Optimal Design of Energy-Efficient Multi-User MIMO Systems: Is Massive MIMO the Answer?
2015 (English)In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 14, no 6, 3059-3075 p.Article in journal (Refereed) Published
Assume that a multi-user multiple-input multiple-output (MIMO) system is designed from scratch to uniformly cover a given area with maximal energy efficiency (EE). What are the optimal number of antennas, active users, and transmit power? The aim of this paper is to answer this fundamental question. We consider jointly the uplink and downlink with different processing schemes at the base station and propose a new realistic power consumption model that reveals how the above parameters affect the EE. Closed-form expressions for the EE-optimal value of each parameter, when the other two are fixed, are provided for zero-forcing (ZF) processing in single-cell scenarios. These expressions prove how the parameters interact. For example, in sharp contrast to common belief, the transmit power is found to increase (not to decrease) with the number of antennas. This implies that energy-efficient systems can operate in high signal-to-noise ratio regimes in which interference-suppressing signal processing is mandatory. Numerical and analytical results show that the maximal EE is achieved by a massive MIMO setup wherein hundreds of antennas are deployed to serve a relatively large number of users using ZF processing. The numerical results show the same behavior under imperfect channel state information and in symmetric multi-cell scenarios.
Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE) , 2015. Vol. 14, no 6, 3059-3075 p.
Energy efficiency; massive MIMO; linear processing; system design; downlink; uplink; imperfect CSI; single-cell; multi-cell
Communication Systems Telecommunications Communication Systems
IdentifiersURN: urn:nbn:se:liu:diva-120170DOI: 10.1109/TWC.2015.2400437ISI: 000356178100011OAI: oai:DiVA.org:liu-120170DiVA: diva2:841456
Funding Agencies|ELLIIT; Swedish Research Council; People Programme (Marie Curie Actions) [FP7 PIEF-GA-2012-330731]; FP7 Network of Excellence in Wireless COMmunications NEWCOM ; ERC ; French pole de competitivite SYSTEM@TIC within the project 4G2015-07-132015-07-132016-04-11Bibliographically approved