David Chunhu Li

Improving energy-efficient communications with a battery lifetime-aware mechanism in IEEE802.16e wireless networks

Green network communication has recently received attention because of its economic and environmentally friendly benefits. Energy consumption significantly affects mobile subscriber stations in wireless broadband access networks. Efficient energy saving is an important and challenging issue because all mobile stations are powered by limited battery lifetimes. The IEEE 802.16e standard adopts the sleep mode operation for energy saving with three important parameters: idle threshold, initial sleep window and final sleep window. Adaptively adjusting these parameters to improve energy‐efficient communication is an open research topic. This paper proposes a battery lifetime‐aware energy‐saving mechanism to adaptively adjust three sleep mode parameters for mobile stations and extend batteries lives. The new mechanism considers effect factors, including residual battery lifetime and traffic load on mobile stations. Analytical sleep mode operation models were explored in this work. Our proposed mechanism was examined with a computer simulation using QualNet. The simulation results demonstrate that the proposed mechanism outperforms the IEEE 802.16e standard in the average lives of mobile stations, improving them by up to 30.08% with little increase in the average waiting delay. Copyright

A Bipolar Traffic Density Awareness Routing Protocol for Vehicular Ad Hoc Networks

To support an increasing amount of various new applications in vehicular ad hoc networks (VANETs), routing protocol design has become an important research challenge. In this paper, we propose a Bipolar Traffic Density Awareness Routing (BTDAR) protocol for vehicular ad hoc networks. The BTDAR aims at providing reliable and efficient packets delivery for dense and sparse vehicle traffic network environments. Two distinct routing protocols are designed to find an optimal packet delivery path in varied vehicular networks. In dense networks, a link-stability based routing protocol is designed to take vehicles connectivity into consideration in its path selection policy and maximize the stability of intervehicle communications. In sparse networks, a min-delay based routing protocol is proposed to select an optimal route by analyzing intermittent vehicle connectivity and minimize packets delivery latency. Intervehicles connectivity model is analyzed. The performance of BTDAR is examined by comparisons with three distinct VANET routing protocols. Simulation results show that the BTDAR outperforms compared counterpart routing protocols in terms of packet delivery delay and packet delivery ratio.

A passenger-based adaptive traffic signal control mechanism in Intelligent Transportation Systems

How to improve transportation efficiency with latest green communication networking techniques in Intelligent Transportation Systems is a challenging research issue. In this paper, a passenger-based adaptive traffic signal control mechanism is proposed. Three major transportation and green networking related factors including passenger number, pollutant emission and fuel consumption are included in our mechanism. Vehicular messages containing the information of three factors are disseminated among the vehicles and Road Side Units via inter-vehicle and vehicle-to-infrastructure communication. We treat the Road Side Unit as a traffic signal control agent that can adaptively adjust traffic signal cycle in order to transport more passengers with increasing utilization of fuel consumption and reducing of pollutant emission of vehicles. Our mechanism is examined with extensive computer simulations. The simulation results show that the transportation efficiency is improved with up to 23.09% and the fuel consumption and pollutant emission is reduced up to 10.66% with the help of our mechanism.

Improve Energy Efficiency with a Battery Lifetime Aware Mechanism in the IEEE802.16e Broadband Access Networks

Broadband access networks provide high rate network connection to stationary users. The IEEE 802.16e is defined as a standardized technology that specifies wireless air interface between the fixed or mobile stations. Power saving has been an important challenge issue in mobile broadband wireless access networks because all mobile stations are operating with limited lifetime of batteries. Although the IEEE 802.16e standard adopts the sleep mode operation for power saving with three parameters including the idle threshold, the initial sleep window and the final sleep window. The standard does not define any mechanism to setup these parameters. However, these parameters impose significant effect on average delay and average power consumption. To improve energy efficiency, this paper proposed a battery lifetime aware mechanism to adaptively adjust sleep mode of mobile stations and extend their battery lifetime. Our proposed mechanism was examined with computer simulation. The simulation results demonstrate that the proposed mechanism outperforms the IEEE 802.16e standard in terms of average alive time of mobile stations.

Design and Implementation of a Novel Location-Aware Wearable Mobile Advertising System

Existing mobile advertising systems face criticalchallenges in flexibly updating ad contents and respondingto distinct consumer groups and regions. In this paper, anovel location-aware wearable mobile advertising systemis designed to overcome traditional shortcomings byintegrating electronic paper, location technologies andwireless communication techniques. The off-the-shelfelectronic paper is modified and implemented as awearable mobile ad device embedded in a user’s bag orclothing. This system was implemented and evaluatedusing outdoor experiments. Evaluation results showed thatour system achieves a noticeable improvement in locationperception and enhances the quality of the personalizedmobile service.

Energy Efficient Min Delay-based Geocast Routing Protocol for the Internet of Vehicles

Energy efficient routing protocols can potentially reduce the amount of energy consumed in packet forwarding. However, existing literature lacks studies on improving green performance of geocast routings for the Internet of Vehicles. Therefore, this study proposes an energy efficient min delay (EEMD)-based geocast routing protocol to find optimal relay nodes by incorporating energy consumption and packet delivery delay. We introduce energy efficiency in packet forwarding as a more appropriate indicator than energy consumption. We present a green protocol model and analyze its green networking performance in packet forwarding. Extensive simulation shows that our designed EEMD protocol allows efficient energy-saving data forwarding under various vehicular traffic conditions.