This paper proposes a new QoS framework, called the on-demand QoS path framework (ODP). ODP provides end-to-end QoS guarantees to individual flows with minimal overhead, while keeping the scalability characteristic of Diff-Serv. ODP exercises per-flow admission control and end-to-end bandwidth reservation at the edge of the network and only differentiates traffic classes in the core of the network. In addition, to adapt to dynamically changing traffic load, ODP monitors the bandwidth utilization of the network and performs dynamic bandwidth reconfiguration in the network core. Through extensive simulations, the performance of ODP is investigated and compared with that of IntServ and DiffServ frameworks. The simulation results clearly show that ODP provides end-to-end QoS guarantees to individual flows, which DiffServ can not provide, with much less overhead than IntServ.

Supporting transmission of stream media over wireless mobile networks is often difficult because packets may be lost due to the rerouting of packets during handoff, and also because bursts of packet loss may occur during handoff due to the disparity in the amount of available bandwidth among different cells. In this paper, we propose an end-to-end multipath handoff scheme that provides smooth handoff for stream media in wireless networks with different amounts of available bandwidth from cell to cell. In the proposed scheme, multiple paths are established during handoff to reach a mobile destination node. The stream media sources are equipped with an adaptive multilayer encoder, and important layers in the encoded video stream are duplicated and transmitted over multiple paths during handoff. The effectiveness of the proposed multipath handoff scheme is verified and compared with existing schemes through extensive simulations. The simulation results show that the proposed scheme provides higher throughput and better quality for stream media.

In this paper, we propose and investigate a bandwidth-efficient multicast routing protocol for ad-hoc networks. The proposed protocol achieves low communication overhead, namely, it requires a small number of control packet transmissions for route setup and maintenance. The proposed protocol also achieves high multicast efficiency, namely, it delivers multicast packets to receivers with a small number of transmissions. In order to achieve low communication overhead and high multicast efficiency, the proposed protocol employs the following mechanisms: (1) on-demand invocation of the route setup and route recovery processes to avoid periodic transmissions of control packets, (2) a new route setup process that allows a newly joining node to find the nearest forwarding node to minimize the number of forwarding nodes, and (3) a route optimization process that detects and removes unnecessary forwarding nodes to eliminate redundant and inefficient routes. Our simulation results show that the proposed protocol achieves high multicast efficiency with low communication overhead compared with other existing multicast routing protocols, especially in the ease where the number of receivers in a multicast group is large.

In this paper, we propose and investigate a bandwidth-efficient multicast routing protocol for ad-hoc networks. The proposed protocol achieves low communication overhead, namely, it requires a small number of control packet transmissions for route setup and maintenance. The proposed protocol also achieves high multicast efficiency, namely, it can deliver multicast packets to receivers with a small number of multicast transmissions. To achieve high multicast efficiency with low communication overhead, the proposed protocol employs the following mechanisms: (1) on-demand invocation of the route setup and route maintenance process to avoid periodical control packet transmissions, (2) a new route setup mechanism that allows a newly joining node to find the nearest forwarding node, in order to minimize the number of added forwarding nodes, and (3) a route optimization mechanism that can detect and delete unnecessary forwarding nodes. Our simulation results show that the proposed protocol achieves high multicast efficiency with low communication overhead compared with other multicast routing protocols.

In the next generation high-speed wireless networks, it is important to provide quality-of-service (QoS) guarantees as they are expected to support multimedia applications. This paper proposes an admission control scheme based on adaptive bandwidth reservation to provide QoS guarantees for multimedia traffic carried in high-speed wireless cellular networks. The proposed scheme allocates bandwidth to a connection in the cell where the connection request originates and reserves bandwidth in all neighboring cells. When a user moves to a new cell and a handoff occurs, bandwidth is allocated in the new cell, bandwidth is reserved in the new cell's neighboring cells, and reserved bandwidth in more distant cells is released. The amount of bandwidth to reserve is dynamically adjusted, reflecting the current network conditions. The performance of the proposed scheme is evaluated through simulations of realistic cellular environments. The simulated network consists of a large number of cells, mobile users with various movement patterns are assumed, and a variety of multimedia applications (e.g., audio phone, video conference, video on demand, file transfer, etc.) is considered. It is shown that the proposed scheme provides small handoff dropping probability (i.e., the probability that handoff connections are dropped due to a lack of bandwidth) and achieves high bandwidth utilization.