廣義的機會式通訊---無線行動網路中之競爭、合作與感知---子計畫四：感知無線行動網路之協力式媒體存取控制協定設計與用戶/基地台選取研究

Abstract

感知無線網路（Cognitive Radio Networks）和協力無線通訊（Cooperative Wireless Communication s）是近年來新興起的無線通訊技術。在感知無線網路中，通訊設備必須 能夠智慧地感知週遭通訊環境中所有的頻譜機會（Spectrum Opportunity），並將讓使用 者能適當地分享所感知到的頻譜機會，以達到頻譜最佳化的利用。而協力無線網路的基 本構想在於協調各節點分享自己的天線，藉由傳送端或接收端的協力合作，形成一個虛 擬的天線陣列。如此將使系統中單天線的節點也能獲得MIMO (Multi-Input Multi-Output，多輸入多輸出) 系統的好處。因此，在感知協力式網路中，利用智慧型感 知技術找尋閒置的可用頻帶，並協調用戶或是基地台彼此共同協力傳送，將可更進一步 地提升整體頻譜使用效率、增大涵蓋範圍 (Coverage)、降低功率消耗、並提供可靠之高 速率傳輸。 在本計劃中，主要是針對異質感知協力無線系統，探討各種形式的感知協力網路架 構。此子計劃三年的工作將包括三方面: .. 第一、 針對具有多頻道的感知傳輸隨意(Ad hoc)網路中，發展分散式協力媒 體存取控制，以改善無線網路整體容量、涵蓋範圍、以及降低功率消耗。 .. 第二、針對多個細胞系統(Multi-Cellular System)，研究如何協調多個細胞的基 地台，藉著合作傳輸來減少傳送時基地台之間相互的干擾。 .. 第三、 研究如何利用具有位置感知優點的超寬頻無線系統，幫助協力無線網 路中決定最佳的協力夥伴。將更進一步結合時間- 空間- 頻率 (Space-Time-Frequency, STF) 編碼技術和網路資訊混合(Network Information Mixing) 技術，以增強感知協力網路中之涵蓋區及系統容量。

Cognitive radio (CR) networks and cooperative wireless communications are emerging wireless communication technologies. In CR networks, the users can intelligently sense, learn, and identify all the possible spectrum opportunities, and share the spectrum opportunities properly to achieve the optimal spectrum efficiency. In cooperative wireless networks, all users will share their own antennas to form a distributed antenna array in either transmitter-cooperation or receiver-cooperation fashion. By doing so, even if each user has only one antenna, the single-antenna users can reap the benefits of MIMO (Multi-Input Multi-Output) systems. Combining these two emerging technologies can further improve overall spectrum efficiency, enhance the coverage, reduce the power consumption, and provide reliable high data-rate transmission. In this sub-project, the main goal is to investigate the appropriate network architecture for heterogeneous cognitive cooperative wireless systems. Specific tasks include three folds: .. First, we will design a distributed cooperative medium access control (MAC) protocol to improve the capacity, coverage, and power efficiency in a CR-based multi-channel ad hoc network. An optimal partner selection algorithm based on the CSMA-type cooperative MAC will be developed. .. Second, we will investigate how to develop base station coordination mechanism to mitigate the inter-cell interference in a multi-cellular system. Multiuser scheduling and base station coordination will be designed jointly to optimize the overall throughput for cooperative wireless networks. .. Third, we will also examine how to exploit the location-awareness of UWB cognitive radio in determining the optimal partner and enhancing performances for cooperative wireless networks. We will incorporate the STF (Space-Time-Frequency) coding and network information mixing techniques to improve the coverage and capacity performances for cognitive cooperative networks, respectively.