Behrouz Maham

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This letter studies information-theoretic security without knowing the eavesdropper’s channel fading state. We present an alternative secrecy outage formulation to measure the probability that message transmissions fail to achieve perfect secrecy. Using this formulation, we design two transmission schemes that satisfy the given security requirement while(More)
Cooperative communications via distributed spacetime codes has been recently proposed as a way to form virtual multiple-antennas that provide dramatic gains in slow fading wireless environments. In this paper, we consider the design of practical distributed space-time codes for wireless relay networks using the amplify-and-forward (AF) scheme, where each(More)
We consider a half-duplex wireless relay network with hybrid-automatic retransmission request (HARQ) and Rayleigh fading channels. In this paper, we analyze the average throughput and outage probability of the multi-relay delaylimited HARQ system with opportunistic relaying scheme in decode-and-forward mode, in which the best relay is selected to transmit(More)
Small cell networks are seen as a promising technology for boosting the performance of future wireless networks. In this paper, we propose a novel context-aware user-cell association approach for small cell networks that exploits the information about the velocity and trajectory of the users while also taking into account their quality of service (QoS)(More)
Existing studies on physical layer security often assume the availability of perfect channel state information (CSI) and overlook the importance of channel training needed for obtaining the CSI. In this letter, we discuss how an active eavesdropper can attack the training phase in wireless communication to improve its eavesdropping performance. We derive a(More)
The deployment of small cells, overlaid on existing cellular infrastructure, is seen as a key feature in next-generation cellular systems. In this paper, the problem of user association in the downlink of small cell networks (SCNs) is considered. The problem is formulated as a many-to-one matching game in which the users and SCBSs rank one another based on(More)
The idea of space-time coding, devised for multiple-antenna systems, can be applied to communication over a wireless relay network. In this paper, we derive an approximate formula for the bit error rate (BER) of distributed space-time codes in amplify-and-forward (AF) mode, in which each relay transmits a scaled version of the linear combination of its(More)
The idea of space-time coding, devised for multiple-antenna systems, can be applied to communication over a wireless relay network. This paper is on the design of practical distributed space-time codes for wireless relay networks, in which uses amplify-and-forward (AF) scheme in a way that each relay transmits a scaled version of linear combination of the(More)