Decision
Adding an additional chapter to the TR-532 document, which is proposing (but not prescribing) a method for calculating the current air interface capacity from the status attributes of the microwave information model.
Proposing to calculate the air interface capacity = AirInterface::AirInterfaceStatus::transmissionModeCur->TransmissionModeType::channelBandwidth / AirInterface::AirInterfaceStatus::transmissionModeCur->TransmissionModeType::symbolRateReductionFactor * log2( AirInterface::AirInterfaceStatus::transmissionModeCur->TransmissionModeType::modulationScheme) * AirInterface::AirInterfaceStatus::transmissionModeCur->TransmissionModeType::codeRate / 1.15
Explaining the AirInterface::AirInterfaceStatus::transmissionModeCur->TransmissionModeType::symbolRateReductionFactor to express a reduced symbol rate e.g. symbolRateReductionFactor = 4 for ¼ BPSK or symbolRateReductionFactor = 2 for ½ BPSK.
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Adding a calculation prescription into the comments of the AirInterface::AirInterfaceStatus::codeRateCur attribute
Prescribing to calculate the AirInterface::AirInterfaceStatus::codeRateCur = number of symbols carrying payload information / number of transmitted symbols
Prescribing to calculate the number of symbols carrying payload information = number of transmitted symbols - (number of symbols carrying overhead information + number of redundant symbols for forward error correction)
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Ignoring the request for advice for calculating the capacity of different link configurations (example: 1+1HSB), because link configuration does not impact air interface capacity
Background
Content of the Mantis Bugtracker
| Description | The capacity calculation of an airInterface is described in an email but should be part of ONF-TR-532. In addition the algorythm for calculation of AirInterface::AirInterfaceStatus::codeRateCur should be added to this attribute, so that every vendor calculate the code-rate the same way. Not sure, whether a reference implemenation in Centennial will help. How to calculate the structure capacity in case of - 1:1 between Structure and AirInterface - XPIC - MEMO - Diversity - 1+1 HSB | ||||
| Additional Information | […] txCapacity = AirInterface::AirInterfaceConfiguration::txChannelBandwidth * log2(AirInterface::AirInterfaceStatus::modulationCur) * AirInterface::AirInterfaceStatus::informationRateCur / 1,15 ; https://login.opennetworking.org/bin/c5i?mid=6&rid=49&k1=36&k2=1882&tid=1489367352 [^] AirInterface::AirInterfaceStatus::informationRateCur should be replaced by AirInterface::AirInterfaceStatus::codeRateCur according to 161215_TR-532_MW_IM_v1_0.02 […] | ||||
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1 Comment
Petr Jurcik
Minor comment: bits can be used instead fo symbols, Number of bits mapped on the symbol depends on the modulation level (16QAM = 4 bits per symbol), Redundant bits are added to the useful (data) bits and then mapped on symbols - code rate = number of bits carrying useful (payload) data / total number of bits