Cross-layer Design for IEEE 802.11ac Downlink Multi-user MIMO
Date Issued
2011
Date
2011
Author(s)
Chen, Chih-Hsuan
Abstract
In 802.11ac standard, downlink multi-user MIMO (DL MU-MIMO) is one of the main technologies to enhance system throughput. However, the overall performance of DL MU-MIMO in 802.11ac networks is not yet investigated. In this paper, we implemented an 802.11ac module on NS-2 platform. By simulations, we found that DL MU-MIMO is only suitable to operate at a certain SNR range. Besides, the channel state information feedback delay and overhead can also have an impact on DL MU-MIMO performance. Considering these effects, we then propose two algorithms to optimize the performance of DL MU-MIMO in 802.11ac networks. The first algorithm is hybrid channel sounding algorithm (HCS), which schedules the users in the channel sounding process and uses hybrid feedback frequency to reduce feedback overhead. The second is the MU-MIMO scheduling and transmission (MUST) mechanism, which performs transmission mode selection and user grouping. MUST jointly considers the queue status information, channel conditions, and impact of feedback information delay to optimize the system throughput. Simulation results demonstrate the effectiveness of the proposed algorithms.
Subjects
MU-MIMO
cross-layer design
user grouping
scheduling
feedback design
Type
thesis
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