Transmit array processing for cyclic-prefix CDMA

This paper explores the addition of frequency-domain transmit antenna arrays to the cyclic-prefix CDMA (CP-CDMA) system concept. CP-CDMA is a novel type of single carrier DS-CDMA that employs OFDM-style cyclic prefixes to facilitate efficient frequency-domain receiver processing in broadband CDMA cellular systems. CP-CDMA is intended for high-bandwidth, high-delay-spread cellular channels, such as those envisioned for systems that evolve from current 3G CDMA standards. This paper examines both single-data stream (i.e., maximal ratio transmission) and multiple data stream (i.e., spatial multiplexing also known as multiple-input, multiple-output or MIMO) techniques for CP-CDMA systems that operate with high code usage and multi-level modulation in broadband high delay-spread channels. In the proposed algorithms, both the transmit and receive array processing is performed completely in the frequency-domain to allow the tracking of frequency-selective MIMO channels. Simulation results are presented to show the efficacy of the proposed methods.