Chee-Onn Chow

A Survey on the Taxonomy of Cluster-Based Routing Protocols for Homogeneous Wireless Sensor Networks

The past few years have witnessed increased interest among researchers in cluster-based protocols for homogeneous networks because of their better scalability and higher energy efficiency than other routing protocols. Given the limited capabilities of sensor nodes in terms of energy resources, processing and communication range, the cluster-based protocols should be compatible with these constraints in either the setup state or steady data transmission state. With focus on these constraints, we classify routing protocols according to their objectives and methods towards addressing the shortcomings of clustering process on each stage of cluster head selection, cluster formation, data aggregation and data communication. We summarize the techniques and methods used in these categories, while the weakness and strength of each protocol is pointed out in details. Furthermore, taxonomy of the protocols in each phase is given to provide a deeper understanding of current clustering approaches. Ultimately based on the existing research, a summary of the issues and solutions of the attributes and characteristics of clustering approaches and some open research areas in cluster-based routing protocols that can be further pursued are provided.

Enhancing real-time video streaming over mobile ad hoc networks using multipoint-to-point communication

Supporting video applications over mobile ad hoc networks is more challenging than over other best-effort networks due to the lack of a preinstalled infrastructure to provide centralized control for the entire networks. As mobile ad hoc networks emerge as a promising technology for untethered, ubiquitous service in future communication system, a solution to support increasingly popular video applications is essential. A considerable amount of research has been done to provide solution for video streaming over lossy networks, among which are the diversity techniques. Path and server diversities are proven feasible to guarantee reliable video delivery wired networks. Besides, using disjoint multipath to support video streaming over mobile ad hoc networks has also been widely studied. In this paper, we investigate the possibility of implementing server diversity over ad hoc networks. More specifically, we use multipoint-to-point transmission together with Multiple Description Coding to enhance the quality of video streaming. In order to discover maximally disjoint routes for each sender and to distribute the workload evenly within the network, an extension for video applications is added to the dynamic source routing (DSR) protocol. Simulation study is carried out using NS-2 to demonstrate the feasibility of the proposed mechanism and it shows that better quality of video streaming is achieved, in terms of fewer and shorter interruptions during the video session. Moreover, we also show that the number of transmission points should be limited because using too many transmission points burdens the network with unnecessary control overhead.

Multiple Tree Multicast Ad Hoc On-Demand Distance Vector (MT-MAODV) Routing Protocol for Video Multicast over Mobile Ad Hoc Networks

Video multicast over wireless medium has gained increasing popularity in a wide range of applications, such as video-on-demand and group video conferencing. With mobile ad hoc networks emerging as a promising solution for future ubiquitous communications, supporting reliable video multicast over mobile ad hoc networks is a timely research topic. In this paper we tackle this issue by using multiple tree multicast routing protocol. Specifically, we introduce an extension to the Multicast Ad Hoc On-demand Distance Vector (MAODV) routing protocol to construct two optimally disjoint trees in a single routine. The extended protocol is called Multiple Tree Multicast Ad Hoc On-demand Distance Vector (MT MAODV) routing protocol. In order to distribute the video evenly and independently between these disjoint trees, the Multiple Description Coding (MDC) scheme is used for video coding. Simulation shows that the proposed protocol demonstrates video multicast with better quality than the conventional video multicast using a single tree only.

A survey on design of self-powered wireless sensor network

Supporting sensor application over wireless sensor node (WSN) is more challenging than over any other sensor due to the absence of a convenient way to maintenance the sensor node, especially in changing of energy source (batteries). In this paper, we solve this problem by using the ambient energy source (solar), design the efficient power conversion, and low-power consumption in WSN system. Some modifications have been introduced considering the differences between wired and wireless network. The modifications also consider the differences wide of WSN for detection. Simulation study is carried out using PSPICE to demonstrate the performance of the power conversion mechanism. MPLAB is used for the proposed logical control (PIC). We show that the proposed mechanism outperforms the wireless sensor node reception and transmission in every situation (different levels of darkness).

An enhanced framework for providing multimedia broadcast/multicast service over heterogeneous networks *

Multimedia broadcast multicast service (MBMS) with inherently low requirement for network resources has been proposed as a candidate solution for using such resources in a more efficient manner. On the other hand, the Next Generation Mobile Network (NGMN) combines multiple radio access technologies (RATs) to optimize overall network performance. Handover performance is becoming a vital indicator of the quality experience of mobile user equipment (UE). In contrast to the conventional vertical handover issue, the problem we are facing is how to seamlessly transmit broadcast/multicast sessions among heterogeneous networks. In this paper, we propose a new network entity, media independent broadcast multicast service center (MIBM-SC), to provide seamless handover for broadcast/multicast sessions over heterogeneous networks, by extensions and enhancements of MBMS and media independent information service (MIIS) architectures. Additionally, a network selection scheme and a cell transmission mode selection scheme are proposed for selecting the best target network and best transmission mode. Both schemes are based on a load-aware network capacity estimation algorithm. Simulation results show that the proposed approach has the capability to provide MBMS over heterogeneous networks, with improved handover performance in terms of packet loss rate, throughput, handover delay, cell load, bandwidth usage, and the peak signal-to-noise ratio (PSNR).

Threat Models and Security Issues in Wireless Sensor Networks

Security is a crucial issue for wireless sensor networks due to the deployment nature and the resources limitations of tiny sensor devices used in such networks. Sensor networks are used sometime in very sensitive applications such as healthcare and military. With this in mind we must address the security concerns from the beginning of network design. Owing to limited resources and computing constraints security in sensor networks poses more severe challenges as compare to the traditional networks. There are currently enormous approaches in the field of wireless sensor networks security. No comprehensive study lists the security issues and the threat models which pose unique threats to the wireless sensor networks. In this paper we have corroborated well known security issues and have provided the direction of research towards effective countermeasures against the threats posed by these issues.

A Simulation Study on Multipoint-To-Point Video Streaming Over Mobile Ad Hoc Networks

Supporting video applications over infrastructureless mobile ad hoc networks is more challenging than over any other networks due to the absence of fixed infrastructure and rapid changes in network topology. In this paper, we tackle this problem by adopting the concept of multipoint-to-point (M2P) video transmission together with multiple description coding (MDC) scheme. Some modifications have been introduced considering the differences between wired and wireless networks and the dynamic source routing (DSR) protocol is extended accordingly to support M2P video transmission. Simulation study is carried out using NS-2 to demonstrate the performance of the proposed mechanism as compared to point-to-point transmission and the original dynamic source routing protocol. We show that the proposed mechanism outperforms the conventional point-to-point transmission, especially at high mobility

Directional multi-hop clustering routing protocol for wireless sensor networks

In recent years, cluster-based routing protocol in wireless sensor networks WSNs has drawn great attention among researchers. In this paper, we propose directional multi-hop clustering routing DMCR protocol for wireless sensor networks that chooses the least number of hops within a straight line through the most reliable path for data transmission. The route-finding process is carried out by using low-cost devices like angle of arrival AoA antennas. This mechanism is especially suitable for large network topologies because not only the energy efficiency of the network is improved by limiting the number of nodes participating in data transmission to the BS, but the necessity of re-clustering is also reduced by choosing the most energetic node nearest to the BS in each cluster to relay the aggregated data. The proposed protocol was proven through extensive simulations to outperform existing protocols in terms of network lifetime and data packet delivery.

BER-Driven Resource Allocation for Scalable Bitstreams Over OFDMA Networks

Conventional resource-allocation schemes in orthogonal frequency-division multiple-access (OFDMA) systems consider only one bit-error-rate (BER) requirement. When these schemes are applied to transmit bitstreams with multiple BER requirements, low resource utilization will occur since the target BER has to be the strictest one. We develop a BER-driven resource allocation for generic bitstreams (BRA-G) algorithm by exploiting multiple predetermined target BERs. Then, this scheme is extended to transmission of realistic scalable bitstreams (BRA-SB) where more important (MI) layers possess lower target BERs as compared with less important (LI) layers. The objective here is to maximize the expected quality of all JPEG 2000 (J2K) scalable bitstreams subject to a total power constraint. Instead of using static target BERs for different layers, BRA-SB water-fills over all layers to determine the number of transmit layers and the target BER of each layer simultaneously based on the importance of each layer in terms of reconstructed quality and average channel conditions. Bit-level results show that BRA-SB provides significant image quality improvement over a scheme that ignores the layers importance in terms of target BER and a BRA-SB-like scheme with static target BERs. A suboptimal algorithm is also proposed to reduce the computational complexity and its performance is close to the optimal one.

Multiple tree video multicast over mobile ad hoc networks

Recently, video multicast over wireless medium has gained increasing popularity in a wide range of applications, such as video-on-demand and group video conferencing. As mobile ad hoc networks emerge as a promising solution for future ubiquitous communication, it is a timely research topic to propose a reliable video multicast framework over these networks. In this paper we tackle this issue by using multiple tree multicast routing protocol. Specifically, we introduce an extension to the multicast ad hoc on-demand distance vector (MAODV) to construct two optimally-disjoint trees for a multicast group in a single routine; it is called multiple tree multicast ad hoc on-demand distance vector (MT-MAODV) routing protocol. Besides, the video is coded into independent video streams using the multiple description coding (MDC) scheme in order to distribute the encoded video independently between these disjoint trees. Simulation study shows that our proposed routing protocol demonstrates video multicast with better quality than conventional model using single tree.