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Chapter 8<br />

The <strong>Design</strong> of Partially Survivable <strong>Network</strong>s<br />

Syam Menon<br />

Abstract In cellular telecommunications networks, a mobile telephone switching<br />

office (MTSO) co-ordinates the activities of the mobile units either directly or<br />

through intermediate hubs. In order to increase reliability, cells often split their traffic<br />

via multiple hubs — this ensures partial survivability in the face of equipment<br />

failures. This chapter examines three related problems in the context of partial survivability.<br />

The first is a single-period model that addresses the question of assigning<br />

cells to hubs at minimum cost, while incorporating diversity requirements. The second<br />

extends the problem into a multi-period context, while the third incorporates<br />

capacity requirements at the hubs. Results from extensive computational tests are<br />

presented for the first two versions of the problem, while limited results are presented<br />

for the third.<br />

8.1 Introduction<br />

Cellular telecommunications systems have three basic components — mobile units,<br />

base transceivers or hubs at the cell sites <strong>and</strong> the mobile telephone switching office<br />

(MTSO). The MTSO co-ordinates the activities of the base transceivers in addition<br />

to connecting calls to the wired telephone network. Calls from (or to) mobile<br />

units are routed via the base transceivers to the MTSO for processing. The mobile<br />

units connect to the transceivers via radio links while the transceivers connect to<br />

the MTSO either via microwave or via terrestrial digital lines. Readers interested in<br />

details of the components of cellular networks are referred to books in this area (e.g.<br />

Lee [11]).<br />

The number of simultaneous calls that can be h<strong>and</strong>led by a cell can be expressed<br />

in terms of the number of 64 kbps DS-0 channels it needs in order to communicate<br />

Syam Menon<br />

School of Management, University of Texas at Dallas, Richardson, TX 75083, USA, e-mail:<br />

syam@utdallas.edu<br />

J. Kennington et al. (eds.), <strong>Wireless</strong> <strong>Network</strong> <strong>Design</strong>: <strong>Optimization</strong> <strong>Models</strong> <strong>and</strong> <strong>Solution</strong><br />

Procedures, International Series in Operations Research <strong>and</strong> Management Science 158,<br />

DOI 10.1007/978-1-4419-6111-2_8, © Springer Science+Business Media, LLC 2011<br />

177

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