Wireless Oom

The spreading procedure in the UTRAN consists of two separate operations:

1. channelization

2. scrambling

Channelization uses orthogonal codes. Scrambling uses PN (Pseudo-Noise) codes.

Downlink:

channelization is for differentiating users.

scrambling is for differentiating base station.

Uplink:

channelization is for differentiating channels per UE

scrambling is for differentiating users.

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Orthogonality requires time synchronous properties. Thus, it cannot separate different uplink users as all UEs are unsynchronized in time.