Performance of multicarrier DS-SS with imperfect carrier phase on multipath Rayleigh fading channels

We analyze the bit error performance of multicarrier direct-sequence spread spectrum (DS-SS) systems with imperfect carrier phase on multipath Rayleigh fading channels. We consider the phase errors arising from the receiver phase locked loops (PLLs) on the individual sub-carriers to be Tikhonov distributed. We derive a simple upper bound on the average bit error probability by approximating the phase error loss function by a staircase function. We show that the bound is inexpensive to compute and is reasonably accurate. We present the effect of imperfect phase coherence on the bit error performance under various channel and system conditions.