GPRS bitrates » History » Version 1
laforge, 02/19/2016 10:47 PM
| 1 | 1 | laforge | [[PageOutline]] |
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| 2 | = GPRS and EDGE bit-rates = |
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| 3 | |||
| 4 | This page tries to outline the possible achievable GPRS bit-rates. |
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| 5 | |||
| 6 | There are multiple aspects that relate to the problem |
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| 7 | * channel coding, which in turn depends on |
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| 8 | * capabilities of the BTS and MS |
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| 9 | * performance of the radio channel |
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| 10 | * multi-slot operation, which depends on |
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| 11 | * capabilities of the BTS and MS |
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| 12 | * contention on the radio channel / resource sharing by multiple phones |
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| 13 | |||
| 14 | == channel coding == |
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| 15 | === GPRS channel coding === |
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| 16 | |||
| 17 | Each of the 8 GSM time-slots can operate i a number of different coding schemes: |
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| 18 | |||
| 19 | ||Coding Scheme||kbit/s|| |
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| 20 | ||CS-1||8.0|| |
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| 21 | ||CS-2||12.0|| |
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| 22 | ||CS-3||14.4|| |
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| 23 | ||CS-4||20.0|| |
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| 24 | |||
| 25 | === EDGE channel coding === |
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| 26 | |||
| 27 | Each of the 8 GSM time-slots can operate i a number of different coding schemes: |
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| 28 | |||
| 29 | ||Coding Scheme||kbit/s|| |
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| 30 | ||MCS-1||8.80|| |
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| 31 | ||MCS-2||11.20|| |
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| 32 | ||MCS-3||14.80|| |
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| 33 | ||MCS-4||17.60|| |
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| 34 | ||MCS-5||22.40|| |
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| 35 | ||MCS-6||29.60|| |
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| 36 | ||MCS-7||44.80|| |
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| 37 | ||MCS-8||54.54|| |
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| 38 | ||MCS-9||59.20|| |
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| 39 | |||
| 40 | == multi-slot capabilities == |
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| 41 | |||
| 42 | 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). |
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| 43 | |||
| 44 | For example, a total of 7 time-slots in MCS-9 coding scheme would render |
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| 45 | 59.20 kbps * 7 = 414.40 kbps |
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| 46 | |||
| 47 | 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'' |
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| 48 | |||
| 49 | 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]. |
