廣義認知無線網路的資源管理

Abstract

感知無線電網路由高優先級的主用戶和低優先級的次用戶組成。當主用戶不使用他們的許可頻譜時，次用戶可以暫時利用未使用的頻譜。廣義感知無線電系統應能運用所有可用頻道之不同頻寬，而當主用戶打斷時即應歸還所借的通道。

當中斷發生時，次用戶需從不同頻寬的通道中選擇一個新的操作通道，或在相同的通道等待，直到主連接完成其傳輸。因此，一個次用戶的連接在其傳輸過程中可能會執行多次切換或使用不同的路由。為了克服因主用戶打斷造成的潛在性能下降問題，可用資源管理技術來提高廣義感知無線電網路之性能。在本論文中，我們探討廣義感知無線電網路中資源管理的三個議題。

第一個議題是不同頻寬通道對頻譜選擇的影響。我們介紹了負載平衡頻譜選擇機制，用於具有各種頻寬通道的感知無線電網路。此負載平衡頻譜選擇機制是基於延遲與頻寬之乘積，從各頻寬通道中選擇合適的通道。

第二個議題是考慮多次頻譜換手中斷之影響。我們介紹了一個基於先占復原優先權 M / G / 1 排隊理論的分析架構。基於先占復原優先權 M / G / 1 排隊網路模型，我們可以評估多次換手與各種頻寬通道對整個系統的時間的影響。

第三個議題是考慮多個中間路由節點對決定路由路徑的影響。我們設計了一個決定有效路由的方法，以適應當主用戶出現在節點現有的路線時需頻繁建立新路由路徑之需求。此路由決定是基於選擇性路由機制的概念，並根據需要迅速選擇具有最低端到端延遲之路徑。

總結來說，本論文的主要貢獻是從宏觀視點並基於各種頻寬通道和多次主用戶打斷，調查廣義感知無線電網路之建模技術。我們所提出的分析框架可幫助分析感知無線電網路之性能，並在設計各種具有增強性能的資源管理技術時提供重要的洞見。

A cognitive radio (CR) network consists of the high-priority primary users and the low-priority secondary users. When the primary users do not use their licensed spectrum, the secondary users can temporarily utilize the unused spectrum. A generalized CR system shall be able to utilize all the available channels of various bandwidths, but shall return the borrowed channels whenever the active primary users interrupt. When the interruption occurs, the secondary connections need to select a new operational channel from various bandwidth channels or wait at the same channel till the primary connection ¯nishes its transmission. Consequently, a secondary user connection may execute multiple handoffs or use different routing paths during its transmission period. In order to overcome the potential performance degradation due to primary user interruptions, resource management techniques can be used to enhance generalized CR networks performance.

In this dissertation, we investigate resource management in generalized CR networks for three issues. The first issue is considering the effects of various bandwidth channels on spectrum decision. Thus, a load balancing spectrum decision scheme for CR networks with various bandwidth channel is introduced. This load balancing spectrum decision scheme is based on the concept of the delay bandwidth (DB) product to select suitable channel from various bandwidth channels. The second issue is to consider the effect of multiple interruptions on spectrum handoffs. Hence, an analytical framework based on the preemptive resumption priority (PRP) M/G/1 queueing theory is introduced. Based on the PRP M/G/1 queueing network model, we can evaluate the effects of multiple handoffs and various bandwidth channels on the overall transmission latency. The third issue is to consider the effects of multiple intermediate routing nodes on routing path decision. As a result, an effective routing decision design is introduced to adapt the frequent need to establish a new route path as primary user appears in the nodes of the existing route. This routing decision is based on the concept of selective routing mechanism to select the minimum end-to-end delay route as quickly as needed.

To summarize, the main contribution of this report is to investigate the modelling techniques for generalized CR networks from a macroscopic view-point based on the various-bandwidth channels and multiple primary user interruptions. The proposed analytical framework can help analyze the performances of CR networks and provide important insights into the design of various resource management techniques with enhanced performance.