42170888
LVQ Based Distributed Video Coding with LDPC in Pixel Domain
Presently, distributed source coding (DSC) and distributed video coding (DVC) are given high attention in sensor network and other multimedia transmission. That is due to their contribution to easy encoding and robust multimedia communication. In this paper, we propose a new DVC framework where two LVQ (lattice vector quantization) and a rate-variable LDPC (low-density parity-check) are exploited. In both LVQ and LDPC, we use the interpolated from decoded frames as side information to help coding. Because of LVQ's exploitation to dependence of source and the better error-correcting capacity of LDPC, our system achieves more than 1 dB improvement in PSNR than the referenced. Meanwhile, the property of low-complexity encoding is still preserved.
857940
Performance Comparisons of Different Channel Codes in Distributed Video Coding
This paper introduces advanced channel codes turbo and LDPC to distributed video coding (DVC), and compares their performance in the whole system. From the simulation results, we can find that the LDPC codes are superior to turbo codes when the video sequence has high motion. Additionally, whether turbo or LDPC, the DVC system outperforms the conventional intra-frame coding though underperforms conventional motion-compensated inter-frame coding. But DVC has the advantage of easy encoding which can meet the demands of friendly up-linking media communication
3369144
Adaptive Multi-Channel MAC Protocol for Dense VANET with Directional Antennas
Directional antennas can increase the spatial reuse of the wireless channels and reach a higher antenna gain. This paper presents the design, implementation and simulation results of a multi-channel medium access control protocols for high density vehicular ad hoc networks using directional antennas with local beam tables. Simulation shows that our protocol has a higher throughput than the existing multi-channel protocols.
10887794
Packet doppler: network monitoring using packet shift detection
Due to recent large-scale deployments of delay and loss-sensitive applications, there are increasingly stringent demands on the monitoring of service level agreement metrics. Although many end-to-end monitoring methods have been proposed, they are mainly based on active probing and thus inject measurement traffic into the network. In this paper, we propose a new scheme for monitoring service level agreement metrics, in particular, delay distribution. Our scheme is passive and therefore will not cause perturbation to real traffic. Using realistic delay and traffic demands, we show that our scheme achieves high accuracy and can detect burst events that will be missed by probing based methods.
6306890
APPLE: A Novel P2P Based e-Learning Environment
With the rapid development of information technology, dramatic changes have been taken place in the fundamental ways that people acquire and disseminate knowledge. Various e-Learning systems have been designed to help people take full advantage of the benefit brought by the technology. The newly emerged Peer to Peer (P2P) and grid computing will serve as the key driven forces to bring revolutionary impact on the future society. This paper evaluates the potential contribution of the P2P and grid technology into the e-Learning system and introduces a novel P2P based e-Learning environment, called APPLE. With the help of Gnutella-like P2P network, APPLE provides live broadcasting services to share services of education resources. We build a virtual classroom service based on WSRF.NET, which exposes the service as a grid service that could be accessed by all the users among the grid.
16457860
A New Secure Authentication Scheme Based Threshold ECDSA For Wireless Sensor Network
Security is an important issue for Wireless Sensor Network (WSN), especially for security-sensitive application. In this paper, we address secure authentication problems in WSN. First, we propose distributed authentication model for WSN, and secondly, advance the threshold ECDSA authentication scheme in this model, finally construct a new way to choose distributed CA severs of threshold authentication scheme. Our simulation results and analysis show that our scheme can reduce effectively bandwidth and computation resources while providing a robust, highly secure and highly available authentication service.
18986616
Verifying Real-Time Systems using Explicit-time Description Methods
Timed model checking has been extensively researched in recent years. Many new formalisms with time extensions and tools based on them have been presented. On the other hand, Explicit-Time Description Methods aim to verify real-time systems with general untimed model checkers. Lamport presented an explicit-time description method using a clock-ticking process (Tick) to simulate the passage of time together with a group of global variables for time requirements. This paper proposes a new explicit-time description method with no reliance on global variables. Instead, it uses rendezvous synchronization steps between the Tick process and each system process to simulate time. This new method achieves better modularity and facilitates usage of more complex timing constraints. The two explicit-time description methods are implemented in DIVINE, a well-known distributed-memory model checker. Preliminary experiment results show that our new method, with better modularity, is comparable to Lamport's method with respect to time and memory efficiency.