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.

Method of prioritizing handoff procedures in a cellular system

Abstract: A method of prioritizing handoff requests in a cellular system is disclosed in which at least one handoff request for assignment of a communication channel is received from at least one mobile unit. A cutoff time for the handoff request is determined. The handoff requests are arranged in a priority queue based on the cutoff time associated with each handoff request. Available communication channels are assigned to the mobile units requesting handoff in the order of the queue.

Conflict Avoidance between Mobility Robustness Optimization and Mobility Load Balancing

Abstract: In Long Term Evolution (LTE) networks, Mobility Robustness Optimization (MRO) and Mobility Load Balancing (MLB) are two important functions to auto-optimize the network performances. There is a close correlation between them, as they both choose adjusting handover parameters as optimization actions. The conflict may occur between the two functions when they adjust the same handover parameter in opposite directions. This can not improve the performances but waste network resources. In this paper, we present a novel scheme to solve the problem. In order to prevent the occurrence of the conflict, we set an allowed range for MLB in which the handover problems can be prevented. Analyses and simulation results demonstrate that the proposed scheme can effectively solve the conflict problem and improve the performances of both functions.

Intersystem base station handover

Abstract: A mobile wireless telecommunications system includes base stations of a first type operating according to a first air interface, and base stations of a second type operating according to a second air interface. Methods and apparatus are provided for handing over a mobile station in the system from a first base station, which is of the first type, to a second base station, which is of the second type. A communications link is established over the first air interface between the mobile station and the first base station. Data are received from the mobile station responsive to a signal received by the mobile station over the second air interface from the second base station, substantially without breaking the communications link with the first base station. The mobile station is handed over form the first to the second base station responsive to the data received therefrom. In particular, a method of conducting intersystem handover from a multicarrier system to a direct spread system is provided. Timing synchronization is also advantageously made available through the mobile station.

A Dynamic Decision Model for Vertical Handoffs across Heterogeneous Wireless Networks

Abstract: The convergence of heterogeneous wireless access technologies characterizes the 4G wireless networks. In such converged systems, the seamless and efficient handoff between different access technologies (vertical handoff) is essential and remains a challenging problem. The heterogeneous co-existence of access technologies with largely different characteristics creates a decision problem of determining the “best” available network at “best” time to reduce the unnecessary handoffs. This paper proposes a dynamic decision model to decide the “best” network at “best” time moment to handoffs. The proposed dynamic decision model make the right vertical handoff decisions by determining the “best” network at “best” time among available networks based on, dynamic factors such as “Received Signal Strength(RSS)” of network and “velocity” of mobile station simultaneously with static factors like Usage Expense, Link capacity(offered bandwidth) and power consumption. This model not only meets the individual user needs but also improve the whole system performance by reducing the unnecessary handoffs. Keywords—Dynamic decision model, Seamless handoff, Vertical handoff, Wireless networks.

A multicell model of handover initiation in mobile cellular networks

Abstract: A model is provided for the analysis of handover initiation algorithms in cellular systems, which are based on the averages of signal strength measurements and hysteresis. An extension of Vijayan's and Holtzman's (1993) model is achieved, which accounts for: (1) the effects of the angular direction when a mobile terminal moves from a current to a target base station; (2) the presence of more than two base stations; and (3) the effects of cross correlation of shadow fadings affecting the links between the mobile terminal and the various base stations. The level crossing theory of Gaussian processes is used to derive the algorithm performance. The results obtained from the model are in good agreement with those obtained from simulations. It is seen that the model tends to underestimate the algorithm performance, thus yielding a lower performance bound and guaranteeing an intrinsic design margin. It is also seen that, for a typical trajectory of the mobile terminal from the current base station, the number of handovers might be noticeably increased due to the presence of disturbant stations. Moreover, when cross correlation among shadow fadings is also accounted for, significant variations are observed in both the number of handovers and handover delay. As a final result, tradeoff curves are derived and presented for the most general case.