結合頻譜分配與傳送機率於感知無線網路

Abstract

感知網路中目前可分成三個主要的運作模式和相關研究主題，包含軟體定義無線電、頻道感測和頻道管理。在本篇論文中，我們著重在頻道感測與頻道存取，提出了一套在802.11無線網路環境下感知網路中的同步頻道感測與存取。此套機制包含了兩種階段：快速頻道感測及釋放頻道。一對感知網路使用者可藉由快速頻道感測從目前可使用的頻道中，取得成功傳送機率高的頻道，進而傳送資料；主動釋放頻道是讓感知網路使用者察覺主要使用者要使用頻道時，能快速的釋放頻道給主要使用者，避免干擾。我們更利用頻道跳躍序以減少平均頻道感測時間。經由模擬值的結果，我們所提出的方法，可以有效的利用頻道及減少主要使用者的等待時間。

There are three main operator types and research subjects in cognitive radio systems, consisting of software define radio (SDR), channel sensing and channel management. In this paper, we focus on a channel-sensing and accessing and a synchronized channel-sensing and accessing for cognitive radio users in IEEE 802.11 wireless networks is proposed. The mechanism consists of two phases: fast channel sensing and channel vacating. A pair of cognitive radio users can search an available channel with the most success transmission probability from those available channels presently and further proceed to transmit data by fast channel sensing time-efficiently; proactive channel vacating is for the pair of cognitive radio users to be aware of the presence of primary users and vacate the occupied channel as quick as possible. We utilize the concept of channel hopping to reduce the average channel sensing time of cognitive radio users. Besides, we propose one equation to decide how to set TXQ (the bounded time interval during which a CR user can send as many frames as possible) by PU traffic load and make the caused interference to primary users within tolerable range. We further evaluate the performance of a considered cognitive radio network through simulations. From the simulation results, our proposed protocol can efficiently balance the tradeoff between throughput performance of a cognitive radio network and waiting time of primary users.