An internally coded partial-band DS-CDMA system and its performance analysis

We propose a new partial-band DS-CDMA scheme for UWB communication systems, which is based on frequency-hopping (FH) and direct-sequence (DS) spread spectrum techniques. The total bandwidth is divided into N_s subbands. The output of a super-orthogonal encoder and a pseudorandom (PN) sequence select one subband, in which the user´s data is sent in the form of DS-CDMA signal using the second PN sequence. We consider soft detection at the receiver front end. We obtain the upper and lower bounds on the bit error rate for the proposed method. For comparison, we also consider the conventional DS-CDMA system. It is shown that the proposed multiple access method outperforms the conventional DS-CDMA system significantly without requiring any extra bandwidth.