TABLE OF CONTENTS The forward link comprises of 64 logic channels represented by 64 Walsh codes (W 0, W 1, , W 63). Each code is made of 64 chips which are transmitted at the chip rate of 1228800 chip/s. These codes are used to modulate (spread) the digital information signals that are transmitted on the forward channel. Since Walsh codes are perfectly orthogonal to each other, they provide channelization scheme on the forward channel so that all these signals (broadcast and traffic) are transmitted over the same bandwidth of the forward channel, hopefully with little or no mutual interference between them when used in a synchronous IS-95 CDMA system. The overall structure of the forward channel is shown in Figure 8.3.
The forward link consists of the following logic channels: one pilot channel using Walsh code W 0 for spreading all 0's signals; one synch channel using Walsh code W 32 for spreading the synch data transmitted at data rate 1200 bps; up to seven paging channels using Walsh codes W 1 to W 7 for spreading the 9600 bps and 4800 bps paging data; and between 55 up to 63 Traffic channels depending on how many paging channels are in use at that particular instant. There are two sets of rates for the traffic data: rate set 1 provides rates of 9600, 4800, 2400, and 1200 bps; and rate set 2 supports rates 14,400, 7200, 3600, and...
