感知無線電頻譜管理之交易策略研究

A Study on Trading Strategy for Spectrum Management in Cognitive Radio Networks

目前無線通訊業務需求的快速增長，可用頻譜資源變得越來越稀少。隨著通訊技術不斷進步，民眾上網的方式越來越多樣化，上網環境不再受到時間和地點拘束，應用服務也日趨豐富多元，因此無線服務的需求日益增加，有效的資源管理成為最重要的一部分。主要頻譜和次級頻譜使用的差異化是感知無線系統特有的法則，為了解決頻譜利用率低才有感知無線電的提出。感知無線電網路的主要概念是利用無線頻譜上的感知，使頻譜壅塞時，尋找週遭環境可使用的頻譜，暫時使用此空閒的頻譜完成通訊的目地，使得整個無線資源的利用率達到最佳化，由此感知無線電網路將會是未來無線通訊發展的重要主軸，本論文先針對此議題作初步的相關背景介紹，並利用交易機制來達到頻譜管理的效果。透過頻譜交易的機制，將閒置頻譜出售使主要使用者獲得相對收益，而次要使用者購得閒置頻譜進而使用來提高頻譜的使用率。在研究中我們使用的競價策略有英式拍賣、公開申購及契約，並探討此競價策略在供不應求、供過於求、供求相等所得到的頻譜使用率及收益結果。研究結果顯示英式拍賣所使用競標次數最多但可獲得最高的頻譜利益;公開申購對於短期的頻譜使用率為最好;契約所使用的競標次數最少且對於長期的頻譜使用率為最好。

With the growing demands for wireless services, more and more resources are needed for scarce spectrum. Besides, with the advance of communication techniques, there are diverse ways for Internet access. Therefore, effective radio resource management plays an important role in fulfilling the increasing demands of wireless users. The cognitive radio technique has been proposed to solve the problem of low spectrum utilization. The main concept of cognitive radio network is to utilize the cognition of wireless spectrum. While the spectrum is congested, secondary users can search their surroundings for available spectrum and then utilize the idle spectrum to complete the data transmission. In this study, we will investigate the trading mechanisms for the spectrum management. The bidding strategies include the English auction, public purchase, and contract. This study discusses the spectrum utilization and bidding benefits under the condition of short supply, glut, and supply and demand balance for the bidding strategy. The results show that the English auction strategy has the highest spectrum benefit at the expense of frequent competitive bidding. Public purchase strategy will be the best bidding strategy in terms of short-term spectrum usage. On the other hand, the contract strategy has the lowest number of competitive bidding, and could obtain the highest utilization in terms of long-term spectrum usage.