Spectrum Sharing in DS-CDMA and MC-CDMA

Speaker: Ali Pezeshk
Time: Thursday 1:05-1:55pm, 12/11/2003
Place: EERC 226

Abstract:

The performance of hybrid FDMA/DS-CDMA and MC-CDMA is studied in a cellular system with a simple intra-cell inter-vendor spectrum sharing algorithm. Their performance is then compared both with each other and a system without sharing. The comparison is based on the following performance measures: a) total bandwidth efficiency, b) average call blocking rate, c) average spreading code change rate, d) total revenue and e) implementation complexity. Both systems improve the spectrum utilization compared to the system without sharing. MC-CDMA is seen to have better performance than DS-CDMA with higher complexity and implementation cost. An important problem associated with inter-vendor spectrum sharing in MC-CDMA systems is the code change rate of all users whenever a user arrives or departs the system in order to keep maximum number of channels available for sharing at each instant of time. A novel approach for mitigating the rate of change in system spreading codes is introduced by dividing all subcarriers available in MC-CDMA into groups called clusters. Using the proposed method, code change affects just a single user at a time. Spectrum sharing (SS) performance of the system in terms of bandwidth efficiency, blocking rate and bit-error-rate (BER) performance are studied and compared for various cluster sizes.

References:

• Ali Pezeshk and Seyed A. Zekavat, “Inter-vendor spectrum sharing in DS-CDMA and MC-CDMA systems,” accepted in IEEE 37th Asilomar conference on Signals, Systems and Computers, Nov. 9-12, 2003.
• Ali Pezeshk and Seyed A Zekavat, “Intervendor Spectrum Sharing in MC-CDMA Systems Using Subcarrier Clustering,” accepted in 2003 Wireless Networking Symposium, Oct 22-24, 2003, The University of Texas at Austin.