基於分散式天線無線蜂巢系統之涵蓋範圍與訊號干擾比性能之研究

Abstract

基於分散式天線無線蜂巢系統之涵蓋範圍與信號干擾比性能之研究 摘要本論文主要研究在基於分散式天線蜂巢式無線網路系統的涵蓋範圍及 訊號干擾比之電腦模擬分析。在單細胞的分散式天線系統 (Distributed Antenna Based System) 架構中，訊號經調變及多工在有線電纜同時廣播 傳送出去，射頻放大器和頻率轉換器可用來補償訊號在電纜的損耗。對建 立一個無線蜂巢式架構網路而言，從本文的電腦模擬可以觀察出基於分散 式天線系統比基於集中式天線系統在涵蓋範圍 (Coverage Performance) 及抗干擾訊號 (CIR) 的能力有較佳的性能。對單細胞基於分散式天線系 統而言，從電纜長度效應考量來獲得最佳天線位置，同時對下鏈傳送找出 較佳的功率分配，接著考量如何將基於分散式天線系統設計在現有有線電 視的網路 (CATV Network) 架構上。我們針對單細胞系統架構，在 Rayleigh和shadow衰減通道環境下，從接收信號強度分佈來比較基於分散 式天線系統和基於集中式天線系統的涵蓋範圍性能。並且針對慢跳頻的分 時多重進接 (SFH Based TDMA) 蜂巢式系統架構，在Rayleigh和shadow衰 減通道環境下，比較基於分散式天線系統和基於集中式天線系統的訊號干 擾比分佈。實質上，對一個蜂巢式系統的信號干擾比分佈而言，基於分散 式天線系統比起基於集中式天線系統有較好的性能改善。 A Study on Coverage and CIR Performance of a Distributed Antenna Based Cellular SystemAbstract In this thesis, a computer simulation study on coverage performance and interference rejection capability of a distributed antenna based wireless cellular network is presented. The same signal is simulcast from several antennas in a cell of a distributed antenna based system. Signals could be modulated and multiplexed for radio transmission at a single node, then transmitted through a coaxial cable based distribution system to distributed antennas in a cell. Frequency up/down conversion and radio frequency(RF) amplification may be needed at each remote antenna port. It is observed from our simulation study that a distributed antenna based system has the potential to provide a larger cell coverage area and better CIR performance as compared with a central antenna based system in establishing a wireless cellular network. The cable length effect is simulated to find the optimum location for deploying antenna nodes. Downlink radiation power is adjusted in our simulation in order to obtain the best power distribution ratio in a distributed antenna based system. We also discuss how to plant the cell topology of a distributed antenna based system onto the architecture of a existing CATV network system.Computer simulations are used to evaluate the coverage performance from the distribution of received signal strength in a single cell architecture for both a central antenna based system and a distributed antenna based system in both a shadow fading environment and a Rayleigh fading environment. This paper also presents simulation results on carrier-to-interference ratio (CIR) performance for both a distributed antenna based system and a central antenna based system in a slow frequency hopping based TDMA system. The use of distributed antennas can substantially improve the CIR distribution of a cellular radio system over a central antenna based system in both a shadow fading environment and a shadow/ Rayleigh fading environment.