廣義的機會式通訊---無線行動網路中之競爭、合作與感知---子計畫二：感知無線行動網路之協力式跨層設計

Abstract

在無線網路中協力式通訊是一種利用分散的空間資源的重要技術，然而，節點間的 合作關係及各節點在網路中的位置造成協力通訊系統在設計上的困難。而在有限的傳送 能量限制下，如何有效率的利用能量在訊源端與中繼端之間傳送訊號是一個非常重要的 議題，因此在設計任何可以提升網路服務品質的技術時，亦都必須考慮網路的分散特性。 另一方面，為了能夠有效率的使用網路資源，能夠自我重置（Reconfigurable）的感知式 （Cognitive）網路功能（例如軟體無線電）亦逐漸變成一種典型的策略。本子計畫目標 在設計各種能應付協力式網路特有問題的軟體無線電解決方案，於計畫第一年中，吾人 將從跨層設計的角度建立能有效利用能量的節點對節點傳輸策略，其結合了節點選擇與 最小化路由能量的功能。於第二年中，吾人將著重於分散式前置編碼（Precoding）法則 之設計，此舉除了可避免共通道的節點互相干擾外，亦可同時獲得訊號多樣（Diversity） 增益。最後，於第三年中吾人將針對資源分配最佳化之議題（如在通道已知的條件下進 行頻譜與能量分配）進行研析，以大福提昇全網路之服務品質。所有在本子計畫所提出 之方法皆能依網路環境（如通道狀況或鏈結通道之訊雜比）適應性地進行調整，因此能 自然地使用軟體無線電實現，使得吾人所提出的方法能更適用於未來的無線通訊網路。

Cooperative communication is a key technique to exploit the distributed spatial resource for data-rate-boosting & link-quality-improvement in modern wireless Ad-Hoc networks. However, user cooperation together with the distributed nature of node location imposes unique design challenges in this scenario. Indeed, subject to the limited power budget of battery-driven user terminals, energy-efficient information transmission/exchanging between source and relays is rather crucial. Also, any feasible schemes for enhancing network-wide QoS must specifically take into account the underlying distributed network architecture. On the other hand, self-reconfigurable cognitive network functionality via, e.g., software-defined-radio (SDR) principle, has become a typical strategy for efficient radio resource exploitation. This subproject aims to devise prospective solutions which are capable of tackling the design concerns of cooperative networks, and can also be cast into an SDR based architecture. In the first year we will develop energy-efficient node-to-node information transmission strategies from a cross-layer perspective which specifically combines, e.g., antenna (node) selection and minimal energy routing. Afterwards the study will focus on effective distributed precoding for interference mitigation as well as for signal diversity enhancement. Finally, we will address the issues of optimal resource allocation, e.g., in a channel-aware bandwidth/power allocation setup, toward an utmost promotion of the global QoS performance. All the developed solutions in this project are adaptive to the network radio environments, e.g., channel spatial correlation and link SNR etc.; this naturally leads to an associated SDR based self-reconfigurable cognitive system implementation, thus making the proposed scheme a practical solution for future wireless communication networks.