2012/05/30 by Horia Vlad Balan, Balan, Horia Vlad, Ryan Rogalin +8 · 2 citations
Computer Science · Engineering · #Advanced MIMO Systems Optimization #Advanced Wireless Communication Techniques #Cooperative Communication and Network Coding #FOS: Computer and information sciences #Networking and Internet Architecture (cs.NI) #Wireless Communication Networks Research
paper · pdf · doi:10.48550/arxiv.1205.6862
openalex publication_date 2012/05/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The enormous success of advanced wireless devices is pushing the demand for\nhigher wireless data rates. Denser spectrum reuse through the deployment of\nmore access points per square mile has the potential to successfully meet the\nincreasing demand for more bandwidth. In theory, the best approach to density\nincrease is via distributed multiuser MIMO, where several access points are\nconnected to a central server and operate as a large distributed multi-antenna\naccess point, ensuring that all transmitted signal power serves the purpose of\ndata transmission, rather than creating "interference." In practice, while\nenterprise networks offer a natural setup in which distributed MIMO might be\npossible, there are serious implementation difficulties, the primary one being\nthe need to eliminate phase and timing offsets between the jointly coordinated\naccess points.\n In this paper we propose AirSync, a novel scheme which provides not only time\nbut also phase synchronization, thus enabling distributed MIMO with full\nspatial multiplexing gains. AirSync locks the phase of all access points using\na common reference broadcasted over the air in conjunction with a Kalman filter\nwhich closely tracks the phase drift. We have implemented AirSync as a digital\ncircuit in the FPGA of the WARP radio platform. Our experimental testbed,\ncomprised of two access points and two clients, shows that AirSync is able to\nachieve phase synchronization within a few degrees, and allows the system to\nnearly achieve the theoretical optimal multiplexing gain. We also discuss MAC\nand higher layer aspects of a practical deployment. To the best of our\nknowledge, AirSync offers the first ever realization of the full multiuser MIMO\ngain, namely the ability to increase the number of wireless clients linearly\nwith the number of jointly coordinated access points, without reducing the per\nclient rate.\n