Two-Stage Random-Access Using Two-Hop Relay for Multi-Hop Systems

Yoichiro MIZUNO

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E89-A    No.10    pp.2630-2639
Publication Date: 2006/10/01
Online ISSN: 1745-1337
DOI: 10.1093/ietfec/e89-a.10.2630
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Information Theory and Its Applications)
Category: Spread Spectrum
4G,  multi-hop systems,  random access,  CDMA,  slotted-ALOHA,  

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Higher transmission rates are one of the main characteristics of the fourth-generation (4G*) of mobile communications. These systems are expected to operate at higher frequency bands, which experience larger propagation loss. This results in larger required transmission power, which causes several problems, particularly for uplink communications, as the typical mobile station (MS) has limited transmission power. Multi-hop systems have been proposed to address this problem. In this paper, we consider the issue of random-access (RA) in a multi-hop system. It is clear that a two-hop mobile communication system requires a two-stage RA process. In this paper, we propose a two-stage RA process that is an extension of the RA process of the CDMA-based 3GPP standard. The proposed method uses a hybrid of code division multiple access (CDMA) and Slotted-ALOHA. To realize the proposed two-hop RA, we dedicate one slot for second-hop transmissions in each interval (predefined); we refer to this as the interval slots allocation (ISsA) technique. Numerical analyses and simulations are conducted to evaluate its basic performance in a multi-hop system. The results demonstrate the superior throughput-delay performance of the proposed two-stage RA multi-hop system with ISsA.