W-CDMA

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Specs

W-CDMA is used by the UMTS.

UMTS's Magic Numbers
Property Value
Modulation/Access scheme W-CDMA
Channel bandwidth 5MHz
Chip rate 3.84MHz
Common pilot channel (CPICH) Fixed-rate 30 Kbps, spreading factor (SF) 256
Primary CPICH (CCPCH) 14 slots in one radio frame
CCPCH slot First 256 chips Tx OFF, then 18 data bits (20 bits/2560 chips in total)
CCPCH frame 10ms total duration

References

  • A great PDF that deals with many technical aspects of the air interface.

Auto-correlation

  • 3G UMTS at 2.1125GHz:

W-CDMA FAC.png

Strong peaks precisely on the 10ms grid line are indicative of the pilot channel.

There is also a smaller peak at ~0.7ms, which should be the repeating slot of the pilot channel.

  • Telstra NextG at 842.5MHz:

NextG FAC.png

Waterfall plot shows bursty traffic on the downlink. This would likely contribute to the correlation graph looking more 'noisy' about the pilot channel peaks.