1 One-way Delays in Operating LTE Networks ITU Workshop on “Monitoring and Benchmarking of QoS and QoE of Multimedia Services in Mobile Networks” (Buenos Aires, Argentina, July 2014) Martin Brand Vice Chair ITU-T Study Group 11 Joachim Pomy OPTICOM, Germany

2 Speech path delay of VoLTE Networks

3 LTE UL/DL one way delay RAN

4 Latency of different technologies

5 Typical Implementation GBR Uplink / downlink

6 One way delay for LTE LTEUE Delay between P-GW and the eNB+ S1-U Transfer DelaySUM Sending Packet size 20 ms 71 (note 1) 21 ms (notes 3 and 4)92 Receiving 40 ms de-jitter Buffer Packet size 20 ms 64 (note 1) 12 ms (notes 3 and 4)76 According TR for AMR and AMR/WB T sample = 25 ms (duration of the 20 ms speech frame and 5 ms look ahead). NOTE 1:UE UL: 20 ms (Codec)+5ms (look ahead)+ 46,24 ms (16,24 ms - Note ms) = 71,24 UE DL: 20 ms(JB)+43,6 ms (13,6ms - Note ms )= 63,6 The LTE scheduling is between 10 ms [i.32] and 30 ms depending of the scheduler implementation. NOTE 2According to TR [i.38]. NOTE 3:Measured values at ETSI, CISCO, Ericsson and TeliaSonera premises [i.33] to [i.36]. NOTE 4:The delay budget was measured in production environments, The S1-U delay is bandwith depended.

7 U-plane latency analysis (estimated average in downlink) according TR and S1-U Transfer Delay StepDescriptionValue (30 % HARQ) 1eNB Processing Delay (S1-U->Uu)1 ms 2Frame Alignment1,022 ms 3TTI for DL DATA PACKET0,675 ms 4HARQ Retransmission0,3 * 5 ms 5UE Processing Delay1 ms 6S1-U Transfer Delay and aGW7 ms (Note) Total one way delay12,2 ms NOTE:The delay budget was measured in production environments, The S1-U delay is bandwith depended.

8 U-plane latency analysis (estimated average in uplink) according TR and S1-U Transfer Delay Step DescriptionValue (30 % HARQ) 0UE wakeup timeImplementation dependent - Not included 1UE Processing Delay1 ms 2Frame Alignment1,423 ms 3TTI for UL DATA PACKET (Piggy back scheduling information)0,675 ms 4HARQ Retransmission0,3 * 5 ms 5eNB Processing Delay (Uu -> S1-U)1 ms 6S1-U Transfer Delay and aGW15 ms (Note) Total one way delay20,6 ms NOTE:The delay budget was measured in production environments, The S1-U delay is bandwith depended.

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