感知無線電系統之可適性特徵波形設計

Abstract

近年來，隨著無線通訊技術的快速發展，無線電磁頻譜變成了一項珍貴的天然資源。許多研究和報告指出了非有效率使用頻寬的問題。感知無線電 (CR)，包括軟體無線電 (software-defined radio)，已被視為一種藉由發掘無人使用的頻譜，進而提升頻譜使用效率的工具。 在本篇論文中，我們將探討小波包封的特性，並且利用它們來設計感知無線電使用者的特徵波形。我們分別考慮了原註冊許可的使用者為正交分頻多工系統 (OFDM system) 以及小波包封多工系統 (WPDM system)，並且比較在感知系統中，對於頻率－時間平面不同的切割方式所造成的差異。 我們也提出一個演算法，根據所測量得到的干擾訊號去切割CR使用者的頻率－時間平面，並且與任意切割去比較其效果的差異。

Recently, with the fast development of wireless communications, the radio electromagnetic spectrum becomes a precious natural resource. Many researches and reports reveal the problems of inefficient spectrum utilization. Cognitive radio (CR), inclusive of software-defined radio, has been proposed as a means to promote the efficient use of the spectrum by exploiting the existence of spectrum holes. In this thesis, we discuss the properties of wavelet packet, and utilize them to design the signature waveforms of CR users. We consider that legacy users are Orthogonal frequency division multiplexing (OFDM) system users and Wavelet packet division multiplexing (WPDM) system users, respectively, and show the comparisons between the different tiling methods of Frequency-Time plane (F-T plane) of CR systems. We also propose an algorithm to tile the F-T plane of CR systems according to the measured interference, and compare the performances with those of arbitrary tiling of F-T plane.