在感知無線電網路支援差異化服務的研究

The Study of Supporting Differentiated Services in Cognitive Radio Networks

感知無線電是以不干擾主要系統傳輸為原則的跨系統資源分享網路。目前研究大多以頻譜偵測、頻譜管理、頻譜分享及媒體存取控制層設計等為主，鮮少探討在感知無線電網路上提供差異化服務的議題。本篇提出一方法研究在TDMA(Time Division Multiple Access, 分時多重存取)排程存取的主要系統中，根據不同服務設定基本值(Basic Value, BV)並計算出隨機等待時間(Waiting Time, WT)，來探討感知使用者在語音及數據服務類型下，使用主要系統資源的差異，以確保高優先權使用者的服務品質及避免感知使用者同時使用通道的碰撞問題。研究結果顯示，採用BV 方式能確保高優先權服務在使用系統資源上的優先性。此外，所提方法能比競爭機制有更高的通道存取率及產出。

Cognitive radio network promises an effective way of enhancing spectrum usage by exploiting the unused resources of primary system, while not interfering with the transmission of primary users. Previous works are mainly focused on spectrum sensing, spectrum sharing, primary user detection, and MAC design. Few works are performed on the issues of supporting the differentiated services in cognitive radio networks. In this paper, we proposed a mechanism to guarantee the QoS of high priority users for the integrated services in cognitive radio network. Through the concept of random waiting time with priority, high priority traffic can issue channel request to base station earlier than low priority traffic, ensuring preferential channel access. The results showed that the proposed scheme can ensure high priority services having priority access to the system resources. In addition, the proposed scheme can achieve higher channel access probability and throughput than competitive mechanism scheme.