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Interleaved Polling with Adaptive Cycle Time (IPACT) has great significance in the Ethernet Passive Optical Network (EPON), which is regarded as one of the best choices for next generation access networks. In this paper, we propose an estimation-based scheme, IPACT with Grant Estimation (IPACT-GE), to improve the performance of the IPACT. By estimating the amount of new packets arriving in one polling cycles and granting transmission windows to ONUs based on the estimation, the proposed scheme can provide a shorter waiting delay for the packets and less buffer occupancy than those of the IPACT scheme at the light traffic load so that the light load penalty could be greatly mitigated when combined with the Strict Priority Queue (SPQ) mechanism to provide the Differentiated Services.

Recent developments on wireless communication technology have resulted in tremendous innovations to make wireless access networks able to replace the wired access networks with much more bandwidth. The IEEE 802.16e, which was officially published in February 2006, has specified all the techniques needed at the physical layer, and the services that should be provided at the medium access control (MAC) layer in the WiMax systems. With the support of mesh networking, WiMax systems can be easily configured as a wireless metropolitan area networks (WMAN). It has further enhanced the ability of WMANs with mobility support. In this tutorial, the WiMax system will be explained according to the IEEE 802.16d/e standard. An introduction on the mesh networks and mobility support in WiMax systems will also be included.

Coexistence of Cellular and WiFi networks is an inescapable fact. Current initiatives that address mobility across these networks are cellular centric. Further they are limited to connection mobility restricting user service experience. The application session is bound to the constrained portable device used to establish the connection. The result is sub-optimal solutions that have limited user uptake. This paper defines a novel approach to mobility. An agent is installed on the user access device to act as a client proxy. Application sessions are initiated through the agent enabling the agent to maintain session state information. The session can then be transferred to another device preferred by the user when he roams into another access network. The concept is demonstrated with a prototype embedding the several functionalities required to achieve seamless session mobility. Simulation results establish the ease of session restoration at a new device. The utility of the proposal is investigated using micro-economic frameworks.

Recent developments on the wireless communication technology have brought much innovativeness to make wireless access networks, e.g. WiMAX systems, to be able to compete with the wired access networks with much more bandwidth. QoS service provisioning is an important issue for deploying such networks. The IEEE 802.16d standard has specified the services should be provided at the medium access control (MAC) layer in WiMAX networks. However, it has left a wide space for research to develop and implement those specified services. In this paper, the issue of differentiated service provisioning will be addressed with the non-real-time polling service in WiMAX systems. The proposed solution has been designed to have an ability to accommodate integrated traffic in the networks with effective scheduling schemes. A series of simulation experiments have been carried out to evaluate the performance of the proposed hierarchical scheduling algorithm. The results reveal that the proposed solution performs effectively to the integrated traffic composed of messages with or without time constraints and achieves proportional fairness among different types of traffic.

Network video on demand is one kind of favorite VOD services nowadays. P2P technology is adopted to improve system capacity without increasing infrastructure cost. However, the limitation of upstream bandwidth in ADSL networks deteriorates P2P networks' extensible capability. The traditional P2P admission control schemes become inapplicable for network VOD service in ADSL networks. The paper presents a novel admission control scheme for VOD service in ADSL P2P networks. In our scheme, a buffer will be reserved in every client. Our scheme indicates that media server can insure clients playing without interruption in case they are admitted initially. At the same time, the response latency is reduced and the efficiency of utilizing bandwidth is increased. Foremost, the buffer space in client improves P2P extensible capability for ADSL networks. System capacity is increased remarkably than without buffer and it will be infinite in theory if waiting coefficient beta is no less than 1. With waiting coefficient beta increases blocking probability decreases. The new scheme significantly improves the system performance in ADSL P2P networks. The detailed admission control policy is described in the paper