Jiakang Liu

An Improved LEACH Protocol for Application-Specific Wireless Sensor Networks

For wireless sensor networks, how to efficiently utilize limited energy directly affects the lifetime and the cost. LEACH is a clustering-based protocol with good performance, which employs localized coordination to balance the energy usage. In this paper, an improved LEACH protocol is proposed with a more reasonable set-up phase. The proposed protocol focuses on saving the energy cost induced due to redundant nodes and balancing the energy consumption among sensor nodes by splitting large clusters into smaller ones. Simulation results, compared with LEACH, demonstrate that the proposed protocol can reduce energy consumption and hence prolong the lifetime of WSN.

Minimum Node Degree and Connectivity of Two-dimensional MANETs under Random Waypoint Mobility Model

The performance of Mobile Ad Hoc Networks (MANETs) is influenced by many factors including node mobility, node density, and wireless transmission range. The mobility model representing the moving behavior of mobile nodes plays an important role in performance analysis and simulation of MANETs. In this paper, we first investigate the effect of node mobility on two fundamental characteristics of MANETs: minimum node degree and k-connectivity under the commonly used mobility mode, Random Waypoint (RWP) model. We derive an accurate closed-form network connectivity formula for a two-dimensional MANETs and use simulations to validate our analytical formula based on MATLAB. Hence, this work helps in better understanding the impact of RWP on network performance, and can facilitate the design and deployment of new, improved MANETs.

Energy Consumption & Lifetime Analysis in Cluster-Based Wireless Sensor Networks for Periodic Monitoring Applications

Clustering is one of the most popular approaches used in wireless sensor networks to conserve energy and increase node as well as network lifetime. LEACH is among the most popular clustering protocols proposed for wireless sensor networks. In this paper we have carried out network lifetime and energy consumption analysis for cluster-based wireless sensor networks based upon LEACH protocol for periodic monitoring applications. Simulation results based upon this protocol identify some important factors that induce unbalanced energy consumption among sensor nodes and hence affect the network lifetime when compared with the results obtained from the analytical model of this protocol. This highlights the need for an adaptive clustering protocol that can increase the network lifetime by further balancing the energy consumption among sensor nodes. Paper concludes with some recommendations for such protocol.

A Context-Aware Architecture for Wireless Sensor Networks

Unlike those traditional layered architectures, a non-layered protocol architecture for WSNs is proposed in this paper. The goals are greater flexibility and reliability with less network resource consumption. Based on the concept of micro-modularization, the context-aware architecture allows functions to be automatically composed within each sensor node according to the context information. An experimental simulation shows that, our proposal efficiently utilizes network resources, meanwhile provides good network performances.

Affect of Confinement of Event Field within the Sensor Field on Network Lifetime and Energy Consumption for Cluster-Based Wireless Sensor Networks

Clustering is one of the most popular approaches used in wireless sensor networks to conserve energy and increase node as well as network lifetime. In this paper we have analyzed the affect of confinement of event field within the sensor field on network lifetime and network energy consumption for cluster-based wireless sensor networks based upon LEACH protocol which is among the most popular clustering protocols proposed for these types of networks. Simulation results based upon this protocol identify some important factors that induce unbalanced energy consumption among sensor nodes which are located inside the event field to those which are located outside the event field and hence affect the network lifetime. This highlights the need for an adaptive clustering protocol that can increase the network lifetime by further balancing the energy consumption among sensor nodes. Paper concludes with some recommendations for such protocol.

A Cluster-Based Data Delivery Scheme for Delay Tolerant Mobile Sensor Networks

The Delay Tolerant Mobile Sensor Network (DTMSN) is a new type of sensor network for pervasive information acquisition, which is different from traditional sensor networks in several characteristics like sensor mobility and intermittent connectivity. In this paper, we propose a hierarchical data delivery scheme tailored for DTMSN, called Cluster-Based Direct Transmission (CBDT). By using variable power to transmit data, the single-copy scheme provides a new way to utilize network resources and make tradeoffs between network performances and resource consumptions. Simulation results show that, with low complexity and high flexibility, our proposal is more suitable for the DTMSN applications that the bandwidth and storage resources are quite limited.

A Backup Relay Technology for the Paired Slot Relay of JTIDS

In this paper we present a novel technology named Dynamic Relay Handover (DRH) for leveraging DSR and AODV for the benefit of providing a guaranteed network performance. The key points of DRH are the connectivity checking of the existing relay node and the assignment of a new relay node. In simulation of this algorithm based on OPNET Modeler 10.5, the effect of DRH on the network performance and the invulnerability is estimated according to the mostly used network performance indices and some new indices we propose. The simulation results indicate that as a backup relay mode for the paired slot relay, DRH can largely improve the invulnerability of JTIDS, while the extra cost on the network resources is little.

A Dynamic Relay Handover Technology for the Paired Slot Relay of JTIDS under Selective Attacks

In this paper we present a novel technology named Probability Dynamic Relay Handover (PDRH) for the benefit of providing a mechanism to recover from selective attacks on some important terminals of JTIDS. The key points of PDRH are the probability model to simulate selective attacks using the theory of scale-free network and addressing for a new relay node. In simulation based on OPNET Modeler 10.5, the effect of PDRH on the network performance and survivability are estimated according to the mostly used network performance indices and some new indices proposed. The results indicate that as a candidate relay handover technology for the paired slot relay, PDRH can largely improve the survivability of JTIDS under the attacks on the important terminals, while the extra cost on the network resources is little.