Content for TR 36.881 Word version: 14.0.0
2 References
3 Definitions, symbols and abbreviations
4 Study Objectives
5 Overview of LTE latency
6 Scenarios, Applications and Use Cases
7 Evaluation Structure and Assumptions
8 Solutions for latency reduction
9 Performance Evaluation
10 Conclusion
A Simulation assumptions
B System evaluation results
C Link-level evaluation results
$ Change History
2 References
3 Definitions, symbols and abbreviations Word‑p. 7
4 Study Objectives
5 Overview of LTE latency
5.1 Delay components
5.2 Current performance Word‑p. 12
5.3 Existing means to limit latency Word‑p. 14
6 Scenarios, Applications and Use Cases
7 Evaluation Structure and Assumptions Word‑p. 15
8 Solutions for latency reduction
8.1 Semi-Persistent Scheduling
8.2 UL Grant reception
8.3 Handover Latency Word‑p. 16
8.3.1 Solution 1: RACH-less handover
8.3.2 Solution 2: Maintaining Source eNB Connection during Handover Word‑p. 17
8.4 Contention based PUSCH transmission Word‑p. 18
8.5 Reduced TTI and processing time Word‑p. 19
9 Performance Evaluation Word‑p. 20
9.1 Protocol evaluations on TTI reduction and Fast UL
9.1.1 Simulation 1: TCP slow-start behavior for FTP file download based on reduced TTI and reduced SR periodicity [4] Word‑p. 21
9.1.2 Simulation 2: Capacity and throughput gain with 0.5ms TTI [5] Word‑p. 24
9.1.3 Simulation 3: Throughput and packet download time with reduced latency in LTE [3] Word‑p. 26
9.1.4 Simulation 4: Latency evaluation results for TTI reduction and Fast UL [6] Word‑p. 27
9.1.4.1 Simulation assumptions
9.1.4.2 TTI shortening simulations Word‑p. 28
9.1.4.3 Fast UL system simulations Word‑p. 30
9.1.5 Simulation 5: System Performance with TTI shortening [6] Word‑p. 34
9.1.5.1 General information
9.1.5.2 Simulation assumptions and parameters Word‑p. 35
9.1.5.3 Performance results
9.1.5.3.1 Various backhaul latency
9.1.5.3.2 Various FTP file size Word‑p. 37
9.1.5.3.3 Various Uu throughput Word‑p. 39
9.1.5.3.4 Fast UL access Word‑p. 42
9.1.6 Simulation 6: Evaluation results for TTI reduction [6] Word‑p. 44
9.1.7 Simulation 7: Performance evaluation of latency reduction enhancements [6] Word‑p. 46
9.1.7.1 Simulation setup
9.1.7.2 Simulated schemes Word‑p. 47
9.1.7.3 Simulation results for shorter TTI Word‑p. 48
9.1.7.4 Simulation results for Fast UL grant with shorter TTI Word‑p. 50
9.1.8 Simulation 8: TTI reduction gain with additional L1/L2 overhead [6] Word‑p. 52
9.1.9 Simulation 9: Effect of UE and eNB processing times on TCP performance [6] Word‑p. 54
9.1.10 Simulation 10: System Performance Gain with TTI reduction [6] Word‑p. 58
9.1.10.1 Faster UE Feedback and Rate Control
9.1.10.2 Simulation Assumptions: Word‑p. 59
9.1.10.3 Simulation Results
9.1.11 Simulation 11: TTI reduction gain with additional L2 overhead [9] Word‑p. 60
9.1.12 Simulation 12: TTI reduction gain with additional L2 overhead [10] Word‑p. 61
9.2 Protocol evaluations on Contention based PUSCH transmission Word‑p. 64
9.2.1 Evaluation 1 on solution 1 [16]
9.2.2 Evaluation on solution 2 [17] Word‑p. 66
9.2.2.1 Resource efficiency analysis on current solutions
9.2.2.2 Uplink latency Word‑p. 67
9.2.2.3 Resource efficiency Word‑p. 69
9.2.3 Evaluation 2 on solution 1 [18] Word‑p. 70
9.3 Handover latency [11] Word‑p. 74
9.4 Findings from system evaluations on TTI reduction and reduced processing time
9.5 Findings from link evaluations on TTI reduction and reduced processing time Word‑p. 76
10 Conclusion
A Simulation assumptions Word‑p. 79
A.1 Protocol Simulations
A.1.1 Simulation 1 [4]
A.1.2 Simulation 2 [5] Word‑p. 81
A.1.3 Simulation 4 [6] Word‑p. 82
A.1.4 Simulation 9 [6] Word‑p. 83
A.1.5 Simulation 5 [6] Word‑p. 85
A.1.6 Simulation 11 [9] Word‑p. 87
A.1.7 Simulation on contention based PUSCH transmission Word‑p. 90
A.2 System simulation assumptions for reduced TTI and processing delay Word‑p. 92
A.2.1 Evaluation assumption for TDD Word‑p. 93
A.3 Link level simulation assumptions Word‑p. 95
B System evaluation results Word‑p. 98
C Link-level evaluation results
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