Steven Chamberland

On the wireless local area network design problem with performance guarantees

In this paper, we propose a model for the wireless local area network (WLAN) design problem with performance guarantees. This problem consists of selecting the location of the access points (APs) as well as the power and the channel of each AP. The performance guarantees we refer to are coverage and minimum bandwidth guarantees. Since this problem is NP-hard, we propose a tabu search algorithm to find solutions for real-size instances of the problem. Finally, numerical results are presented. The results show that good solutions can be found with the proposed algorithm in a reasonable amount of time.

Topological Design of Two-Level Telecommunication Networks with Modular Switches

In this article we propose a mixed 0-1 linear programming model for the topological network design problem with modular switches such as the ones that will be used in asynchronous transfer mode (ATM) frame relay and other broadband networks. The model includes the location of switches, their configuration with respect to ports and multiplexers, the design of an access network with a star topology, and a backbone network with a fixed topology (ring or tree). To obtain a solution, we propose a greedy heuristic that provides a good starting solution, and a tabu search heuristic to improve the solution. Finally, we present an example of the application of the heuristics and results for a set of randomly generated problems with up to 500 users and 30 potential switch sites. For the hundreds of problems generated, the tabu algorithm produced solutions that were, on average, within 1.5% of the optimal solution, and in the worst case within 4.95% of the optimal solution.

A New Routing-Based Admission Control for MPLS Networks

In this paper, we propose a routing-based admission control mechanism for the IP traffic flows in MPLS networks. This mechanism is based on solving exactly a mathematical programming model including end-to-end delay constraints for all traffic flows. The numerical results show that considering end-to-end delay constraints for already admitted flows has not an important impact on the blocking rate but significantly reduces the mean end-to-end delay of each flow

An efficient heuristic for the expansion problem of cellular wireless networks

In this paper we propose a model for the expansion problem of the network subsystem (NSS) of a universal mobile telecommunication system (UMTS) wireless cellular network considering an update in the base station subsystem (BSS). The objective is to minimize the expansion cost of the network subsystem while considering network performance (e.g., call and handover blocking). Since the network expansion problem is a generalization of the design problem, the proposed model can also be used for designing networks. In order to find good solutions, we propose a heuristic based on the tabu search principle. Finally, we present a performance analysis of the proposed heuristic. The analysis shows that quasi-optimal solutions are found with the proposed heuristic.

A tabu search algorithm for the global planning problem of third generation mobile networks

In this paper, we propose a tabu search (TS) algorithm for the global planning problem of third generation (3G) universal mobile telecommunications system (UMTS) networks. This problem is composed of three NP-hard subproblems: the cell, the access network and the core network planning subproblems. Therefore, the global planning problem consists in selecting the number, the location and the type of network nodes (including the base stations, the radio network controllers, the mobile switching centers and the serving GPRS (General Packet Radio Service) support nodes) as well as the interconnections between them. After describing our metaheuristic, a systematic set of experiments is designed to assess its performance. The results show that quasi-optimal solutions can be obtained with the proposed approach.

On the design problem of cellular wireless networks

In this paper, we deal with the problem of how to design cellular networks in a cost-effective way. We first propose an optimization model that deals with selecting the location of the base station controllers (BSCs) and mobile service switching centers (MSCs), selecting their types, designing the network topology and selecting the link types. In order to find a “good” solution, we propose a tabu search algorithm. Numerical results show that the tabu search algorithm produces solutions close to a proposed lower bound.

On the joint topological, dimensioning and location problem for broadband networks

In this paper we tackle the problem of jointly finding the optimal location of the ATM switches, the topology of the backbone and local access networks, the dimension of switches and links between switches. We propose a mixed 0-1 integer programming formulation for the problem. Computational results for two examples will be presented and discussed.

A New Approach for Designing WiMAX Networks

The new era of wireless communications is marked by the promising aspects of broadband wireless network. Worldwide interoperability for microwave access (WiMAX) as a leading broadband wireless solution offers many types of applications. This paper approaches the planning and optimization view of a cellular network based on WiMAX technology, known equivalently as IEEE 802.16 Wireless MAN air interface standard. In the problem formulation, the decision variables are the location of each base station (BS) including particular beam and channel of each sector, and the optimized power per each subcarrier. The proposed algorithm tries to select a BS and the appropriate downlink channel per subscriber station (SS). It solves the problem in two phases. At first step, with relaxing some constraints, it finds an initial solution, and then moves to approach to a good feasible solution.

Point of presence design in Internet protocol networks with performance guarantees

In this paper, we propose a model for the point of presence (POP) design problem in Internet protocol (IP) networks with performance guarantees, where a POP is a node composed of several interconnected co-located backbone routers within a central office. This problem consists of selecting the number of routers and their types, selecting the interface card types, connecting the access and the backbone links to the ports and selecting the link types between the co-located routers. Furthermore, the model considers the routing of the IP traffic. The performance guarantees we refer to are bandwidth guarantees between the routers for the normal state of the POP and also for all failure scenarios of interest to the network planner. A tabu search heuristic to find solutions for real-size instances of the problem is proposed. Finally, we present a systematic set of experiments designed to assess the performance of the proposed heuristic.

A constraint programming approach for the design problem of cellular wireless networks

In this paper, we propose a constraint programming model for the design problem of cellular wireless communication networks. It consists of selecting the location of the base station controllers (BSCs) and mobile service switching centres (MSCs), selecting their types, designing the network topology and selecting the link types, and considering the location of base transceiver stations (BTSs). Next, we propose a heuristic to find a good solution of the model in a reasonable amount of time. This heuristic is a local search combined with constraint programming techniques. Numerical results show that our approach, on average, found better solutions than the best algorithm of the literature.