Inter-Band Load Balancing

1
Inter-Band Load Balancing
David Rossetti Orlett W. Pearson Lucent Technologies Michael Wang Nortel Networks

• 18 October, 2004

2
Overview

• As cdma2000 is adopted more widely, it is
  expected that some networks will support more
  than one band class in the same geographic area.
• To maximize overall system capacity, the load
  across band classes should be balanced. This
  includes both overhead loading (Paging and
  Access) and traffic channel load balancing.
• Existing standards do not give us enough
  flexibility to solve this issue as would be
  desired.

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Benefit

• Provide inter-band load balancing capabilities
  for multi-band cdma2000 networks similar to
  existing intra-band capabilities.
• Effective load balancing techniques will improve
  system capacity without adversely affecting
  system performance.

4
Existing Problem

• Each Band Class is assumed to be a separate
  network.
• When more than one Band Class is available,
  mobile stations use custom system selection
  procedures to chose which system to use.
• As a result, distribution of mobile stations
  across band classes is not easily controlled, and
  can become significantly imbalanced.

5
Example without Inter-Band Hashing
Mobile Population 100 Dual Band
75 operating in Band Class 1 25 operating
in Band Class 2
Base Station Configuration Band Class 1 Two
Carriers Band Class 2 One Carrier
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Inter-Band Hashing

• Inter-band hashing is proposed when all of the
  following are true
• Cells in each band class are co-located
• Cells in each band class have the same Channel
  Configuration (PCH/BCCH)
• Coverage areas of both band classes are
  equivalent
• Performs static load balancing.
• Minimizes Paging and Access loading imbalance on
  carriers on different bands.
• Reduces need to perform call-time load balancing,
  since static load is already balanced.

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Inter-Band Hashing Approach

• Network optionally lists operating carriers in
  one or more alternate band classes in the ECCLM.
• Mobile stations that support only one band class,
  hash only over Operating Carriers in that band
  class.
• Mobile stations that support one or more
  alternate band classes, will hash over a combined
  list of Operating Carriers in all supported band
  classes.

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Example with Inter-Band Hashing
Base Station Configuration Band Class 1 Two
Carriers Band Class 2 One Carrier Inter-Band
Hashing Active
Mobile Population 100 Dual Band