One of the most important issues in wireless and mobile communication technologies is to provide seamless handoff when a mobile node(MN) moves between different access networks. In this paper we have taken Wi-Fi/WiMAX heterogeneous networks in to consideration and reviewed the various seamless handoff schemes for vertical handoff between Wi-Fi and WiMAX networks at different layers. We assume the mobile terminals in our proposed network support IEEE 802.11 and IEEE802.16e dual interface. And also we have compared the schemes based on different criteria viz., handoff latency, packet loss, to provide a better QoS in real-time user scenarios. The comparison reveals the pros and cons of each scheme and aids to adopt a better scheme to achieve seamless handoff in next generation wireless networks.

A survey of seamless vertical handoff schemes for Wi-Fi/WiMAX heterogeneous networks

This paper presents a novel middleware architecture in order to support multimedia services across inter-technology nodes in a seamless manner and with minimum perceived QoS degradation. The proposed architecture is based on the Media Independent Handover (MIH) framework. The novelty of the proposed architecture is based on a number of enhancements on top of the original MIH scheme. Firstly, the handover decision function is based on triggering/collecting statistics from physical, network and application layer, so that an ongoing multimedia session (video) can be transferred seamlessly. Secondly, the original MIH scheme is coupled with a novel mechanism that updates the video encoding parameters in real time, allowing video QoS adaptation and/or video QoS based vertical handover based on an estimated value of the current Peak Signal to Noise Ratio received by the mobile user. The simulation results carried out with the NS-2 tool parametrized for supporting MIH functionality and H.264 encoded video traffic, have shown a significant improvement both in the received video QoS in terms of PSNR and the network throughput, during WiFi to UMTS handover, under the proposed scheme.

Enhanced vertical handover based on 802.21 framework for real-time video streaming

The explosive demands of multimedia services have been grown up to support delay-sensitive applications, e.g., VoIP and streaming using codec. When a mobile node (MN) moves across different types of networks, the codec should be effectively adapted according to the significant change of network condition, i.e., throughput and delay. Therefore, in this paper, we propose a codec adaptation for vertical handover (ACAV), aiming not only to increase throughput but also to decrease delay at MNs. Using media independent information service (MIIS), the ACAV is able to proactively estimate network conditions of the target network then determine a proper type of codec for on-going multimedia services. The simulation results show that the proposed ACAV outperforms typical codec adaptation mechanism in terms of throughput and delay by determining a proper codec for the target network.

An Effective Codec Adaptation for MIH Based Vertical Handover in Heterogeneous Wireless Networks

A lots of different networks are developed in these days such as cellular networks (2G, 3G, 3G+), WiBRo, WiMax, Bluetooth, HSDPA and so on. And now we are prepare to the next generation, 4G. As heterogeneous networks are appeared, we have to prepare the general handover protocol. There are many handover protocols developed for between two specific network, but it is not insufficient to combine each network. Handover for heterogeneous network is developed nowadays. We can say that main handover protocols for heterogeneous network are MIH and UMA. In this paper, MIH and UMA will be covered. Each handover protocols are discussed. In detail, structures, handover working architecture, and preparation for each network protocols. Second, comparation of each handover protocols and which protocol is more efficient in specific situations will be discussed. Third, the direction of the MIH will be shown.

BumWook Kim

Papers

An Effective Codec Adaptation for MIH Based Vertical Handover in Heterogeneous Wireless Networks

SEAMLESS HANDOVER between HETEROGENEOUS NETWORK (Comparison MIH, UMA)