多層式網路中具統計性服務品質保證之感知無線資源管理

Cognitive Radio Resource Management for Statistical QoS Guarantees in Multi-tier Networks

連紹宇(Shao-Yu Lien)

指導教授 ： 陳光禎

國立臺灣大學/電機資訊學院/電信工程學研究所/博士(2011年)

https://doi.org/10.6342/NTU.2011.00181

摘要

為了滿足下一代通訊系統對於極高傳送速率之要求，擴展通訊頻寬與縮短傳送端與接收端之距離已被視為提升傳送速率之有效方法。此對於極高傳送速率之要求促進了(i)佈建覆蓋於傳統大型網路上之毫微微網路與微微網路之異質網路架構成為一個多層式網路與(ii)全域頻率複用與(iii)載波合併技術之發展。然而，若沒有一個有效的無線資源管理機制，將全域頻率複用使用於異質網路架構將因網路間的干擾而使得通訊無法進行。基於潛在的高計算複雜度問題，中央控管式的資源分配是不合適於下一代通訊系統的方法。不僅止於此，能否提供服務品質保證是一個成功的無線通訊系統之關鍵。因此，如何在每個網路中個別消除干擾並提供服務品質保證成為下一代通訊系統最嚴峻的挑戰。
受到感知無線電技術讓每個通訊裝置皆具備感知並適應周遭通訊環境之能力的啟發，在此論文中，一個感知無線電資源管理架構將被提出。藉由所提出的感知無線電資源管理架構，第二層網路可以感測第一層網路的無線電資源使用情況並進而適應第一層網路，此技術解決了下一代網路最重要的網路擴展性問題。將所提出的感知無線電資源管理架構應用於毫微微網路，將能提供最重要的服務性品質保證。基於此感知無線電資源管理架構，進而提出一個以賽局理論為基礎的無線電資源管理以解決第二層網路中之網路間干擾問題。然而，在此架構背後有一個重要的假設，所有的第二層網路皆須與第一層網路同步。因此，一個網路同步演算法被提出用來解決此多層式網路上的網路間同步問題。為了更進一步將感知無線電資源管理架構應用於具有較大涵蓋範圍之微微網路，壓縮感測理論被用來提出一個以頻譜圖為基礎的無線電資源管理。因此，多層式網路間的感擾問題可被所提出的完整解決方案所有效的解決。
為了更進一步將第一層網路的使用頻寬擴展到ISM band上，來自於ISM band上既有通訊系統（例如WiFi）的干擾必須被有效的消除。為解決此問題，感知無線通道存取技術被用於第一層網路以共存於WiFi。然而，感知無線通道存取將導致通道可用性的嚴重變動使得提供服務性品質保證成為嚴峻的挑戰。為了降低通道可用性的嚴重變動，網路多輸入多輸出技術近年來受到相當的重視。為了解決第一層網路上網路多輸入多輸出技術的兩大挑戰：(i)一個有效的封包傳送控制機制與(ii)一個有效的無線資源分配機制，所提出的統計性流量控制機制將有效提供第一層網路最重要之服務品質保證。

關鍵字

異質型網路 ； 全域頻率複用 ； 豪微微網路 ； 微微網路 ； 服務品質保證 ； 干擾消除 ； 感知無線電資源管理 ； 賽局理論 ； 壓縮感測 ； 網路同步 ； 統計流量控制

並列摘要

To satisfy the extreme high data rate requirement of the next generation cellular system, extending the available communications bandwidth and shortening the distance between the transmitter and the receiver have been regarded as effective means to further enhance the data rate in the cellular system. Such a requirement motives the developments of (i) the heterogeneous network architecture to deploy femto- cells and picocells overlaying the conventional Macrocell as a multi-tier network to shorten the distance between the transmitter and the receiver, (ii) the universal frequency reuse resource utilization scheme and (iii) the carrier aggregation technology to further extend the available bandwidth. However, without an effective radio resource management scheme, applying the universal frequency reuse to the heterogeneous network architecture may fail all communications due to severe inter-cell interference. Due to a potentially high computational complexity, it is infeasible to apply centralized resource managements to the next generation cellular system. In addition, providing quality-of-service (QoS) is the key for a successful wireless communications system. As a result, the most critical challenge lies in that inter-cell interference mitigation as well as QoS provisioning shall be autonomously achieved by each "cell" in the next generation cellular system.
Inspired by the cognitive radio technology that enables a communication station to autonomously sense and adapt to the surrounding communications environment, in this dissertation, the cognitive radio resource management framework is proposed. By the proposed cognitive radio resource management framework, the second-tier network can sense the radio resource utilization of the first-tier network and adapt to the first-tier network, which provides the most important property of scalability for the next generation network. By applying the proposed cognitive radio resource management framework to femtocells, the most critical QoS guarantees provisioning is shown. Based on such a cognitive radio resource management framework,
a game-theoretical radio resource management is further proposed with the facilitation of game theory for the intra-tier interference mitigation of the second-tier network. However, there is one critical assumption under such a framework that all the second-tier shall synchronize to the first-tier. A network synchronization algorithm is consequently proposed to achieve this critical synchronization in the multi-tier network. To further generalize the cognitive radio resource management
framework to picocells with larger coverage areas as compared with that of femtocells, the spectrum map based radio resource management scheme is proposed with the facilitation of the compressed sensing theory. Consequently, cross-tier interference as well as intra-tier interference can be effectively mitigated autonomously by
the proposed complete solution for the second-tier.
To further extend the bandwidth of the first-tier by leveraging the ISM band, interference of the legacy system deployed on the ISM band (such as WiFi) shall be mitigated, which derives the development of the cognitive channel access for the first-tier to coexist with the legacy system. However, cognitive channel access results in severe variation on channel availability and poses a critical challenge to provide QoS guarantees. To alleviate end-to-end channel availability variation, a powerful means known as network multiple-input-multiple-output (MIMO) in cellular systems is particularly noted. To tackle two critical obstacles in the first-tier by leveraging
network MIMO transmissions, (i) an effective packet transmissions coordination and (ii) an e±cient radio resources allocation, the statistical tra±c control scheme
comprising packet transmission scheduling and admission control are consequently proposed to enable guaranteed QoS for the first-tier.

並列關鍵字

heterogeneous network ； universal frequency reuse ； femtocells ； picocells ； QoS guarantees ； interference mitigation ； cognitive radio resource management framework ； game theory ； compressed sensing ； network synchronization ； statistical traffic control

參考文獻

[1] W.-C. Ao and K.-C. Chen, End-to-end HARQ in cognitive radio networks,"

in Proc. IEEE WCNC, 2010.

[4] 3GPP TS 36.300 V10.0.0, Evolved universal terrestrial radio access (E-UTRA)

and evolved universal terrestrial radio access network (E-UTRAN)," June 2010.

works part 16: air interface for broadband wireless access systems," in revision