正交分頻分碼多工接取系統之適應性無線資源管理

Abstract

正交分頻多工技術以良好的頻譜效益且具有抵抗多路徑衰減通道效應能力，成為未來高速無線傳輸技術主流；廣為採用的分碼多工接取技術在蜂巢系統具單一頻率重覆使用與軟式換手增益等多項優點，故兩種技術的結合現今已廣為討論研究。 為因應下一世代行動通訊系統提供高速資料傳輸速率與支援寬頻多媒體服務的趨勢，本論文研究針對正交分頻分碼多工接取系統提供多重服務型態下無線資源管理之領域進行研究。首先以OFDM技術為基礎，引入蜂巢架構的概念，設計無多工接取干擾的實體層系統。以此為依據，同時考量多項無線資源管理演算法效應：允入控制、封包排程、功率控制，建置支援使用者移動行為與高資料傳輸率需求的行動通訊系統模擬平台。接著從有效利用系統整體資源的觀點，在滿足使用者對服務品質的要求、所欲傳輸的資料量與延遲下，透過調變機制、編碼速率、展頻碼長度、子載波個數的調整，針對系統內使用者進行資源分配程序最佳化問題的探究，並在低複雜度與動態調整的考量下，提出以功率效益為基礎的資源分配演算法，得以在系統傳輸量略為減少下，大幅地節省系統運算量。最後，將探討通道品質資訊的回傳對系統負載的影響，並提出合理的資料壓縮回傳方式，以符合系統規畫時的設定。

The OFDM-CDMA benefiting from both OFDM (orthogonal frequency-division multiplexing) and CDMA (code-division multiple access) has merged as a powerful technology for next generation mobile multimedia networks. In this thesis, an air-interface architecture is proposed for next generation OFDM-CDMA forward link systems with flexible data rate provisioning and diversity usage and more importantly is MAI (multiple access interference) free. Based on the proposed air-interface architecture, potential radio resource management issues such as resource allocation, admission control, and packet scheduling are investigated, with emphasis on the adaptive radio resource allocation. The adaptations on modulation scheme, coding rate, spreading factor and number of sub-carriers are converged into data rate and power allocation in order to relate with quality of services (QoS). Meanwhile, a throughput-optimal radio resource allocation algorithm is proposed to maximize throughput and guarantee QoS for mobile multimedia OFDM-CDMA networks. With a proposed compression technique, we further explore the problem on reporting channel information in OFDM-CDMA systems.