28503977
Adoption of Cognitive Radio Scheme to Class-Based Call Admission Control
By using cognitive radio technology, opportunistic spectrum access has the potential to solve the underused spectrum problem. In this paper, by first introducing a specific cognitive radio scheme, we analyze the secondary user's capacity and the collision probability. Employing this scheme, we build two call admission control models for three classes of service, namely, handoff voice calls, new voice calls and data calls. We show that they achieve improved blocking probability and throughput by exploiting the cognitive radio scheme. Further, we show a tradeoff between collision probability and blocking/throughput in the call admission control.
46510068
Design of Pork Traceability Information System
53246406
A bipolar IF amplifier/RSSI for ASK receiver
12168164
Lessons learned from the practice of mobile health application development
This fast abstract briefly discusses lessons learned in terms of how to overcome limitations of PDA devices, effectively capture requirements for mobile health application development and effectively reengineer a desktop application on PDA. The limitation of PDA devices includes: (1) small screen size, which limits text-based data entry, reporting and browsing; (2) limited storage space and slow processing, which requires effective and efficient coding generation; (3) security limitations and inadequate third party application support, which poses challenge for application development. The corresponding strategies addressing the above challenges are: (1) providing check box, radio button, drop down list, text field, combo box based data entry and minimize text-based data entry, such as text area; (2) allocating as much as possible data storage, communication and computation tasks to the desktop system and minimize the function PDA component needs to handle, store data in file instead of database on PDA; (3) carefully selecting the device and implementation platform that supports development. To maximize the usability of PDA-based health application, the solution to be implemented on PDA ideally should be data management tasks with minimum text-based data entry and high frequency of recording. Challenges and solutions for software reengineering from desktop system to PDA-based application is outlined based on one application developed for World Health Organisation. In this example, the complex task of communication among PDA-based application, desktop system and the existent desktop application EpiData is effectively handled through the utilisation of XML files. A dynamic tool 'Questionnaire Designer' provides a completely dynamic user interface generation tool that could easily be handled by end user. The design idea for this application sets up a model for mobile health application with adequate flexibility of handling changing data management needs of end users.
6172514
Dynamic Subchannel and Power Allocation in OFDMA-Based DF Cooperative Relay Networks
This paper focuses on subchannel and power allocation problem in OFDMA-based decode-and-forward (DF) cooperative relay networks. The objective of this problem is to maximize the total data rate under the constraints of joint total transmission power and subchannels occupation, while maintaining the maximum fairness among multiple relay nodes. We transform this mixed integer programming problem to a standard convex optimization one through Lagrangian relaxation method. Accordingly, the optimal solution can be achieved by using Karush-Kuhn-Tucker (KKT) conditions. In addition, we propose two suboptimal subchannel allocation schemes with and without subchannel permutation (SP), which reduce significantly the computational complexity with small performance loss. The simulation results show that the performance of the proposed suboptimal algorithms with SP approaches asymptotically that of the optimal algorithm and with the increment of the number of relay nodes.
18580310
1-Persistent Collision-Free CSMA Protocols for Opportunistic Optical Hyperchannels
Recently, a new WDM optical network infrastructure named SMART [1], which is capable of dynamically setting up, modifying, and tearing down optical connections, was proposed. The performance of SMART is determined by the performance of its hyperchannels, which are essentially optical buses or light-trails. Previously proposed CSMA protocols for unidirectional optical buses can be used as distributed medium access control protocols for hyperchannels. However, these protocols are either unfair, or not work-conserving. In this paper, we propose a class of work-conserving, collision-free, and fair CSMA protocols for opportunistic hyperchannels which are tailored hyperchannels for SMART. We show that the performances of our proposed protocols are much better than that of p i -persistent CSMA and that of priority-based CSMA protocol in terms of throughput and fairness.
10763979
Flocking Motion of Mobile Agents with a Leader Based on Distance-Dependent Adjacency Matrix
In this study, a novel procedure is presented for control and analysis of multiple autonomous agents with point mass dynamics achieving flocking motion with a time variant leader. Two control laws are proposed for a group of autonomous agents to achieve flocking formations related to two different centers (mass center and geometric center) of the flock. The first one is designed for flocking motion based on mass center and the second for geometric center. Distance-dependent adjacency matrix is used to quantify the way agents influence each other. Theoretical analysis is established to indicate the stability (cohesiveness, collision avoidance and velocity matching) of the control systems using classical Lyapunov theory. Finally, a simulation example is demonstrated to validate the theoretical results.