Blind Channel Estimation and Signal Detection for Direct Sequence(DS) Code Division Multiple Access (CDMA) Systems Employing Long Spreading Codes

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ABSTRACT0207931Xu, Zhengyuan U of California - RiversideThe rapid evolution of the global information society has been fostered by the increasing demand for seamless wideband integrated services. The development of advanced communication technologies is becoming imperative to meet such a demand. Future desired services will range from the traditional voice and paging services to interactive multimedia, including high speed data communications. To support multiple bit-rate transmissions, direct sequence (DS) code division multiple access (CDMA) technology appears as an appealing solution due to the inherent merits of CDMA modulation. In DS spreading, the spreading sequence which will be adopted for next generation wireless systems will be aperiodic with period much longer than the bit duration. Employment of long codes bestows several benefits on the communication system. First, it increases the immunity of the system to multiuser interference (MUI) on the average because of less correlation of signature waveforms of different bits from different users. This leads to improved system performance. Secondly, spreading by long codes can uniformly distribute the signal bandwidth over the available spectrum, thus improving the bandwidth efficiency. In addition, longspreading codes provide end-users more secure communication and prevents interception by eavesdroppers.