Explain reverse link features of CDMA 2000.
1 Answer

Following are the reverse link features of CDMA 2000:

a) Channels are primarily code multiplexed

b) Separate channels are used for different QoS and physical layer characteristics

c) Transmission is continuous to avoid EMI (Electro-magnetic interference)

d) Channels are orthogonalized by Walsh functions and I/Q split so that performance is equivalent to BPSK

e) Hybrid combination of QPSK and BPSK modulation

f) Coherent reverse link with continuous pilot

g) Forward power control information is time-multiplexed with the pilot By restricting alternate phase changes of the complex scrambling, power peaking is reduced and side lobes are narrowed

h) Forward error correction:

  • Convolutional codes (k=9) are used for voice and data
  • Parallel turbo codes (k= 4) are used for high data rates on supplemental channels

i) Fast reverse power control: 800 times per second Frame lengths

  • 20-ms frames are used for signaling and user information
  • 5-ms frames are used for control information

j) physical channels (PHCH) used by CDMA 2000 for Reverse link are

  • Pilot (R-PICH)* channel
  • Access (R-ACH)
  • Dedicated Control (R-DCCH)* channel
  • Fundamental (R-FCH)
  • Common Control (R-CCH) channel
  • Enhanced Access (R-EACH)*
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