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We consider a cognitive radio system in which primary user stores packets in a queue for transmission. For proper functioning of primary system, the cognitive user must ensure that primary queue remains stable. We show that such a queue stability constraint can be converted to an equivalent interference constraint on cognitive user's transmission. Under this constraint, we propose a power allocation...
We present a natural and low-complexity technique for achieving the capacity of the Gaussian relay network in the high SNR regime. Specifically, we propose the use of end-to-end structured lattice codes with the amplify-and-forward strategy, where the source uses a nested lattice code to encode the messages and the destination decodes the messages by lattice decoding. All intermediate relays simply...
We study the Gaussian one-to-many interference network which is obtained as a special case of a general interference network, where only one transmitter generates interference in the network. We allow transmission of messages on all the links of the network. This communication model is different from the corresponding one-to-many interference channel. We formulate two transmission strategies for the...
In this paper, the analytical channel capacity of the decode-and-forward (DF) based dual-hop free space optical (FSO) system is studied. The FSO links are assumed to be asymmetric in nature and the turbulence is considered to follow the Gamma-Gamma distribution. For the considered DF FSO cooperative system, power series based mathematical expressions of the average channel capacity are derived, under...
In this paper, we investigate the impact of outdated channel state information (CSI) on the channel capacity of an opportunistic relaying system in conjunction with adaptive transmission techniques. We derive the closed-form expressions of the channel capacity and its associated outage probability for four adaptive transmission techniques: (1) optimal rate adaptation with constant transmit power,...
The paper presents the improvement offered by spatial diversity to reduce fading in ultra wideband (UWB) body-centric wireless communication channel in context of second order statistics for five different measured links, i.e., waist-to-chest, waist-to-head, waist-to-wrist, waist-to-ankle and waist-to-back. Average fade duration (AFD) and level crossing rate (LCR) values are presented and compared...
This paper presents closed-form expressions for the space-frequency (SF) second-order statistics for the power gain of indoor wideband channels. These expressions hold for channel models in which multi-path components are clustered, both in their arrival angles and their arrival times. Assuming that the arrival times are independent of the angles of arrival, we derive a closed-form expression for...
For cluster-based stochastic channel modeling, selection of clustering method is crucial for the final modeling results. Since a clustering algorithm can generate as many partitions as required, identification of the optimal number of clusters is a vital consideration in clustering, which is called cluster validity. In this contribution, five widely used indices for cluster validity are employed to...
In recent years, short range wireless communications have been used more and more frequently in our life. But the electromagnetic fields waves also have some disadvantages. One of these disadvantages is health problems. Many studies shows the electromagnetic field waves using for communication may damage our health. And in most hospitals, they also have bans on the use of mobile phones and wide area...
Channel characterization is the primary phase of wireless radio frequency identification (RFID) system based tracking processes. Traditional approaches of path-loss modeling of indoor RFID channel lack of the ability to assess the consistency and reliability of the fit. In this paper, we propose two approaches to ensure the reliability of the goodness-of-fit parameters of a fit and quantify its consistency...
Inter-Cell Interference Coordination (ICIC) is commonly identified as a key radio resource management mechanism to enhance system performance of 4G networks. This paper addresses the problem of ICIC in the downlink of cellular OFDMA systems where the resource selection process is apprehended as a congestion game. Proving the existence of Pure Nash equilibriums (PNE) shows that stable resource allocations...
This paper proposes a distributed routing mechanism for the multi-hop Cognitive Radio Networks (CRNs) over multiple primary channels. The Secondary Users (SUs) attempts to utilize the channels and minimize their delay along the route while avoiding causing interference to the Primary Users (PUs). In order to address the problem of time-varying channel condition due to the PU dynamics, the route-selection...
In this paper, the issue of energy-aware competitive resource allocation in an amplify-and-forward (AF) relay-assisted multiple-antenna interference network is considered. A non-cooperative game-theoretic approach is taken and the EE of each communication link is defined as the ratio of the achievable rate over the consumed power. The proposed resource allocation algorithm jointly allocates the relay...
In this paper, we study the problems of power allocation in a multi-user relay-assisted wireless network. From the perspective of game theory, we formulate and analyze this power allocation problem as a power trading game by considering users as bidders and the relay as an auctioneer. Aiming at solving this problem where each bidder has a private budget limit, we apply an adaptive clinching auction...
Motivated by the cooperative game theory, we propose an efficient physical layer network coding technique for compute-and-forward (C&F) relaying systems, which jointly optimizes the sum and the minimum transmission rate, while minimizing the total transmitting power. Specifically, we show that relay selection in C&F networks leads to an increase of both rates. We also propose an algorithmic...
This paper investigates energy and interference aware Cooperative Routing algorithms in Cognitive Radio Ad-Hoc Networks. Two routing algorithms have been proposed. In Algorithm I, we propose to minimize transmission power based on the rate required, and investigate the total transmission power consumption of the shortest path from source to destination whereby each link on the path is given the option...
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