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Cooperative relay has been recognized as a promising approach for improving transmission efficiency and error performance in wireless networks. A number of realizations of cooperative relay communications, such as Amplify-and-Forward (AF), Decode-and-Forward (DF), have been proposed and the capacity gain of these replay approaches has been widely investigated. In this paper, we consider a cooperative...
This paper considers a target localization problem whose goal is to estimate the location of an unknown object. It is one of the key issues in applications of wireless sensor networks (WSNs). With recent advances in fabrication technology, deployment of a large WSNs has become economically feasible. On the other hand, this has caused the curse of dimensionality in applying learning algorithms such...
We deal with positioning of node in wireless sensor network (WSN) using received signal strength (RSS) when there is no priori knowledge about path-loss exponent and transmission power. Since the RSS decreases on the average with distance, it carries some information about the distance to an unknown node. By ordering the RSS's, we conclude that there are some convex sets where the position of the...
Wireless source localization has found a number of applications in wireless sensor networks. In this work, we investigate robust and low complexity solutions to the problem of source localization based on the time-difference of arrivals (TDOA) measurement model. By adopting a min-max approximation to the maximum likelihood source location estimation, we develop two low complexity algorithms that can...
IEEE 802.15.4 Wireless Sensor Networks (WSNs) share the 2.4 GHz Industrial, Scientific, and Medical (ISM) license-free band with many other wireless technologies such as IEEE 802.11b/g Wireless Local Area Networks (WLANs). Because of the low-power, however, IEEE 802.15.4 WSNs are potentially vulnerable to the interference introduced by the other wireless technologies such as IEEE 802.11b/g WLANs,...
Emerging wireless sensor and actuator network (WSAN) technology has the potential to enable semi-autonomous air-flow control to improve the aerodynamic performance of aircraft. In this paper, a WSAN topology comprising of multiple linear sensor clusters terminated by actuators is proposed for active flow control. Two interference aware convergecast scheduling strategies are presented and analyzed,...
In this paper, we study the resource allocation problem in relay aided two-hop uplink multi-user transmission with a single relay node and a single destination node. The orthogonal frequency division multiple access (OFDMA) is adopted as the main transmission modulation. We investigate the problems of subcarrier allocation, subcarrier coupling, and power allocation. The optimization is formulated...
This paper considers relay wireless network whose users are noncooperative to transmit the traffic to the gateway. To investigate network performance, the tandem queueing model is developed based on multiple-input multiple-output (MIMO) antenna system with space-time block code (STBC) transmission in a physical layer. Based on this queueing model, optimal traffic rate control is formulated as the...
In this paper we analyze performance of network coding focusing on two specific network coding schemes: XOR and random linear network coding. We have simulated different topologies and traffic patterns in order to provide better understanding of network coding behavior and its possible bottlenecks. As a part of our performance evaluation we address computational complexity of coding and decoding operations...
A novel distributed localization method for wireless sensor networks (WSN) is proposed in this paper. Linear frequency modulation (LFM) waves are emitted from two anchors simultaneously to create an interference field. Through the frequency measurement of local RSSI (Received Signal Strength Indication) signal, the TDoA (Time-Difference-of-Arrival) is estimated independently at each sensor to detect...
Experiments show that IEEE 802.11 DCF system exhibits unstable behavior in the congestion onset load range where the system starts to become saturated. This phenomenon is not well investigated due to the lack of proper models. In this paper, we propose a two-dimensional (2-D) Markov chain model by combining the well-known saturated model with newly created idle states. Closed-form solution to the...
In this paper, we consider a general bi-directional relay network with two sources and relays when neither the source nodes nor the relays know the channel state information~(CSI). A bi-directional relay selection scheme is proposed using differential analog network coding~(BRS-DANC), and a simple linear detector is given to recover the received signals. In the proposed scheme, we provide an optimal...
In this paper, we study the relay assignment problem in cooperative wireless networks with self-interested nodes. Such systems should be organized from the point of view of efficiency, stable and providing consistent incentives to all nodes. We propose a cooperation mechanism which includes the cooperative relationship formation stage and cooperation maintenance stage. The cooperative relationship...
In this paper, we introduce the concept of "route robustness" for path selection in multi-hop cognitive radio networks. We demonstrate that the aggregate throughput and robustness for routes determined by the introduced route robustness selection strategy are much better than those determined by other selection strategies as proposed in existing work. The rationale behind our approach is...
A Round-Robin Timing Exchange (RRTE) protocol is proposed for the distributed synchronization of wireless sensor network. Compared to the Timing-sync Protocol for Sensor Network (TPSN) and the Pairwise Broadcasting Synchronization (PBS) scheme, the power consumption for each sensor node (SN) of RRTE is much smaller than that of TPSN and is evenly distributed among each SN in contrast to the PBS method...
This paper deals with the partial target coverage (PTC) problem in wireless sensor networks with the objective of optimizing network lifetime. We first build a linear programming formulation, which takes total time a sensor spends on covering some targets into consideration, in order to obtain a lifetime upper bound. Then, based on the information of this formulation, we develop a sensor assignment...
Key distribution plays an important role in wireless sensor networks (WSNs), for information must be kept secure, even in an environment with limited storage ability and low data processing speed. However, it is a challenge to work in such a harsh requirement environment, the traditional key management scheme such as key distribution center (KDC) and public key cannot be used. Key pre-distribution...
Cooperative communication is an emerging and effective technology which can overcome the limitation and improve overall system performance of wireless networks. As important design parameters, relay selection, power and bandwidth allocation have been investigated respectively in previous literature. However, most of the existing schemes mainly consider single-relay selection, which may result in imbalance...
VoIP offers cheap voice communication which instigated its quick market growth. IEEE 802.11 WLANs offer cheap wireless coverage which can be used to provide VoIP service in mobile devices. But call capacity of such networks is very low compared to wired networks. To increase voice capacity in WLANs incorporation of power capture, increased data rate, and use of multiple channels are of great importance...
Multichannel solutions are increasingly used to cope with the problem of low capacity in sensor networks resulting from high contention during wake-up periods of nodes. We can consider wake-up schedules as virtual channels, because nodes using different schedules cannot communicate with each other. In this paper, we show that multiple virtual channel solutions come at the cost of an increased energy...
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