GPRS and EDGE bit-rates¶
- Table of contents
- GPRS and EDGE bit-rates
This page tries to outline the possible achievable GPRS bit-rates.
There are multiple aspects that relate to the problem- channel coding, which in turn depends on
- capabilities of the BTS and MS
- performance of the radio channel
- multi-slot operation, which depends on
- capabilities of the BTS and MS
- contention on the radio channel / resource sharing by multiple phones
channel coding¶
Depending on the characteristics of the radio channel (interference, bit errors, link quality, C/I), the network will
dynamically select the best coding scheme. The lower numbers (CS-1/MCS-1) have the most error coding and are very
resiliant but have little throughput. MCS-9 has no error correction coding at all, but t
GPRS channel coding¶
Each of the 8 GSM time-slots can operate i a number of different coding schemes:
Coding Scheme | kbit/s | |||
CS-1 | 8.0 | |||
CS-2 | 12.0 | |||
CS-3 | 14.4 | |||
CS-4 | 20.0 |
EDGE channel coding¶
Each of the 8 GSM time-slots can operate i a number of different coding schemes:
Coding Scheme | kbit/s | |||
MCS-1 | 8.80 | |||
MCS-2 | 11.20 | |||
MCS-3 | 14.80 | |||
MCS-4 | 17.60 | |||
MCS-5 | 22.40 | |||
MCS-6 | 29.60 | |||
MCS-7 | 44.80 | |||
MCS-8 | 54.54 | |||
MCS-9 | 59.20 |
multi-slot capabilities¶
BTS side¶
BTS equipment is normally capable to run all timeslots in GPRS mode. If you're running a single-TRX small BTS, the first timeslot is always allocated for the BCCH/CCCH, leaving 7 time-slots available for voice (TCH) and data (PDTCH).
For example, a total of 7 time-slots in MCS-9 coding scheme would render
59.20 kbps * 7 = 414.40 kbps
MS side¶
On the MS (phone) side, things are not that simple. Normally, phones can not decode all 7/8 time-slots, as they operate in half-duplex mode and need some time for transmit, too. The capabilities of each phone are specified as so-called multislot class
For a table of multislot classes, please see 3GPP TS 45.002, or a summarized version at wikipedia.
multi-slot class 10¶
For example, a phone with EDGE multislot class 10 permits for a total of 5 active time-slots, which can be either 4+1 (4 downlink, 1 uplink) or (3+2) (3 uplink, 2 downlink).Under ideal radio conditions (MCS-9), such a phone can thus reach the following two bit-rates:
Coding Scheme | multislot | downlink | uplink | |||||
MCS-9 | 4+1 | 236.80 | 59.20 | |||||
MCS-9 | 4+2 | 177.60 | 118.40 |
multi-slot class 32¶
Coding Scheme | multislot | downlink | uplink |
Updated by fixeria almost 5 years ago · 5 revisions