Current Issue : October - December Volume : 2011 Issue Number : 1 Articles : 5 Articles
Wireless sensor networks (WSNs) are a vibrant research field for the last several years. Especially, design of MAC protocols supporting multimedia traffic QoS is recent challenging work. However, the mechanisms of protocols that can guarantee multimedia traffic QoS have several problems in multihop wireless sensor networks. There are a lot of reasons, including limited end-to-end delay and high throughput. In this paper, we propose ascalable MAC protocol that guarantees multimedia traffic, still images, and scalar sensor data QoS in multi-hop wireless sensor networks. The MAC protocol has made it possible to transmit multimedia streaming traffic without a great change of the end-to-end delay for a specific time. And if there are the some link failures in multi-hop transmission, the protocol can recover the links quickly. Using this algorithm, the proposed MAC protocol outperforms the IEEE 802.11e EDCF and the IEEE 802.15.4 MAC protocol in terms of the end-to-end delay and stable transmission of multimedia streaming data....
Due to the imbalance of energy consumption of nodes in wireless sensor networks (WSNs), some local nodes die prematurely, which causes the network partitions and then shortens the lifetime of the network. The phenomenon is called ââ?¬Å?hot spotââ?¬Â or ââ?¬Å?energy holeââ?¬Â problem. For this problem, an energy-aware distributed unequal clustering protocol (EADUC) in multihop heterogeneous WSNs is proposed. Compared with the previous protocols, the cluster heads obtained by EADUC can achieve balanced energy, good distribution, and seamless coverage for all the nodes. Moreover, the complexity of time and control message is low. Simulation experiments show that EADUC can prolong the lifetime of the network significantly....
Large-scale wireless sensor networks follow the two-tiered architecture, where master nodes take charge of storing data and processing queries. However, if a master node is compromised, the information stored in it may be exposed, and query results can be juggled. This paper presents a novel scheme called SEF for secure range queries. To preserve privacy, SEF employs the order-preserving symmetric encryption which not only supports efficient range queries, but also maintains a strong security standard. To preserve authenticity and integrity of query results, we propose a novel data structure called Authenticity & Integrity tree. Moreover, SEF is flexible since it allows users to include or exclude the authenticity and integrity guarantee. To the best of our knowledge, this paper is the first to use the characteristic of NAND flash to achieve high storage utilization and query processing efficiency. The efficiency of the proposed scheme is demonstrated by experiments on real sensor platforms....
The TDOA-based source localization problem in sensor networks is considered with sensor node location uncertainty. A total least squares (TLSs) algorithm is developed by a linear closed-form solution for this problem, and the uncertainty of the sensor location is formulated as a perturbation. The sensitivity of the TLS solution is also analyzed. Simulation results show its improved performance against the classic least squares approaches....
As more and more wireless devices use the 2.4?GHz radio spectrum, the coexistence of 2.4?GHz wireless devices operating in one place has become a hot topic. With low transmit power, the widely deployed IEEE?802.15.4-based networks are easily interfered with by other 2.4?GHz wireless networks, such as IEEE?802.11. IEEE 802.15.4-based wireless networks have paid great attention to the coexistence between themselves and with other non-IEEE?802.15.4 wireless networks. This problem has been further promoted by two new industry wireless standards, WirelessHART and ISA100, to meet special industry requirements. This paper surveys the studies on the coexistence between IEEE?802.11 and IEEE?802.15.4-based networks following the general analysis method of ââ?¬Å?question-analysis-solution.ââ?¬Â Based on the survey study, we discuss about some open research issues and developments in this field....
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