Appendix A: Gprs Coding Schemes - Quectel M50 Hardware Design

M50 Hardware Design

Appendix A: GPRS coding schemes

Four coding schemes are used in GPRS protocol. The differences between them are shown in
Table 39.
Table 39: 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 60:
USF
Figure 59: Radio block structure of CS-1, CS-2 and CS-3
Radio block structure of CS-4 is shown as Figure 61:
USF
Block
code
M50_HD_V2.0
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
No coding
456 bits
Figure 60: Radio block structure of CS-4
BCS Tail Coded Punctured
bits bits
40 4 456
16 4 588
16 4 676
16 - 456
BCS
Data
rate
Kb/s
0 9.05
132 13.4
220 15.6
- 21.4
BCS
- 87 -