485 research outputs found
Cooperative Precoding with Limited Feedback for MIMO Interference Channels
Multi-antenna precoding effectively mitigates the interference in wireless
networks. However, the resultant performance gains can be significantly
compromised in practice if the precoder design fails to account for the
inaccuracy in the channel state information (CSI) feedback. This paper
addresses this issue by considering finite-rate CSI feedback from receivers to
their interfering transmitters in the two-user multiple-input-multiple-output
(MIMO) interference channel, called cooperative feedback, and proposing a
systematic method for designing transceivers comprising linear precoders and
equalizers. Specifically, each precoder/equalizer is decomposed into inner and
outer components for nulling the cross-link interference and achieving array
gain, respectively. The inner precoders/equalizers are further optimized to
suppress the residual interference resulting from finite-rate cooperative
feedback. Further- more, the residual interference is regulated by additional
scalar cooperative feedback signals that are designed to control transmission
power using different criteria including fixed interference margin and maximum
sum throughput. Finally, the required number of cooperative precoder feedback
bits is derived for limiting the throughput loss due to precoder quantization.Comment: 23 pages; 5 figures; this work was presented in part at Asilomar 2011
and will appear in IEEE Trans. on Wireless Com
Non-cooperative Feedback Rate Control Game for Channel State Information in Wireless Networks
It has been well recognized that channel state information (CSI) feedback is
of great importance for dowlink transmissions of closed-loop wireless networks.
However, the existing work typically researched the CSI feedback problem for
each individual mobile station (MS), and thus, cannot efficiently model the
interactions among self-interested mobile users in the network level. To this
end, in this paper, we propose an alternative approach to investigate the CSI
feedback rate control problem in the analytical setting of a game theoretic
framework, in which a multiple-antenna base station (BS) communicates with a
number of co-channel MSs through linear precoder. Specifically, we first
present a non-cooperative feedback-rate control game (NFC), in which each MS
selects the feedback rate to maximize its performance in a distributed way. To
improve efficiency from a social optimum point of view, we then introduce
pricing, called the non-cooperative feedback-rate control game with price
(NFCP). The game utility is defined as the performance gain by CSI feedback
minus the price as a linear function of the CSI feedback rate. The existence of
the Nash equilibrium of such games is investigated, and two types of feedback
protocols (FDMA and CSMA) are studied. Simulation results show that by
adjusting the pricing factor, the distributed NFCP game results in close
optimal performance compared with that of the centralized scheme.Comment: 26 pages, 10 figures; IEEE Journal on Selected Areas in
Communications, special issue on Game Theory in Wireless Communications, 201
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