Applied Mechanics and Materials Vols. 347-350

Abstract: This paper presents the design of a high definition video communication system with real-time performance in the network. In order to process and transmit the high definition video, the design combines FPGA and SOC, follows the H.264 video coding compression. The FPGA realizes the highspeed video acquisition via Cameralink interface, and convert the raw image to ITU-R BT.1120 stream. The SOC contains CPU and Codec, it compresses the BT.1120 stream to H.264 steam and transmit the stream in the network. The low-delay rate control algorithm can limit the bitrate in a very low level. The result shows that the system reduces bandwidth and lowers the latency, the design is adaptable to the real time environments.

Abstract: The large wireless sensor networks are often structured hierarchically by grouping nodes into different domains in order to deal with the scaling problem. This paper proposes a new protocol called hierarchical QoS routing protocol (HQRP) that achieves scalability by organizing the network as a hierarchy of domains using the full-mesh aggregation technique. In HQRP, each local node just only needs to maintain local routing and summary information of other domains, but does not requires any global states maintained. The HQRP uses a Reverse Best Metric Path Forwarding approach with hierarchical, topological and QoS forwarding conditions to construct the multicast tree while minimizing message overhead and satisfying delay-bandwidth and minimum energy consumption. The paper presents proof of correctness and complexity analysis of the HQRP. Simulation results show very good performance in terms of success ratio and message overhead.

Abstract: Currently, P2P is a very popular network model. Compared with the traditional model, it bears the advantages of high transmission speed and no centralization etc, and it performs much better in the cyber source utilization and server bottlenecks elimination. This article, starting from the basic principle of P2P technology, proceeds with the structure modes and characteristics of P2P to combine it with the application of campus network, so as to analyze the current problems in campus network and to give the solutions to such problems of P2P .

Abstract: Cross-layer design of routing protocol for mobile ad hoc networks (MANETs) has become a hot research topic in recent years. By integrating physical layer, MAC layer and network layer together for cross-layer design, a cross-layer routing protocol called MIR is proposed in this paper. Via predicting the duration of the interference imposed by the neighbors at every hop along the route, a new routing metric is presented which guarantees that the established routes will not break frequently while having the minimum interference. Simulation results show that MIR can significantly improve the network performance.

Abstract: The multipath fading and interference problems in the wireless communication lead to the link quality decrease severely. However, the conventional frequency hopping scheme cannot solve the problems in an effective way. Adaptive frequency hopping scheme, which is based on the automatically link quality analysis, can avoid the bad frequencies and guarantee the desired level of channel quality. The system is analyzed based on the adaptive frequency hopping model equipped with link quality analyzer which is different from the traditional one. In the paper, some newly proposed adaptive frequency hopping schemes have been summarized, which provide an important reference for the practical application.

Abstract: IETF has specified Mobile IPv4 and Mobile IPv6 in RFC3344 and RFC3775 respectively, but not yet discussed Mobile IPv4/v6 in any published RFC. This paper proposes a scheme to solve one of Mobile IPv4/v6 problems which Home Agent (HA) locates in IPv6 network, and Correspondent Node (CN) locates in IPv4 network, while Mobile Node (MN) moves within IPv4 network. In the solution, a gateway called Mobile IPv4/v6 translation gateway (MIPv4/v6-TG) is introduced to bridge between IPv4 network and IPv6 network, which is made up of a traditional NAT-PT gateway and a Mobile IP application level gateway (MIP-ALG) built upon the NAT-PT gateway. MIP-ALG maintains a MIP table, a data structure, which is formed by entries. We use the MIP table to realize the communication between the IPv4 entities and the IPv6 entities. The creation, usage and update processes of MIP table are described in this paper. And it can work compatibly with RFC3344 and RFC3775.

Abstract: One OCDMA PON system is discussed in this paper. Multi-length Two-Weight Carrier Hopping Prime Codes is selected as encoder scheme, encoded information is transmitted through Optical fiber. Hard Limiter is utilized in receiver terminal to ensure lower bit error rate. Simulation shows that it can be used for large capacity optical networks.

Abstract: A Mobile Ad Hoc Network (MANET) is a popular research topic. In this paper, we first describe characteristics of MANET, proactive and reactive routing protocols. Then AODV and DSDV, which are widely investigated in Ad Hoc network are introduced. We use simulation tool NS-2 to design three experiments to evaluate AODV and DSDV based on measure such as the packet drop rate, delays and average throughout. According to experimental results, conclusions and improvement suggestions are given to help further develop and optimize routing protocols.

Abstract: Reliability is most important for structured p2p systems and how to exactly evaluate the metric-loss rate which is tightly related to reliability is a hot topic and challenge. Many research works of the loss rate only consider the situation that the loss rate is caused by next hop node failure (NF). Indeed, the lost of queuing message (QF) on the failure node also contribute to the loss rate. This paper presents an analytical model of loss rate caused by NF and NQ. In order to achieve the optimal performance of system through minimizing the NQ, we propose two methods: process power enhancing (PPE) and Space Partition (SP). In the heterogeneous systems, we can obtain the minimal loss rate via improving each nodes process power; in the homogeneous structured p2p systems, the partition space method can evenly partition the ID space so as to ensure the traffic load is uniformly distributed over all nodes.

Abstract: How to degrade the delay time of gateway queuing with heavy network load in train communication networks is the key to guarantee the stability of the train. This article models the queue scheduling problem modeling into reinforcement learning process, puts forward an adaptive weights learning polling scheduling algorithm with the purpose of dynamic scheduling for vehicle gateway node queue. With the compare of algorithm in this paper and weighted round-robin scheduling algorithm in adequate and inadequate bandwidth resources situations, we have approved the superiority of the algorithm in this paper.