Inter-switch Handoff Research Articles

Integrated Interswitch Cable and Handoff Cost Minimizing Heuristics for Cell-to-Switch Assignment in Wireless Cellular Networks

Cell-to-switch assignment (CSA) is a well-known NP-hard problem for location management in a wireless cellular network (WCN). In this paper, we focus on the probabilistic CSA problem, where interswitch handoffs, call arrivals, and call dwell times are considered stochastic with certain distributions, and propose two heuristic approaches to solve the problem. We present an analytical framework to derive interswitch handoff frequencies among the cells. The first heuristic does not consider the load-balancing issue, whereas the second heuristic considers the load balancing among the different switches while assigning cells to them. We compare our heuristics with taboo search (TS) and find that they significantly outperform the metaheuristic TS. After minimizing the objective function comprising amortized cable and variable interswitch handoff costs, our heuristics attain a minimum that is very close to the theoretical lower bound. The merit of our heuristics lies in the fact that those can be deployed online and can provide an adaptive solution to the design problem.

A cost optimisation policy for handoff rerouting

A two-phase handoff protocol has been proposed to support interswitch handoff in Wireless Asynchronous Transfer Mode (WATM) networks. An important issue is the determination of the best time to perform Phase 2. In this paper, it is shown that none of the existing conventional path optimisation policies is optimal at all network situations; hence, a general Cost Optimisation Policy (COP) applicable to a wide range of network conditions is proposed. It is based on the decision whether to exclude Phase 2 or select among the best path optimisation policies for this phase. The proposed policy avoids unnecessary path optimisations and achieves the lowest total expected cost at variable mobility factors and network conditions. A comparison between the proposed policy and conventional path optimisation policies is performed. The numerical results show a significant improvement of the total expected cost over conventional path optimisation policies at all network situations.

Stochastic control of path optimization for inter-switch handoffs in wireless ATM networks

One of the major design issues in wireless ATM networks is the support of inter-switch handoffs. An inter-switch handoff occurs when a mobile terminal moves to a new base station connecting to a different switch. Apart from resource allocation at the new base station, inter-switch handoff also requires connection rerouting. With the aim of minimizing the handoff delay while using the network resources efficiently, the two-phase handoff protocol uses path extension for each inter-switch handoff, followed by path optimization if necessary. The objective of this paper is to determine when and how often path optimization should be performed. The problem is formulated as a semi-Markov decision process. Link cost and signaling cost functions are introduced to capture the tradeoff between the network resources utilized by a connection and the signaling and processing load incurred on the network. The time between inter-switch handoffs follows a general distribution. A stationary optimal policy is obtained when the call termination time is exponentially distributed. Numerical results show significant improvement over four other heuristics.

Dynamic connection rerouting and wired-resource reservation scheme on ATM-based PCN

In this paper, we propose a connection rerouting and dynamic resource reservation scheme for fast inter-switch handoffs on ATM-based personal communications networks. The proposed rerouting and reservation scheme can reduce the delay in connection rerouting by reserving VPI/VCIs for possible inter-switch handoff calls in advance. It also improves the utilization of wired resources by reserving statistically the wired resources in separate ways according to the classes (i.e., real-time vs. non-real-time traffic) of possible inter-switch handoff calls. Our simulation results show that the proposed scheme can decrease the dropping rate of inter-switch handoff calls without the sacrifice of the blocking probability of new calls and, moreover, can flexibly cope with the time-variant environment.

Performance evaluation of path optimization schemes for inter-switch handoff in wireless ATM networks

One of the major design issues in wireless ATM is the support of inter‐switch handoff. An inter‐switch handoff occurs when a mobile terminal moves to a new base station connecting to a different switch. Recently, a two‐phase handoff protocol has been proposed to support inter‐switch handoff in wireless ATM networks. With the aim of shortening handoff delay while using the network resources efficiently, the two‐phase handoff protocol employs path extension for each inter‐switch handoff, followed by path optimization if necessary. To implement the two‐phase handoff protocol efficiently, we need to determine when to trigger path optimization. In this paper, we propose and analyze three path optimization schemes, namely: periodic, exponential, and Bernoulli, for the two‐phase handoff protocol. The design objective is to determine the time to invoke path optimization such that the average cost per connection is minimized. We develop a discrete time analytical model and a discrete‐event simulation model for comparing the performance of the three path optimization schemes. Results indicate that the Bernoulli path optimization scheme outperforms the other two schemes by providing a lower average cost per connection. The proposed models can also be adapted to analyze other path optimization schemes in general.

A path optimization signalling protocol for inter-switch handoff in wireless ATM networks

In this paper, we study the connection rerouting problem due to inter-switch handoffs. The design objective is to guarantee the bandwidth and delay of a connection during its connection lifetime. We propose to use path extension for each inter-switch handoff, and invoke path optimization whenever one of the potential handoff paths exceed the delay constraint. During path extension, the selection of the extended path is modeled as a bandwidth-delay-constrained path problem. The path optimization signalling protocol ensures that ATM cell sequencing is maintained on the uplink and downlink by buffering cells at the anchor switch and the crossover switch, respectively.