Paul de Kerret - Academia.edu (original) (raw)

Papers by Paul de Kerret

IEEE Transactions on Wireless Communications, 2016

2015 53rd Annual Allerton Conference on Communication, Control, and Computing (Allerton), 2015

2011 Ieee 12th International Workshop on Signal Processing Advances in Wireless Communications, Feb 14, 2011

Interference is emerging as a fundamental bottleneck in many important wireless communication sce... more Interference is emerging as a fundamental bottleneck in many important wireless communication scenarios, including dense cellular networks and cognitive networks with spectrum sharing by multiple service providers. Although multipleantenna (MIMO) signal processing is known to offer useful degrees of freedom to cancel interference, extreme-value theoretic analysis recently showed that, even in the absence of MIMO processing, the scaling law of the capacity in the number of users for a multi-cell network with and without inter-cell interference was asymptotically identical provided a simple signal to noise and interference ratio (SINR) maximizing scheduler is exploited. This suggests that scheduling can help reduce inter-cell interference substantially, thus possibly limiting the need for multiple-antenna processing. However, the convergence limits of interference after scheduling in a multi-cell setting are not yet identified. In this paper1 we analyze such limits theoretically. We consider channel statistics under Rayleigh fading with equal path loss for all users or with unequal path loss. We uncover two surprisingly different behaviors for such systems. For the equal path loss case, we show that scheduling alone can cause the residual interference to converge to zero for large number of users. With unequal path loss however, the interference are shown to converge in average to a nonzero constant. Simulations back our findings.

The Degrees of Freedom (DoF) of a K-User MISO Broadcast Channel (BC) is studied when the Transmit... more The Degrees of Freedom (DoF) of a K-User MISO Broadcast Channel (BC) is studied when the Transmitter (TX) has access to a delayed channel estimate in addition to an imperfect estimate of the current channel. The current estimate could be for example obtained from prediction applied on past estimates, in the case where feedback delay is within the coherence time. Building on previous recent works on this setting with two users, the estimation error of the current channel is characterized by its scaling as P −α where α = 1 (resp. α = 0) corresponds to an estimate being essentially perfect (resp. useless) in terms of DoF. In this work, we contribute to the characterization of the DoF region in such a setting by deriving an outerbound for the DoF region and by providing an achievable DoF region. The achievable DoF is obtained by developing a new alignment scheme, called the K α -MAT scheme, which builds upon both the principle of the MAT alignment scheme from Maddah-Ali and Tse and Zero-Forcing to achieve a larger DoF when the delayed CSIT received is correlated with the instantaneous channel state.

In this work, we consider the joint precoding across K transmitters (TXs), sharing the knowledge ... more In this work, we consider the joint precoding across K transmitters (TXs), sharing the knowledge of the user's data symbols to be transmitted towards K single-antenna receivers (RXs). We consider a distributed channel state information (DCSI) configuration where each TX has its own local estimate of the overall multiuser MIMO channel. The focus of this work is on the optimization

This document provides an overview of the proposed innovations and activities in Task 1.2 of Work... more This document provides an overview of the proposed innovations and activities in Task 1.2 of Work Package 1 (WP1) of the ARTIST4G project, related to interference avoidance. Focus is on the technical approaches applicable at layer 2, which are grouped into five different classes of innovations related to clustering & user grouping, inter-cell interference coordination, coordinated scheduling, scheduling for joint processing and game theory based scheduling. Descriptions of the proposed innovations are given including basic ideas, potential of performance, simulation results, realization options and possible implementation restrictions. https://ict-artist4g.eu

In this work, we discuss the joint precoding with finite rate feedback in the so-called network M... more 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 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.

This deliverable presents analysis and simulation results related to moving relays and mobility o... more This deliverable presents analysis and simulation results related to moving relays and mobility optimization for relay enhanced networks. The results reported in this deliverable are ranging from fundamental performance limits expressed in terms outage probability to practical implementations of the moving relay concepts through architecture discussion, coordinated moving relays and network coded moving relays. https://ict-artist4g.eu

2015 IEEE International Symposium on Information Theory (ISIT), 2015

2015 IEEE International Conference on Communications (ICC), 2015

2014 48th Asilomar Conference on Signals, Systems and Computers, 2014

2013 IEEE 14th Workshop on Signal Processing Advances in Wireless Communications (SPAWC), 2013

2013 IEEE International Symposium on Information Theory, 2013

2010 IEEE International Conference on Acoustics, Speech and Signal Processing, 2010

ABSTRACT

2009 Conference Record of the Forty-Third Asilomar Conference on Signals, Systems and Computers, 2009

ABSTRACT

2011 IEEE 12th International Workshop on Signal Processing Advances in Wireless Communications, 2011

Interference is emerging as a fundamental bottleneck in many important wireless communication sce... more Interference is emerging as a fundamental bottleneck in many important wireless communication scenarios, including dense cellular networks and cognitive networks with spectrum sharing by multiple service providers. Although multipleantenna (MIMO) signal processing is known to offer useful degrees of freedom to cancel interference, extreme-value theoretic analysis recently showed that, even in the absence of MIMO processing, the scaling law of the capacity in the number of users for a multi-cell network with and without inter-cell interference was asymptotically identical provided a simple signal to noise and interference ratio (SINR) maximizing scheduler is exploited. This suggests that scheduling can help reduce inter-cell interference substantially, thus possibly limiting the need for multiple-antenna processing. However, the convergence limits of interference after scheduling in a multi-cell setting are not yet identified. In this paper 1 we analyze such limits theoretically. We consider channel statistics under Rayleigh fading with equal path loss for all users or with unequal path loss. We uncover two surprisingly different behaviors for such systems. For the equal path loss case, we show that scheduling alone can cause the residual interference to converge to zero for large number of users. With unequal path loss however, the interference are shown to converge in average to a nonzero constant. Simulations back our findings.

2010 IEEE Global Telecommunications Conference GLOBECOM 2010, 2010

In this paper, we present a general analytical framework for the exact mutual information (MI) cu... more In this paper, we present a general analytical framework for the exact mutual information (MI) cumulants of multiple-input multiple-output (MIMO) systems with perfect receiver channel state information (CSI) and no transmitter CSI. Our derivation is based on a recent parameterization of the joint ordered eigenvalue probability density function (PDF), that encompasses both uncorrelated/semi-correlated Rayleigh channels as well as uncorrelated Rician

2011 IEEE International Conference on Communications (ICC), 2011

In this paper, the rate region of the two user MIMO broadcast channel (BC) is investigated in the... more In this paper, the rate region of the two user MIMO broadcast channel (BC) is investigated in the high signal-to-noise ratio (SNR) regime, when linear precoding is used without time sharing. The transmitter is assumed to have more antennas than the sum of the receiving antennas, which is a meaningful assumption in cellular network after a scheduler has been used. To reach the rate region's boundary, the sum rate is maximized subject to a given ratio between the user's rates. The sum rate is first considered asymptotically when the SNR tends to infinity and the well known high SNR affine approximation in terms of the logarithm of the SNR is used. The multiplicative and the additive parameters are called respectively the multiplexing gain (MG) and the rate offset (RO) and the maximal values of these two parameters, which were not known in that case with proportional rate fairness considered, are derived at every point of the boundary of the rate region, as well as the optimal stream allocations associated with them. Analytical bounds for the boundary of the high SNR approximated rate region are then developed. Finally, the maximization of the rate subject to a rate ratio constraint is studied at finite SNR and algorithmic inner and outer bounds for the rate region boundary are derived. They are shown to be very close to each other and accurate even at intermediate SNR.

2013 IEEE International Conference on Communications (ICC), 2013

We consider the problem of downlink precoding for Network (multi-cell) MIMO networks where Transm... more We consider the problem of downlink precoding for Network (multi-cell) MIMO networks where Transmitters (TXs) are provided with imperfect Channel State Information (CSI). Specifically, each TX receives a delayed channel estimate with the delay being specific to each channel component. This model is particularly adapted to the scenarios where a user feeds back its CSI to its serving base only as it is envisioned in future LTE networks. We analyze the impact of the delay during the backhaul-based CSI exchange on the rate performance achieved by Network MIMO. We highlight how delay can dramatically degrade system performance if existing precoding methods are to be used. We propose an alternative robust beamforming strategy which achieves the maximal performance, in DoF sense. We verify by simulations that the theoretical DoF improvement translates into a performance increase at finite Signal-to-Noise Ratio (SNR) as well.