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Coalition formation games for distributed cooperation among roadside units in vehicular networks
- IEEE J. Sel. Areas Commun
, 2011
"... Abstract Vehicle-to-roadside (V2R) communications enable vehicular networks to support a wide range of applications for enhancing the efficiency of road transportation. While existing work focused on non-cooperative techniques for V2R communications between vehicles and roadside units (RSUs), this ..."
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Cited by 9 (2 self)
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Abstract Vehicle-to-roadside (V2R) communications enable vehicular networks to support a wide range of applications for enhancing the efficiency of road transportation. While existing work focused on non-cooperative techniques for V2R communications between vehicles and roadside units (RSUs), this paper investigates novel cooperative strategies among the RSUs in a vehicular network. We propose a scheme whereby, through cooperation, the RSUs in a vehicular network can coordinate the classes of data being transmitted through V2R communications links to the vehicles. This scheme improves the diversity of the information circulating in the network while exploiting the underlying content-sharing vehicle-to-vehicle communication network. We model the problem as a coalition formation game with transferable utility and we propose an algorithm for forming coalitions among the RSUs. For coalition formation, each RSU can take an individual decision to join or leave a coalition, depending on its utility which accounts for the generated revenues and the costs for coalition coordination. We show that the RSUs can self-organize into a Nash-stable partition and adapt this partition to environmental changes. Simulation results show that, depending on different scenarios, coalition formation presents a performance improvement, in terms of the average payoff per RSU, ranging between 20.5% and 33.2%, relative to the non-cooperative case.
On Analytical Derivations of the Condition Number Distributions of Dual Non-Central Wishart Matrices
"... Abstract—In this paper, we explore the statistical characterization of Multiple-Input Multiple-Output (MIMO) channel correlation matrices with the main focus being on their condition number statistics. More specifically, novel expressions are derived for the probability density function (PDF) and cu ..."
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Cited by 4 (2 self)
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Abstract—In this paper, we explore the statistical characterization of Multiple-Input Multiple-Output (MIMO) channel correlation matrices with the main focus being on their condition number statistics. More specifically, novel expressions are derived for the probability density function (PDF) and cumulative distribution function (CDF) of the MIMO condition number. Contrary to the majority of related studies, where only the common case of Rayleigh fading was considered, our investigation is extended to account for the generalized case of Ricean fading where a deterministic Line-of-Sight (LoS) component exists in the communication link. The overall analysis is based on the principles of random matrix theory and particularly of dual complex noncentral Wishart matrices; the latter represent a practical class of MIMO systems, namely dual-branch systems which are equipped with two transmit and receive antenna elements. All the derived formulae are validated through extensive simulations with the attained accuracy being remarkably good. Index Terms—MIMO systems, non-central Wishart matrices, condition number, Ricean fading.
Mutual Information Statistics and Beamforming Performance Analysis of Optimized LoS MIMO Systems
"... Abstract—This paper provides a systematic mutual informa-tion (MI) and multichannel beamforming (MBF) characterization of optimized multiple-input multiple-output (MIMO) commu-nication systems operating in Ricean fading. These optimized configurations are of high practical importance since, contrary ..."
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Cited by 4 (1 self)
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Abstract—This paper provides a systematic mutual informa-tion (MI) and multichannel beamforming (MBF) characterization of optimized multiple-input multiple-output (MIMO) commu-nication systems operating in Ricean fading. These optimized configurations are of high practical importance since, contrary to the common belief, benefit from the presence of direct Line-of-Sight (LoS) components and deliver maximum multiplexing gains, by deploying specifically designed antenna arrays at both ends. In the following, using elements from random matrix theory, novel analytical expressions are derived for the exact and asymptotic MI statistics while the prevalent Gaussian ap-proximation is examined. Moreover, new explicit expressions for the marginal eigenvalues are deduced which are thereafter used to analyze the BF performance of the associated eigenmodes in terms of Signal-to-Noise ratio (SNR) outage probability. We note that all derived formulas are given in tractable determinant form and therefore allow for fast and efficient computation and also yield an excellent match with Monte-Carlo simulations, under different fading scenarios and model parameters. Index Terms—Mutual information, MIMO systems, Ricean fading, Wishart matrices, eigenvalue distributions.
Reduced Complexity Detection for Ricean MIMO Channels Based on Condition Number Thresholding
"... Abstract—In this paper, a novel adaptive detection scheme for the case of Multiple-Input Multiple-Output (MIMO) Ricean channels with two transmit and receive antenna elements is presented. Our prime aim is to reduce the extensive complexity of Maximum-Likelihood (ML) detectors by developing an adapt ..."
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Abstract—In this paper, a novel adaptive detection scheme for the case of Multiple-Input Multiple-Output (MIMO) Ricean channels with two transmit and receive antenna elements is presented. Our prime aim is to reduce the extensive complexity of Maximum-Likelihood (ML) detectors by developing an adaptive scheme which switches between a ML and a much simpler Zero-Forcing (ZF) detector depending on the instantaneous spatial conditions. The kernel of the adaptive detector (AD) is a harddecision criterion based on the condition number of the MIMO correlation matrix. It is demonstrated that the proposed scheme offers a remarkable reduction in terms of complexity along with a satisfactory performance when specifically designed antenna arrays are employed. I.
Modelling for Vehicle to Vehicle Applications
"... Abstract — Rapid growth of personal communications has led to the development of many wireless systems, competing for radio bandwidth. In the vehicular environment, there is recognition of the importance of communications, and therefore the ability to model these channels is important. This paper ad ..."
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Abstract — Rapid growth of personal communications has led to the development of many wireless systems, competing for radio bandwidth. In the vehicular environment, there is recognition of the importance of communications, and therefore the ability to model these channels is important. This paper addresses this issue through the exploration of both vehicle to roadside (VTR) and vehicle to vehicle (VTV) communications. The paper presents a design methodology for achieving the maximum capacity under the above mentioned propagation conditions as well as reference and stochastic simulation models for vehicular environments. I.
Measurement-Based Modeling of Vehicle-to-Vehicle MIMO Channels
"... Abstract — Vehicle-to-vehicle (VTV) communications are of interest for applications within traffic safety and congestion avoidance, but the development of suitable communications systems requires accurate models for VTV propagation channels. This paper presents a new wideband MIMO (multiple-inputmul ..."
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Abstract — Vehicle-to-vehicle (VTV) communications are of interest for applications within traffic safety and congestion avoidance, but the development of suitable communications systems requires accurate models for VTV propagation channels. This paper presents a new wideband MIMO (multiple-inputmultiple-output) channel model for VTV channels based on extensive MIMO channel measurements performed at 5.2 GHz in rural environments in Lund, Sweden. The measured channel characteristics, in particular the non-stationarity of the channel statistics, motivate the use of a geometry-based stochastic channel model (GSCM) instead of the classical tapped-delay line model. We introduce generalizations of the generic GSCM approach and find it suitable to distinguish between diffuse and discrete scattering contributions. The time-variant contributions from discrete scatterers are tracked over time and delay using a high resolution algorithm, and our observations motivate their power being modeled as a combination of a deterministic part and a stochastic part. The paper gives a full model parameterization and the model is verified by comparison of MIMO antenna correlations derived from the channel model to those obtained directly from measurements. I.
Ergodic Capacity Upper Bound for Dual MIMO Ricean Systems: Simplified Derivation and Asymptotic Tightness
"... Abstract—An analytical upper bound on the ergodic capacity of Multiple-Input Multiple-Output (MIMO) systems is deduced with the aid of a simplified approach that relies on a fundamental power normalization. Given their high practical usability, we are particularly interested in dual configurations w ..."
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Abstract—An analytical upper bound on the ergodic capacity of Multiple-Input Multiple-Output (MIMO) systems is deduced with the aid of a simplified approach that relies on a fundamental power normalization. Given their high practical usability, we are particularly interested in dual configurations where both ends deploy two antenna elements. Contrary to the majority of related studies, where only the common case of Rayleigh fading is considered, our analysis is extended to account for Ricean fading where a deterministic Line-of-Sight (LoS) component exists in the communication link and both ends are affected by spatial correlation. In the following, it is shown that the proposed bound is applicable for any arbitrary Signal-to-Noise Ratio (SNR) and rank of the mean channel matrix. In fact, we consider both conventional and optimized MIMO configurations with equal LoS eigenvalues. Moreover, the tightness of the bound is explored where it is demonstrated that as the SNR tends to zero the bound becomes asymptotically tight; at high SNRs, the offset between empirical capacity and the bound is analytically computed which implies that an explicit asymptotic capacity expression can ultimately be obtained. Index Terms—MIMO systems, ergodic capacity, Ricean fading, spatial fading correlation.
Measurement-Based Modeling of Vehicle-to-Vehicle MIMO Channels
"... Abstract — Vehicle-to-vehicle (VTV) communications are of interest for applications within traffic safety and congestion avoidance, but the development of suitable communications systems requires accurate models for VTV propagation channels. This paper presents a new wideband MIMO (multiple-inputmul ..."
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Abstract — Vehicle-to-vehicle (VTV) communications are of interest for applications within traffic safety and congestion avoidance, but the development of suitable communications systems requires accurate models for VTV propagation channels. This paper presents a new wideband MIMO (multiple-inputmultiple-output) channel model for VTV channels based on extensive MIMO channel measurements performed at 5.2 GHz in rural environments in Lund, Sweden. The measured channel characteristics, in particular the non-stationarity of the channel statistics, motivate the use of a geometry-based stochastic channel model (GSCM) instead of the classical tapped-delay line model. We introduce generalizations of the generic GSCM approach and find it suitable to distinguish between diffuse and discrete scattering contributions. The time-variant contributions from discrete scatterers are tracked over time and delay using a high resolution algorithm, and our observations motivate their power being modeled as a combination of a deterministic part and a stochastic part. The paper gives a full model parameterization and the model is verified by comparison of MIMO antenna correlations derived from the channel model to those obtained directly from measurements. I.
