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Multihopping in unlicensed spectrum
KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS.
2005 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

It is a common knowledge that certain radio frequency band is licensed for certain type of  wireless/radio communication system. Most of the radio frequency bands are licensed  and to get a license can cost money in some countries. However there are certain  frequency bands which are unlicensed. Thus everybody who wants to use these frequency  bands to transmit is allowed to do that. As frequency bands are limited resources and can  cost, the operators are very keep to use these frequency bands. This is causing  interference problems.

One possible scenario is that two operators decide to operate in the same area using the  same frequency band. One previous study conducted by O. Queseth showed that the two  networks belonging to the two operators cause a lot of interference to each other and thus  suffer very much in capacity. It was further shown that the problem was more critical for  the mobiles far away from own base stations but close to the competitive network’s base  stations. Multi-hopping was suggested by me and my colleagues Thomas E. and Sujata  M. as a solution to improve the capacities for the networks. Though the result showed a  substantial improvement, we believed that it could be done better. The purpose of this  thesis work has been to find a better working strategy for this system.

By modifying the routing and scheduling algorithms it has been found in this thesis that a  routing algorithm which minimizes the total power consumed when sending packets and  an adaptive S-TDMA as scheduling algorithm gives us very satisfying results.

It is also shown that by only changing the routing or the scheduling, we get either the  same or even worse performance. The best strategy was to change both the routing  algorithm and the scheduling. The profound strategy is working very well but it does not  mean that there aren’t other pairs of routing and scheduling algorithms which could work  better.

Place, publisher, year, edition, pages
2005. , 24 p.
TRITA-S3-RST, ISSN 1400-9137 ; 0514
National Category
Computer and Information Science
URN: urn:nbn:se:kth:diva-28100OAI: diva2:383957
Available from: 2011-03-10 Created: 2011-01-06 Last updated: 2014-10-15Bibliographically approved

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Bayat, Zabihullah
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Communication Systems, CoS
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