Achieving the Degrees of Freedom of Wireless Multi-User Relay Networks
2012 (English)In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 60, no 9, 2612-2622 p.Article in journal (Refereed) Published
We study the available degrees of freedom (DOF) of a class of wireless single-antenna multi-user relay networks. In these networks the communications between M unconnected source-destination pairs are provided by a large number of half-duplex relays. To conduct the communications we propose a cluster successive relaying protocol that divides the relays into two equal-size clusters. Unlike the conventional orthogonal relaying protocol that demands all the relays to simultaneously assist the sources, we require the two relay clusters to take turns forwarding the source messages to more efficiently use the channel. In a time-varying fading environment, through appropriate interference alignment the negative impact of inter-user interference can be effectively minimized. Thus the two clusters of half-duplex relays can mimic a cluster of full-duplex relays. When the number of relays is infinitely large, we show that the M-user half-duplex relay networks have M DOF, i.e. their sum capacity can be characterized as C-Sigma(SNR) = M log(SNR)+ o(log(SNR)). This result implies that allowing only distributed processing and half-duplex operation is able to provide the same DOF performance as permitting joint processing and full-duplex operation in wireless relay networks.
Place, publisher, year, edition, pages
2012. Vol. 60, no 9, 2612-2622 p.
Multi-user relay networks, half-duplex operation, degrees of freedom (DOF), interference alignment, cluster successive relaying
Electrical Engineering, Electronic Engineering, Information Engineering
IdentifiersURN: urn:nbn:se:kth:diva-104705DOI: 10.1109/TCOMM.2012.062512.100580ISI: 000309204600026ScopusID: 2-s2.0-84866743310OAI: oai:DiVA.org:kth-104705DiVA: diva2:567734
FunderSwedish Research Council, 2010-891ICT - The Next Generation
QC 201211142012-11-142012-11-092013-04-11Bibliographically approved