Browsing by Author "Wang, Honggang"

Now showing 1 - 2 of 2

Comparative Investigation on CSMA/CA-Based Opportunistic Random Access for Internet of Things
(IEEE, 2014-01) Tang, Chong; Song, Lixing; Balasubramani, Jagadeesh; Wu, Shaoen; Biaz, Saad; Yang, Qing; Wang, Honggang
Wireless communication is indispensable to Internet of Things (IoT). Carrier sensing multiple access/collision avoidance (CSMA/CA) is a well-proven wireless random access protocol and allows each node of equal probability in accessing wireless channel, which incurs equal throughput in long term regardless of the channel conditions. To exploit node diversity that refers to the difference of channel condition among nodes, this paper proposes two opportunistic random access mechanisms: overlapped contention and segmented contention, to favor the node of the best channel condition. In the overlapped contention, the contention windows of all nodes share the same ground of zero, but have different upper bounds upon channel condition. In the segmented contention, the contention window upper bound of a better channel condition is smaller than the lower bound of a worse channel condition; namely, their contention windows are segmented without any overlapping. These algorithms are also polished to provide temporal fairness and avoid starving the nodes of poor channel conditions. The proposed mechanisms are analyzed, implemented, and evaluated on a Linux-based testbed and in the NS3 simulator. Extensive comparative experiments show that both opportunistic solutions can significantly improve the network performance in throughput, delay, and jitter over the current CSMA/CA protocol. In particular, the overlapped contention scheme can offer 73.3% and 37.5% throughput improvements in the infrastructure-based and ad hoc networks, respectively.
Towards Trustworthy Vehicular Social Network
(IEEE, 2015-06) Yang, Qing; Wang, Honggang
Wireless vehicular networks offer the promise of connectivity to vehicles that could provide a myriad of safety-and driving-enhancing services to drivers and passengers. With wireless technology available on each car, it is expected that huge amounts of information will be exchanged between vehicles or between vehicles and roadside infrastructure. Due to defective sensors, software viruses, or even malicious intent, legitimate vehicles might inject untrustworthy information into the network. Besides relying on the public key infrastructure (PKI), this article proposes a social network approach to study trustworthy information sharing in a vehicular network. We first cover recent research progress in measuring direct trust and modeling in direct trust in online social networks then discuss how to apply them to vehicular social networks despite several pressing research challenges.