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Mobile Computing COE 446 Network Planning

Mobile Computing COE 446 Network Planning. Tarek Sheltami KFUPM CCSE COE http://faculty.kfupm.edu.sa/coe/tarek/coe446.htm. Principles of Wireless Networks K. Pahlavan and P. Krishnamurth. Outline. Signal to interference ratio calculation Capacity expansion techniques.

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Mobile Computing COE 446 Network Planning

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  1. Mobile Computing COE 446Network Planning Tarek Sheltami KFUPM CCSE COE http://faculty.kfupm.edu.sa/coe/tarek/coe446.htm Principles of Wireless Networks K. Pahlavan and P. Krishnamurth

  2. Outline • Signal to interference ratio calculation • Capacity expansion techniques

  3. 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

  4. Signal-to-Interference Ratio Calculation.. • If there are Js interfering BS surrounding a given BS then: Where d0: the distance of MT from a given BS and dn is the distance from the nth BS

  5. Sr as a function of frequency reuse factor, N

  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) dB= Pt(dB) – (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 appropriate for first cut approximations in system design

  7. Capacity Expansion Techniques • There are four methods: • Obtain additional spectrum to new MTs • 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

  8. Capacity Expansion Techniques.. • 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

  9. 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

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