1. CDMA (from Tanenbaum, Computer Networks p. 137)
Assume the following CDMA chip sequences for +1 (0 has the complementary chip sequence):
A: (-1 –1 – )
B: (-1 –1 +1 – –1)
C: (-1 +1 – –1 –1)
D: ( –1)

2. Complementary codes (for 0)
B: ( )
C: ( )
D: ( )
To show that these chipsets are orthogonal we assume that A, B, C, D send bits at some time and receiver can recover individual signals

3. Example A sends 0, B sends 1, C sends 0, D does not send Signals sent
received

4. Example from CDMA 1 -1 3 -3 -1 +1 1 -1
Multiple this termwise with each of the chipsets
At A ((1)(-1) + (-1)(-1) +(3)(-1)+(-3)(1)+
(-1)(1) +(+1)(-1)+ (1)(1) + (-1)(1))/8 =
( )/8 = -8/8 = -1 (for 0)
At D (1)(-1) + (-1)(1)+(3)(-1)+ (-3)(-1) +
(-1)(-1) +(1)(-1) +(1) 1+ (-1)(-1) = 0 (did not send)