CDMA2000 Measurements
R&S
®
CMW-KG8xx/-KM8xx/-KS8xx
726
User Manual 1173.9511.02 ─ 11
For the spreading operation the binary symbols of the Walsh function are mapped as
follows: "0" is mapped to +1 and "1" is mapped to "-1".
Orthogonal Variable Spreading Factor (OVSF) codes provide an alternative scheme of
generating codes that preserve orthogonality between channels. They are derived from
a hierarchical tree:
The OVSF spreading factor SF corresponds to the Walsh function order N. For a given
spreading factor SF, Walsh codes and OVSF codes can be derived from each other
via the binary representation of the channelization code numbers. The Walsh code with
code number n is equal to the OVSF code with code number m, where m has the
inverse binary representation of n (n is converted into m by reversing the order of bits
in the binary representation of n). For numbers with symmetrical binary representation
(e.g. 00 or 1001), the Walsh code and OVSF code numbers are equal.
Example for SF=4 and N=4:
Hadamard (Walsh codes)
after mapping to +1/-1
Code number
Bit reverse (OVSF codes)
decimal
binary
1 1 1 1
0
00
1 1 1 1
1 -1 1 -1
1
01
1 1 -1 -1
1 1 -1 -1
2
10
1 -1 1 -1
1 -1 -1 1
3
11
1 -1 -1 1
To obtain the Bit reverse representation from the Hadamard representation, the codes
with number 01 and 10 (binary) must be interchanged.
General Description
深圳德标仪器
135-1095-0799
