GPRS bitrates » History » Revision 3
Revision 2 (laforge, 02/19/2016 10:47 PM) → Revision 3/5 (laforge, 02/19/2016 10:47 PM)
[[PageOutline]] = 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 [https://secure.wikimedia.org/wikipedia/en/wiki/GPRS#Multislot_Class 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||
