Distributed Antenna Systems and Linear Relaying for Gigabit MIMO Wireless
AuthorsArmin Wittneben and Boris Rankov
ReferenceIEEE Vehicular Technology Conference, VTC Fall 2004, Los Angeles, Sept. 2004
AbstractSpatial multiplexing is mandatory to achieve the extreme bandwidth efficiency of future Gigabit/sec WLANs. Both distributed Antenna Systems (DAS) at the access point and cooperative relaying (the infrastructureless counterpart) have been recognized as means to meet coverage/range requirements and to enable spatial multiplexing in a low scattering environment. In this paper we compare three candidate schemes under a two-hop (relay) traffic pattern: (i) DAS with decode&forward in the access point (DDAS), (ii) DAS with linear processing in the access point (LDAS) and (iii) linear relaying without any information exchange between the relay nodes. We derive a lower bound on the capacity of the LDAS scheme and show that it suffers at most a 3dB loss w.r.t DDAS in the large SNR regime. The main contributions of this paper are a novel relay gain allocation for N-antenna source and destination and a simple signaling protocol for the local estimation of these gains at the relay nodes. Our performance results suggest, that asymptotically (large number of relays) linear relaying with M.N support nodes performs similar to LDAS with M distributed antenna elements.
KeywordsDistributed antenna systems, linear relaying, amplify-and-forward, decode-and-forward
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