## Adding Capacity Points to a Wireless Mesh Network Using Local Search

Citations: | 6 - 1 self |

### BibTeX

@MISC{Robinson_addingcapacity,

author = {Joshua Robinson and Mustafa Uysal and Ram Swaminathan and Edward Knightly},

title = {Adding Capacity Points to a Wireless Mesh Network Using Local Search},

year = {}

}

### OpenURL

### Abstract

Abstract — Wireless mesh network deployments are popular as a cost-effective means to provide broadband connectivity to large user populations. As the network usage grows, network planners need to evolve an existing mesh network to provide additional capacity. In this paper, we study the problem of adding new capacity points (e.g., gateway nodes) to an existing mesh network. We first present a new technique for calculating gateway-limited fair capacity as a function of the contention at each gateway. Then, we present two online gateway placement algorithms that use local search operations to maximize the capacity gain on an existing network. A key challenge is that each gateway’s capacity depends on the locations of other gateways and cannot be known in advance of determining a gateway placement. We address this challenge with two placement algorithms with different approaches to estimating the unknown gateway capacities. Our first placement algorithm, MinHopCount, is adapted from a solution to the facility location problem. MinHopCount minimizes path lengths and iteratively estimates the wireless capacity of each gateway location. Our second algorithm, MinContention, is adapted from a solution to the uncapacitated k-median problem and minimizes average contention on mesh nodes, i.e. the number of links in contention range of a mesh node and the number of routes using each link. We show that our gateway placement algorithms outperform a greedy heuristic by up to 64 % on realistic topologies. For an example topology, we study the set of all possible gateway placements and find that there is large capacity gain between near-optimal and optimal placements, but the near-optimal placements found by local search are similar in configuration to the optimal. I.

### Citations

403 | Impact of interference on multi-hop wireless network performance
- Jain, Padhye, et al.
(Show Context)
Citation Context ...nique to incorporate the effects of wireless contention and calculate the gateway-limited fair capacity of a wireless mesh network. While previous work provides a computational framework for capacity =-=[7]-=-, we focus here on access networks without direct client-to-client communication, i.e., networks in which all traffic traverses the gateway. Thus, capacity points necessarily carry more traffic than o... |

139 | On the capacity of hybrid wireless networks
- Liu, Liu, et al.
- 2003
(Show Context)
Citation Context ...the paths in the network, the amount of congestion, and the available bandwidth to and from the Internet. Prior work has shown how capacity scales asymptotically with the number of gateways and nodes =-=[10]-=-, but does not consider how to choose gateway locations in specific topologies. Likewise, greedy heuristics [4] and local search operations J. Robinson, and E. Knightly are with Rice University, Houst... |

113 | Improved approximation algorithms for metric facility location problems
- Mahdian, Ye, et al.
- 2002
(Show Context)
Citation Context ... IP: (i) an IP cannot solve the problem exactly in polynomial time, (ii) prior work has shown that a simplified version of the problem, capacitated facility location, has an unbounded integrality gap =-=[12]-=-, and (iii) an IP is not suitable for online computation, e.g., it precludes the case of incrementally adding gateways without recomputing the locations of every gateway. We therefore take an alternat... |

91 | Measurement driven deployment of a two-tier urban mesh access network
- Camp, Robinson, et al.
- 2006
(Show Context)
Citation Context ...lso a better placement as per measurements. TFA is a multitier mesh network providing Internet access in a densely populated, single-family residential, urban neighborhood with 18 deployed mesh nodes =-=[3]-=-. In the topology, two mesh nodes are connected if their link is on average usable at greater than 1 Mbps. At the time of these experiments, the TFA network, featured two capacity points: gateway GW-A... |

46 | Facility location with nonuniform hard capacities
- Pál, Tardos, et al.
- 2001
(Show Context)
Citation Context ...s feature two different approaches to estimating the unknown gateway capacities. The first algorithm, termed MinHopCount, adapts a local search algorithm for the capacitated facility location problem =-=[13]-=- and iteratively estimates the unknown wireless gateway capacities. The idea of local search is to carefully choose a set of gateways to close and open a set of new gateways subject to capacity and bu... |

27 | Universal Facility Location
- Mahdian, Pal
(Show Context)
Citation Context ...ations are known to exist for these problems using both local search [2], [13] and LP relaxation methods [9]. The algorithms we present can be improved with more sophisticated local search techniques =-=[11]-=-, [16] that achieve better approximation ratios. For the closely related capacitated k-median problem, there is a constant-factor algorithm with up to 50× violation of capacity constraints [6], making... |

24 | A Multi-exchange Local Search Algorithm for the Capacitated Facility Location Problem
- Zhang, Chen, et al.
(Show Context)
Citation Context ... are known to exist for these problems using both local search [2], [13] and LP relaxation methods [9]. The algorithms we present can be improved with more sophisticated local search techniques [11], =-=[16]-=- that achieve better approximation ratios. For the closely related capacitated k-median problem, there is a constant-factor algorithm with up to 50× violation of capacity constraints [6], making the a... |

22 | Optimizing the placement of integration points in multi-hop wireless networks
- Chandra, Qiu, et al.
(Show Context)
Citation Context ...work has shown how capacity scales asymptotically with the number of gateways and nodes [10], but does not consider how to choose gateway locations in specific topologies. Likewise, greedy heuristics =-=[4]-=- and local search operations J. Robinson, and E. Knightly are with Rice University, Houston, TX (http://networks.rice.edu). M. Uysal and R. Swaminathan are with HP Labs, Palo Alto, CA. The research of... |

16 | LP-based approximation algorithms for capacitated facility location
- Levi, Shmoys, et al.
- 2004
(Show Context)
Citation Context ...acitated facility location problem and uncapacitated k-median problem. Constant-factor approximations are known to exist for these problems using both local search [2], [13] and LP relaxation methods =-=[9]-=-. The algorithms we present can be improved with more sophisticated local search techniques [11], [16] that achieve better approximation ratios. For the closely related capacitated k-median problem, t... |

12 | A performance study of deployment factors in wireless mesh networks
- Robinson, Knightly
(Show Context)
Citation Context ... capacity of hybrid wired and wireless networks has been studied in [10], though this study only provides asymptotic bounds and does not address the gateway placement problem. For regular topologies, =-=[15]-=- studies the impact of gateway density on network capacity and presents techniques to calculate connectivity to gateways. We adapt our algorithms from solutions to the related capacitated facility loc... |

10 |
Rohit Khandekar, Kamesh Munagala, and Vinayaka Pandit. Local search heuristic for k-median and facility location problems
- Arya, Garg
- 2001
(Show Context)
Citation Context ...rithm, MinContention, adapts from a solution to the uncapacitated k-median facilityslocation problem and minimizes the average contention for all mesh nodes with provable approximation ratio of 3 + ɛ =-=[2]-=-, where the ɛ parameter determines accuracy and runtime. To minimize contention, we assign link weights equal to the amount of contention caused by each link, considering contention on all nodes inste... |

6 |
Wi-fi nodes to talk amongst themselves
- Cherry
- 2006
(Show Context)
Citation Context ...s found by local search are similar in configuration to the optimal. I. INTRODUCTION Multi-tier wireless mesh networks are being deployed in many cities in order to provide ubiquitous Internet access =-=[5]-=-. A mesh network’s directional links and gateway nodes that connect the wireless mesh with the wired Internet are critical capacity points as their location and quantity determines the maximum through... |

3 |
Minimum-cost gateway deployment in cellular wi-fi networks
- Prasad, Wu
- 2006
(Show Context)
Citation Context ...versity, Houston, TX (http://networks.rice.edu). M. Uysal and R. Swaminathan are with HP Labs, Palo Alto, CA. The research of Robinson and Knightly was supported by HP Labs and NSF grant CNS-0325971. =-=[14]-=- have been developed for gateway placement, but neither incorporates wireless contention nor studies incremental deployment. In this paper, we study the gateway placement problem and then present and ... |

1 |
Tropos unwire
- net
- 2007
(Show Context)
Citation Context ...rue connectivity matrix is not observable externally, we assume a link exists if the physical distance is less than 200 meters. The first deployed topology corresponds to the 195 node Chaska topology =-=[1]-=-. We begin with four known gateways and place additional capacity points in the network using the greedy, MinHopCount, and MinContention algorithms, plotting the results in Figure 2. Optimal does not ... |

1 |
Chuzhoy and Yuval Rabani. Approximating k-median with non-uniform capacities
- Julia
- 2005
(Show Context)
Citation Context ...niques [11], [16] that achieve better approximation ratios. For the closely related capacitated k-median problem, there is a constant-factor algorithm with up to 50× violation of capacity constraints =-=[6]-=-, making the algorithm too inaccurate for our purposes. VI. CONCLUSIONS We study the gateway placement problem, first introducing a technique to efficiently compute gatewaylimited fair mesh capacity a... |