A Cognitive MAC Protocol Using Statistical Channel Allocation for Wireless Ad-hoc Networks

論文發表人：徐家俊(南加州大學電機系)

 

http://www.ieee-wcnc.org/2007/

 

配備認知型MAC通訊協定的無線裝置能隨機搜尋已分配頻寬中未使用或很少使用的頻率再加以利用,並在此一同時對原本的頻率使用者造成最小的影響.為實現此一目標,本研究提出利用統計原理分配使用頻寬的MAC通訊協定,稱為SCA-MAC.SCA-MAC是由CSMA/CA通訊協定為基礎加上以統計數據為頻率指定的判斷依據所構成的.在每一次傳輸時,傳送和接收兩方必須先在管理頻道(Control channel)上協商相關參數.傳送的成功率可事先經由本研究開發的理論模型加以評估.只有在通過此一協商的關卡後傳送和接收雙方才能在資訊頻道(Data channel)上進行通訊.傳輸效能可以透過此通訊協定的兩個參數加以控制:搜尋範圍(Operating range)和頻道集成(Channel aggregation).透過理論的分析和模擬實驗可確認SCA-MAC能提升處理量方面的表現同時將對原本頻率使用者的干擾維持在一可控制的範圍內.因為此一MAC通訊協定是根據CSMA/CA發展而來所以在無任何集中控制的狀況下亦可運作.

 

The MAC protocol of a cognitive radio (CR) device is supposed to enable the device to dynamically access unused or under-utilized spectrum without (or with minimal) interference to primary users. To fulfill such a goal, we propose a cognitive MAC protocol using statistical channel allocation and call it SCA-MAC in this work. SCA-MAC is a CSMA/CA-based protocol, which exploits statistics of spectral usage for decision making on channel access. For each transmission, the sender negotiates with the receiver on transmission parameters through the control channel. A model is developed for CR devices to evaluate the successful rate of the transmission. A CR device should pass the threshold of the successful transmission rate via negotiation before it can begin a valid transmission on data channels. The operating range and channel aggregation are two control parameters introduced to maintain the MAC performance. To validate our ideas, we conducted theoretical analysis and simulations to show that SCAMAC does improve the throughput performance and guarantees the interference to incumbents to be bounded by a predetermined acceptable rate. The proposed MAC protocol does not need a centralized controller, as the negotiation between the sender and the receiver is performed using the CSMA/CA-based algorithm.