Multi-user Extension of Low-Power-Density Baseband Radio Based on Frequency-Domain Differential Coding for Spectrum Spreading

Jin NAKAZATO  Yoshio KARASAWA  

Publication
B - Abstracts of IEICE TRANSACTIONS on Communications (Japanese Edition)   Vol.J101-B   No.2   pp.100-110
Publication Date: 2018/02/01
Online ISSN: 1881-0209
Type of Manuscript: Special Section PAPER (Special Section on Student Research)
Category: 
Keyword: 
adaptive radio communication,  baseband radio,  low power density communication,  spread spectrum communication,  

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Summary: 
In a secondary-user communication system under the existence of primary-user systems, the target of this paper is to realize an “adaptive baseband radio” that could be collectively used vacant frequency bands (so-called white space) dispersed in wide radio-frequency range based on digital signal processing. In our previous paper, we proposed low-power-density baseband radio with frequency-domain differential spreading code and demonstrated the principle of single-user case. In this paper, we propose an extended method to a multi-user system where each user link has different delay spread and quantitatively evaluate the system performance through computer simulation. For the multi-user application, it is necessary to clarify the relationship between the propagation environment and the transmission characteristics of a single-user case, in particular, the BER characteristic depending on the relationship between the subcarrier bandwidth and delay spread, and we investigate the detailed performance. Furthermore, based on the evaluation results in the single-user case, we propose a multi-user transmission scheme where each user link has different delay spread. Computer simulations show the validity and effectiveness of the proposed method.