Gprs error coding schemes
GPRS provides various coding schemes with different levels of error detection and correction. These are used dependent upon the radio frequency signal conditions and the requirements for the data being sent. These are given labels CS-1 to CS-4.
GPRS coding: These coding are labeled and given labels CS-1 to CS-4:
- CS-1: It is used when interference levels are high or signal levels are low. With such high levels of detection and correction, it prevents the data having to be re-sent too often. This level of detection and coding results in a half code rate, i.e. for every 12 bits that enter the coder, 24 bits result. It results in a throughput of 9.05 kbps actual throughput data rate.
- CS-2: This error detection and coding scheme is for better channels. It effectively uses a 2/3 encoder and results in a real data throughput of 13.4 kbps which includes the RLC/MAC header etc.
- CS-3: This effectively uses a 3/4 coder and results in a data throughput of 15.6 kbps.
- CS-4: This scheme is used when the signal is high and interference levels are low. No correction is applied to the signal allowing for a maximum throughput of 21.4 kbps. If all eight slots were used then this would enable a data throughput of 171.2 kbps to be achieved.