Downlink Multiuser MIMO Systems With Adaptive Feedback Rate

Sohn, Illsoo; Park, Chang Soon; Lee, Kwang Bok

doi:10.1109/tvt.2012.2184807

Cited by 17 publications

(20 citation statements)

References 23 publications

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“…14 The sum rate in temporally correlated channels is explored, and based on the individual CSI of the channels, a 2-stage feedback scheme is also proposed. 15,16 Moreover, the bit allocation in MIMO single cell and multicell systems with coordinated limited feedback techniques is proposed by many authors to study the system performance bottleneck.…”

Section: Discussionmentioning

confidence: 99%

“…12 The interference management in random clustering with adaptive bit partitioning is discussed in detail. 15,16 Moreover, the bit allocation in MIMO single cell and multicell systems with coordinated limited feedback techniques is proposed by many authors to study the system performance bottleneck. 14 The sum rate in temporally correlated channels is explored, and based on the individual CSI of the channels, a 2-stage feedback scheme is also proposed.…”

Section: Introductionmentioning

confidence: 99%

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Performance analysis of adaptive limited feedback coordinated zero‐forcing multicell systems in time‐varying channels: A practical approach

Balaji

Mallick

2017

Int J Communication

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In this paper, coordinated limited feedback zero-forcing beamforming multicell system in time-varying channel is studied. In time-varying channels, the actual rate loss arising from error in channel quantization of both interuser and intercell inferences is quantified in this work. Using the actual degradation of rate loss, a limited feedback bit allocation is proposed to reduce interuser and intercell interference simultaneously with feedback update period as one of the parameters. Furthermore, the scaling law of bits required to maintain a constant rate loss is formulated in varying channel conditions for a given feedback update period. Simulation results demonstrated the practical feedback requirement in multicell systems in the presence of both intercell and interuser interference over conventional schemes to maintain a constant rate offset. The key finding from the proposed feedback allocation is that practically much higher allocation of feedback bits and feedback scaling are required in time-varying channels to reduce throughput degradation.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Performance analysis of adaptive limited feedback coordinated zero‐forcing multicell systems in time‐varying channels: A practical approach

Balaji

Mallick

2017

Int J Communication

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“…the number of DoFs at RX 1, and we assume that the beamformers t 1 and t 2 are given by (23). We still assume w.l.o.g.…”

Section: Proposition 2 Active-passive Zf Achieves the Number Of Dofsmentioning

confidence: 99%

“…In fact, the beamformer can be multiplied arbitrarily by any unit-norm complex number without impacting the rate achieved so that only the power used at TX 1 needs to be decided. According to (23), the power used at TX 1 is set to P/(2 log 2 (P )).…”

Section: Proposition 2 Active-passive Zf Achieves the Number Of Dofsmentioning

confidence: 99%

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Degrees of Freedom of the Network MIMO Channel With Distributed CSI

Kerret

Gesbert

2012

IEEE Trans. Inform. Theory

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Abstract-In this work, we discuss the joint precoding with finite rate feedback in the so-called network MIMO where the TXs share the knowledge of the data symbols to be transmitted. We introduce a distributed channel state information (DCSI) model where each TX has its own local estimate of the overall multi-user MIMO channel and must make a precoding decision solely based on the available local CSI. We refer to this channel as the DCSI-MIMO channel and the precoding problem as distributed precoding. We extend to the DCSI setting the work from Jindal in [1] for the conventional MIMO Broadcast Channel (BC) in which the number of Degrees of Freedom (DoFs) achieved by Zero Forcing (ZF) was derived as a function of the scaling in the logarithm of the Signal-to-Noise Ratio (SNR) of the number of quantizing bits. Particularly, we show the seemingly pessimistic result that the number of DoFs at each user is limited by the worst CSI across all users and across all TXs. This is in contrast to the conventional MIMO BC where the number of DoFs at one user is solely dependent on the quality of the estimation of his own feedback. Consequently, we provide precoding schemes improving on the achieved number of DoFs. For the two-user case, the derived novel precoder achieves a number of DoFs limited by the best CSI accuracy across the TXs instead of the worst with conventional ZF. We also advocate the use of hierarchical quantization of the CSI, for which we show that considerable gains are possible. Finally, we use the previous analysis to derive the DoFs optimal allocation of the feedback bits to the various TXs under a constraint on the size of the aggregate feedback in the network, in the case where conventional ZF is used.

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