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Recently, there has been increasing interest and progress in lowering the worstcase time complexity for well-known NP-hard problems, particularly for the Vertex Cover problem. In this paper, new properties for the Vertex Cover problem are indicated, and several simple and new techniques are introduced, which lead to an improved algorithm of time O kn + 1(More)
Recent research shows that significant energy saving can be achieved in wireless sensor networks with a mobile base station that collects data from sensor nodes via short-range communications. However, a major performance bottleneck of such WSNs is the significantly increased latency in data collection due to the low movement speed of mobile base stations.(More)
Recent research shows that significant energy saving can be achieved in wireless sensor networks by using mobile elements (MEs) which are capable of carrying data mechanically. However, the low movement speed of MEs hinders their use in a class of data-intensive applications that need to collect highbandwidth sensor data under temporal constraints. To(More)
Mobile sinks can be used to balance energy consumption for sensor nodes in Wireless Sensor Networks (WSNs). Mobile sinks are required to inform sensor nodes about their new location information whenever necessary. However, frequent location updates from mobile sinks can lead to both rapid energy consumption of sensor nodes and increased collisions in(More)
The IEEE 802.16a standard defines WiMax mesh network, using the base station (BS) as a coordinator for the centralized scheduling. This paper proposes a centralized scheduling algorithm for WiMax mesh networks. In our scheme, each node has one transceiver and can be tuned between multiple channels, intending to eliminate the secondary interference for(More)
The increasing popular personal communications and mobile computing require a wireless network infrastructure that supports selfconfiguration and self-management. Efficient clustering protocol for constructing virtual backbone is becoming one of the most important issues in wireless ad hoc networks. The weakly connected dominating set (WCDS) is very(More)
Vehicular networks are experiencing rapid growth and evolution under the increasing demand of vehicular traffic management and ubiquitous network connectivity. In particular, the amount of information to be downloaded from the roadsidedeployed gateways is dramatically increasing. Infected by high mobility, intermittent connectivity, and unreliability of the(More)
Energy consumption is a major issue when designing routing protocols in wireless sensor networks. We propose a novel hole avoiding in advance routing protocol (HAIR) to address this issue. In the proposed protocol, a data packet can avoid meeting a "hole" in advance instead of bypassing a hole when it meets the hole as existing hole avoiding re-routing(More)
Due to low cost, ease of deployment, increased coverage, and enhanced capacity, multiradio mesh networks that utilize inexpensive and readily available Institute of Electrical and Electronics Engineers (IEEE) 802.11 wireless interfaces are touted as the new frontier of wireless networking. In a multihop mesh system, the close interaction between topology(More)
Contiguous spectrum assignment generates many small spectrum fragments that cannot be fully utilized, which leads to low spectrum utilization. With the development of advanced wireless radio technology, especially Discontiguous Orthogonal Frequency Division Multiplexing (DOFDM), discontiguous spectrum access and spectrum aggregation in a single radio has(More)