In a multiuser CDMA system of DSSS, all transmitters are at equal distances from the receivers. The additive white Gaussian noise density Sn(f) = 5x10^-7 W/Hz. BPSK is used by all users with bit rate = 16 kb/s. There are 16 users.
(a) Assuming that the spreading codes Ci for the users are orthogonal, find the desired user power signal Pi to achieve Bit Error Rate = 10^-5.
(b) Now assume that the spreading codes are not orthogonal, specifically: Ri,i = 1 and Ri,j = -1/16; i does not equal j. Determine the required user signal power to achieve the same BER (10^-5).