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Describe IS – 95 forward link channel structure.
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The IS-95 forward Channel structure consists of four types of logical Channels - pilot Channel, synchronization Channel, paging Channel, and forward traffic Channels. Each forward carrier Channel contains one pilot, one synchronization Channel, up to seven paging Channels, and a number of forward traffic Channels. 


The pilot Channel (Channel 0): It is an un-modulated Channel. This Channel allows the mobile phone to acquire timing information, provides phase reference for the demodulation process, and provides a means for signal strength comparison for the purpose of hand-off determination. The pilot Channel consists of all logical zeros.

The sync Channel (Channel 32): It has low-rate data that is convolutionally encoded and interleaved. It is used with the pilot Channel to acquire initial time synchronization. It is a 1200-bps Channel used by the mobile user to obtain identification information about the system (system time, long-code state, protocol revision, etc.). 

The paging Channel (Channels 1 to 7): It has low rate data that is also encoded and interleaved. Prior to being spread, the paging data is randomized with a scrambler that is specific to the mobile user for which the page is intended. The paging Channel provides system information and instructions to the MSs 

The forward traffic Channel (Channels 8 to 31 and 33 to 63):It is FEC encoded and interleaved and then scrambled with a sequence that is specific to the intended mobile user, the signaling and control bits are multiplexed with the forward traffic Channel which is meant for adjusting the power of the mobile transmitter

The process that are carried out on the forward channel are as follows 1. Encoding of user data. 2.IInterleaving 3. Block of 6 bits are converted to one of the 64 Walsh codes. 4.Data is spread using a42bit user specific code. This code is known as the channel identifier. This code is different for each user

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