This is a great improvement compared to the system applying Walsh Codes, which need to cancel N-1 users in the worst case.
5 MHz rate Modulation Number of 256 Cyclic prefix Data sub-carriers (FFT length) Maximum Doppler 111Hz Channel model Frequency Spreading Sequences CQS Walsh codes OFDM symbol period PT OFDM DT OFDM symbol number in 7 symbol number in one period one period Signal bit 8-PSK scheme Number of 5.
This relationship holds for both the Hadamard numbering of the Walsh codes
in IS-95 and CDMA2000 as well as the bit-reversed Hadamard code numbering used in wideband CDMA (W-CDMA).
OVSF codes are orthogonal codes similar to the Walsh codes
used in 2G CDMA (IS-95) BTS.
Unique codes for each mobile are created on the forward channel by combining the voice data with 1 of 64 user Walsh codes
and then combining that with a sector unique offset of the PN (pseudo-noise) short code (see the Figure).
Spreading function using Walsh codes
and Quasi Orthogonal
2288 Mbps chip rate, an IS-95 forward link pilot channel and 16 orthogonal channels with 0 to 63 selectable Walsh codes