請用此 Handle URI 來引用此文件:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/79001
標題: | 無線異質網路上流量卸載之研究 Traffic Offloading in Wireless Heterogeneous Networks |
作者: | Shi-Sheng Sun 孫士勝 |
指導教授: | 廖婉君(Wanjiun Liao) |
關鍵字: | 異質網路,流量卸載,基地台範圍擴展,傳輸功率調整,使用者連線,干擾消除, Heterogeneous Network,HetNet,traffic offloading,Cell Range Expansion,CRE,transmit power control,user association,Interference Cancellation, |
出版年 : | 2018 |
學位: | 博士 |
摘要: | 佈署由高功率大型基地台配合低功率小型基地台所組成的異質網路(HetNets)對無線通訊業者是種成本效益高且有效率的解決方案。佈建異質網路擁有提高頻譜效率、增加網路容量、同時帶來流量卸載之優勢;然而小型基地台之傳輸範圍受大小型基地台之間的傳輸功率差異而有所侷限,而大型基地台對小型基地台之干擾也影響使用者連線至小型基地台之訊號品質,進而導致小型基地台往往無法被充份利用且降低了將流量由大型基地台卸載至小型基地台之機會。本論文探討了在異質網路架構中所遭遇到的問題,並提出了下列三種機制以提高流量卸載、進而提升系統容量:
首先,我們在無線異質網路中提出了以使用者流量需求為基礎的基地台範圍擴展(Cell Range Expansion)偏移值設定,使用者能根據其上下載之網路流量需求決定其連線之基地台,上載需求量較高之使用者連線至小型基地台之能力得以提升,我們進一步考量了小型基地台之間的無線資源分配以增加使用者對小型基地台之連線並提高了小型基地台的使用率。 再者,我們在異質網路中將大型基地台之頻段進行分割以減少對小型基地台之干擾,讓異質網路能同時兼顧使用者覆蓋率以及系統流量,我們同時考慮了大型基地台之傳輸功率調整、並考量使用者對基地台之連線負擔以調整使用者連線,進而增加小型基地台之服務效能、並提升了異質網路之流量卸載能力。 其三,我們提出了使用者端的干擾消除機制,藉由適當地調整大型基地台傳輸之調變編碼結構(Modulation and Coding Scheme)來增加小型基地台使用者對大型基地台之訊號干擾消除能力,進而提升小型基地台使用者之網路連線品質、並增加了無線頻譜之使用效率。 綜觀以上,本論文研究了在無線異質網路上如何進行流量卸載並增加無線頻譜利用率之相關議題。我們相信在本論文中所提出之問題分析以及所提議的解決機制可以提供行動通訊營運商可行且有價值的方針,並協助行動通訊營運商善用珍稀的無線頻譜資源。 Deploying high power macro BSs together with low power small cells to form a heterogeneous network (HetNet) is a cost-effective and efficient solution for mobile network operators to increase spectral efficiency, raise network capacity, and offload traffic. However, since the transmission range of the small cells are limited due to the large transmission power difference between macro BSs and small cells, and the interference from macro BSs to small cells influences the signal quality of small cell users and degrades the link quality, small cells are typically underutilized and lose the opportunity to offload traffic from macro BSs. In this dissertation, we discuss some issues encountered in HetNets and propose three schemes to increase the traffic offloading gain and improve the network throughput: First, we propose rate-based CRE offset in HetNets and let UEs choose their associations based on their traffic demands. UEs with higher uplink traffic demand have higher opportunities to associate with small cells. We further consider the radio resource allocation among small cells to help UEs associate with small cells and improve the utilization of small cells. Second, bandwidth of the macro BS is divided into two sub-bands to lighten the interference to small cells and balance the user coverage and system throughput. Transmit power control of the macro BS and load-aware user association are jointly considered to improve the utilization of small cells and offload more traffic in HetNets. Third, a novel UE-side interference cancellation (IC) scheme is proposed to exploit the wireless broadcast advantage of interference cancellation. Multiple small cell UEs can concurrently cancel the interference from the macro BS by properly adjusting the MCS of the macro BS. This UE-side IC scheme can efficiently improve the link quality of small cell UEs and improve the radio resource efficiency and utilization. To summarize, this dissertation investigates how to offload traffic and increase resource utilization in HetNets. We believe that our study and the proposed schemes are feasible and valuable for mobile network operators to better utilize precious radio resource of the wireless spectrum. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/79001 |
DOI: | 10.6342/NTU201802208 |
全文授權: | 有償授權 |
電子全文公開日期: | 2023-08-21 |
顯示於系所單位: | 電機工程學系 |
文件中的檔案:
檔案 | 大小 | 格式 | |
---|---|---|---|
ntu-107-D96921023-1.pdf 目前未授權公開取用 | 1.93 MB | Adobe PDF |
系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。