Avoidance of Hidden Terminal Problems in Cluster-Based Wireless Networks Using Efficient Two-Level Code Assignment Schemes

Chyi-Ren DOW
Cheng-Min LIN
Da-Wei FAN

IEICE TRANSACTIONS on Communications   Vol.E84-B    No.2    pp.180-190
Publication Date: 2001/02/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technology
multi-hop wireless networks,  clustering,  hidden terminal,  code assignment,  CDMA,  

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To enhance throughput and reuse bandwidth, clustering techniques can effectively manage nodes in multi-hop wireless networks. However, in such networks, hidden terminal interference degrades the system performance and increases the average packet delay time. Therefore, this work presents novel two-level cluster-based code assignment techniques to resolve the hidden terminal problems. At the low level, five basic and an optimized intra-cluster code assignment schemes are developed to calculate the number of codes used in each cluster. At the high level, two inter-cluster code assignment schemes (coarse-grained and fine-grained controls) are proposed to obtain the minimal number of code sets. The merits of our schemes include low execution time, low probability of code re-assignment, and low overhead. Furthermore, the proposed schemes allow us to regionally update orthogonal codes when the topology varies. Experimental results demonstrate that the proposed schemes outperform conventional techniques. Among the five basic intra-cluster code assignment schemes, the ordering criteria of increasing number of one-hop neighbors is the best in terms of the number of orthogonal codes to avoid hidden terminal interference. The optimized intra-cluster code assignment scheme generally obtains fewer orthogonal codes than other schemes. For inter-cluster code assignment schemes, the coarse-grained control has a lower code allocation time. However, the fine-grained control requires fewer orthogonal codes.