感知無線電頻譜交易之效能分析

Performance Analysis of Spectrum Trading in Cognitive Radio Networks

無線通訊業務需求的快速增長，使得可用頻譜資源變得越來越稀少。有研究的結果顯示，雖然頻譜資源有限，但導致資源不足的原因是頻譜配置採取靜態配置的關係。一般認為感知無線電(cognitive radio, CR)是解決頻譜使用率不佳的一項關鍵技術。之前在感知無線電的研究大都聚焦在頻譜感測及頻譜分享等技術方面的議題，較少有研究探討頻譜分享在經濟方面的議題。本研究透過一個簡單分析模型探討感知無線電網路執行頻譜交易的收益與頻譜利用率的情形。研究結果顯示當主要系統的負載低時，允入次要使用者對系統收益及頻譜利用率的增幅較大。結果也顯示若主要使用者具有搶佔優先權，主要系統採用預留通道機制對系統的收益及頻譜利用率影響不大。

The growing demands for the wireless services lead to the insufficiency of available spectrum resources. Although the spectrum resources are limited, the main reason of the resource shortage is caused by the static spectrum allocation. Cognitive radio is considered one of the key technologies to solve the problem of low spectrum utilization. Most of the previous researches emphasized on the technical aspect of spectrum sensing and spectrum sharing. Few researches focused on the economic aspect of spectrum trading. In this paper, we proposed a simple analytical model to investigate the performance of spectrum trading in the cognitive radio networks. The analytical results show that when the traffic load of the primary system is low, accommodating the secondary users into the system will have large increment in system revenue and spectrum utilization. The results also show that if the primary user has preemptive priority, the channel reservation mechanism for the primary system will have little impact on the system revenue and spectrum utilization.