In CDMA IS95 we have some physical channel to transmit codes. BTS and mobile communicate via these channels. Physical channel is known by fundamental channel or logical channels. There are several channels in both forward and reverse direction.
Forward Channel: Pilot channel, Paging Channel, Sync Channel, Forward Traffic channel
Reverse Chanel: Access Channel, Reverse traffic Channel
Pilot Channel: It obtains a phase offset by short PN sequence to identify different base station. It has timing information. It is used to assist handoff. Mobile station use pilot strength comparison between pilots of base station to identify and perform handoff.
Sync Channel: It carries a data stream of essential system identification and parameter information used by mobiles during system acquisition stage like Pilot number, System time, Long code and paging rate (PRAT).
Paging Channel: it notify mobile station that they are receiving a call. It transmits information at a fixed rate 9600 or 4800 bps, as specified by the “PRAT” parameter sent in sync channel message. It carries system configuration parameter message, access parameters message and CDMA channel list message.
Forward Traffic Channel: It is used to transmit user and signaling information to a specific mobile station during a call.
Access Channel: Initiate communication with the base station not yet in a Call (such as transmit registration requests, call setup requests/origination message) in reverse direction. It is used to respond paging channel message.
Reverse Traffic Channel: It is used when call is in progress state to send voice traffic from subscriber, response to command from base station, request to base station.
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