Quectel M20

M20 Hardware Design
Appendix A: GPRS Coding Schemes
Four coding schemes are used in GPRS protocol. The differences between them are shown in
Table 40.
Table 40: Description of different coding scheme
Scheme Code
rate
USF Pre-coded
USF
Radio
Block
excl.USF
and BCS
BCS Tail Coded
bits
Punctured
bits
Data
rate
Kb/s
CS-1 1/2 3 3 181 40 4 456 0 9.05
CS-2 2/3 3 6 268 16 4 588 132 13.4
CS-3 3/4 3 6 312 16 4 676 220 15.6
CS-4 1 3 12 428 16 - 456 - 21.4
Radio block structure of CS-1, CS-2 and CS-3 is shown as Figure 54:
rate 1/2 convolutional coding
puncturing
456 bits
USF BCS
Radio Block
Figure 54: Radio block structure of CS-1, CS-2 and CS-3
Radio block structure of CS-4 is shown as Figure 55:
block
code
no coding
456 bits
USF BCS
Radio Block

Figure 55: Radio block structure of CS-4
M20_HD_V1.01 - 79 -
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