GPRS bitrates » History » Version 5
fixeria, 07/16/2019 09:39 AM
1 | 1 | laforge | h1. GPRS and EDGE bit-rates |
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2 | 4 | laforge | |
3 | 5 | fixeria | {{>toc}} |
4 | 4 | laforge | |
5 | 1 | laforge | This page tries to outline the possible achievable GPRS bit-rates. |
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7 | There are multiple aspects that relate to the problem |
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8 | 4 | laforge | * channel coding, which in turn depends on |
9 | ** capabilities of the BTS and MS |
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10 | ** performance of the radio channel |
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11 | * multi-slot operation, which depends on |
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12 | ** capabilities of the BTS and MS |
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13 | ** contention on the radio channel / resource sharing by multiple phones |
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14 | 1 | laforge | |
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16 | 4 | laforge | h2. channel coding |
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19 | 3 | laforge | Depending on the characteristics of the radio channel (interference, bit errors, link quality, C/I), the network will |
20 | 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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21 | resiliant but have little throughput. MCS-9 has no error correction coding at all, but t |
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24 | 4 | laforge | h3. GPRS channel coding |
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27 | 1 | laforge | Each of the 8 GSM time-slots can operate i a number of different coding schemes: |
28 | |||
29 | ||Coding Scheme||kbit/s|| |
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30 | ||CS-1||8.0|| |
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31 | ||CS-2||12.0|| |
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32 | ||CS-3||14.4|| |
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33 | ||CS-4||20.0|| |
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36 | 4 | laforge | h3. EDGE channel coding |
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39 | 1 | laforge | Each of the 8 GSM time-slots can operate i a number of different coding schemes: |
40 | |||
41 | ||Coding Scheme||kbit/s|| |
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42 | ||MCS-1||8.80|| |
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43 | ||MCS-2||11.20|| |
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44 | ||MCS-3||14.80|| |
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45 | ||MCS-4||17.60|| |
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46 | ||MCS-5||22.40|| |
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47 | ||MCS-6||29.60|| |
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48 | ||MCS-7||44.80|| |
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49 | ||MCS-8||54.54|| |
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50 | ||MCS-9||59.20|| |
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53 | 4 | laforge | h2. multi-slot capabilities |
54 | 1 | laforge | |
55 | 4 | laforge | |
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58 | h3. BTS side |
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60 | 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). |
61 | 2 | laforge | |
62 | For example, a total of 7 time-slots in MCS-9 coding scheme would render |
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63 | 1 | laforge | 59.20 kbps * 7 = 414.40 kbps |
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66 | 4 | laforge | h3. MS side |
67 | 1 | laforge | |
68 | 4 | 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_ |
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70 | For a table of multislot classes, please see 3GPP TS 45.002, or a summarized version at "wikipedia":https://secure.wikimedia.org/wikipedia/en/wiki/GPRS#Multislot_Class. |
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73 | h3. multi-slot class 10 |
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75 | 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). |
76 | 3 | laforge | Under ideal radio conditions (MCS-9), such a phone can thus reach the following two bit-rates: |
77 | 2 | laforge | ||Coding Scheme||multislot||downlink||uplink|| |
78 | ||MCS-9||4+1||236.80||59.20|| |
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79 | ||MCS-9||4+2||177.60||118.40|| |
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81 | 4 | laforge | |
82 | h3. multi-slot class 32 |
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84 | 3 | laforge | ||Coding Scheme||multislot||downlink||uplink|| |