| How PN Codes are used in IS-95 Systems
By Dr. Ernest Simo
25.0 How does the Long PN Code affect the Reverse Link and the Forward Link transmissions?
The Long PN Code affects the Reverse and Forward Links in the following manner:
The 4.4 trillion chip long Long PN code is truncated into billions of starting-offsets where adjacent offsets are separated by 64 chips or multiples of 64 chips.
On the Reverse Link, Long PN offsets are assigned to Mobile Units on a dedicated basis. Used as such, they provide isolation between Handsets due to their relatively small cross-correlation factor.
On the Reverse Link, the Long Code is also used in the Data Burst Randomizer algorithm in order to determine the position of active Power Control groups within a Frame.
On the Forward Link, the Long Code is also used for the following purposes:
- Scramble the Paging and Traffic Channels
- Determine the position of Power Control bits
Click here to view Figure 15
© 2001 DR. ERNEST SIMO - SPACE2000 |