Change search
ReferencesLink to record
Permanent link

Direct link
Energy Efficient Transmissions in Cognitive MIMO Systems With Multiple Data Streams
KTH, School of Electrical Engineering (EES), Centres, ACCESS Linnaeus Centre.
KTH, School of Electrical Engineering (EES), Automatic Control.
KTH, School of Electrical Engineering (EES), Signal Processing.ORCID iD: 0000-0002-3599-5584
2015 (English)In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 14, no 9, 5171-5184 p.Article in journal (Refereed) Published
Abstract [en]

We investigate energy-efficient communications for time-division multiple access (TDMA) multiple-input multiple-output (MIMO) cognitive radio (CR) networks operating in underlay mode. In particular, we consider the joint optimization over both the time resource and the transmit precoding matrices to minimize the overall energy consumption of a single cell secondary network with multiple secondary users (SUs), while ensuring their quality of service (QoS). The corresponding mathematical formulations turn out to be non-convex, and thus of high complexity to solve in general. We give a comprehensive treatment of this problem, considering both the cases of perfect channel state information (CSI) and statistical CSI of the channels from the SUs to the primary receiver. We tackle the non-convexity by applying a proper optimization decomposition that allows the overall problem to be efficiently solved. In particular, we show that when the SUs only have statistical CSI, the optimal solution can be found in polynomial time. Moreover, if we consider additional integer constraints on the time variable which is usually a requirement in practical wireless system, the overall problem becomes a mixed-integer non-convex optimization which is more complicated. By exploring the special structure of this particular problem, we show that the optimal integer time solution can be obtained in polynomial time with a simple greedy algorithm. When the SUs have perfect CSI, the decomposition based algorithm is guaranteed to find the optimal solution when the secondary system is under-utilized. Simulation results show that the energy-optimal transmission scheme adapts to the traffic load of the secondary system to create a win-win situation where the SUs are able to decrease the energy consumption and the PUs experience less interference from the secondary system. The effect is particularly pronounced when the secondary system is under-utilized.

Place, publisher, year, edition, pages
IEEE Press, 2015. Vol. 14, no 9, 5171-5184 p.
Keyword [en]
Cognitive radio networks, energy consumption, resource allocation, MIMO, precoding
National Category
URN: urn:nbn:se:kth:diva-176986DOI: 10.1109/TWC.2015.2434372ISI: 000363205300039ScopusID: 2-s2.0-84959462287OAI: diva2:871836

QC 20151117

Available from: 2015-11-17 Created: 2015-11-13 Last updated: 2015-11-17Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Fu, LiqunJohansson, MikaelBengtsson, Mats
By organisation
ACCESS Linnaeus CentreAutomatic ControlSignal Processing
In the same journal
IEEE Transactions on Wireless Communications

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 48 hits
ReferencesLink to record
Permanent link

Direct link