The IS-95 Channel

• Semi-connection-oriented

  • hardware allocated to call, but air resource is dynamically shared

• Designed for variable-data-rate vocoder

  • Frames sent at constant 50 Hz (20ms) rate

• Four fixed-size frames with raw sizes:

  • Rate set 1 ("9.6"): 24, 48, 96, 192 bits
  • Rate set 2 ("14.4"): 36, 72, 144, 288 bits

• Viterbi decoder tails and CRCs of varying sizes reduce usable payload

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