PN Sequences - Part 2
How PN Codes are used in IS-95 CDMA Systems
By Dr. Ernest Simo
2.0 Using the Long PN Code
How the Long PN Code is Used
Let us assign the Long PN Offsets LC(t - t A) and
LC(t - t B) to Mobile A and Mobile B respectively.
The signal from Mobile A to cell A is of the form di(t) • LC(t - t
A). Likewise the signal from Mobile B tocell B is of the form dj(t) • LC(t
- t B).
The received signal at cell A is the composite signal from Mobile A and Mobile B.
(Both Mobiles are on the same 1.25 MHz Frequency band.). Likewise, the received signal at
cell B is the same composite signal. This composite signal received by each cell can be
represented as:
Rx = di(t) • LC(t - t A) + dj(t) • LC(t - t B)
Here, we have ignored the propagation delay which can be readily resolved by the
Synchronization process at the cells.
