Handover

About: Handover is a research topic. Over the lifetime, 24219 publications have been published within this topic receiving 296416 citations. The topic is also known as: handoff.

Vertical handoff decision algorithm for improved quality of service in heterogeneous wireless networks

Abstract: Fourth-generation networks are expected to integrate heterogeneous wireless technologies. To ensure seamless mobility across disparate wireless technologies, efficient handoff schemes are required to enhance quality of service (QoS) and offer reliable ubiquitous computing environment. This study reviews classical and existing fuzzy approaches adopted for vertical handoff to ensure seamless mobility across overlaid heterogeneous networks. A neuro-fuzzy multi-parameter-based vertical handoff decision algorithm (VHDA) is proposed. The proposed VHDA considers six parameters and applies rule-based system for vertical handoff decision. The number of vertical handoffs measured in a simulated environment shows that average number of vertical handoffs for the proposed VHDA reduces by 13.3 and 29.8% for the existing fuzzy technique and the classical technique, respectively. Further, reduction in number of unnecessary vertical handoffs in the proposed algorithm shows reduction in ping-pong effect by 15.9%, improvement in end-point service availability (ESA) and throughput by 16.57 and 5.97%, with respect to existing fuzzy technique leading towards improved QoS. Finally, the results of performance assessment, carried out using handoff quality indicator (used to quantify QoS) which is dependent upon ping-pong effect, ESA and throughput, show that the proposed VHDA offers better QoS than existing vertical handoff techniques.

System and method to facilitate handover

Abstract: A method (500) to facilitate handover includes detecting (506) that a mobile unit resides within at least one predetermined zone where a handover event from a first radio technology to a second radio technology may need to occur, the second radio technology being different from the first radio technology.

Timely Effective Handover Mechanism in Heterogeneous Wireless Networks

Abstract: Next-generation wireless networks should be able to coordinate and integrate different communication systems. It has been a challenging problem to support a seamless handover in these diverse wireless network environments. Link level triggers can provide information about events which can help handover decision and layer 3 entities better streamline their handover related activities. In most conventional layer 2 triggering approaches, a pre-defined threshold for a specific perspective such as the received signal strength is used. This may cause too late or too early handover executions. In this paper we propose a new predictive handover framework that uses the neighbor network information to generate timely the link triggers so that the required handover procedures can appropriately finish before the current link goes down. First we estimate a required handover time for the given neighbor network conditions, then using a predictive link triggering mechanism the handover start time is dynamically determined to minimize handover costs. The handover costs are analyzed in terms of the total required handover time and the service disruption time. The numerical analysis and simulation results show that the proposed method significantly enhances the handover performance in heterogeneous wireless networks.

Idle handoff with neighbor list channel replacement

Abstract: Techniques for avoiding handoff to a channel impaired due to frequency dependent fading, while minimizing idle mode signaling are disclosed. In one aspect, an access terminal (106) determines the assigne chancel on an access point (104) and caches the channel. In another aspect, the access terminal (106) replaces a default channel associated with an access point (104) in a cache (270) with the assigned channel. In yet another aspect, the access terminal (106) uses the cached channel associated with an access point when measuring channel quality (220) of neighbor access points for use in handoff determination (240). In yet another aspect, the access terminal (106) hands off to the cached channel of a neighbor access point (104) during handoff. Various other aspects are also presented. These aspects have the benefit of factoring in frequency dependent channel characteristics when making handoff decisions, thus avoiding handoff to an access point where the assigned channel may be impaired.

Lossless handover for wireless ATM

Abstract: Handover is one of the key research topics for the emerging wireless ATMnetworks This paper describes a handover mechanism for intra-switch handovers for wireless ATM The handover procedure is simple enough to be implementable as a limited enhancement to ATM switch platforms for fixed network, yet provides lowdelay and lossless handover when used together with a suitable radio interface The paper also reports on initial simulation result