1. 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, 24-25 July 2014) Martin Brand Vice Chair ITU-T Study Group 11 Joachim Pomy Consultant@joachimpomy.de OPTICOM, Germany

2. 2 Speech path delay of VoLTE Networks

3. 3 LTE UL/DL one way delay RAN

4. 4 Latency of different technologies

5. 5 Typical Implementation GBR Uplink / downlink

6. 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 126 976 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 2 + 30 ms) = 71,24 UE DL: 20 ms(JB)+43,6 ms (13,6ms - Note 2 + 30 ms )= 63,6 The LTE scheduling is between 10 ms [i.32] and 30 ms depending of the scheduler implementation. NOTE 2According to TR 126 976 [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. 7 U-plane latency analysis (estimated average in downlink) according TR 125 912 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. 8 U-plane latency analysis (estimated average in uplink) according TR 125 912 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.

9. 9 Any questions ? Contact: Consultant@joachimpomy.de