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Wireless sensor networks are often battery-powered, and hence extending the network lifetime is one of the primary concerns in the ubiquitous deployment of wireless sensor networks. One approach to efficiently utilize the limited energy supplies of the sensors is to have the medium access control (MAC) protocol duty-cycle the sensors, periodically putting(More)
SMAC is a popular duty-cycled MAC protocol, designed for wireless sensor networks to save energy and prolong the network lifetime. However, existing work evaluates the performance of SMAC solely through simulations or field measurements. To the best of our knowledge, there are no analytical models for evaluating the performance of SMAC. In this paper, we(More)
IEEE fixed 802.16 network aims at providing broadband wireless access with quality of service (QoS) guarantee. In all its services, real-time video traffic plays an impeditive role because of its varying bit-rate. In this paper, by taking advantage of traffic characteristics, a new scheduling and call admission control (CAC) scheme for real-time video(More)
IEEE 802.16 networks are going to provide broadband wireless access with quality of service (QoS) guarantee. In all of services, real-time video traffic plays an impeditive role because of its varying bit-rate and stringent delay constraint. To the best of our knowledge, no call admission control (CAC) and scheduling schemes cover throughput expectation,(More)
In this paper we propose a new routing protocol for mobile wireless sensor networks, which fixed and mobile sensor nodes in the same network, called Energy-efficient Chain-cluster Routing protocol (ECRM). The protocol organizes the fixed node, whose battery is impossible to be recharged, into the communication backbone to maintain the basic connectivity of(More)
Single-hop centralized wireless sensor networks are widely used for applications ranging from security and surveillance to medical monitoring. Often the goal of these networks is to provide satisfactory quality of service (QoS) to the application under different system states, but it is difficult to determine how the appropriate sensor sets should be(More)
Sensor sleeping is a widely-used and cost-effective technique to save energy in wireless sensor networks. Protocols at different stack levels can, either individually or simultaneously, make the sensor sleep so as to extend the application lifetime. To determine the best choice for sensor sleeping under different network conditions and application(More)
Various applications of wireless sensor networks require multihop data transmission over error-prone wireless links, hence multipath routing can be used to meet the application's reliability requirement. On the other hand, wireless sensors are usually battery powered, and thus it is very important to save energy in order to prolong the network lifetime. In(More)
In wireless sensor networks, multipath routing is used to alleviate reliability degradation due to multihop transmissions over error-prone wireless channels. However, multipath routing is not energy-efficient, as it requires all the nodes in the network to always be awake. To prolong the network lifetime while maintaining a certain reliability performance,(More)
It is difficult for hearing-impaired people to communicate with others when they go out alone and meet trouble. Because the number of Chinese hearing-impaired people is about 30 million, there are only 20 thousand interpreters in China. On the other hand, it is quite difficult to arrange for an interpreter in every hospital or information center. Therefore,(More)