Spread Spectrum & CDMA

Spreading Parameters

Spreading factor 16 PN code type

Channel & Users

Number of users 2 SNR (dB) 10 Near-far ratio (dB) 0

Metrics

Processing gain-

Max |ρ_cross|-

Code orthogonality-

Separable users-

CDMA User Separation
Processing Gain = 10log₁₀(SF) dB
ρ(c_i,c_j) = (1/N) Σ c_i[n]·c_j[n]

Orthogonal codes (Walsh): ρ_cross = 0 → perfect user separation, zero MAI.
Quasi-orthogonal (Gold): |ρ_cross| ≤ bounded → residual interference between users.

Correlator: Despread with user k's code → only user k's data survives.