Semi-soft Handoff Research Articles

Improvement of Handoff-state and QOS in Wireless Environment

In this paper, we propose for improving QoS in wireless micro cellular network using Cellular-IP/PRC(Paging Route Cache) with Paging Cache and Route Cache in Cellular-IP and propose for performance of realtime and non-real time handoff service using Handoff state machine Paging Route Cache. Although the Cellular-IP/PRC technology is devised for mobile internet communication, it bas its vulnerability in frequent handoff environment. On the other hand, Cellular IP combines the capability of cellular networks to provide high performance handoff and efficient location management of active and idle mobile users with the inherent flexibility, robustness and scalability found in IP networks. Also Cellular-IP/PRC use semi-soft handoff. During semi-soft hand off a mobile host may be in contact with either of the old and new base stations and receive packets from them. Packets intended to the mobile node are sent to both base stations and buffered, so when the mobile host eventually moves to the new location it can continue to receive packets without interruption. It should be suitable for realtime service such as multimedia traffic. But, much waste of resource will occur in this method, especially for non-real time services such as FTP and E-mail. Therefore, a new algorithm that performs different handoff according to characteristic of each traffic by use of reserved field in IP packet is proposed in this thesis. This hand off state machine using differentiated handoff improves quality of services in Cellular-IP/PRC. Suggested algorithm shows better performance than existing technology in wireless mobile internet communication environment. Matlab simulation results are improving QoS, show call drop and call blocking provided to Paging Router Cache during handoff state machine in Cellular-IP/PRC.

Adaptive semi-soft handoff for Cellular IP networks

Various advances in technologies have led to a myriad of wireless mobile devices to ubiquitously connect to the internet. This creates a significant demand for seamless wireless network connectivity. The Cellular IP semi-soft handoff protocol has been proposed to satisfy this demand. Studies have shown that it performs better than the conventional hard handoff protocol. However, these studies are based on unrealistic assumptions of symmetrical network topologies and fixed loads. In practice, network topology can be asymmetric and network load fluctuates. Semi-soft handoff uses fixed handoff parameters for stream synchronization and mobile host's tune-in time, which may work well for the symmetrical network setups, but performs poorly with unbalanced and dynamically changing networks. This paper proposes adaptive semi-soft handoff protocol (Adaptive-SS) to address this issue by dynamically changing handoff parameters based on network conditions during handoff. Our simulation study shows that Adaptive-SS significantly reduces network traffic and packet losses/duplications during handoff, while still minimising handoff latency.

A novel location management in IP-based cellular networks

Mobile IP provides a simple and scalable global mobility solution that supports users to access the internet at anytime and anywhere. However, as the number or the velocity of the Mobile IP users grows, so will the signalling overhead associated with the mobility management. One of the solutions, Cellular IP, a micro-mobility protocol, provides a seamless mobility support for semi-soft handoff and paging in limited geographical areas. In this paper, we propose a new micro-mobility management, which is an extension of Cellular IP. Two special features are added in our scheme: page area group and pointer forwarding. Analytical model is developed to evaluate the reduction of signaling overhead of the proposed scheme. Simulation results are also conducted to verify our analysis. Our numerical results show that the proposed scheme can reduce the signalling overhead effectively.

Cellular IP 핸드오프 성능개선

핸드오프는 무선 데이터 네트웍에서 TCP 성능을 저하시키는 가장 중요한 요인중 하나이다. 본 논문에서 패킷의 유신과, 중복이 없는 핸드오프 방법인 LPM(Last Packet Marking)을 제시한다. LPM은 Cellular IP 세미소프트 핸드오프를 개선한 방법으로 이동호스트에게 안전한 핸드오프 시점 알려준다. 새고 소개한 제어 패킷은 SPM(Semisoft reply Message) 하나이다. 컴퓨터 시뮬레이션을 통한 실험에서 LPM 방법은 패킷의 중복이나 유신이 없어서 TCP의 성능을 상당히 향상시켰다. Handoff is one of the most important factors that ma? degrade the performance of TCP connections in wireless data networks. In this paper, we present a lossless and duplication free handoff scheme called LPM (Last Packet Marking) for improving Cellular If semisoft handoff. LPM signals the safe handoff cue by sending a specially marked packet to mobile hosts. SPM (Semisoft rePly Message) is the only newly introduced control packet. Our performance study shows that LPM achieves lossless packet delivery without duplication and increases TCP throughput significantly.