Three-user MISO broadcast channel: How much can CSIT heterogeneity help?

Lashgari, Sina; Tandon, Ravi; Avestimehr, Salman

doi:10.1109/icc.2015.7248980

Cited by 6 publications

(5 citation statements)

References 17 publications

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“…The range of interest 1 is α ∈ [0, 1]. We also assume availability of delayed CSIT (as in for example [6], as well as in a variety of subsequent works [2], [3], [7]- [14], see also [15]- [18] as well as [19]- [21]) where now the delayed estimates of any channel, can be received without error but with arbitrary delay, even if this delay renders this CSIT completely obsolete. As it is argued in [2], this mixed CSI model (partial current CSIT, and delayed CSIT) nicely captures different realistic settings that might involve channel correlations and an ability to improve CSI as time progresses.…”

Section: B Coded Caching and Csit-type Feedbackmentioning

confidence: 99%

Fundamental limits of cache-aided wireless BC: Interplay of coded-caching and CSIT feedback

Zhang

Elia

2016

2016 54th Annual Allerton Conference on Communication, Control, and Computing (Allerton)

107

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Building on the recent coded-caching breakthrough by Maddah-Ali and Niesen, the work here considers the K-user cache-aided wireless multi-antenna (MISO) symmetric broadcast channel (BC) with random fading and imperfect feedback, and analyzes the throughput performance as a function of feedback statistics and cache size. In this setting, our work identifies the optimal cache-aided degrees-of-freedom (DoF) within a factor of 4, by identifying near-optimal schemes that exploit the new synergy between coded caching and delayed CSIT, as well as by exploiting the unexplored interplay between caching and feedback-quality.The derived limits interestingly reveal that -the combination of imperfect quality current CSIT, delayed CSIT, and coded caching, guarantees that -the DoF gains have an initial offset defined by the quality of current CSIT, and then that the additional gains attributed to coded caching are exponential, in the sense that any linear decrease in the required DoF performance, allows for an exponential reduction in the required cache size.

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Section: B Coded Caching and Csit-type Feedbackmentioning

confidence: 99%

Fundamental limits of cache-aided wireless BC: Interplay of coded-caching and CSIT feedback

Zhang

Elia

2016

2016 54th Annual Allerton Conference on Communication, Control, and Computing (Allerton)

107

View full text Add to dashboard Cite

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Section: B Coded Caching and Csit-type Feedbackmentioning

confidence: 99%

Fundamental Limits of Cache-Aided Wireless BC: Interplay of Coded-Caching and CSIT Feedback

Zhang

Elia

2017

IEEE Trans. Inform. Theory

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Abstract-Building on the recent coded-caching breakthrough by Maddah-Ali and Niesen, the work here considers the K-user cache-aided wireless multi-antenna (MISO) symmetric broadcast channel (BC) with random fading and imperfect feedback, and analyzes the throughput performance as a function of feedback statistics and cache size. In this setting, our work identifies the optimal cache-aided degrees-of-freedom (DoF) within a factor of 4, by identifying near-optimal schemes that exploit the new synergy between coded caching and delayed CSIT, as well as by exploiting the unexplored interplay between caching and feedback-quality.The derived limits interestingly reveal that -the combination of imperfect quality current CSIT, delayed CSIT, and coded caching, guarantees that -the DoF gains have an initial offset defined by the quality of current CSIT, and then that the additional gains attributed to coded caching are exponential, in the sense that any linear decrease in the required DoF performance, allows for an exponential reduction in the required cache size.

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“…, tm of G n j , and the rest of the elements of G n j are zero. 1 Now, consider the decoding of x j at Rx j (i.e., decoding the m j (n) information symbols for Rx j ). The corresponding interference subspace at Rx j will be…”

Section: System Modelmentioning

confidence: 99%

“…. , 1, 1 2 |P| . Therefore, if, with slight abuse of notation, we denote K |P| + 1, we need to show that the following DoF tuple is linearly achievable:…”

Section: Appendix F Proof Of Proposition 1 (Constant Gap Characteriza...mentioning

confidence: 99%

“…In particular, it was shown in [3] that even when the transmitter(s) only have access to delayed CSIT, there is significant potential for degrees-of-freedom (DoF) gain. They studied the problem of k-user multiple-input single-output broadcast channel (MISO BC) with delayed CSIT, and showed that for such network DoF = k 1+ 1 2 +...+ 1 k . This work was followed by several other works which studied other network configurations under the assumption of delayed CSIT, including interference channel [4]- [7], X-channel [8], [9], multi-hop networks [10], and other variations of delayed CSIT [11].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

MISO Broadcast Channel With Hybrid CSIT: Beyond Two Users

Lashgari

Tandon

Avestimehr

2016

IEEE Trans. Inform. Theory

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We study the impact of heterogeneity of channel-state-information available at the transmitters (CSIT) on the capacity of broadcast channels with a multiple-antenna transmitter and k single-antenna receivers (MISO BC). In particular, we consider the k-user MISO BC, where the CSIT with respect to each receiver can be either instantaneous/perfect, delayed, or not available; and we study the impact of this heterogeneity of CSIT on the degreesof-freedom (DoF) of such network. We first focus on the 3-user MISO BC; and we completely characterize the DoF region for all possible heterogeneous CSIT configurations, assuming linear encoding strategies at the transmitters. The result shows that the state-of-the-art achievable schemes in the literature are indeed sum-DoF optimal, when restricted to linear encoding schemes. To prove the result, we develop a novel bound, called Interference Decomposition Bound, which provides a lower bound on the interference dimension at a receiver which supplies delayed CSIT based on the average dimension of constituents of that interference, thereby decomposing the interference into its individual components. Furthermore, we extend our outer bound on the DoF region to the general k-user MISO BC, and demonstrate that it leads to an approximate characterization of linear sum-DoF to within an additive gap of 0.5 for a broad range of CSIT configurations. Moreover, for the special case where only one receiver supplies delayed CSIT, we completely characterize the linear sum-DoF.This work has been presented in part in [1], [2].

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Three-user MISO broadcast channel: How much can CSIT heterogeneity help?

Cited by 6 publications

References 17 publications

Fundamental limits of cache-aided wireless BC: Interplay of coded-caching and CSIT feedback

Fundamental limits of cache-aided wireless BC: Interplay of coded-caching and CSIT feedback

Fundamental Limits of Cache-Aided Wireless BC: Interplay of Coded-Caching and CSIT Feedback

MISO Broadcast Channel With Hybrid CSIT: Beyond Two Users

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