A so-termed chip-interleaved block-spread (CIBS) code division multiple access (CDMA) system has been introduced for cellular applications in the presence of frequency selective multipath channels. In both uplink and downlink operation, CIBS-CDMA achieves multiuser-interference (MUI) free reception within each cell. This paper focuses on the cellular downlink configuration and compares CIBS-CDMA against the conventional direct-sequence (DS) CDMA system, which relies on a chip equalizer to restore code orthogonality and, subsequently, suppresses MUI by despreading. We provide a unifying framework for both systems and investigate their performance in the presence of intercell interference and soft-handoff operation. Extensive comparisons from load, performance, complexity, and flexibility perspectives illustrate the merits, along with the disadvantages, of CIBS-CDMA over DS-CDMA, and reveal its potential for future wireless systems.
Bibliographical noteFunding Information:
Manuscript received February 7, 2002, revised September 9, 2002; accepted November 12, 2002. The editor coordinating the review of this paper and approving it for publication is Q. Bi. This work was supported in part by the ARL/CTA under Grant DAAD19-01-2-011 and by the National Science Foundation under Grant 0105612. This paper was presented in part at the International Conference on Acoustics, Speech, and Signal Processing (ICASSP), Orlando, FL, May 2002, and at the International Conference on Circuits and Systems (ISCAS), Scottsdale, AZ, May 2002.
- Cellular downlink
- Code division multiple access (CDMA)
- Frequency-selective channel
- Multiuser interference (MUI)