g-Chang Chen

BUFE-MAC: A Protocol With Bandwidth Utilization and Fairness Enhancements for Mesh-Backbone-Based VANETs

Vehicular ad hoc network technologies can improve traffic safety for drivers and provide comfort services for passengers. Because the hardware of a roadside unit (RSU) is costly, in most previous research, vehicles might exchange data with an RSU through multihop transmissions. However, the vehicle with a larger number of hops to the RSU has fewer opportunities and longer time to exchange its data with the RSU because the contentions and collisions increase with the number of hops. This paper proposes the bandwidth utilization and fairness enhancements medium access control (BUFE MAC) protocol, which considers a vehicular ad hoc network that accesses the Internet through fixed Internet Gateways along the road. BUFE-MAC aims at increasing bandwidth utilization, maintaining fairness, and avoiding collision. The performance study reveals that the proposed MAC protocol not only avoids the collision problem but improves the performance in terms of end-to-end throughput and fairness as well.

A dead-end free deployment algorithm for wireless sensor networks with obstacles

In wireless sensor networks (WSNs), the performance of robot deployment is highly determined by the obstacle-resistance capability which refers to how well the robot can overcome the Dead-End problem and deploy minimal number of sensors for achieving full coverage even though the environment contains multiple obstacles. This paper presents a Dead-End free robot deployment algorithm, called DFD, that efficiently deploys minimal number of sensors for achieving full coverage while the Dead-End problem raised by obstacles can be overcome. Performance results reveal that the proposed DFD outperforms existing robot deployment mechanisms in terms of coverage ratio, energy consumption as well as deployment time.

An efficient scheduling algorithm for maximizing throughput in WiMAX mesh networks

WiMAX Mesh Network architecture is defined in IEEE 802.16 for increasing the network coverage and improving the communication performance. In the past few years, many greedy or heuristic approaches have been proposed to cope with the scheduling problem in WiMAX mesh networks. However, their performances highly depend on the network topology and the bandwidth requests and none of them achieves optimal for all cases. This paper proposes an efficient scheduling algorithm that exploits the opportunities of spatial reuse and maximize the network throughput based on the network topology and the uplink transmission requests of each Subscriber Station(SS). Simulation study reveals that the proposed efficient scheduling algorithm provides the WiMAX mesh network with maximal throughput and shortest transmission time.

JTEF: joint throughput enhancement and fairness MAC protocol for vehicular ad hoc networks

Vehicular Ad-Hoc Networks (VANETs) technologies can improve traffic safety for drivers and provide comfort services for passengers through copious amounts of Internet resources. Since the hardware of Road Side Unit (RSU) is costly, in most previous researches, vehicles exchange their data with RSU in a multi-hop manner. However, the vehicle with a larger number of hops to the RSU has fewer opportunities and longer time to communicate with RSU since the contentions and collisions increase with the number of hops. This paper proposes a Joint Throughput Enhancement and Fairness (JTEF) MAC protocol aiming to increase bandwidth utilization, maintain fairness, and avoid collision in a VANET environment. Performance study reveals that the proposed JTEF protocol outperforms existing CVIA protocol in terms of end-to-end throughput and fairness.

A Stepwise Multichannel MAC Protocol for Improving Bandwidth Utilization in Wireless Ad Hoc Networks

Multichannel media access control (MAC) protocols can increase wireless network capacities. The rendezvous problem is the most frequently encountered challenge in developing multichannel MAC protocols. Some studies have assumed that each device is equipped with one additional antenna; however, this increases the hardware cost. Other studies have divided the timeline of each channel into several beacon intervals. All stations are awake simultaneously on a predefined channel to enable rendezvous opportunities; however, this leads to low bandwidth utilization. This paper presents an efficient staggered multichannel MAC protocol (SMC-MAC) for ad hoc networks. By using a single antenna, the proposed SMC-MAC applies a staggered channel model with a home channel concept for exploiting multichannel bandwidth resources. Performance results reveal that the proposed SMC-MAC outperforms existing multichannel MAC protocols in terms of network throughput, control packet collision ratio, packet delay time, packet discarding, packet loss ratio, control overhead, and robustness.

Reduced Idle Listening Based Medium Access Control Protocol for Wireless Sensor Networks

In this paper, an energy efficient MAC protocol based on the finite projective plane (FPP) theory is proposed. Our protocol introduces an adaptive energy-efficient duty cycle for the sensor nodes to reduce the idle listening problem. By assigning each node with an FPP-set, we propose to decrease wake-up time and to determine the sleep or wake-up schedules based on the existing number of neighbors of a network coordinator. We have done rigorous simulation to analyze and compare the performance of our MAC protocol with some important and well known MAC protocols of wireless sensor. The simulation results show that our protocol outperforms over other MAC protocols in terms of energy consumption and end-to-end delay.