Abstract
Distributed antenna systems (DASs) can reduce the access distance, increase system capacity and improve system performance compared with conventional centralized multiple antenna systems. In this paper, the system capacity of downlink DAS with beamforming is investigated. The mathematical expression of system capacity is derived over the composite channel including Rayleigh fading, shadowing and path loss. At the same time, the interference from other APs is also considered for the studied AP. Numerical methods including Gauss-Hermite integral and composite Simpson’s rule are used to compute the system capacity of DAS under different MS distributions. Numerical results verify the precision of the mathematical analysis of system capacity by comparing Monte-Carlo simulation results. The results also show interference among APs shouldn’t be ignored when APs are close to each other or there are many APs.
Highlights
IntroductionA distributed antenna system (DAS), which has multiple antenna ports (APs) in each cell, has attracted wide attention recently because it can increase coverage, reduce transmit power and improve the sum rate and cell-edge performance in cellular communication systems [1, 2, 3]
A distributed antenna system (DAS), which has multiple antenna ports (APs) in each cell, has attracted wide attention recently because it can increase coverage, reduce transmit power and improve the sum rate and cell-edge performance in cellular communication systems [1, 2, 3].Many efforts have been devoted to analyze the performance of Distributed antenna systems (DASs) with random or fixed antenna layout
Capacity performance and antenna placement design of DAS in different scenarios were studied well in [4, 5, 6], but the previous studies rarely discuss the capacity of DAS with beamforming. [7] derived the optimal beamforming vector of downlink DAS with a single user at the fixed location and analyzed the outage probability and ergodic capacity
Summary
A distributed antenna system (DAS), which has multiple antenna ports (APs) in each cell, has attracted wide attention recently because it can increase coverage, reduce transmit power and improve the sum rate and cell-edge performance in cellular communication systems [1, 2, 3]. [7] derived the optimal beamforming vector of downlink DAS with a single user at the fixed location and analyzed the outage probability and ergodic capacity. It didn’t consider the random location of the user. In this paper, based on what we have studied in [9], system capacity of downlink DAS with beamforming have been studied here for two scenarios including neglecting the interference from other APs and considering the interference from other APs. First, based on the composite channel model including path loss, shadow fading and Rayleigh fading, a DAS model with beamforming is built. The expectation of a random variable is given by E (⋅)
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