Appendix A: Gprs Coding Schemes - Quectel M12 Hardware Design

M12 Hardware Design

Appendix A: GPRS coding schemes

Four coding schemes are used in GPRS protocol. The differences between them are shown in
Table 33.
Table 33: Description of different coding schemes
Scheme Code USF Pre-coded
Rate
CS-1 1/2 3
CS-2 2/3 3
CS-3 3/4 3
CS-4 1 3
Radio block structure of CS-1, CS-2 and CS-3 is shown as Figure 52:
USF
Figure 52: Radio block structure of CS-1, CS-2 and CS-3
Radio block structure of CS-4 is shown as Figure 53:
USF
Block
Code
M12_Hardware_Design_V3.2
Radio
USF Block
excl.USF
and BCS
3 181
6 268
6 312
12 428
Radio Block
Rate 1/2 Convolutional Coding
Puncturing
456 bits
Radio Block
456 bits
Figure 53: Radio block structure of CS-4
BCS Tail Coded
Bits
40 4 456
16 4 588
16 4 676
16 - 456
No coding
Punctured Data
Bits Rate
Kb/s
0 9.05
132 13.4
220 15.6
- 21.4
BCS
BCS
- 73 -