Test loop mode 1 and 2 being used in RLC and MAC.docx

Test loop mode 1 and 2 being used in RLC and MAC Senthil Kumar Last Updated: 16/0 9/2007 The Test loop mode feature in UMTS Layer 2 is class ified into Test loop mode 1, Test loop mode 2. Test loop mode 1 The test loop mode 1 can be applied on the PDCP module, if the radio bearer setup includes configuration of PDCP protocol layer.Then every PDCP SDU received by the UE on the downlink active radio bearer shall be taken from the output of the PDCP service access point (SAP) and be input to t he corresponding PDCP SAP and transmitted uplink.Normally, when loopback is not configured it is sent to the higher layers. If UE test mode 1 has been selected and radio bearer setup does not include configuration of PDCP protocol layer ,then the loop back will be for RLC SDUs. The RLC SDUs received in the downlink will not be sent to the upper layers,but instead data block received by the UE on the downlink active radio bearer shall be taken from t he output of the RLC service access point (SAP) and be inpu t to the corresponding RLC SAP and transmitted uplink. Here four scenarios are possible For the case when the "UL RLC SDU size" parameter is set to "0" no data shall be returned. For the case when the "UL RLC SDU size" parameter is set to the same value as the down link (DL) RLC SDU block size then the complete user data block shall be returned. For the case when the "UL RLC SDU size" parameter is set to a value less than the down link (DL) RLC SDU block size then the UE shall return the first K bits of the received block, where K is the UL block size. For the case when the "UL RLC SDU size" parameter is set to a value bigger than the down link (DL) RLC SDU block size then the UE shall pad the UL send block by repeating the received data block until the UL send block has been filled (truncating the last block if necessary) Use of Test loop mode 1 Measurement of Bit Error Rate(BER),a receiver characteristics can be carried out in test loop mode 1 in RLC TM. BER is calculated by the System Simulator (SS) in RLC Transparent mode by checking the downlink bits that is looped back in the uplink direction.Here in this case, UL and DL transport block size should be same. Another receiver characteristic, Block Error Rat e(BLER) can be measured using UE test loop

Test loop mode 1 and 2 being used in RLC and MAC.docx

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