The development of the IEEE 802.22 standard is aimed at providing broadband access in rural areas by effectively utilizing the unused TV band, provided no harmful interference is caused to the incumbent operation. This thesis presents the analytical framework to evaluate the number of active customer premise equipments (CPEs) in a wireless regional area network. Initial ranging is the primary process in IEEE 802.22 networks for CPEs to access the network and establish their connections with the base station (BS). A comprehensive analysis of initial ranging mechanism is provided in this work and initial ranging request success probability is derived based on the number of contended CPEs and the initial contention window size. Further, the average ranging success delay is derived for the maximum backoff stages. The collision probability is highly dependent on the size of the initial contention window and the number of contended CPEs. To keep it at a specific level, it is necessary for the BS to schedule the required size of the initial contention window to facilitate the maximum number of CPEs to establish their connections with reasonable delay. Therefore, the optimized initial window size is proposed that meets the collision probability constraint for a particular number of contended CPEs. An analytical model is also developed to estimate the ranging request collision probability depending upon the size of initial contention window and the number of contended CPEs. Moreover, this approximation provides the threshold size for contention window to start the initial ranging process in the IEEE 802.22 network.

The development of the IEEE 802.22 standard is aimed at providing broadband access in rural areas by effectively utilizing the unused TV band, provided no harmful interference is caused to the incumbent operation. This thesis presents the analytical framework to evaluate the number of active customer premise equipments (CPEs) in a wireless regional area network. Initial ranging is the primary process in IEEE 802.22 networks for CPEs to access the network and establish their connections with the base station (BS). A comprehensive analysis of initial ranging mechanism is provided in this work and initial ranging request success probability is derived based on the number of contended CPEs and the initial contention window size. Further, the average ranging success delay is derived for the maximum backoff stages. The collision probability is highly dependent on the size of the initial contention window and the number of contended CPEs. To keep it at a specific level, it is necessary for the BS to schedule the required size of the initial contention window to facilitate the maximum number of CPEs to establish their connections with reasonable delay. Therefore, the optimized initial window size is proposed that meets the collision probability constraint for a particular number of contended CPEs. An analytical model is also developed to estimate the ranging request collision probability depending upon the size of initial contention window and the number of contended CPEs. Moreover, this approximation provides the threshold size for contention window to start the initial ranging process in the IEEE 802.22 network. / Bahauddin Zakariya University Multan, Pakistan.

Radio access technologies evolving fast, mobile operators have to handle an increasing amount of base stations and frequency bands for their network to continue to function. This is a costly venture for mobile network operators that continuously have to keep up to date with never-ending advancements in technologies, as base stations are costly to build and to maintain. It is therefore necessary for these companies to investigate when to close down base stations that are not necessary anymore. With the upcoming release of 5G, it is expected that 3G is going to be less and less used—as of 2018, it is already less used than 4G in developed countries.This thesis analyses the corporate data of a mobile operator, Telenor Sweden, in order to make clear which metrics are important to take into account as regards to deciding whether or not to close down a base station. It provides methods and models to help a mobile operator to take such a decision. It focuses on UMTS (3G) base stations, even though the results can be generalized for other technologies as well.It evaluates the economic feasibility of closing a base station, with regards to how many users are still connecting to it. More importantly, it explains for what reasons users’ devices switch to 3G, and investigates what can be done to avoid switching from 4G to 3G, so as to make it easier to close down a 3G site. It provides eventually a model to help to know when closing a site, given the traffic data of the operator. / Radioåtkomstteknologier utvecklas snabbt, mobiloperatörer måste hantera en ökande mängd basstationer och frekvensband för att deras nätverk fortsätter att fungera. Detta är ett dyrt satsning för mobilnätoperatörer som kontinuerligt måste hålla sig uppdaterade med oändliga tekniska framsteg, eftersom basstationerna är kostsamma att bygga och underhålla. Det är därför nödvändigt för dessa företag att undersöka när man ska stänga basstationer som inte längre är nödvändiga. Med den kommande utgåvan av 5G förväntas 3G att bli mindre och mindre används. Från och med 2018 används den redan mindre än 4G i industriländer. Denna avhandling analyserar företagsdata från en mobiloperatör, Telenor, för att klargöra vilka mätvärden som är viktiga att ta hänsyn till när det gäller att avgöra om en basstation ska stängas eller inte. Det ger metoder och modeller för att hjälpa en mobiloperatör att fatta ett sådant beslut. Den fokuserar på UMTS (3G) basstationer, även om resultaten kan generaliseras för annan teknik också. Det utvärderar den ekonomiska möjligheten att stänga en basstation, med tanke på hur många användare som fortfarande ansluter till den. Viktigare är det att det förklaras av vilka anledningar användarens enheter växlar till 3G och undersöker vad som kan göras för att undvika att växla från 4G till 3G, så att det blir lättare att stänga en 3G-basstation. Det ger så småningom en modell som hjälper till att veta när man stänger en webbplats, med tanke på operatörens trafikdata.

No / Avoiding collision among contending customer premise equipments (CPEs) attempting to associate with a base station (BS) in a wireless regional area network (WRAN) is a challenging issue. The collision probability is highly dependent upon the size of the initial contention window and the number of contending CPEs. To reduce the collision probability among CPEs in order to start the ranging process in an IEEE 802.22 network, the BS needs to adjust the initial contention window size. This paper provides an analytical framework to estimate the ranging request collision probability depending upon the size of the initial contention window and the number of CPEs attempting to join the IEEE WRAN cell. The accuracy of the estimated curve is analyzed for various numbers of contention CPEs on the basis of the relative errors. The numerical results confirm that the approximation works reasonably well for finding the ranging request collision probability for any number of contention CPEs at a particular value of initial contention window size. Moreover, this approximation provides the threshold size for a contention window to start the initial ranging process for any number of CPEs in an IEEE 802.22 network. (C) 2014 Elsevier B.V. All rights reserved.