Macroscopic Diversity Combining Technique for Forward-Link of CDMA Cellular Systems

Yuh-Ren TSAI

IEICE TRANSACTIONS on Communications   Vol.E90-B    No.1    pp.69-77
Publication Date: 2007/01/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e90-b.1.69
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Terrestrial Radio Communications
code division multiple access,  spread spectrum communication,  soft-handoff,  macroscopic diversity,  

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In CDMA cellular systems, the frequency reuse factor equals one. Therefore, the soft-handoff technology with combining macroscopic diversity was introduced to enhance the link performance. In this work, a novel macroscopic diversity combining scheme is proposed to enhance the link performance of the forward-link. The basic concept of this scheme is to integrate error correction coding into the soft-handoff technology. According to the number of soft-handoff channels, the source information is encoded by a convolutional code with a lower code rate. The coded symbols are then equally distributed to all channels from different BSs to the MS, and each channel carries a disjointed set of coded symbols. For this proposed scheme, no extra transmission power or bandwidth is required. The only cost is a slight increase of the encoding and decoding complexity of the convolutional codes. Numerical and simulation results show that a performance gain of 1 dB in bit energy-to-total noise power density ratio can be obtained as compared with the conventional scheme in the same conditions.