Transcript Scenarios for (Video) Streaming in Mobile Networks

Video Streaming over UMTS:
practical issues
Stefan Rugel, Klaus Schäfer
February 2008
Confidential
Slide 1
12/10/2006
Agenda
1. Scenarios for video streaming in mobile networks
2. Influences on Video Streaming Quality
Confidential
Slide 2
12/10/2006
•
Problems
•
Summary
Scenarios for (Video) Streaming in Mobile Networks
Mobile Operator & Partner
Internet
Increasing
Bandwidth
Mobile
Network
More
streaming
content
Increasing
Streaming
Capability
mobile content, e.g
videos:
pay per video
Confidential
Slide 3
12/10/2006
mobile content: pay
per byte
Scenarios for (Video) Streaming in Mobile Networks
Mobile Devices:
•
Dedicated mobile content provided by network operators, partners and
independent mobile web sites. Content adapted to SW-platform, display
and bandwidth.
•
Growing streaming capability of handsets (display, UMTS, software)
•
Mobile Internet: Limitations due to bandwidth and software
interoperability.
Notebooks with wireless access:
•
Fixed-internet user experience limited by bandwidth.
Confidential
Slide 4
12/10/2006
Scenarios: Some types of Video Streaming
Player
Availability on
Mobile Devices
Streaming Features
Session
Control /
Transport
.flv
Adobe Flash
Player
Restricted
Progressive Download,
Restricted Media Control
HTTP / TCP
.wmv
Windows
Media Player
Restricted
Constant Bitrate,
Bandwidth Adaption
Media Control
RTSP / TCP
.3gp
Real Player
Available
File
Format
.rm
Real Player
Available
Contstant Bitrate,
Media Control
Constant Bitrate,
Bandwidth Adaption,
Media Control
RTSP /
RTP(UDP)
RTSP / RTP
(UDP)
Without bandwidth constraints, progressive download
is the best choice (simple, cheap) => todays internet
dominated by Flash.
Confidential
Slide 5
12/10/2006
Scenarios: Video Streaming Bandwidth
Mbit/s
UMTS bearer (384 kbit/s) too
low for open internet
streaming.
1
Quality
Improvement?
HSDPA
0.5
384kbit/s
UMTS Bearer
Open Internet
Mobile Content
Confidential
Slide 6
0.1
12/10/2006
No changes by codec
improvement
Influences on Video Streaming Quality
Application (Player)
Flash, Real, Windows Media, iPhone...
Codec / Compression
Session Control
Media Transport
Transport
MPEG4, H.264, DivX...
HTTP / RTSP
RTP (RTCP)
TCP / UDP
IP
Network
Device
Interface
PDCP
RLC
MAC
L1
Relay
PDCP GTP-U
RLC
UDP/IP
MAC
L2
L1
L1
Relay
GTP-U GTP-U
UDP/IP UDP/IP
L2
L2
L1
L1
GTP-U
UDP/IP
L2
L1
MS
UTRAN
SGSN
GGSN
Uu (wireless If)
Iu PS
Gn
IP
IP
IP
IP
IP
L2
L1
L2
L1
L2
L1
L2
L1
L2
L1
Proxies
Firewall
Gi
Server
Internet
Streaming Quality depends on many factors
wireless If:
Quality limit regarding Bitrate, jitter / packet loss
Proxies:
Adapts content presentation to capabilities of mobile device, may improve protocol dynamics with regard to
wireless access conditions.
Firewall:
May block RTP streams.
Mobile Device:
Quality of implementation is crucial for video quality. May compensate shortcomings of wireless access.
Server:
Special care with encoding and compression in order to meet conditions at wireless interface.
Confidential
Slide 7
12/10/2006
Measuring of User perceived quality
Test Equipment
Network Traces, DPI
Network wide Overview on
Quality, network centric
Quality view.
Customer
Experience
Use Case Statistics
only spot
checks
expensive
Confidential
Slide 8
12/10/2006
Measuring of User perceived quality (Core Network)
•
Quality Statistics: RTCP Receiver Report (Packet Loss, Jitter).
•
TCP Analysis
•
Bandwidth measurement
•
Open Internet: Statistic on Protocols used
•
RTSP (Flash): User Behaviour statistics
•
Open Internet: how many sessions do not get enough bandwidth?
Confidential
Slide 9
12/10/2006
Measuring of User perceived quality
TCP graph core network of open internet streaming
(windows media player) with UMTS bearer.
Stream bitrate > throughput capacity
low (no) quality
Automatisation & Statistics !
Receiver
Window
transmitted
bytes to
mobile
Acked
bytes by
mobile
Confidential
Slide 10
12/10/2006
Slope: 384kbit/s
Quality Model
Key Frame
Delta Frames
Application
Minimum Key Frame Period
RLC
Not visible
Visible, if Key Frame Frequency < 25 Hz
•
High minimum key frame rate: lower video quality at given bitrate
•
Low minimum key frame rate: RLC packet loss impacts video quality
•
Influence RLC mode, TCP / UDP transport?
Optimum key frame rate parameter (MTU size) often determined experimentally.
Confidential
Slide 11
12/10/2006
Capacity and Video Streaming Quality
•
Currently no issue: enough reserve.
•
Dimensioning rules?
•
Benefit of QoS?
Confidential
Slide 12
12/10/2006
QoS and Protocols: How long do we need RTSP/RTP
Benefit of UDP, Effect of TCP
Streaming Quality at capacity limit with TCP/UDP traffic mix
Confidential
Slide 13
12/10/2006
Video Streaming in Mobile Networks: Main Issues
•
Good Video Streaming Performance in UMTS networks with dedicated
mobile content.
•
Open internet streaming only partly successful, improvements with
HSDPA expected (will mobile networks keep up with fixed internet
access then?)
•
Quality of Service needed in higher loaded networks? Will RTSP/RTP
survive?
•
Definitions/Algorythms for network KPIs for end user streaming quality?
Confidential
Slide 14
12/10/2006
Thank you.
Confidential
Slide 15
12/10/2006