Outage Probability Analysis of Multi-Relay Delay-Limited Hybrid-ARQ Channels

We consider a wireless relay network with with hybrid-automatic retransmission request (HARQ) and Rayleigh fading channels. In this paper, we analyze the outage probability of the multi-relay delay-limited HARQ system with opportunistic relaying scheme in decode-and-forward mode. A simple and distributed relay selection strategy is proposed for multi-relay HARQ channels. Then, we analyze the performance of the system. We first derive the cumulative density function (CDF) and probability density function (PDF) of the selected relay channels. Then, the CDF and PDF are used to determine the outage probability in the l-th round of HARQ. The packet delay constraint is represented by L, the maximum number of HARQ rounds. Furthermore, closed-form upper-bounds on outage probability are derived, which are used to investigate the diversity order of the system. Based on the derived upper-bound expressions, it is shown that the proposed schemes achieve the full spatial diversity order of N + 1, where N is the number of potential relays. Our analytical results are confirmed by simulation results

Network Formation Games for Distributed Uplink Tree Construction in IEEE 802.16j Networks

International audienceThis paper investigates the problem of the formation of the uplink tree structure among the mobile multi-hop relay (MMR) network's base station (MMR-BS) and its different relay stations (RSs). We model the problem as a network formation game in which the RSs want to form a directed tree graph to improve their utility in terms of the Packet Success Rate (PSR) by using multi-hop cooperative transmission while accounting for a link maintenance cost. In this game, the relay stations engage in bilateral negotiations which result in a contractual agreement to form a directed link between each pair. For network dynamics, we propose a myopic algorithm based on the local best responses of the RSs that converges to a local Nash network. Moreover, the proposed dynamics algorithm allows the RSs to autonomously adapt the network topology to changes in the environment due to mobility or to the presence of heterogeneous traffic. Simulations results show how the RSs can self-organize in a tree structure while improving the network's overall PSR up to 17:5% and 15:6% compared, respectively, to the cases where no RSs exist and where the RSs are directly connected to the MMR-BS

Delay-Tolerant Decode-and-Forward Based Cooperative Communication over Ricean Channels

International audienceIn this paper, we propose a TDMA based simple transmission scheme, which overcomes the effect of the delays caused by the poor synchronization of the relaying nodes over Ricean channels. The proposed scheme is able to provide an optimized coding gain in unsynchronized cooperative networks as compared to the existing delay tolerant distributed space-time block codes

Physical Layer Security Game: Interaction between Source, Eavesdropper and Friendly Jammer

Special issue on physical layer securityInternational audiencePhysical layer security is an emerging security area that explores possibilities of achieving perfect secrecy data transmission between the intended network nodes, while possible malicious nodes that eavesdrop the communication obtain zero information. The so-called secrecy capacity can be improved using friendly jammers that introduce extra interference to the eavesdroppers. Here, we investigate the interaction between the source that transmits the useful data and friendly jammers who assist the source by \masking" the eavesdropper. In order to obtain a distributed solution, one possibility is to introduce a game theoretic approach. The game is de¯ned such that the source pays the jammers to interfere the eavesdropper, therefore increasing the secrecy capacity. The friendly jammers charge the source with a certain price for the jamming and there is a tradeo® for the price. If the price is too low, the pro¯t of the jammers is low and if the price is too high, the source would not buy the \service" (jamming power) or would buy it from other jammers. To analyze the game outcome, we de¯ne and investigate a Stackelburg type of game and construct a distributed algorithm. Our analysis and simulation results show the e®ectiveness of friendly jamming and the tradeo® for setting the price. The distributed game solution is shown to have similar performances to those of the centralized one. This work was supported by NSF CNS-0831371, and was supported by the Research Council of Norway through the project entitled "Mobile-to-Mobile Communication Systems (M2M)"

A New Energy Efficiency Measure for Quasi-Static MIMO Channels

International audienceIn this paper, we consider the multiple input multiple out- put (MIMO) quasi static channel. Our objective is to study the power allocation (over the transmit antennas) problem where not only the performance with respect to (w.r.t.) the transmission reliability but also the cost in terms of the consumed power is accounted for. We first review the existing results w.r.t energy effciency functions (benefit per cost) which focus mainly on the single input single output (SISO) case and then propose several extensions to the MIMO case. Then, we introduce a new energy effciency metric based on the outage probability. We conjecture that there is a non-trivial solution to the proposed optimization problem. Several special cases are thoroughly analyzed and simulation results will be provided to sustain the conducted analysis

Learning Distributed Power Allocation Policies in MIMO Channels

International audienceIn this paper, we study the discrete power allocation game for the fast fading multiple-input multiple-output multiple access channel. Each player or transmitter chooses its own transmit power policy from a certain finite set to optimize its individual transmission rate. First, we prove the existence of at least one pure strategy Nash equilibrium. Then, we investigate two learning algorithms that allow the players to converge to either one of the NE states or to the set of correlated equilibria. At last, we compare the performance of the considered discrete game with the continuous game in [7]

Improved Wireless Secrecy Capacity using Distributed Auction Theory

International audiencePhysical layer security is an emerging security area that explores possibilities of achieving perfect secrecy data transmission between the intended network nodes, while possible malicious nodes that eavesdrop the communication obtain zero information. The so-called secrecy capacity can be improved using friendly jammers that introduce extra interference to the eavesdroppers. Here, we investigate the interaction between the multiple source-destination links and a friendly jammer who assists by “masking” the eavesdropper. In order to obtain a distributed solution, one possibility is to introduce a distributed auction theoretic approach. The auction is defined such that the source-destination links provide bids for the jammer to interfere the eavesdropper, therefore increasing their secrecy capacities. We propose a distributed auction using the share auction and iteratively updating the bids. To compare with the performances, we construct a centralized solution and a VCG auction, which cannot be implemented in practice. Our analysis and simulation results show the effectiveness of friendly jamming and convergence of the proposed scheme. The distributed game solution is shown to have similar performances to those of the centralized ones