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Publications (10 of 423) Show all publications
Ghauch, H., Imtiaz, S., Skoglund, M., Koudouridis, G. & Gross, J. (2018). Fairness and user assignment in cloud-RAN. In: IEEE Vehicular Technology Conference: . Paper presented at 86th IEEE Vehicular Technology Conference, VTC Fall 2017, 24 September 2017 through 27 September 2017 (pp. 1-5). Institute of Electrical and Electronics Engineers Inc.
Open this publication in new window or tab >>Fairness and user assignment in cloud-RAN
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2018 (English)In: IEEE Vehicular Technology Conference, Institute of Electrical and Electronics Engineers Inc. , 2018, p. 1-5Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, we extend our previous work on user assignment in Cloud-RAN, where we proposed an algorithm for user assignment (UA). We motivate the inherent fairness issue that is present in the latter UA scheme, since some users in the system will never get served. To improve the fairness, we propose that the UA scheme is preceded by a user scheduling step which aims at selecting at any time the users that should be considered by the UA algorithm for scheduling (in the next time slot). Two user scheduling approaches have been studied. The first scheme improves the minimum throughput (MT), by selecting at any time the users with the lowest throughput. The second scheme is based on round-robin (RR) scheduling, where the set of potentially scheduled users for the next slot, is done by excluding all the previously served users, in that round. Moreover, the subset of actual users to be served, is determined using the UA algorithm. We evaluate their fairness and sumrate performance, via extensive simulations. While one might have expected a tradeoff between the sum-rate performance and fairness, our results show that MT improves both metrics, when compared to the original UA algorithm (without fairness), for some choice of parameter values. This implies that both fairness and aggregate system performance can be improved, by a careful choice of the number of assigned and served users.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers Inc., 2018
Keywords
Cloud radio access networks, Fairness scheduling, User assignment, Communication channels (information theory), Routers, Scheduling, Choice of parameters, Extensive simulations, Round Robin, Time slots, User scheduling, Scheduling algorithms
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:kth:diva-227440 (URN)10.1109/VTCFall.2017.8288047 (DOI)2-s2.0-85045234015 (Scopus ID)9781509059355 (ISBN)
Conference
86th IEEE Vehicular Technology Conference, VTC Fall 2017, 24 September 2017 through 27 September 2017
Note

Conference code: 134637; Export Date: 9 May 2018; Conference Paper; CODEN: IVTCD. QC 20180528

Available from: 2018-05-28 Created: 2018-05-28 Last updated: 2018-05-28Bibliographically approved
Cao, P., Oechtering, T. J. & Skoglund, M. (2018). Precoding Design for Massive MIMO Systems with Sub-connected Architecture and Per-antenna Power Constraints. In: : . Paper presented at The 22nd International ITG Workshop on Smart Antennas.
Open this publication in new window or tab >>Precoding Design for Massive MIMO Systems with Sub-connected Architecture and Per-antenna Power Constraints
2018 (English)Conference paper, Published paper (Refereed)
Abstract [en]

This paper provides the necessary conditions to design precoding matrices for massive MIMO systems with a sub-connected architecture, RF power constraints and per-antenna power constraints. The system is configured such that each RFchain serves a group of antennas. The necessary condition to design the digital precoder is established based on a generalized water-filling and joint sum and per-antenna optimal power allocation solution, while the analog precoder is based on a per-antenna power allocation solution only. We study the analytically most interesting case where the power constraint on the RF chain is smaller than the sum of the corresponding per-antenna power constraints. For this, the optimal power is allocated based on two properties: Each RF chain uses full power and if the optimal power allocation of the unconstraint problem violates a per-antenna power constraint then it is optimal to allocate the maximal power for that antenna.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-225420 (URN)
Conference
The 22nd International ITG Workshop on Smart Antennas
Note

QCR 20180411

Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2018-04-11Bibliographically approved
Do, H. T., Oechtering, T. J., Skoglund, M. & Vu, M. (2017). Interfering Relay Channels. Entropy, 19(9), Article ID 441.
Open this publication in new window or tab >>Interfering Relay Channels
2017 (English)In: Entropy, ISSN 1099-4300, E-ISSN 1099-4300, Vol. 19, no 9, article id 441Article in journal (Refereed) Published
Abstract [en]

This paper introduces and studies a model in which two relay channels interfere with each other. Motivated by practical scenarios in heterogeneous wireless access networks, each relay is assumed to be connected to its intended receiver through a digital link with finite capacity. Inner and outer bounds for achievable rates are derived and shown to be tight for new discrete memoryless classes, which generalize and unify several known cases involving interference and relay channels. Capacity region and sum capacity for multiple Gaussian scenarios are also characterized to within a constant gap. The results show the optimality or near-optimality of the quantize-bin-and-forward coding scheme for practically relevant relay-interference networks, which brings important engineering insight into the design of wireless communications systems.

Place, publisher, year, edition, pages
MDPI AG, 2017
Keywords
interference channel, relay channel, interference channel with two relays, interference relay channel, deterministic relay channel, quantize-forward, quantize-bin-and-forward, hash-forward, interference management
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-215829 (URN)10.3390/e19090441 (DOI)000411527100013 ()2-s2.0-85029153177 (Scopus ID)
Note

QC 20171017

Available from: 2017-10-17 Created: 2017-10-17 Last updated: 2017-11-29Bibliographically approved
Do, T. T., Ngo, H. Q., Duong, T. Q., Oechtering, T. & Skoglund, M. (2017). Massive MIMO Pilot Retransmission Strategies for Robustification Against Jamming. IEEE Wireless Communications Letters, 6(1), 58-61
Open this publication in new window or tab >>Massive MIMO Pilot Retransmission Strategies for Robustification Against Jamming
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2017 (English)In: IEEE Wireless Communications Letters, ISSN 2162-2337, E-ISSN 2162-2345, Vol. 6, no 1, p. 58-61Article in journal (Refereed) Published
Abstract [en]

This letter proposes anti-jamming strategies based on pilot retransmission for a single user uplink massive MIMO under jamming attack. A jammer is assumed to attack the system both in the training and data transmission phases. We first derive an achievable rate which enables us to analyze the effect of jamming attacks on the system performance. Counter-attack strategies are then proposed to mitigate this effect under two different scenarios: random and deterministic jamming attacks. Numerical results illustrate our analysis and benefit of the proposed schemes.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2017
Keywords
Massive MIMO, jamming, pilot retransmission
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-205139 (URN)10.1109/LWC.2016.2631163 (DOI)000395868700015 ()2-s2.0-85013651383 (Scopus ID)
Note

QC 20170412

Available from: 2017-04-12 Created: 2017-04-12 Last updated: 2017-11-29Bibliographically approved
Huang, S. & Skoglund, M. (2017). On linear coding over finite rings and applications to computing. Entropy, 19(5), Article ID 233.
Open this publication in new window or tab >>On linear coding over finite rings and applications to computing
2017 (English)In: Entropy, ISSN 1099-4300, E-ISSN 1099-4300, Vol. 19, no 5, article id 233Article in journal (Refereed) Published
Abstract [en]

This paper presents a coding theorem for linear coding over finite rings, in the setting of the Slepian-Wolf source coding problem. This theorem covers corresponding achievability theorems of Elias (IRE Conv. Rec. 1955, 3, 37-46) and Csiszár (IEEE Trans. Inf. Theory 1982, 28, 585-592) for linear coding over finite fields as special cases. In addition, it is shown that, for any set of finite correlated discrete memoryless sources, there always exists a sequence of linear encoders over some finite non-field rings which achieves the data compression limit, the Slepian-Wolf region. Hence, the optimality problem regarding linear coding over finite non-field rings for data compression is closed with positive confirmation with respect to existence. For application, we address the problem of source coding for computing, where the decoder is interested in recovering a discrete function of the data generated and independently encoded by several correlated i.i.d. random sources. We propose linear coding over finite rings as an alternative solution to this problem. Results in Körner-Marton (IEEE Trans. Inf. Theory 1979, 25, 219-221) and Ahlswede-Han (IEEE Trans. Inf. Theory 1983, 29, 396-411, Theorem 10) are generalized to cases for encoding (pseudo) nomographic functions (over rings). Since a discrete function with a finite domain always admits a nomographic presentation, we conclude that both generalizations universally apply for encoding all discrete functions of finite domains. Based on these, we demonstrate that linear coding over finite rings strictly outperforms its field counterpart in terms of achieving better coding rates and reducing the required alphabet sizes of the encoders for encoding infinitely many discrete functions.

Place, publisher, year, edition, pages
MDPI AG, 2017
Keywords
Field, Linear coding, Ring, Source coding, Source coding for computing
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-216497 (URN)10.3390/e19050233 (DOI)000404453700050 ()2-s2.0-85024833883 (Scopus ID)
Note

QC 20171201

Available from: 2017-12-01 Created: 2017-12-01 Last updated: 2017-12-01Bibliographically approved
Tanaka, T., Skoglund, M. & Ugrinovskii, V. (2017). Optimal Sensor Design and Zero-Delay Source Coding for Continuous-Time Vector Gauss-Markov Processes. In: 2017 IEEE 56TH ANNUAL CONFERENCE ON DECISION AND CONTROL (CDC): . Paper presented at IEEE 56th Annual Conference on Decision and Control (CDC), DEC 12-15, 2017, Melbourne, AUSTRALIA. IEEE
Open this publication in new window or tab >>Optimal Sensor Design and Zero-Delay Source Coding for Continuous-Time Vector Gauss-Markov Processes
2017 (English)In: 2017 IEEE 56TH ANNUAL CONFERENCE ON DECISION AND CONTROL (CDC), IEEE , 2017Conference paper, Published paper (Refereed)
Abstract [en]

We consider the situation in which a continuoustime vector Gauss-Markov process is observed through a vector Gaussian channel (sensor) and estimated by the Kalman-Bucy filter. Unlike in standard filtering problems where a sensor model is given a priori, we are concerned with the optimal sensor design by which (i) the mutual information between the source random process and the reproduction (estimation) process is minimized, and (ii) the minimum mean-square estimation error meets a given distortion constraint. We show that such a sensor design problem is tractable by semidefinite programming. The connection to zero-delay source-coding is also discussed.

Place, publisher, year, edition, pages
IEEE, 2017
Series
IEEE Conference on Decision and Control, ISSN 0743-1546
National Category
Computer and Information Sciences
Identifiers
urn:nbn:se:kth:diva-223871 (URN)000424696903137 ()978-1-5090-2873-3 (ISBN)
Conference
IEEE 56th Annual Conference on Decision and Control (CDC), DEC 12-15, 2017, Melbourne, AUSTRALIA
Note

QC 20180305

Available from: 2018-03-05 Created: 2018-03-05 Last updated: 2018-03-05Bibliographically approved
Wang, Q. & Skoglund, M. (2017). Secure Symmetric Private Information Retrieval from Colluding Databases with Adversaries. In: 2017 55TH ANNUAL ALLERTON CONFERENCE ON COMMUNICATION, CONTROL, AND COMPUTING (ALLERTON): . Paper presented at 55th Annual Allerton Conference on Communication, Control, and Computing (Allerton), OCT 03-06, 2017, Monticello, IL (pp. 1083-1090). IEEE
Open this publication in new window or tab >>Secure Symmetric Private Information Retrieval from Colluding Databases with Adversaries
2017 (English)In: 2017 55TH ANNUAL ALLERTON CONFERENCE ON COMMUNICATION, CONTROL, AND COMPUTING (ALLERTON), IEEE , 2017, p. 1083-1090Conference paper, Published paper (Refereed)
Abstract [en]

The problem of symmetric private information retrieval (SPIR) from replicated databases with colluding servers and adversaries is studied. Specifically, the database comprises K files, which are replicatively stored among N servers. A user wants to retrieve one file from the database by communicating with the N servers, without revealing the identity of the desired file to any server. Furthermore, the user shall learn nothing about the other K - 1 files in the database. Any T out of N servers may collude, that is, they may communicate their interactions with the user to guess the identity of the requested file. An adversary in the system can tap in on or even try to corrupt the communication. Three types of adversaries are considered: a Byzantine adversary who can overwrite the transmission of any B servers to the user; a passive eavesdropper who can tap in on the incoming and outgoing transmissions of any E servers; and a combination of both - an adversary who can tap in on a set of any E nodes, and overwrite the transmission of a set of any B nodes. The problems of SPIR with colluding servers and the three types of adversaries are named T-BSPIR, T-ESPIR and T-BESPIR respectively. The capacity of the problem is defined as the maximum number of information bits of the desired file retrieved per downloaded bit. We show that the information-theoretical capacity of the T-BSPIR problem equals 1-2B+T/N, if the servers share common randomness (unavailable at the user) with amount at least 2B+T/N-2B-T times the file size. Otherwise, the capacity equals zero. The information-theoretical capacity of the T-ESPIR problem is proved to equal 1 - max(T, E)/N, if the servers share common randomness with amount at least max(T, E)/N-max(T, E) times the file size. Finally, for the problem of T-BESPIR, the capacity is proved to be 1 - 2B+max(T, E)/N, where the common randomness shared by the servers should be at least 2B+max(T, E)/N-2B-max(T, E) times the file size. The results resemble those of secure network coding problems with adversaries and eavesdroppers.

Place, publisher, year, edition, pages
IEEE, 2017
Series
Annual Allerton Conference on Communication Control and Computing, ISSN 2474-0195
National Category
Telecommunications
Identifiers
urn:nbn:se:kth:diva-226278 (URN)000428047800148 ()978-1-5386-3266-6 (ISBN)
Conference
55th Annual Allerton Conference on Communication, Control, and Computing (Allerton), OCT 03-06, 2017, Monticello, IL
Note

QC 20180419

Available from: 2018-04-19 Created: 2018-04-19 Last updated: 2018-05-24Bibliographically approved
Ghauch, H., Kim, T., Bengtsson, M. & Skoglund, M. (2017). Sum-Rate Maximization in Sub-28-GHz Millimeter-Wave MIMO Interfering Networks. IEEE Journal on Selected Areas in Communications, 35(7), 1649-1662
Open this publication in new window or tab >>Sum-Rate Maximization in Sub-28-GHz Millimeter-Wave MIMO Interfering Networks
2017 (English)In: IEEE Journal on Selected Areas in Communications, ISSN 0733-8716, E-ISSN 1558-0008, Vol. 35, no 7, p. 1649-1662Article in journal (Refereed) Published
Abstract [en]

MIMO systems in the lower part of the millimetre-wave (mmWave) spectrum band (i.e., below 28 GHz) do not exhibit enough directivity and selectively, as compared to their counterparts in higher bands of the spectrum (i.e., above 60 GHz), and thus still suffer from the detrimental effect of interference, on the system sum rate. As such systems exhibit large numbers of antennas and short coherence times for the channel, traditional methods of distributed coordination are ill-suited, and the resulting communication overhead would offset the gains of coordination. In this paper, we propose algorithms for tackling the sum-rate maximization problem that are designed to address the above-mentioned limitations. We derive a lower bound on the sum rate, a so-called difference of log and trace (DLT) bound, shed light on its tightness, and highlight its decoupled nature at both the transmitters and receivers. Moreover, we derive the solution to each of the subproblems that we dub non-homogeneous waterfilling (a variation on the MIMO waterfilling solution), and underline an inherent desirable feature: its ability to turn-OFF streams exhibiting low SINR, and contribute to greatly speeding up the convergence of the proposed algorithm. We then show the convergence of the resulting algorithm, max-DLT, to a stationary point of the DLT bound. Finally, we rely on extensive simulations of various network configurations, to establish the fast-converging nature of our proposed schemes, and thus their suitability for addressing the short coherence interval, as well as the increased system dimensions, arising when managing interference in lower bands of the mmWave spectrum. Moreover, our results suggest that interference management still brings about significant performance gains, especially in dense deployments.

Place, publisher, year, edition, pages
IEEE, 2017
Keywords
Sub-28 GHz millimeter-wave, interference management, fast-converging algorithms, distributed optimization, difference of log and trace (DLT), non-homogeneous waterfilling, max-DLT, alternating iterative maximal separation (AIMS)
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-210997 (URN)10.1109/JSAC.2017.2698779 (DOI)000404242600018 ()2-s2.0-85021337121 (Scopus ID)
Note

QC 20170807

Available from: 2017-08-07 Created: 2017-08-07 Last updated: 2017-08-07Bibliographically approved
Molavipour, S., Bassi, G. & Skoglund, M. (2017). Testing for Directed Information Graphs. In: 2017 55TH ANNUAL ALLERTON CONFERENCE ON COMMUNICATION, CONTROL, AND COMPUTING (ALLERTON): . Paper presented at 55th Annual Allerton Conference on Communication, Control, and Computing (Allerton), OCT 03-06, 2017, Monticello, IL (pp. 212-219). IEEE
Open this publication in new window or tab >>Testing for Directed Information Graphs
2017 (English)In: 2017 55TH ANNUAL ALLERTON CONFERENCE ON COMMUNICATION, CONTROL, AND COMPUTING (ALLERTON), IEEE , 2017, p. 212-219Conference paper, Published paper (Refereed)
Abstract [en]

In this paper, we study a hypothesis test to determine the underlying directed graph structure of nodes in a network, where the nodes represent random processes and the direction of the links indicate a causal relationship between said processes. Specifically, a k-th order Markov structure is considered for them, and the chosen metric to determine a connection between nodes is the directed information. The hypothesis test is based on the empirically calculated transition probabilities which are used to estimate the directed information. For a single edge, it is proven that the detection probability can be chosen arbitrarily close to one, while the false alarm probability remains negligible. When the test is performed on the whole graph, we derive bounds for the false alarm and detection probabilities, which show that the test is asymptotically optimal by properly setting the threshold test and using a large number of samples. Furthermore, we study how the convergence of the measures relies on the existence of links in the true graph.

Place, publisher, year, edition, pages
IEEE, 2017
Series
Annual Allerton Conference on Communication Control and Computing, ISSN 2474-0195
National Category
Probability Theory and Statistics
Identifiers
urn:nbn:se:kth:diva-226276 (URN)000428047800030 ()978-1-5386-3266-6 (ISBN)
Conference
55th Annual Allerton Conference on Communication, Control, and Computing (Allerton), OCT 03-06, 2017, Monticello, IL
Note

QC 20180419

Available from: 2018-04-19 Created: 2018-04-19 Last updated: 2018-05-24Bibliographically approved
Gerami, M., Xiao, M. & Skoglund, M. (2017). Two-Layer Coding in Distributed Storage Systems With Partial Node Failure/Repair. IEEE Communications Letters, 21(4), 726-729
Open this publication in new window or tab >>Two-Layer Coding in Distributed Storage Systems With Partial Node Failure/Repair
2017 (English)In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 21, no 4, p. 726-729Article in journal (Refereed) Published
Abstract [en]

We a distributed storage system where parts of the stored packets in storage nodes are subject to being lost. In a process, termed as the partial repair, the lost packets in a faulty node are recovered by the transmitted packets from other storage nodes and the available packets in the faulty node. To improve reliability of the stored data, and reduce the transmission costs, we propose a scheme that implements two-layer coding for storing files in the system. We study the minimum possible partial-repair bandwidth, and the codes that achieve the optimal bound.

Place, publisher, year, edition, pages
IEEE, 2017
Keywords
Network coding, Data storage systems, Optimization
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:kth:diva-208260 (URN)10.1109/LCOMM.2016.2646678 (DOI)000399388400010 ()2-s2.0-85018173583 (Scopus ID)
Note

QC 20170622

Available from: 2017-06-22 Created: 2017-06-22 Last updated: 2017-06-22Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-7926-5081

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