Mobile Computing COE 446 Network Planning

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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
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Outline

• Signal to interference ratio calculation
• Capacity expansion techniques

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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

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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

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Sr as a function of frequency reuse factor, N
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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

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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

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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

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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