence with the length N
h[n] ... Channel impulse response
n[n] ... with Gaussian noise
L
h[n] = sum w_l driacDelta(n-tau_l)
l=1
with: L ... # of multipath comp.
tau_l ... time delay of the l'th multipath comp.
w_l ... complex gain of the l'th multipath comp.


the resulting signal is:
L
z[k]= sum w_l Ruu[k-tau_l] + Noise[k]
l=1

with: N
Ruu[k]= sum u[n]u*[n+k] ... auto correlation of u[n]
n=1

Noise[k] = Run[k] = u*n ... cross correlation of u[n] and n[n]


I am looking for the CRLB of z[k] with unknown tau_l and L. I am no
sure, if it is possible to calculate the CRLB for an unknown L so the CRL
for a known L would help me also a lot (even L=1 would be great).

Thanks a lot for all results for the CRLB and/or tipps how to caluclat
it.


best regards
Thomas Blocher

student of telecommunication
TU Graz Austria



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