Proposal of Combined Multi-Level Modulation Methods on Wireless Access Networks and Its Application Effects

Hitomi TERAOKA  Masahiro NISHI  Teruaki YOSHIDA  

IEICE TRANSACTIONS on Communications   Vol.E86-B   No.2   pp.777-784
Publication Date: 2003/02/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Terrestrial Radio Communications
multi-level modulation,  wireless access networks,  micro-wave frequency band,  antenna directivity,  identical frequency reuse,  

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In wireless access system, we need to use a limited frequency and electric power efficiently. And so we propose the fixed wireless access network using 5 GHz frequency which band has a good propagation performance in line of sight (LOS). In the proposed network, the several multi-level modulation methods are combined and identical frequency is reused by considering on the antenna directivity. As constructing this network, we can efficiently use frequency in 5 GHz band and enlarge system capacity. In this paper, it is assumed that user terminals are distributed nonuniformly over the service area. We analyze accommodation number of user terminals and the optimum combination of modulation methods. Numerical results show that most effective method is the combination of 16QAM and 256QAM, which can accommodate up to about 1.4 times as many users as only QPSK modulation method.