Forward link channels in CDMA system: a.) Pilot Channel b.) Sync. Channel

Explain following forward link channels in CDMA system: a.) Pilot Channel b.) Sync. Channel

Pilot Channel

- A forward link channel which is a base to mobile that modulates only by the pilot PN. It spreads common codes to all signals transmitted from a given base station.
- Several critical important functions are provided by the pilot channel for forward links in IS-95 systems
- The pilot channel modulation facilitates the process of time synchronized replica generation at the receiver of the PN spreading sequences. These are utilized at the transmitter for modulating the synchronization, paging and traffic channels. These are transmitted from the same base station.

Sync. Channel

- A base station transmits a Sync-Channel that spreads with Walsh code 32.
- The frame of synch channel is 80/3ms long with frame boundary is aligned to the pilot.
- Sync channel transmits a single message continually, called Sync Channel Message.
- The Sync Channel Message contains network information, including the PN offset that is used by the Base Station sector.
- The length and content of the message is dependent on the P_REV.
- The message transmission rate is 32 bits / frame.
- The message is encoded to 128 symbols
- The message yielding rate is 1200 bits / s.