Browsing by Author "Jiang, Shuhua"

Now showing 1 - 3 of 3

F(2)-MAC: an efficient channel sensing and access mechanism for cognitive radio networks
(2011-07-01)
Chao, Hsi-Lu
;
Lou, TakChon
;
Jiang, Shuhua
;
資訊工程學系
;
Department of Computer Science
One of the most challenging issues in cognitive radio (CR) systems is channel sensing and accessing. In this paper, a CR channel access mechanism is proposed. The mechanism consists of two phases: fast channel accessing and proactive channel vacating. In fast channel accessing, a pair of CR users time-efficiently searches an available channel to deliver data. In proactive channel vacating, a pair of CR users periodically makes channel access opportunities to primary users (PUs) and vacates the occupied channel as quick as possible. We utilize the concept of channel hopping to reduce the average channel searching time. Furthermore, our vacating mechanism allows CR users to create opportunities for PUs to claim the spectrum and thus minimize the caused interference to PUs. We evaluate the performance of our approach through a two-dimensional Markov chain model as well as simulations. The performance study indicates that the proposed protocol achieves low channel searching time, high throughput, and fairness.
F-2-MAC: an efficient channel sensing and access mechanism for cognitive radio networks
(2011-07-01)
Chao, Hsi-Lu
;
Lou, TakChon
;
Jiang, Shuhua
;
資訊工程學系
;
Department of Computer Science
One of the most challenging issues in cognitive radio (CR) systems is channel sensing and accessing. In this paper, a CR channel access mechanism is proposed. The mechanism consists of two phases: fast channel accessing and proactive channel vacating. In fast channel accessing, a pair of CR users time-efficiently searches an available channel to deliver data. In proactive channel vacating, a pair of CR users periodically makes channel access opportunities to primary users (PUs) and vacates the occupied channel as quick as possible. We utilize the concept of channel hopping to reduce the average channel searching time. Furthermore, our vacating mechanism allows CR users to create opportunities for PUs to claim the spectrum and thus minimize the caused interference to PUs. We evaluate the performance of our approach through a two-dimensional Markov chain model as well as simulations. The performance study indicates that the proposed protocol achieves low channel searching time, high throughput, and fairness.
Linear Cooperative Detection for Alarm Messages in Cluster-Based Vehicular Ad Hoc Networks
(2010)
Jiang, Shuhua
;
Chao, Hsi-Lu
;
資訊工程學系
;
Department of Computer Science
Vehicular ad hoc network (VANET) is a special class of mobile ad hoc Networks (MANET), and is an important component of Intelligent Transportation System (ITS). VANET has a future potential in terms of a rich set of applications that it can provide to its customer. Accident detection is a key functionality of ITS. Due to the effects of channel fading and shadowing, individual vehicles may not be able to reliably detect the existence of an accident. In this paper, we propose a linear cooperation framework for accident detection in a cluster-based VANET. In this framework, accident detection is based on the linear combination of local statistics gathered by individual vehicles. Our objectives are minimizing the probability of false alarm and avoiding broadcast storm. Based on the problem formulation and derivation, we proposed two efficient algorithms to do alarm detection: local detection and global detection. The numerical results show that our heuristic strategies perform well on false alarm detection.