How Sync Channel work in CDMA?
A long code is used for scrambling. However, a long code has too long a period, which cannot be wholly used for scrambling. We can only sample some chips of a long code at some point of time and use them as the sequences of scrambling.
This requires that a mobile station should know the following information: when the long code chip used for scrambling begins, what the mask of a generated long code is, etc. All these pieces of information are so-called long code synchronization.
The sync channel is used by the mobile station to synchronize with the network. W32 is used to spread Sync Channel.
The synchronization message includes:
- Pilot PN sequence offset: PILOT_PN
- System time: SYS_TIME
- Long code state: LC_STATE
- Paging channel rate: P_RAT
- Here note that, sync channel rate is 1200bps