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A lot of access points (APs) in wireless mesh networks (WMNs) are battery powered. In order to minimize their energy consumption, the APs can adaptively adjust their transmission power and time based on various network conditions. In this paper, the problem of minimizing the AP energy consumption is formulated as an optimization problem with the constraint to satisfy the throughput requirements of...
A spectrum-sharing communication system where the secondary user is aware of the instantaneous channel state information (CSI) of the secondary link, but knows only the statistics and an estimated version of the secondary transmitter-primary receiver (ST-PR) link, is investigated. The optimum power profile and the ergodic capacity of the secondary link are derived for general fading channels (with...
Localization in underwater environments has been constrained by the dependencies on the line of sight (LOS) due to the challenging variability's of the environment. This dependency hinders node discovery and ad-hoc formation in underwater networks and limits the performance of routing protocols. Most proposed algorithms in the literature rely on anchor nodes that are at fixed positions to serve as...
In this paper, we propose a relay selection amplify-and-forward (RS-AF) protocol in general bi-directional relay networks with two sources and relays. In the proposed scheme, the two sources first transmit to all the relays simultaneously, and then a single relay will be selected to broadcast the received signals back to both sources to achieve a minimum sum symbol error rate (SER). To facilitate...
Dynamic spectrum auction is an effective way to stimulate primary users to lease their idle spectrum and meanwhile solve the competitions among secondary users through bidding. Due to the spatial reusability of spectrum, multiple users which are separate enough can have access to the same spectrum simultaneously without interfering each other. In this paper, we propose a spectrum auction framework...
In this paper, we propose a novel peak to average power ratio (PAPR) reduction scheme of orthogonal frequency division multiplexing (OFDM) signals. In our proposed scheme we exploit the repeated rotation and recombination of the in-phase and the quadrature components of an OFDM symbol in time domain. Our proposed scheme has two main advantages over the previously known scheme such as iterative partial...
Wireless Sensor Network (WSN) are usually used in hostile environment to collect informations. The sensors use to get there energy form batteries. It is a crucial point for live time of the network. Energy has to be saved for this type of networks. In WSN, routing protocol usually take care on this parameter. In this paper, we propose to use an image representation of the energy dissemination in the...
Service composition is a useful technology to achieve dynamic requests. But in cloud, the cloud provider should guarantee the QoS of the user request as well. Previous work investigated how to select proper available replicas (the similar functional services located on different physical nodes) to effectively achieve the composite services. However, as the requirements for some service grow, even...
When there are multiple storage node failures in distributed storage system, regenerating them individually is suboptimal as far as repair bandwidth minimization is concerned. The tradeoff between storage and repair bandwidth is derived in the case where data exchange among the newcomers is enabled. The tradeoff curve with cooperation is strictly better than the one without cooperation. An explicit...
The ideas of wireless network coding at the physical layer promise high throughput gains in wireless systems with relays and multi--way traffic flows. This gain can be ascribed to two principles: (1) joint transmission of multiple communication flows and (2) usage of a priori information to cancel the interference. In this paper we use these principles to devise new transmission schemes in wireless...
The design of packet schedulers involves a tradeoff between implementation complexity, on one hand, and delay and fairness guarantees, on the other. In this paper, we present worst-case fair bin sort queuing (WBSQ), a new scheduler that has good worst-case fairness and delay properties, yet has low complexity and is amenable to simple hardware implementation. WBSQ achieves this performance by combining...
In this paper, efficient deployment algorithms are proposed for a mobile sensor network to improve coverage. The proposed algorithms calculate the position of the sensors iteratively based on the existing coverage holes in the target field. The multiplicatively weighted Voronoi diagram (MW-Voronoi diagram) is used to discover the coverage holes corresponding to different sensors with different sensing...
An advanced CSMA/CA (carrier sense multiple access with collision avoidance) system incorporating total precedence transmission of all CA and MAC frames (known as a full-flying synchronous CSMA/v-MCA system in Japan, where v- MCA means a variable multiple CA) was developed to minimize the time wasted for upstream channels. In this system, the CA procedures and the controls of the MAC frame transmission...
Both grid and cloud applications may require specific softwares for their execution. Introducing such requirements into the DAG describing the dependencies among the tasks of an application leads to a combinatorial problem with numerous possibilities of modified DAGs. This paper introduces an algorithm to obtain a single DAG with the minimum possible makespan by reducing the need for data transfer...
The time and space varying nature of channel availability among cognitive radio nodes challenges connectivity and robustness of ad-hoc cognitive radio networks. Clustering of neighbouring cognitive radio nodes is a suitable approach to address this challenge. A cluster utilizes the same channel for payload communication among the nodes. As a consequence, clustering enables cooperative spectrum sensing,...
Wireless body sensor networks (BSN) are being used to continuously monitor the patient's conditions and recovery progress. It is very important to secure the confidentiality, integrity and authenticity of the patient's health record in such applications. In this paper, we propose a novel key distribution and management scheme that uses keychains to establish group keys for body sensor networks. This...
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