A Spectrum-Efficient Multicarrier CDMA Array-Receiver with Diversity-Based Enhanced Time and Frequency Synchronization

Abstract

This paper proposes a spectrum-efficient spatio-temporal array-receiver for multi-carrier CDMA systems named MC-STAR. First, we derive a new post-correlation model for MC-CDMA that characterizes the structure of the channel in space, time and frequency. Based on this model, we introduce a new multi-carrier array-receiver with rapid and accurate joint synchronization in time and frequency. There, we exploit jointly the spatial, temporal and frequency diversities as well as the intrinsic inter-carrier correlation (termed hereafter frequency gain) to improve the channel identification and the synchronization operations. In addition, based on a new link/system-level performance analysis, with a band-limited chip waveform assumption, we provide a comparative performance study of MC-STAR over two multi-carrier CDMA air-interface configurations, namely MT-CDMA and MC-DS-CDMA, in the most realistic operating conditions. Link/system-level results confirm the advantages of MT-CDMA in increasing throughput and bandwidth efficiency. The current trend is to design radio air-interfaces with flat fading subcarriers. In contrast, with MC-STAR we show that the positive effects of multipath diversity and frequency gain over large strongly-overlapping subcarriers is more significant than the negative effects of multipath and multi-carrier interference.