GPRS bitrates » History » Version 3
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 | 3 | laforge | |
| 16 | Depending on the characteristics of the radio channel (interference, bit errors, link quality, C/I), the network will |
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| 17 | dynamically select the best coding scheme. The lower numbers (CS-1/MCS-1) have the most error coding and are very |
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| 18 | resiliant but have little throughput. MCS-9 has no error correction coding at all, but t |
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| 19 | |||
| 20 | 1 | laforge | === GPRS channel coding === |
| 21 | |||
| 22 | Each of the 8 GSM time-slots can operate i a number of different coding schemes: |
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| 23 | |||
| 24 | ||Coding Scheme||kbit/s|| |
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| 25 | ||CS-1||8.0|| |
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| 26 | ||CS-2||12.0|| |
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| 27 | ||CS-3||14.4|| |
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| 28 | ||CS-4||20.0|| |
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| 29 | |||
| 30 | === EDGE channel coding === |
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| 31 | |||
| 32 | Each of the 8 GSM time-slots can operate i a number of different coding schemes: |
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| 33 | |||
| 34 | ||Coding Scheme||kbit/s|| |
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| 35 | ||MCS-1||8.80|| |
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| 36 | ||MCS-2||11.20|| |
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| 37 | ||MCS-3||14.80|| |
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| 38 | ||MCS-4||17.60|| |
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| 39 | ||MCS-5||22.40|| |
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| 40 | ||MCS-6||29.60|| |
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| 41 | ||MCS-7||44.80|| |
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| 42 | ||MCS-8||54.54|| |
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| 43 | ||MCS-9||59.20|| |
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| 44 | |||
| 45 | == multi-slot capabilities == |
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| 46 | |||
| 47 | 2 | laforge | |
| 48 | === BTS side === |
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| 49 | 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). |
| 50 | |||
| 51 | For example, a total of 7 time-slots in MCS-9 coding scheme would render |
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| 52 | 59.20 kbps * 7 = 414.40 kbps |
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| 53 | |||
| 54 | 2 | laforge | === MS side === |
| 55 | 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'' |
| 56 | |||
| 57 | 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]. |
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| 58 | 2 | laforge | |
| 59 | 3 | laforge | === multi-slot class 10 === |
| 60 | 2 | laforge | 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). |
| 61 | Under ideal radio conditions (MCS-9), such a phone can thus reach the following two bit-rates: |
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| 62 | ||Coding Scheme||multislot||downlink||uplink|| |
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| 63 | ||MCS-9||4+1||236.80||59.20|| |
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| 64 | ||MCS-9||4+2||177.60||118.40|| |
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| 65 | 3 | laforge | |
| 66 | === multi-slot class 32 === |
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| 67 | ||Coding Scheme||multislot||downlink||uplink|| |
