June 5, Mobile Computing COE 446 Network Planning Tarek Sheltami KFUPM CCSE COE Principles of Wireless Networks K. Pahlavan and P. Krishnamurth

June 5, Outline  Signal to interference ratio calculation  Capacity expansion techniques

June 5, 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 S r

June 5, Signal-to-Interference Ratio Calculation..  If there are J s interfering BS surrounding a given BS then: Where d 0 : the distance of MT from a given BS and d n is the distance from the n th BS

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6 S r as a function of frequency reuse factor, N

June 5, 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: P r (d) dB = P t (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

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June 5, Capacity Expansion Techniques  There are four methods: 1. Obtain additional spectrum to new MTs  Very simple, but expensive 2. 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 changesin wireless modem or access techniques  One of the most practical and less expensive solutions to expand the network capacity

June 5, Capacity Expansion Techniques.. 3. 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 4. Expand the network capacity by changing modem and access technology:  The most effective method

June 5, 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