動態分配頻譜:於多個無線系統環境中之頻譜的分配

Abstract

現今的無線通訊應用越來越多，但我們可以使用的頻譜資源卻是有限的。由於頻譜資源的稀少和珍貴，若是我們可以善加利用頻譜，則能提供更多無線應用服務給使用者。因此，我們提出頻譜分享的觀念。由於不同的無線網路業者的使用客戶會隨著時間和空間的不同而改變，若網路業者將暫時不需要的頻譜借給其他網路業者，則頻譜資源可以得到有效的利用。在本論文中，我們提出一個架構讓多個網路業者可以分享他們的頻譜資源。在此架構中，仲裁者(Arbiter)負責管理共有的頻譜資源，網路業者的經紀人(Broker)負責規劃頻譜的分配，並且跟仲裁者進行溝通以得到需要的共有頻譜資源。基地台頻譜資源管理者(Base_Station_Radio_Resource_Manager)需要偵測蜂巢(cell)內使用客戶的交通流量以利評估在各個區域需要多少頻譜資源。我們提出一個簡單的貪婪演算法來規畫頻譜分配，此演算法可以在有限的時間內得到足夠好的答案。在分配共有資源時，我們提出信用機制(credit mechanism)來解決多個網路業者競爭資源的情形。除此之外，我們所設計經紀人和仲裁者之間的溝通模式是有效且簡單的，即使業者不知道其他業者的資訊，依然藉由溝通而調整頻譜分配，讓所有蜂巢內的頻譜需求都被滿足。在兩個網路業者分享頻譜資源的情形下，我們跑的模擬結果顯示，共有資源可以被有效地高度使用，業者們所提供的服務品質(QoS)也因此提升。

While more and more wireless applications and devices are developed, the demand of spectrum has been increasing rapidly. However, the spectrum resource of a popular band is often limited. If multiple network operators share the spectrum in an effective way, the radio resource should be better utilized. We have thus proposed an architecture for multiple networks to partially share the spectrum, in which an Arbiter is recommended to centrally manage the shared band of the spectrum, a Broker is used to handle requests for the shared spectrum after making a plan of frequency assignment, and the Base_Station_Radio_Resource_Manager is made to be responsible of the prediction of regional demand. We have developed a credit mechanism in such architecture for the Arbiter to distribute the shared radio resource among networks, and a greedy algorithm for Brokers to make a plan of frequency assignment within limited time. Moreover, the recommended form of negotiation between Arbiter and Brokers is simple and effective. Although Brokers do not need to know any information of other networks, they can still adjust their frequency assignments to improve the network performance. In a 2 networks scenario, the results show that the shared resource can be highly utilized so that the performance of both networks with spectrum sharing is better than that without spectrum sharing.