Qingchun Ren

Energy and mobility aware geographical multipath routing for wireless sensor networks

In our proposed multipath routing scheme, remaining battery capacity, mobility, and distance to the destination location of candidate sensors in the local communication range are taken into consideration for next hop relay node selection, and a fuzzy logic system is applied to the decision making. Simulation results show that this scheme can extend the network lifetime longer than the original geographic routing scheme which only considers distance to the destination location, and this scheme can reduce the frame loss rate and link failure rate, since mobility is considered.

Secure media access control (MAC) in wireless sensor networks: intrusion detections and countermeasures

Current works on MAC protocols in wireless sensor networks(WSN) mainly concentrate on optimizing the efficiency and fairness of common channel access. We propose a secure MAC protocol improve the security of WSN, which is based on the RTS(request to send)/CTS(clear to send) mechanism. Our major contributions include: analysis of the security problems of RTS/CTS based MAC protocols; design of the intrusion detection method using soft decision theory; discussion of the intrusion strategies and attack and defense simulation models.

An energy-efficient MAC protocol for wireless sensor networks

In this paper, an asynchronous energy-efficient MAC protocol, ASCEMAC, is proposed for wireless sensor networks. In ASCEMAC, by applying free-running method and fuzzy logic rescheduling scheme, time synchronization which is necessary in existing energy-efficient MAC protocols is not required any more. Moreover, we present a traffic-strength- and network-density-based model to determine essential algorithm parameters, such as power on/off duration, interval of schedule broadcast and super-time-slot size and order. Simulation results show that our algorithm can ensure the average successful transmission rate, decrease the data packet average waiting time, and reduce the average energy consumption. Therefore, network performance is improved and network lifetime is extended by using our algorithm.

Cross-layer design for mobile ad hoc networks: energy, throughput and delay-aware approach

In this paper, we introduce a novel method for cross-layer design in mobile ad hoc networks. We use fuzzy logic system (FLS) to coordinate physical layer, data-link layer and application layer for cross-layer design. Ground speed, average delay and packets successful transmission ratio are selected as antecedents for the FLS. The output of FLS provides adjusting factors for the AMC (adaptive modulation and coding), transmission power, retransmission times and rate control decision. Simulation results show that our cross-layer design can reduce the average delay, increase the throughput and extend the network lifetime. The network performance parameters could also keep stable after the cross-layer optimization

A contention-based energy-efficient MAC protocol for wireless sensor networks

Energy-efficient MAC protocols applied for WSNs can be classified into two main categories: con tendon-based and schedule-based protocols, according to their wireless media access strategy. In this paper, we propose an asynchronous energy-efficient MAC protocol: A-MAC from contention perspective. Through applying free-running method and rescheduling scheme, A-MAC does not require network time synchronization any more, which is necessary for existing energy-efficient MAC protocols. So our algorithm is more suitable for the system which is difficult to ensure high quality network time synchronization. Moreover, we present a traffic-intensity- and network-density-based model to yield essential algorithm parameters: power on/off duration and interval of schedule broadcasts. Simulation results show that our algorithm can acquire optimal values of these parameters successfully to increase energy utility, ensure successful transmission rate and decrease data packet average waiting time. Therefore, network performance can be improved and network lifetime can be extended by using our algorithm

A quality-guaranteed and energy-efficient query processing algorithm for sensor networks

Query processing methods have been studied extensively in traditional database systems. But few of them can be directly applied into sensor database systems due to the characteristics of sensor networks: decentralized nature of sensor networks, limited computational power, imperfect information recorded, and energy scarcity of individual sensor nodes. In this paper, we propose a quality-guaranteed and energy-efficient algorithm (QGEE) for sensor database systems. We employ an in-network query processing method to task sensor networks through declarative queries. Given a query, our QGEE will adaptively form an optimal query plan in terms of energy efficiency and query quality. The goal of our approach is to reduce interference coming from measurements with extreme errors and to minimize energy consumption by providing service that is considerably necessary and sufficient for the requirement of applications. Moreover, we employ probabilistic method to formulate the distribution of imperfect information sources in terms of probability distribution function (PDF), and acquire probabilistic query answers on uncertain data. The probability to an answer allows users to place appropriate confidence in it. Simulation results demonstrate that our algorithm can reduce resource usage and supply quality satisfied query answers to users

Energy-efficient medium access control protocols for wireless sensor networks

A key challenge for wireless sensor networks is how to extend network lifetime with dynamic power management on energy-constraint sensor nodes. In this paper, we propose two energy-efficient MAC protocols: asynchronous MAC (A-MAC) protocol and asynchronous schedule-based MAC (ASMAC) protocol. A-MAC and ASMAC protocols are attractive due to their suitabilities for multihop networks and capabilities of removing accumulative clock-drifts without any network synchronization. Moreover, we build a traffic-strength- and network-density-based model to adjust essential algorithm parameters adaptively. Simulation results show that our algorithms can successfully acquire the optimum values of power-on/off duration, schedule-broadcast interval, as well as super-time-slot size and order. These algorithm parameters can ensure adequate successful transmission rate, short waiting time, and high energy utilization. Therefore, not only the performance of network is improved but also its lifetime is extended when A-MAC or ASMAC is used.