Low Latancy in HSPA

> The Importance of Low Latency in HSPA

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Introduction

PacketCore







Why learn about HSPA latency?

› HSPA leading Mobile

Broadband technology

› Latency largely influences

consumer’s service

perception

› Ericsson has industry-

leading latency

performance







Objective and Scope

› Show the importance of low latency in HSPA networks and Ericsson’s leading position

Objectives

Scope

› Explain what latency is

› Describe advantages of low latency

› Give results from Ericsson networks







AGENDA

› What is latency?

› Advantages of low latency

› Latency in HSPA networks

› How to measure latency

› Latency in Ericsson

networks

› Summary

PacketCore







What is Latency?

PacketCore







What is latency?

› Round-trip latency:

–One-way delay from source to

destination + one-way delay from the

destination back to the source

› Good indicator of network quality

› Measured with “ping” instruction

PacketCore

Source: Wikipedia







Advantages of low latency

PacketCore







Advantage of low latency

› E-mail

› File download

› Web browsing







E-MAIL

Client Server

Mail and attachment

Total time to download mail

Handshake signaling part

Download part







File Download (FTP)

› Latency drives increase of

download speed

› Bit rate is gradually

increased to top speed

› Lower latency increases the

acceleration of bit rate

SYN

SYN,ACK

Data, ACK

ACK

Data







Web page download

Client Server

”File download part”

”Signalingpart”







Latency in HSPA Networks

PacketCore








RBSRNCSGSNGGSN

UuIubIu_PS

Iu_PS

Direct Tunnel

Internet








Latency dependent on UL type:› HSPA UL (2 ms TTI)– Typical 5.8 Mbps UL

› HSPA UL (10 ms TTI)– Typical 1.4 Mbps UL

› R99 UL– Typical 384 kbps

UserdeviceCore Network/

Service Network

Radio Access Network

RadioInterface

Typical latency distribution







How to Measure Latency?

PacketCore







PING COMMAND

› Examples:ping www.ericsson.seping 213.132.96.193 –t (press ctrl-C to stop)ping 213.132.96.193 –n 10 (do 10 ping measurements)

Detailed presentation: link







HSPA state machine - Goal: Find Latency of dedicated channel

URA-PCHURA-PCH

HSPA(Dedicated)

HSPA(Dedicated)

FACH(common)

FACH(common)

IdleIdle

Idle to DCHdelay

FACH latencyis much longer

Goal:HSPA latency

› Different operators have different settings› Speedtest sites often measure latency incorrectly







Latency in Ericsson networks

PacketCore







Good latency measurementOn dedicated channel

› “Short ping” result performed on commercial network







HSPA latency

Operator Region UL type* Latency1 Europe 2 ms TTI 22 ms

2 Europe 2 ms TTI 28 ms




5 Asia 10 ms TTI 40 ms

6 Asia 10 ms TTI 42 ms






11 Americas 10 ms TTI 65 ms

12 Europe R99 61 ms

13 Asia R99 63 ms

5 Asia R99 70 ms

6 Asia R99 70 ms

› Measurement results from 13 Ericsson networks

* UL type: Combination of specified network and device capability (not verified during measurement).







Competitor benchmark

Latency(12 Byte payload)

<half the latency

Ericsson 41ms

Competitor 97ms

› Latency measurements performed in Japan







Competitor benchmark

› User experience in commercial networks in Japan

Ericsson HSPA

Vendor B HSPA

Latency (ping) [ms]

12 Byte 41 97

Web page download time [s]

small page 1.3 2.3

large page 12 25

File down/upload time [s]

1MB 2.6 / 3.2 4.4 / 5.9

10MB 21 / 28 37 / 54

HSPA: 7.2/5.8 Mbps device







> QUIZ







Quiz

› Which three of the following processes are included in the

result of a good latency measurement in HSPA?– The time it takes for a connection to go to dedicated channel mode

– The time it takes for a message to travel from the end-user device

to a server on the internet

– The time it takes for the network to move back to idle mode

– The time it takes in a device to process an incoming ping response

– The time it takes for a server to process an incoming ping message

and send a response

– The time it takes to send a message via the FACH channel







Quiz

› Which three of the following processes are included in the

result of a good latency measurement in HSPA?– The time it takes for a connection to go to dedicated channel mode

– The time it takes for a message to travel from the end-user device

to a server on the internet

– The time it takes for the network to move back to idle mode

– The time it takes in a device to process an incoming ping response

– The time it takes for a server to process an incoming ping message

and send a ping response message

– The time it takes to send a message via the FACH channel







Summary

PacketCore







Summary

› Latency: Time for message to travel from

end-user device to server on internet and

back

› Latency largely influences end-user

perceived performance and experience

› Low latency is important for basically all

applications

› Ericsson has industry-leading latency

PacketCore

Low Latancy in HSPA

Documents

incoming ping response

good latency measurement

dedicated channel mode

incoming ping message

file download

fach channel

idle mode

low latency