1.1 Latency
1.1.1 Round Trip Time
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Name: Maximum round trip latency
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Purpose: To verify that Round Trip Time remains within acceptable range
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Measurement method
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Time stamp of “PING Response received by the
UE" - Time stamp of “PING Request sent by the UE
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Acceptable range
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Average
time less than 40 ms
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1.1.1.1
Test conditions and requirements
This
test is to measure round trip time (RTT) in given test network in stationary
conditions
Specifically
the procedure starts at transmission of PING Request by the UE and ends at the
reception of PING Response at the UE.
Radio
latency is round trip time between PDCP layer of UE and PDCP layer of eNB.
Single user per cell scenario is to be considered.
Radio
latency will be measured using ordinary ping.
As
shown in the figure below, end-to-end latency is the sum of radio latency and
core latency.
But
there can be some uncertainties in core latency because the backhaul delay and
delay induced in PDN are variable.
Core
latency shall be separately measured and radio latency is calculated by
end-to-end latency minus core latency.
Ÿ A vehicle for moving, a test UE, and a test laptop computer
connected with GPS and the UE are required.
Ÿ 2ms
backhaul delay between eNB and EPC is assumed.
Ÿ Assumes
UE processing time = 1ms. (one way)
Ÿ The network stability is certainly guaranteed.
1.1.1.2
Test description
1.
Locate the test UE at a predefined
place with good link condition.
2. The test point should be over the cell edge RF conditions. (RSRP: higher than -100dBm, SNR: higher than 5)
3.
Connect
the UE to eNB. (Initial attachment)
4.
Generate 32-bytes ping packet 100 times using DOS windows.
5.
Calculate the min, average and max value of Round
trip time.
6.
Average Round trip time is calculated using
measured data between 5th percentile and 95th percentile.
1.1.1.3 Pass/Fail Criteria
Ÿ The average round trip time shall be
less than 40ms. (median of 95% tile)
Appendix A – Acronyms
DM Diagnostic
Monitor
eNB E-UTRAN
NodeB
EPC Evolved
Packet Core
FTP File
Transfer Protocol
GBR Guaranteed Bit Rate
KPI Key
Performance Indicators
LTE Long
Term Evolution
MIMO Multiple Input Multiple Output
MME Mobility Management Entity
OCNS Other Cell Noise Simulator
PCRF Policy and Charging Rules Function
PDN Packet Data Network
P-GW PDN Gateway
QCI QoS Class Identifier
RRC Radio Resource Control
RSRP Reference Signal Received Power
S-GW Serving
Gateway
SIMO Single Input Multiple Output
SINR Signal to Interference and
Noise power Ratio
TCP Transmission
Control Protocol
UE User
Equipment
UDP User
Datagram Protocol
