Imperial College London

DrDenizGunduz

Faculty of EngineeringDepartment of Electrical and Electronic Engineering

Reader in Information Theory and Communications
 
 
 
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Contact

 

+44 (0)20 7594 6218d.gunduz Website

 
 
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Assistant

 

Ms Joan O'Brien +44 (0)20 7594 6316

 
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Location

 

1016Electrical EngineeringSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

171 results found

Amiri MM, Gunduz D, 2018, Caching and Coded Delivery over Gaussian Broadcast Channels for Energy Efficiency, IEEE Journal on Selected Areas in Communications, ISSN: 0733-8716

IEEE A cache-aided K-user Gaussian broadcast channel (BC) is considered. The transmitter has a library of N equalrate files, from which each user demands one. The impact of the equal-capacity receiver cache memories on the minimum required transmit power to satisfy all user demands is studied. Considering uniformly random demands across the library, both the minimum average power (averaged over all demand combinations) and the minimum peak power (minimum power required to satisfy all demand combinations) are studied. Upper bounds are presented on the minimum required average and peak transmit power as a function of the cache capacity considering both centralized and decentralized caching. The lower bounds on the minimum required average and peak power values are also derived assuming uncoded cache placement. The bounds for both the peak and average power values are shown to be tight in the centralized scenario through numerical simulations. The results in this paper show that proactive caching and coded delivery can provide significant energy savings in wireless networks.

JOURNAL ARTICLE

Bharath BN, Nagananda KG, Gunduz D, Poor HVet al., 2018, Caching With Time-Varying Popularity Profiles: A Learning-Theoretic Perspective, IEEE Transactions on Communications, ISSN: 0090-6778

IEEE Content caching at the small-cell base stations (sBSs) in a heterogeneous wireless network is considered. A cost function is proposed that captures the backhaul link load called the & #x201C;offloading loss & #x201D;, which measures the fraction of the requested files that are not available in the sBS caches. As opposed to the previous approaches that consider time-invariant and perfectly known popularity profile, caching with non-stationary and statistically dependent popularity profiles (assumed unknown, and hence, estimated) is studied from a learning-theoretic perspective. A probably approximately correct result is derived, which presents a high probability bound on the offloading loss difference, i.e., the error between the estimated and the optimal offloading loss. The difference is a function of the Rademacher complexity, the & #x03B2;-mixing coefficient, the number of time slots, and a measure of discrepancy between the estimated and true popularity profiles. A cache update algorithm is proposed, and simulation results are presented to show its superiority over periodic updates. The performance analyses for Bernoulli and Poisson request models are also presented.

JOURNAL ARTICLE

Giaconi G, Gunduz D, Poor HV, 2018, Smart Meter Privacy With Renewable Energy and an Energy Storage Device, IEEE TRANSACTIONS ON INFORMATION FORENSICS AND SECURITY, Vol: 13, Pages: 129-142, ISSN: 1556-6013

JOURNAL ARTICLE

Guler B, Gunduz D, Yener A, 2018, Lossy Coding of Correlated Sources over a Multiple Access Channel: Necessary Conditions and Separation Results, IEEE Transactions on Information Theory, ISSN: 0018-9448

IEEE Lossy coding of correlated sources over a multiple access channel (MAC) is studied. First, a joint source-channel coding scheme is presented when the decoder has correlated side information. Next, the optimality of separate source and channel coding, that emerges from the availability of a common observation at the encoders, or side information at the encoders and the decoder, is investigated. It is shown that separation is optimal when the encoders have access to a common observation whose lossless recovery is required at the decoder, and the two sources are independent conditioned on this common observation. Optimality of separation is also proved when the encoder and the decoder have access to shared side information conditioned on which the two sources are independent. These separation results obtained in the presence of side information are then utilized to provide a set of necessary conditions for the transmission of correlated sources over a MAC without side information. Finally, by specializing the obtained necessary conditions to the transmission of binary and Gaussian sources over a MAC, it is shown that they can potentially be tighter than the existing results in the literature, providing a novel converse for this fundamental problem.

JOURNAL ARTICLE

Ozfatura E, Gunduz D, 2018, Mobility and Popularity-Aware Coded Small-Cell Caching, IEEE COMMUNICATIONS LETTERS, Vol: 22, Pages: 288-291, ISSN: 1089-7798

JOURNAL ARTICLE

Shi J, Liu L, Gunduz D, Ling Cet al., 2018, Polar Codes and Polar Lattices for the Heegard-Berger Problem, IEEE Transactions on Communications, ISSN: 0090-6778

IEEE Explicit coding schemes are proposed to achieve the rate-distortion function of the Heegard-Berger problem using polar codes. Specifically, a nested polar code construction is employed to achieve the rate-distortion function for doublysymmetric binary sources when the side information may be absent. The nested structure contains two optimal polar codes for lossy source coding and channel coding, respectively. Moreover, a similar nested polar lattice construction is employed when the source and the side information are jointly Gaussian. The proposed polar lattice is constructed by nesting a quantization polar lattice and a capacity-achieving polar lattice for the additive white Gaussian noise channel.

JOURNAL ARTICLE

Somuyiwa SO, Gyorgy A, Gunduz D, 2018, A Reinforcement-Learning Approach to Proactive Caching in Wireless Networks, IEEE Journal on Selected Areas in Communications, ISSN: 0733-8716

IEEE We consider a mobile user accessing contents in a dynamic environment, where new contents are generated over time (by the user & #x2019;s contacts), and remain relevant to the user for random lifetimes. The user, equipped with a finite-capacity cache memory, randomly accesses the system, and requests all the relevant contents at the time of access. The system incurs an energy cost associated with the number of contents downloaded and the channel quality at that time. Assuming causal knowledge of the channel quality, the content profile, and the user-access behavior, we model the proactive caching problem as a Markov decision process with the goal of minimizing the long-term average energy cost. We first prove the optimality of a threshold-based proactive caching scheme, which dynamically caches or removes appropriate contents from the memory, prior to being requested by the user, depending on the channel state. The optimal threshold values depend on the system state, and hence, are computationally intractable. Therefore, we propose parametric representations for the threshold values, and use reinforcement-learning algorithms to find near-optimal parametrizations. We demonstrate through simulations that the proposed schemes significantly outperform classical reactive downloading, and perform very close to a genieaided lower bound.

JOURNAL ARTICLE

Yang Q, Gunduz D, 2018, Coded Caching and Content Delivery With Heterogeneous Distortion Requirements, IEEE TRANSACTIONS ON INFORMATION THEORY, Vol: 64, Pages: 4347-4364, ISSN: 0018-9448

JOURNAL ARTICLE

Abad MSH, Gunduz D, Ercetin O, 2017, Communication over a Time Correlated Channel with an Energy Harvesting Transmitter, International Symposium on Wireless Communication Systems (ISWCS), Publisher: IEEE, Pages: 331-336, ISSN: 2154-0217

CONFERENCE PAPER

Amiri MM, Gunduz D, 2017, Fundamental Limits of Coded Caching: Improved Delivery Rate-Cache Capacity Tradeoff, IEEE TRANSACTIONS ON COMMUNICATIONS, Vol: 65, Pages: 806-815, ISSN: 0090-6778

JOURNAL ARTICLE

Amiri MM, Gunduz D, 2017, Decentralized Caching and Coded Delivery over Gaussian Broadcast Channels, IEEE International Symposium on Information Theory (ISIT), Publisher: IEEE, Pages: 2785-2789

CONFERENCE PAPER

Amiri MM, Gunduz D, 2017, Cache-aided data delivery over erasure broadcast channels, ISSN: 1550-3607

© 2017 IEEE. A cache-aided erasure broadcast channel is studied. The receivers are divided into two sets: the weak and strong receivers, where the receivers in the same set all have the same erasure probability. The weak receivers, in order to compensate for the high erasure probability, are equipped with cache memories of equal size, while the receivers in the strong set have no caches. Data can be pre-delivered to weak receivers' caches over the off-peak traffic period before the receivers reveal their demands. A joint caching and channel coding scheme is proposed such that all the receivers, even the receivers without any cache memories, benefit from the presence of caches across the network. The trade-off between the cache size and the achievable rate is studied, and it is shown that the proposed scheme significantly improves the achievable trade-off upon the state-of-the-art.

CONFERENCE PAPER

Amiri MM, Yang Q, Gunduz D, 2017, Decentralized Caching and Coded Delivery With Distinct Cache Capacities, IEEE TRANSACTIONS ON COMMUNICATIONS, Vol: 65, Pages: 4657-4669, ISSN: 0090-6778

JOURNAL ARTICLE

Bharath BN, Nagananda KG, Gunduz D, Poor HVet al., 2017, Learning-Based Content Caching with Time-Varying Popularity Profiles, IEEE Global Communications Conference (GLOBECOM), Publisher: IEEE, ISSN: 2334-0983

CONFERENCE PAPER

Faqir OJ, Kerrigan EC, Gunduz D, 2017, Joint optimization of transmission and propulsion in aerial communication networks, IEEE 56th Annual Conference on Decision and Control (CDC), Publisher: IEEE, ISSN: 0743-1546

CONFERENCE PAPER

Guler B, Gunduz D, Yener A, 2017, On the Necessary Conditions for Transmitting Correlated Sources over a Multiple Access Channel, IEEE International Symposium on Information Theory (ISIT), Publisher: IEEE, Pages: 923-927

CONFERENCE PAPER

Isikman AO, Yuksel M, Gunduz D, 2017, A Low-Complexity Policy for Outage Probability Minimization With an Energy Harvesting Transmitter, IEEE COMMUNICATIONS LETTERS, Vol: 21, Pages: 917-920, ISSN: 1089-7798

JOURNAL ARTICLE

Koken E, Gunduz D, Tuncel E, 2017, Energy-Distortion Exponents in Lossy Transmission of Gaussian Sources Over Gaussian Channels, IEEE TRANSACTIONS ON INFORMATION THEORY, Vol: 63, Pages: 1227-1236, ISSN: 0018-9448

JOURNAL ARTICLE

Li Z, Oechtering TJ, Gunduz D, 2017, Smart Meter Privacy Based on Adversarial Hypothesis Testing, IEEE International Symposium on Information Theory (ISIT), Publisher: IEEE, Pages: 774-778

CONFERENCE PAPER

Mohammadi Amiri M, Gunduz D, 2017, Cache-Aided Content Delivery over Erasure Broadcast Channels, IEEE Transactions on Communications, ISSN: 0090-6778

A cache-aided broadcast network is studied, in which a server delivers contents to a group of receivers over a packet erasure broadcast channel (BC). The receivers are divided into two sets with regards to their channel qualities: the weak and strong receivers, where all the weak receivers have statistically worse channel qualities than all the strong receivers. The weak receivers, in order to compensate for the high erasure probability they encounter over the channel, are equipped with cache memories of equal size, while the receivers in the strong set have no caches. Data can be pre-delivered to weak receivers’ caches over the off-peak traffic period before the receivers reveal their demands. Allowing arbitrary erasure probabilities for the weak and strong receivers, a joint caching and channel coding scheme, which divides each file into several subfiles, and applies a different caching and delivery scheme for each subfile, is proposed. It is shown that all the receivers, even those without any cache memories, benefit from the presence of caches across the network. An information theoretic trade-off between the cache size and the achievable rate is formulated. It is shown that the proposed scheme improves upon the state-of-the-art in terms of the achievable trade-off.

JOURNAL ARTICLE

Murin Y, Kaspi Y, Dabora R, Gunduz Det al., 2017, Finite-Length Linear Schemes for Joint Source-Channel Coding Over Gaussian Broadcast Channels With Feedback, IEEE TRANSACTIONS ON INFORMATION THEORY, Vol: 63, Pages: 2737-2772, ISSN: 0018-9448

JOURNAL ARTICLE

Murin Y, Kaspi Y, Dabora R, Gunduz Det al., 2017, On the Energy-Distortion Tradeoff of Gaussian Broadcast Channels with Feedback, ENTROPY, Vol: 19, ISSN: 1099-4300

JOURNAL ARTICLE

Rassouli B, Varasteh M, Gunduz D, 2017, Capacity Region of a One-Bit Quantized Gaussian Multiple Access Channel, IEEE International Symposium on Information Theory (ISIT), Publisher: IEEE, Pages: 2633-2637

CONFERENCE PAPER

Roig JSP, Gunduz D, Tosato F, 2017, Interference networks with caches at both ends, ISSN: 1550-3607

© 2017 IEEE. A Kt χ Kr cache-aided wireless interference network, in which both the transmitters and the receivers are equipped with cache memories is studied. Each user requests one file from a library of N popular files. The goal is to design the cache contents without the knowledge of the particular user demands, such that all possible demand combinations can be satisfied reliably over the interference channel. The achievable sum degrees-of-freedom (sDoF) and the normalized delivery time (NDT) are studied for centralized and decentralized network architectures, respectively. First, using a combination of interference alignment (IA), zero-forcing (ZF) and interference cancellation (IC) techniques, a novel caching and transmission scheme for centralized networks is introduced, and it is shown to improve the sDoF upon the state-of-the-art. Then, the NDT is studied when the content placement at the receiver caches is carried out in a decentralized manner. Our results indicate that, for this particular network architecture, caches located at the receiver side are more effective than those at the transmitter side in order to reduce the NDT.

CONFERENCE PAPER

Roig JSP, Motahari SA, Tosato F, Gunduz Det al., 2017, Fundamental Limits of Latency in a Cache-Aided 4 x 4 Interference Channel, 2017 IEEE Information Theory Workshop (ITW), Publisher: IEEE, Pages: 16-20, ISSN: 2475-420X

CONFERENCE PAPER

Somuyiwa SO, Gyorgy A, Gunduz D, 2017, Energy-Efficient Wireless Content Delivery with Proactive Caching, 15th International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOpt), Publisher: IEEE

CONFERENCE PAPER

Somuyiwa SO, Gyorgy A, Gunduz D, 2017, Improved Policy Representation and Policy Search for Proactive Content Caching in Wireless Networks, 15th International Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOpt), Publisher: IEEE

CONFERENCE PAPER

Sreekumar S, Gunduz D, 2017, Distributed Hypothesis Testing Over Noisy Channels, IEEE International Symposium on Information Theory (ISIT), Publisher: IEEE, Pages: 983-987

CONFERENCE PAPER

Tan O, Gomez-Vilardebo J, Gundus D, 2017, Privacy-Cost Trade-offs in Demand-Side Management With Storage, IEEE TRANSACTIONS ON INFORMATION FORENSICS AND SECURITY, Vol: 12, Pages: 1458-1469, ISSN: 1556-6013

JOURNAL ARTICLE

Varasteh M, Rassouli B, Simeone O, Gunduz Det al., 2017, Zero-Delay Source-Channel Coding with a Low-Resolution ADC Front End, IEEE Transactions on Information Theory, Vol: 64, Pages: 1241-1261, ISSN: 0018-9448

Motivated by the practical constraints arising in emerging sensor network and Internet-of-Things (IoT) applications, the zero-delay transmission of a Gaussian measurement over a real single-input multiple-output (SIMO) additive white Gaussian noise (AWGN) channel is studied with a low-resolution analog-to-digital converter (ADC) front end. Joint optimization of the encoder and the decoder mapping is tackled under both the mean squared error (MSE) distortion and the distortion outage probability (DOP) criteria, with an average power constraint on the channel input. Optimal encoder and decoder mappings are identified for a one-bit ADC front end under both criteria. For the MSE distortion, the optimal encoder mapping is shown to be non-linear in general, while it tends to a linear encoder in the low signal-to-noise ratio (SNR) regime, and to an antipodal digital encoder in the high SNR regime. This is in contrast to the optimality of linear encoding at all SNR values in the presence of a full-precision front end. For the DOP criterion, it is shown that the optimal encoder mapping is piecewise constant and can take only two opposite values when it is non-zero. For both the MSE distortion and the DOP criteria, necessary optimality conditions are then derived for K-level ADC front ends as well as front ends with multiple one-bit ADCs. These conditions are used to obtain numerically optimized solutions. Extensive numerical results are also provided in order to gain insights into the structure of the optimal encoding and decoding mappings.

JOURNAL ARTICLE

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