The Traveling Salesman Problem A Computational Study

ARCHITECTURES Wireless Mesh Networks: Issues and Solutions MultiRadio MultiChannel Mesh Networks IEEE 802.11-Based Wireless Mesh Networks PROTOCOLS Routing in Wireless Mesh Networks Medium Access Control in Wireless Mesh Networks Security in Wireless Mesh Networks Scalability in Wireless Mesh Networks Load Balancing in Wireless Mesh Networks Cross-Layer Optimization for Scheduling in Wireless Mesh Networks Multimedia Communications over Wireless Mesh Networks Multiple Antenna Techniques for Wireless Mesh Networks STANDARDIZATION AND ENABLING TECHNOLOGIES Standardization of Wireless LAN Mesh Networks in IEEE 802.11s IEEE 802.16 WiMAX Mesh Networking Cognitive Radio and Dynamic Spectrum Management Wireless Mesh Networks Case Study: Fire Emergency Management and Market Analysis Wireless Mesh Networks for Public Safety and Disaster Recovery Applications INDEX

Wireless Mesh Networking : Architectures, Protocols and Standards

We consider the problem of link scheduling in a sensor network employing a TDMA MAC protocol Our link scheduling algorithm involves two phases In the first phase, we assign a color to each edge in the network such that no two edges incident on the same node are assigned the same color We propose a distributed edge coloring algorithm that needs at most (/spl delta/+1) colors, where /spl delta/ is the maximum degree of the graph To the best of our knowledge, this is the first distributed algorithm that can edge color a graph with at most (/spl delta/+1) colors In the second phase, we map each color to a unique timeslot and attempt to identify a direction of transmission along each edge such that the hidden terminal and the exposed terminal problems are avoided Next, considering topologies for which a feasible solution does not exist, we obtain a direction of transmission for each edge using additional timeslots, if necessary Finally, we show that reversing the direction of transmission along every edge leads to another feasible direction of transmission Using both the transmission assignments we obtain a TDMA MAC schedule, which enables two-way communication between every pair of neighbors For acyclic topologies, we show that at most 2(/spl delta/+1) timeslots are required Through simulations we show that for sparse graphs with cycles the number of timeslots assigned is close to 2(/spl delta/+1)

/pdf/link-scheduling-in-sensor-networks-distributed-edge-coloring-4xh1xg4gp5.pdf

Link scheduling in sensor networks: distributed edge coloring revisited

With the limited frequency spectrum and an increasing demand for cellular communication services, the problem of channel assignment becomes increasingly important. However, finding a conflict-free channel assignment with the minimum channel span is NP hard. Therefore, we formulate the problem by assuming a given channel span. Our objective is to obtain a conflict-free channel assignment among the cells, which satisfies both the electromagnetic compatibility (EMC) constraints and traffic demand requirements. We propose an approach based on a modified genetic algorithm (GA). The approach consists of a genetic-fix algorithm that generates and manipulates individuals with fixed size (i.e., in binary representation, the number of ones is fixed) and a minimum-separation encoding scheme that eliminates redundant zeros in the solution representation. Using these two strategies, the search space can be reduced substantially. Simulations on the first four benchmark problems showed that this algorithm could achieve at least 80%, if not 100%, convergence to solutions within reasonable time. In the fifth benchmark problem, our algorithm found better solutions with shorter channel span than any existing algorithms. Such significant results indicate that our approach is indeed a good method for solving the channel-assignment problem.

/pdf/fixed-channel-assignment-in-cellular-radio-networks-using-a-41m3ctpbo7.pdf

Fixed channel assignment in cellular radio networks using a modified genetic algorithm

The authors investigate algorithms based on simulated annealing to solve the channel assignment problem for cellular radio networks. The blocking probability of a network is chosen as the optimization criterion. In order to check the quality of the solutions obtained by simulated annealing, they examine some special types of networks which allow an effective calculation of optimal solutions by tailored algorithms. Their investigations show that simulated annealing is a very powerful tool for solving channel assignment problems. >

Channel assignment in cellular radio networks

Location Problems on Undirected Flow Networks

The problem of assigning channels in a channel-offset-type of cellular mobile radio communication system is formulated as a problem of assigning channels to the vertices of a network. It is shown that the assignment problem in a network is a generalized graph coloring problem. When the interchannel interference function is a rational number, the optimal channel offset scheme is obtained. and upper and lower bounds of the minimum total bandwidth in a channel-offset scheme are derived. These factors give basic and useful knowledge for designing a channel-offset system of a cellular mobile system, and they are useful not only for a fixed channel assignment but also for a dynamic channel assignment and rearrangement. >

http://ieeexplore.ieee.org/iel1/25/7193/00289421.pdf

Graph theoretical considerations of channel offset systems in a cellular mobile system

Some Covering Problems in Location Theory on Flow Networks

Recently, the wireless mesh network attracts the interest of many people as a new broadband network of the next generation. The wireless mesh network consists of terminals only, then a terminal in the network can communicate with the other terminal beyond the transmission range by multihopping in the same way as in the ad hoc networks. In this network, a communication link between two terminals which can communicate directly is required a channel. Since cochannel interference may occur, we need to assign channels to communication links carefully. In this paper, we describe a channel assignment strategy which takes the degree of cochannel interference into consideration, and we also evaluate the effectiveness of this strategy by computer simulations. We show that this strategy is more effective than the strategy which does not take the degree of cochannel interference into consideration.

A new channel assignment strategy towards the wireless mesh networks

Multihop wireless networks consist of mobile terminals with personal communication devices. Each terminal can receive a message from a terminal and send it to the other terminal. In this paper, we discuss a new edge coloring problem in terms of graph and network theory on multihop wireless networks. This edge coloring problem takes the degree of interference into consideration. Then, we discuss this problem in terms of computational complexity.

Hiroshi Tamura

Papers

Location Problems on Undirected Flow Networks

Graph theoretical considerations of channel offset systems in a cellular mobile system

Some Covering Problems in Location Theory on Flow Networks

A new channel assignment strategy towards the wireless mesh networks

On a new edge coloring related to multihop wireless networks