Cellular Communications Explained

with their relevant data. Here, the spreading code stream (a) is multiplied by the data in (c) to

give the spread data stream shown in (d). Similarly, spreading code stream (b) is multiplied

by the data in (e) to give (f). The two resulting spread data streams are then added together

to give the baseband signal ready to be modulated onto the carrier and transmitted.

In this case, it can be seen that chip stream (a) is repeated in waveform (h). This is multiplied by (g)

to give the waveform (i). Each group of four bits (as there are four bits in the chip code used in

the example) is summed, and from this the data can be reconstituted as shown in waveform (j).

When a random or, more correctly, a pseudo-random spreading code is used, a similar proces ...