VoLTE*: A Lightweight Voice Solution to 4G LTE Networks Guan-Hua Tu - - PowerPoint PPT Presentation

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VoLTE*: A Lightweight Voice Solution to 4G LTE Networks Guan-Hua Tu - - PowerPoint PPT Presentation

Jan 02, 2023 331 likes •665 views

VoLTE*: A Lightweight Voice Solution to 4G LTE Networks Guan-Hua Tu 1 , Chi-Yu Li 1 , Chunyi Peng 2 , Zengwen Yuan 1 , Yuanjie Li 1 , Xiaohu Zhao 2 , Songwu Lu 1 1 University of California, Los Angeles 2 The Ohio State University HotMobile16

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SLIDE 1

VoLTE*: A Lightweight Voice Solution to 4G LTE Networks

Guan-Hua Tu1, Chi-Yu Li1, Chunyi Peng2, Zengwen Yuan1, Yuanjie Li1, Xiaohu Zhao2, Songwu Lu1

1University of California, Los Angeles 2The Ohio State University

HotMobile’16

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SLIDE 2

Voice: Essential Cellular Service

§ 30+ years (from 1G to 4G) § Full coverage:

¨ All carriers ¨ Almost all users 2 Chunyi Peng HotMobile'16

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SLIDE 3

Voice Evolution in 4G LTE

§ 4G LTE: packet-switched (PS) only

¨ Traditional voice: circuit-switched (CS) for carrier-

grade quality

Chunyi Peng HotMobile'16 3

Internet

PS Domain 4G Gateway

circuit

Telephony Network

CS Gateways

3G/2G CS Domain

circuit circuit

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SLIDE 4

Voice Evolution in 4G LTE

§ 4G LTE: packet-switched (PS) only

¨ Traditional voice: circuit-switched (CS) for carrier-

grade quality

Chunyi Peng HotMobile'16 4

Internet

PS Domain 4G Gateway Telephony Network

?

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SLIDE 5

VoLTE: Voice over LTE

§ Standard solution (cellular carrier industry) § Carry voice in packets (aka. VoIP)

Chunyi Peng HotMobile'16 5

Internet

PS Domain 4G Gateway Telephony Network IMS Core Media Gateway Signaling Server

Data Packet Flow VoLTE Signaling Flow VoLTE Voice Flow

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SLIDE 6

The Good

§ Successor of cellular voice for LTE users

¨ Comparable carrier-grade quality

§ Enable rich communication

¨ Voice/video calls, video conferencing, HD voice … Chunyi Peng HotMobile'16 6

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SLIDE 7

But, The Ugly

§ Deployment pain

¨ 20 out of 480 LTE carriers support VoLTE (Oct 2015) ¨ Delayed rollout until late 2014 in US carriers (AT&T, Verizon, T-

Mobile)

  • No nationwide deployment yet

§ IP Multimedia Subsystem (IMS): complex and costly

¨ Proposed in 2002 ¨ Little progress

until VoLTE

Chunyi Peng HotMobile'16 7

IMS Core Media Gateway Signaling Server

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SLIDE 8

Alternative to VoLTE

§ VoIP: on-the-top (OTT) mobile data app

¨ Hangouts, Skype, Line, Viber, Whatsapp, …

§ Pros: low cost (Carriers), OTT benefits § Cons (concerns): quality?

Chunyi Peng HotMobile'16 8

4G Gateway PS Domain VoIP Service

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SLIDE 9

Q1: VoLTE or no VoLTE? Q2: Alternative lightweight and cost- effective solution?

Chunyi Peng HotMobile'16 9

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SLIDE 10

VoLTE or No VoLTE?

Comparison VoLTE and VoIP over 4G LTE

§ Deployment cost § Operation complexity § Voice quality

Chunyi Peng HotMobile'16 10

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SLIDE 11

Deployment and Operation

VoLTE

  • Deploy IMS
  • Upgrade 4G infrastructure

¨ BS, PS gateways, and OAM

(Operation, Administration, management) subsystem

¨ Upgrade firmware/OS of

mobile devices to support carrier-specific VoLTE

VoIP over 4G LTE

+ No new deployment/upgrade

¨ Reuse 4G PS infrastructure ¨ Reuse VoIP service provider’s

infrastructure

¨ Existing Cellular – VoIP

translation

¨ No upgrade on mobile devices

  • Concerns
  • Quality?
  • Compatibility with legacy voice

Chunyi Peng HotMobile'16 11

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SLIDE 12

Voice Call Quality

§ Small-scale assessment

¨ 10 static locations, 20 routes, 50 participants ¨ VoIP: Google Hangouts

§ Call setup time § Voice call quality (subjective) § Call drop rate

Chunyi Peng HotMobile'16 12

Note: VoLTE at early deployment (12/2014 – 02/2015)

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SLIDE 13

Call Setup time

§ Comparable performance except VoIP-CS case

¨ Caller-to-Callee: V-to-V, V-to-C, H-to-H, H-to-C ¨ V: VoLTE; C: CS; H: Hangout

§ Takeaway: enhance VoIP-CS call support

Chunyi Peng HotMobile'16 13

Signal strength is week (<-115dbm) Signal strength is strong (>-90dbm)

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SLIDE 14

Voice Call Quality

§ Record calls and offline listening

¨ ITU standard metrics: ACR (Absolute Category Rating) and

CCR (Category Rating Comparison) § Comparable voice quality (VoLTE win: congestion & CS)

Chunyi Peng HotMobile'16 14

ACR: Absolute Category Rating CCR: Category Rating Comparison

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SLIDE 15

Call Drop Rate

§ Comparable in static and most mobility § VoLTE (4G-2G/3G): even worse (implementation issues on SRVCC) [mobicom’15]

Chunyi Peng HotMobile'16 15

[mobicom’15] Yunhan Jia, et.al, Performance Characterization and Call Reliability Problem Diagnosis for Voice over LTE

Scenarios VoLTE Hangout Static (strong/weak coverage) 0% 0% Mobility (4G only, strongà weak) 0% 0.5% Mobility (4G à2G/3G) 8% 4%

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SLIDE 16

VoLTE’s Advantage: High QoS Bearer

Chunyi Peng HotMobile'16 16

Internet

4G Gateway PS Domain IMS Core Media Gateway Signaling Server 4G Gateway PS Domain VoIP Service

VoLTE VoIP

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SLIDE 17

Chunyi Peng HotMobile'16 17

VoLTE’s Advantage: High QoS Bearer

Delivery Priority VoLTE Voice Bearer Guaranteed-Bit-Rate 2 VoLTE Signaling Bearer Best Effort 1 (highest) Data Service Bearer Best Effort 6-9

4G Gateway

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SLIDE 18

VoLTE*: Alternative Solution?

Chunyi Peng HotMobile'16 18

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SLIDE 19

VoLTE*: A Lightweight Voice Solution

§ Both good of VoIP and VoLTE

¨ VoIP-centric: low cost on deployment and operation ¨ High QoS bearer: call quality Chunyi Peng HotMobile'16 19

4G Gateway PS Domain VoIP Service High-QoS bearer

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SLIDE 20

VoLTE*: Voice Service Classes

§ Apply different QoS profiles to VoIP packets in 4G LTE

Chunyi Peng HotMobile'16 20

Service Class Description First Use highest QoS; quality is similar to VoLTE Business Always better than the best-effort QoS profile Deluxe Economy Better than best-effort when needed (e.g., congestion occurs) Economy best-effort

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Modest Support

§ Device: specify QoS profiles (service classes) for VoIP packets § VoIP service providers: connect to the existing IPX used by carriers to ensure QoS § While congestion occurs,

¨ Upgrade QoS of VoIP packets if subscribing the plan (e.g.,

“Deluxe Economy” )

Chunyi Peng HotMobile'16 21

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SLIDE 22

VoLTE*: Benefit all Parties

§ Carriers: gain more revenue from priority voice service without deploying and operating IMS core § VoIP service providers: more daily active users – e.g., have more mobile ad. revenue § Users: better service with cheaper fare

Chunyi Peng HotMobile'16 22

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SLIDE 23

VoLTE* Evaluation in Crowded Areas

§ Hacking: VoLTE signaling bearer reused to carry VoIP traffic [ccs’15] § VoLTE*: congestion-resistant + lightweight

Chunyi Peng HotMobile'16 23

Uplink Downlink

[ccs’15] Chiyu Li, et.al Insecurity of Voice Solution VoLTE in LTE Mobile Networks

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SLIDE 24

Possible Downsides

§ Technical drawbacks (LTE Radio)

¨ No VoLTE-like energy-saving mechanism ¨ No VoLTE-like coverage enhance mechanism

§ Non-Technical drawbacks (business concerns)

¨ Carriers may not want to share customers with VoIP

service providers

¨ Carriers may not easily deploy new multimedia services Chunyi Peng HotMobile'16 24

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Summary

§ VoLTE*: Both good of VoIP and VoLTE

¨ VoIP: Easy deployment/upgrade and low cost ¨ VoLTE: call quality

§ VoLTE (vs. VoIP)

¨ Comparable or slightly better quality ¨ But, may not worth the efforts

§ Promises of VoLTE* deployment

¨ Room for VoLTE (not replacement) ¨ Roles of VoIP provider and cellular carriers

Chunyi Peng HotMobile'16 25

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SLIDE 26

Thank you! Questions?

Chunyi Peng HotMobile'16 26

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SLIDE 27

Open Issues in VoLTE*

§ Interplay of VoIP (external) and cellular CS domain

¨ API, translation

§ Migration from 4G to 2G

¨ Poor support for data (VoIP) in 2G

§ Voice billing (different QoS)

Chunyi Peng HotMobile'16 27

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SLIDE 28

Internet

4G Gateway PS Domain IMS Core Media Gateway Signaling Server

Data Packet Flow VoLTE Signaling Flow VoLTE Voice Flow

Chunyi Peng HotMobile'16 28

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SLIDE 29

VoLTE*: Four Service Classes

§ Apply different QoS profiles to VoIP packets in 4G LTE

29

Service Class

Description

First

Use highest QoS; quality is similar to VoLTE

Business

Always better than the best-effort QoS profile

Deluxe Economy

Better than best-effort when needed (e.g., congestion

  • ccurs)

Economy

best-effort

Chunyi Peng HotMobile'16

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SLIDE 30

VoLTE*: Only Requires Essential Support from Infrastructure

§ Allow devices to specify QoS profile for VoIP packets

¨ It is a operational policy issue not a technical problem

  • QoS negotiation is a mandatory procedure by standards

§ Allow VoIP service providers to connect to the existing IPX used by carriers in practice

¨ To ensure QoS

§ While congestion occurs,

¨ 4G infrastructure will upgrade QoS of VoIP packets if users

subscribe the service class “Deluxe Economy”

30 Chunyi Peng HotMobile'16

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SLIDE 31

VoLTE*: Benefit all Parties

§ Users have better service with cheaper fare § Carriers get more revenue from priority service without deploying and operating IMS core § VoIP service providers have more daily active users – e.g., have more mobile ad revenue

31

Charge (cent/min) T-Mobile AT&T Verizon Sprint Cellular Call 450 mins 6.7 8.9 7.8 6.7 900 mins 3.3 4.4 3.9 3.3 Hangouts 450/900 mins 1.2 1.2 0.6 0.9

(Surveyed on Sep. 2015)

Chunyi Peng HotMobile'16

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SLIDE 32

Evaluation of VoLTE* in Crowded Areas

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¨ Comparison of Jitter of normal VoIP and VoLTE*

(VoIP+ 4G Infrastructure-assisted)

Uplink Downlink

  • VoLTE* is a congestion-resistant voice service, similar to

VoLTE; but VoLTE* is lightweight and benefit all parities

Chunyi Peng HotMobile'16