GPRS bitrates » History » Version 2
laforge, 02/19/2016 10:47 PM
| 1 | 1 | laforge | [[PageOutline]] |
|---|---|---|---|
| 2 | = GPRS and EDGE bit-rates = |
||
| 3 | |||
| 4 | This page tries to outline the possible achievable GPRS bit-rates. |
||
| 5 | |||
| 6 | There are multiple aspects that relate to the problem |
||
| 7 | * channel coding, which in turn depends on |
||
| 8 | * capabilities of the BTS and MS |
||
| 9 | * performance of the radio channel |
||
| 10 | * multi-slot operation, which depends on |
||
| 11 | * capabilities of the BTS and MS |
||
| 12 | * contention on the radio channel / resource sharing by multiple phones |
||
| 13 | |||
| 14 | == channel coding == |
||
| 15 | === GPRS channel coding === |
||
| 16 | |||
| 17 | Each of the 8 GSM time-slots can operate i a number of different coding schemes: |
||
| 18 | |||
| 19 | ||Coding Scheme||kbit/s|| |
||
| 20 | ||CS-1||8.0|| |
||
| 21 | ||CS-2||12.0|| |
||
| 22 | ||CS-3||14.4|| |
||
| 23 | ||CS-4||20.0|| |
||
| 24 | |||
| 25 | === EDGE channel coding === |
||
| 26 | |||
| 27 | Each of the 8 GSM time-slots can operate i a number of different coding schemes: |
||
| 28 | |||
| 29 | ||Coding Scheme||kbit/s|| |
||
| 30 | ||MCS-1||8.80|| |
||
| 31 | ||MCS-2||11.20|| |
||
| 32 | ||MCS-3||14.80|| |
||
| 33 | ||MCS-4||17.60|| |
||
| 34 | ||MCS-5||22.40|| |
||
| 35 | ||MCS-6||29.60|| |
||
| 36 | ||MCS-7||44.80|| |
||
| 37 | ||MCS-8||54.54|| |
||
| 38 | ||MCS-9||59.20|| |
||
| 39 | |||
| 40 | == multi-slot capabilities == |
||
| 41 | |||
| 42 | 2 | laforge | |
| 43 | === BTS side === |
||
| 44 | 1 | laforge | 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). |
| 45 | |||
| 46 | For example, a total of 7 time-slots in MCS-9 coding scheme would render |
||
| 47 | 59.20 kbps * 7 = 414.40 kbps |
||
| 48 | |||
| 49 | 2 | laforge | === MS side === |
| 50 | 1 | laforge | 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'' |
| 51 | |||
| 52 | For a table of multislot classes, please see 3GPP TS 45.002, or a summarized version at [https://secure.wikimedia.org/wikipedia/en/wiki/GPRS#Multislot_Class wikipedia]. |
||
| 53 | 2 | laforge | |
| 54 | 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). |
||
| 55 | Under ideal radio conditions (MCS-9), such a phone can thus reach the following two bit-rates: |
||
| 56 | ||Coding Scheme||multislot||downlink||uplink|| |
||
| 57 | ||MCS-9||4+1||236.80||59.20|| |
||
| 58 | ||MCS-9||4+2||177.60||118.40|| |
