Mobile Computing COE 446 Network Planning Tarek Sheltami
Mobile Computing COE 446 Network Planning Tarek Sheltami KFUPM CCSE COE http: //faculty. kfupm. edu. sa/coe/tarek/coe 446. htm Principles of Wireless Networks K. Pahlavan and P. Krishnamurth 19 December 2021 1
Outline § § Signal to interference ratio calculation Capacity expansion techniques 19 December 2021 2
Signal-to-Interference Ratio Calculation § The objective in a cellular radio system is to allocate the channels to cell within a cluster so that the distance between cochannels or adjacent channels is as large as possible § For urban land mobile ratio, the distance is power gradient is roughly 4 § The received signal strength falls as the fourth power distance § This further improves Sr 19 December 2021 3
Signal-to-Interference Ratio Calculation. . § If there are Js interfering BS surrounding a given BS then: Where d 0: the distance of MT from a given BS and dn is the distance from the nth BS 19 December 2021 4
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Sr as a function of frequency reuse factor, N 19 December 2021 6
Signal-to-Interference Ratio Calculation. . § Assuming that received signal falls as the fourth of the distance from land mobile radio, the path loss model will be: Pr(d) d. B = Pt(d. B) – (40 log d + 10 log K) § The factor 10 log K usually corresponds to the path loss at the first meter or kilometer, d is the distance § This model is system design 19 December 2021 appropriate for first cut approximations in 7
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Capacity Expansion Techniques § 1. There are four methods: Obtain additional spectrum to new MTs § 2. Very simple, but expensive Expand the capacity of a cellular network to change the cellular architecture: § This includes cell splitting, cell sectoring using directional antennas (Lee microcell zone technique) and using multiple reuse factors § These techniques do not need additional spectrum or any major changes in wireless modem or access techniques § One of the most practical and less expensive solutions to expand the network capacity 19 December 2021 11
Capacity Expansion Techniques. . 3. 4. Change the frequency allocation methodology: § Non uniform distribution of the frequency bands among different cells according to their traffic need § Traffic load of each cell is dynamically changed by the geography of the service area with time depending of the traffic load § These techniques do not need any change in MTs or physical architecture of the system Expand the network capacity by changing modem and access technology: § The most effective method 19 December 2021 12
Capacity Expansion Techniques. . § Cell industry started with analog FM modulation then TDMA and it is going to CDMA air interface using digital modems § Digital technology increases the network capacity and also provides a fertile environment for integration of voice and data services § This migration requires the user to purchase new MT and provider to install new components in the infrastructure 19 December 2021 13
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