（南京郵電大學信號處理與傳輸研究院 南京 210003）
摘 要：目前對認知無線電的研究，都是基于次用戶具有認知能力的前提，即假設次用戶可以進行頻譜感知和頻譜接入，但當前普遍使用的無線通信設備不具備認知功能，因而無法共享授權頻譜。本文介紹了一種新的解決方案，引入了中介節點，即認知中繼，可以進行頻譜感知和管理頻譜，并且擇機為主用戶傳輸或次用戶傳輸提供協作，目標是在保持主用戶鏈路傳輸速率不變的條件下，次用戶鏈路吞吐量最大化。該方案的主要特征是，認知中繼使用的協作機制結合了協作傳輸和協作中繼，可以獲得空間分集和頻譜分集增益。仿真結果顯示，在提高次用戶可達速率方面，我們提出的方案明顯優于傳統認知無線網絡，是一種適合當前無線系統進行頻譜共享的有效方案。
關鍵詞：認知無線電網絡；認知協作中繼；協作分集
中圖分類號：TN92
Improved Cognitive Cooperative Relaying
Zhang Hong
(Institute of Signal Processing and Transmission, Nanjing University of Posts and Telecommunications, Nanjing 210003)
Abstract: Previous works about spectrum sharing in licensed band are all based on a default assumption that the secondary users are equipped with cognitive radios, which enable them to accomplish the spectrum sensing and the ensuing spectrum access. Unfortunately, current wireless communication devices generally lack any functionality of cognition. It is rather challenging to enable such wireless devices to share spectrum with licensed primary systems. As a promising solution, in this paper, we propose a scheme called cognitive cooperative relaying, which introduces a kind of intermediate node, i.e., the cognitive relay, who senses the spectrum activity ，also serve the spectrum policy and then opportunistically relays the primary or secondary signal so that the transmission rate of the primary link will keep constant, while that of the secondary link will be maximized. The key feature of the proposed scheme is that, the cognitive relay combines cooperative transmission and cooperative relay，as a result, both spatial diversity and spectrum diversity can be obtained. Simulation results show that, in terms of achievable rate of the secondary user, the proposed spectrum sharing scheme significantly outperforms the conventional one where the secondary user is configured with cognitive radio, which validates a new way of spectrum sharing for current wireless systems.
Key words: cognitive radio networks ; cognitive cooperative relay; cooperative diversity
作者簡介
張紅（1981-），女，南京郵電大學信號與信息處理專業碩士研究生，研究方向為無線通信與信號處理。
