PDF Icon Common-Message Broadcast Channels with Feedback in the Nonasymptotic Regime: Full Feedback

We investigate the maximum coding rate achievable on a two-user broadcast channel for the case where a common message is transmitted with feedback using either fixed-blocklength codes or variable-length codes. For the fixed-blocklength-code setup, we establish nonasymptotic converse and achievability bounds. An asymptotic analysis of these bounds reveals that feedback improves the second-order term compared to the no-feedback case. In particular, for a certain class of anti-symmetric broadcast channels, we show that the dispersion is halved. For the variable-length-code setup, we demonstrate that the channel dispersion is zero.
Original languageEnglish
JournalI E E E Transactions on Information Theory
ISSN0018-9448
StateSubmitted - 2018
Publication categoryResearch
Peer-reviewedNo

PDF IconDownload ''Common-Message Broadcast Channels with Feedback in the Nonasymptotic Regime: Full Feedback''



PDF Icon Hybrid Precoding for Massive MIMO Systems in Cloud RAN Architecture with Capacity-Limited Fronthauls



PDF Icon 5G and Cellular Networks in the Smart Grid

5G and Cellular Networks in the Smart Grid

Nielsen, J. J., Jorguseski, L., Zhang, H., Ganem, H., Zhu, Z. & Popovski, P. 2018 (Accepted/In press) Transportation and Power Grid in Smart Cities: Communication Networks and Services. John Wiley & Sons Ltd.

Research output: Research - peer-reviewBook chapter

Wireless cellular networks will help Distribution System Operators (DSOs) to achieve observability below the substation level, which is needed to ensure stable operation in the smart grid. Both existing and upcoming cellular technologies are considered as candidates for helping to enable the smart grid. In the present chapter, we present the main features of both the non-3GPP technologies, IEEE 802.11ah, SigFox and LoRa, and the main features of past, current and future 3GPP technologies, namely releases <12 (High rate), 12-14 (IoT extensions) and 15-16 (5G). Additionally, we present the challenges and possible solutions for ensuring end-to-end security in smart grid systems.
Original languageEnglish
Title of host publicationTransportation and Power Grid in Smart Cities: Communication Networks and Services
PublisherJohn Wiley & Sons Ltd.
Publication date2018
StateAccepted/In press - 2018
Publication categoryResearch
Peer-reviewedYes

PDF IconDownload ''5G and Cellular Networks in the Smart Grid''



PDF Icon Variable-Length Coding with Stop-Feedback for the Common-Message Broadcast Channel in the Nonasymptotic Regime

We investigate the maximum coding rate for a given average blocklength and error probability over a K-user discrete memoryless broadcast channel for the scenario where a common message is transmitted using variable-length stop-feedback codes. For the point-to-point case, Polyanskiy et al. (2011) demonstrated that variable-length coding
combined with stop-feedback significantly increase the speed of convergence of the maximum coding rate to capacity. This speed-up manifests itself in the absence of a square-root penalty in the asymptotic expansion of the maximum coding rate for large blocklengths, i.e., zero dispersion. In this paper, we present nonasymptotic achievability and converse bounds on the maximum coding rate of the common-message K-user discrete memoryless broadcast channel, which strengthen and generalize the ones reported in Trillingsgaard et al. (2015) for the two-user case. An asymptotic analysis of these bounds reveals that zero dispersion cannot be achieved for certain common-message broadcast channels (e.g., the binary symmetric broadcast channel). Furthermore, we identify conditions under which our converse and achievability bounds are tight up to the second order. Through numerical evaluations, we illustrate that our second-order expansions approximate accurately the maximum coding rate and that the speed of convergence to capacity is indeed slower than for the point-to-point case.
Original languageEnglish
JournalI E E E Transactions on Information Theory
ISSN0018-9448
StateSubmitted - 2018
Publication categoryResearch
Peer-reviewedYes

PDF IconDownload ''Variable-Length Coding with Stop-Feedback for the Common-Message Broadcast Channel in the Nonasymptotic Regime''



PDF Icon Generalized HARQ Protocols with Delayed Channel State Information and Average Latency Constraints

In many practical wireless systems, the signal-to-interference-and-noise ratio (SINR) that is applicable to a certain transmission, referred to as channel state information (CSI), can only be learned after the transmission has taken place and is thereby delayed (outdated). In such systems, hybrid automatic repeat request (HARQ) protocols are often used to achieve high throughput with low latency. This paper put forth the family of expandable message space (EMS) protocols that generalize the HARQ protocol and allow for rate adaptation based on delayed CSI at the transmitter (CSIT). Assuming a block-fading channel, the proposed EMS protocols are analyzed using dynamic programming. When full CSIT is available and there is a constraint on the average decoding time, it is shown that the optimal EMS protocol has a particularly simple operational interpretation and that the throughput is identical to that of the backtrack retransmission request (BRQ) protocol. We also devise EMS protocols for the case in which CSIT is only available through a finite number of feedback messages. The numerical results demonstrate that BRQ approaches the ergodic capacity quickly compared to HARQ, while EMS protocols with only three and four feedback messages achieve throughput that are only slightly worse than the throughput of BRQ.
Original languageEnglish
JournalI E E E Transactions on Information Theory
VolumePP
Pages (from-to)1
Number of pages34
ISSN0018-9448
DOI
StateE-pub ahead of print - 2018
Publication categoryResearch
Peer-reviewedYes

PDF IconDownload ''Generalized HARQ Protocols with Delayed Channel State Information and Average Latency Constraints''



PDF Icon Network Slicing in Industry 4.0 Applications: Abstraction Methods and End-to-End Analysis

Industry 4.0 refers to the fourth industrial revolution, and
introduces modern communication and computation technologies such as
5G, cloud computing and Internet of Things to industrial manufacturing
systems. As a result, many devices, machines and applications will
rely on connectivity, while having different requirements from the
network, ranging from high reliability and low latency to high data
rates. Furthermore, these industrial networks will be highly
heterogeneous as they will feature a number of diverse communication
technologies. In this article, we propose network slicing as a mechanism
to handle the diverse set of requirements to the network. We present
methods for slicing deterministic and packet-switched industrial
communication protocols at an abstraction level which is decoupled
from the specific implementation of the underlying technologies, and
hence simplifies the slicing of heterogeneous networks. Finally, we
show how network calculus can be used to assess the end-to-end properties
of the network slices.
Original languageEnglish
JournalI E E E Network
ISSN0890-8044
StateSubmitted - 2018
Publication categoryResearch
Peer-reviewedYes

PDF IconDownload ''Network Slicing in Industry 4.0 Applications: Abstraction Methods and End-to-End Analysis''



PDF Icon Wireless Channel Modeling Perspectives for Ultra-Reliable Communications

Ultra-Reliable Communication (URC) is one of the distinctive features of the
upcoming 5G wireless communication. The level of reliability, going down to
packet error rates (PER) of $10^{-9}$, should be sufficiently convincing in
order to remove cables in an industrial setting or provide remote control of
robots with mission-critical function. In this paper we present elements of
physical and statistical modeling of the wireless channel that are relevant for
characterization of the lower tail of the channel Cumulative Distribution
Function (CDF). There are channel models, such as Two-Wave with Diffuse Power
(TWDP) or Suzuki, where finding the full CDF is not tractable. We show that,
for a wide range of channel models, the outage probability at URC levels can be
approximated by a simple expression, whose exponent depends on the actual
channel model. Furthermore, it is seen that the two-wave model leads to
pessimistic predictions of the fading in the region of ultra-reliable
communications, while the CDFs of models that contain diffuse components have
slopes that correspond to the slope of a Rayleigh fading. We provide analysis
of the receive antenna diversity schemes for URC-relevant statistics and obtain
a new expression for Maximum Ratio Combining (MRC) in Weibull channels.
Original languageEnglish
JournalIEEE Transactions on Wireless Communications
ISSN1536-1276
StateSubmitted - 2018
Publication categoryResearch
Peer-reviewedYes

PDF IconDownload ''Wireless Channel Modeling Perspectives for Ultra-Reliable Communications''



PDF Icon Coded Pilot Access: A Random Access Solution for Massive MIMO Systems



PDF Icon Random Pilot and Data Access in Massive MIMO for Machine-type Communications

Random Pilot and Data Access in Massive MIMO for Machine-type Communications

Carvalho, E. D., Bjornson, E., Sørensen, J. H., Larsson, E. G. & Popovski, P. Dec 2017 In : I E E E Transactions on Wireless Communications. 16, 2, p. 7703 - 7717

Research output: Research - peer-reviewJournal article

Original languageEnglish
JournalI E E E Transactions on Wireless Communications
Volume16
Issue number2
Pages (from-to)7703 - 7717
ISSN1536-1276
DOI
StatePublished - Dec 2017
Publication categoryResearch
Peer-reviewedYes

PDF IconDownload ''Random Pilot and Data Access in Massive MIMO for Machine-type Communications''



PDF Icon Coverage and Rate of Downlink Sequence Transmissions with Reliability Guarantees

Coverage and Rate of Downlink Sequence Transmissions with Reliability Guarantees

Park, J. & Popovski, P. Dec 2017 In : I E E E Wireless Communications Letters. 6, 6, p. 722 - 725

Research output: Research - peer-reviewJournal article

Real-time distributed control is a promising application of 5G in which communication links should satisfy certain reliability guarantees. In this letter, we derive closed-form maximum average rate when a device (e.g. industrial machine) downloads a sequence of n operational commands through cellular connection, while guaranteeing a certain coverage for all n messages. The result is based on novel closed-form n- successive coverage bounds. The proposed lower bound provides a simple approximation that is increasingly accurate in the high reliability region. For moderate coverage, a linear combination of the proposed bounds enables deriving a tractable approximation. Both techniques can be utilized for calculating the maximum average rate with and without using adaptive modulation and coding (AMC).
Original languageEnglish
JournalI E E E Wireless Communications Letters
Volume6
Issue number6
Pages (from-to)722 - 725
ISSN2162-2337
DOI
StatePublished - Dec 2017
Publication categoryResearch
Peer-reviewedYes

PDF IconDownload ''Coverage and Rate of Downlink Sequence Transmissions with Reliability Guarantees''



Viewing page 1 of 16|Next Page