Video Streaming over UMTS: practical issues

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Video Streaming over UMTS practical issues

• Stefan Rugel, Klaus Schäfer
• February 2008

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Agenda

• 1. Scenarios for video streaming in mobile
  networks
• 2. Influences on Video Streaming Quality
• Problems
• Summary

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Scenarios for (Video) Streaming in Mobile Networks
Mobile Operator Partner
Internet
Mobile
Internet
IncreasingBandwidth
Mobile Network
More streaming content
Increasing Streaming Capability
mobile content, e.g videos pay per video
mobile content pay per byte
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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.

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Scenarios Some types of Video Streaming
File Format 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 Contstant Bitrate, Media Control RTSP / RTP(UDP)
.rm Real Player Available Constant Bitrate,Bandwidth Adaption,Media Control RTSP / RTP (UDP)
Without bandwidth constraints, progressive
download is the best choice (simple, cheap) gt
todays internet dominated by Flash.
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Scenarios Video Streaming Bandwidth
Mbit/s
UMTS bearer (384 kbit/s) too low for open
internet streaming. No changes by codec
improvement
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Quality Improvement?
HSDPA
0.5
384kbit/s UMTS Bearer
Open Internet
Mobile Content
0.1
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Influences on Video Streaming Quality
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.
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Measuring of User perceived quality
Test Equipment
Network Traces, DPI
Network wide Overview on Quality, network centric
Quality view. Use Case Statistics
Customer Experience only spot checks expensive
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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?

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Measuring of User perceived quality

• TCP graph core network of open internet streaming
  (windows media player) with UMTS bearer.
• Stream bitrate gt throughput capacity
• low (no) quality
• Automatisation Statistics !

Receiver Window
Slope 384kbit/s
transmitted bytes to mobile
Acked bytes by mobile
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Quality Model

• 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.
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Capacity and Video Streaming Quality

• Currently no issue enough reserve.
• Dimensioning rules?
• Benefit of QoS?

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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

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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?

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Thank you.