Problem $3.,$ Consider the direct$-$sequence CDMA system as de$-$

scribed in Lecture $15.$ At the receiver suppose that instead of using the local

code $q_1(t)$ we instead use $q_1(t+)$ where $$ is some $+-$ fraction of a bit time,

i$.$e$.,$ the local code may be shifted one direction or the other. Compute the

degradation $($in $dB)$ to $\frac{E_b}{N_0}$ due to a nonzero $$ at the output of the corre$-$

lator for BPSK signaling. You may assume for the local code that adjacent

chips are equally likely to match or differ.

additional notes:Receiver CDMA Operations $($cont$.)$

Now, $d_i(t),i=1,2,$dots,$N$ is a constant $(+-1)$ over $T_b$ seconds.

Note that $q_1^2(t)=1.$

So$,$ for User $1$ we get $($ideally$)$

$\frac{1}{T_b}{\displaystyle \underset{0}{\overset{T_b}{}}}r(t)q_1(t)dt=d_1$

Where $d_1$ just denotes the constant value of $d_1(t)$ at any time in the bit interval

which is either $+1$ or $-1$ in the given $T_b-$second interval.

Each user repeats the above operations using their particular code.CDMA Receiver Block Diagram

CDMA Receiver