Wireless IPTV issues Wireless IPTV issues and solutionsand solutions

Chen ZhifengChen Zhifeng

Electrical and Computer EngineeringElectrical and Computer Engineering

University of FloridaUniversity of Florida

OutlineOutline

• What is IPTV?• IPTV application and protocols• Wireless video technical considerations• Coding issues for wireless video and solutions • networking issues and solutions• 802.11g Connectivity issues and solutions• System considerations

What is IPTV? What is IPTV?

• Traditional TV distribution technologies: terrestrial, satellite and cable.--However, cable can be upgraded to two-way capability and can thus also carry IPTV.

• Two kinds of Internet Protocol Television: a) IPTV --supplied by a broadband operator using a closed network infrastructure -- need a massive connectivity infrastructure upgrade -- User experience is bound to their living rooms and set-top boxes. b) Internet Television--delivery of TV content over the public Internet --anyone can create an endpoint and publish that on a global basis.--the publisher has a direct communication channel to the consumer

IPTV application and protocolsIPTV application and protocols• live TV --real time

a) multicasting-- application layer : Client/Server mode-- network layer: Internet Group Management Protocol (IGMP) version 2--need support from multicast routerb) P2P--emulate an IP multicast tree at the application layer--no need support from multicast router

• Video on Demand --time shifted --use Real Time Streaming Protocol (RTSP) as the application layer--use Real-time Transport Protocol (RTP) and Real-time Transport Control Protocol (RTCP) as the transport protocol --Applications using RTP are less sensitive to packet loss, but typically very sensitive to delays, so UDP is a better choice than TCP for such applications.

Wireless video technical considerationWireless video technical consideration

• Coding– H.264

• Networking– Application layer: RTSP– Transportation layer : RTP/RTCP/UDP/NAT/STUN– IP layer: Mobile IP

• Connectivity– MAC layer: 802.11g/802.11e/802.11i/802.11n– Physical layer

• System consideration-- Platform and CPU capability--Operation system and compiler environment

Coding issues for wireless videoCoding issues for wireless video

• Why H.264?Network Abstraction Layer --The network-friendly design goal of H.264/AVC is addressed via the Network Abstraction Layer that has been developed to transport the coded video data over any existing and future networks including wireless systems.

• Coding issues:--compression efficiency--Error-resilient mechanism

--Channel rate Fluctuate issue--End-to-End Delay Control

--Complexity

H.264 coding for wireless channelH.264 coding for wireless channel

Compression efficiencyCompression efficiency

• Due to limited resources bandwidth and transmission power, compression efficiency is the main target for wireless video and multimedia applications.

• H.264 solutions--Enhanced Motion compensation--Intra Prediction--Deblocking Filter--Context-Adaptive Variable Length Coding (CAVLC) and Context-Adaptive Binary Arithmetic Coding (CABAC)

Error-resilient mechanismError-resilient mechanism

• Channel rate Fluctuate issue

H.264 solution:

--well-known temporal scalability

• End-to-End Delay Control

H.264 solution:

--slice-structured coding

--Flexible MB Ordering (FMO)

--Data partitioning

ComplexityComplexity

• low complexity integer transform and quantization

• Still complexity issue: more complexity than H.263 and MPEG-4Solution: fast algorithms to reduce the complexity of Motion Estimation--hexagon-based search (HBS)--Enhanced predictive zonal search (EPZS)--hybrid unsymmetricalcross multihexagon-grid

search (UMHexagonS)--variable blocksize best motion detection

(VBBMD)

Networking issuesNetworking issues

• P2P issue:--Network Address Translators (NAT) protocol block the data transmitted directly between two clients under different private networks in many P2P (Peer to Peer) applications. --RTP uses a dynamic port range makes it difficult for it to traverse firewalls

• Roaming Issue: roaming from one area to another with different IP subnet

Transportation layer solutionsTransportation layer solutions

• Solution for Cone NAT--STUN protocol--used by google talk

• Solution for symmetric NAT--Traversal Using Relay NAT (TURN) --adopted in big enterprise network

*STUN: Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators (NATs)

IP layer solution --Mobile IPIP layer solution --Mobile IP• Mobile IP

--A mobile node can have two addresses: a permanent home address and a care-of address--A home agent (HA) stores information about mobile nodes whose permanent address is in the home agent's network.--A foreign agent (FA) stores information about mobile nodes visiting its network. Foreign agents also advertise care-of addresses, which are used by Mobile IP.

• How to work:--Receive: packets are intercepted by the home agent, which then tunnels the packets to the mobile node's care-of address with a new IP header. The packets are decapsulated at the end of the tunnel to remove the added IP header and delivered to the mobile node.--Send: mobile node simply sends packets directly to the other communicating node through the foreign agent.

Wireless vedio categoriesWireless vedio categories

• Video over WAN (wide area network)– GSM network/3G network

• Video over MAN (Metropolitan Area Network )– WiMAX network

• Video over LAN (local area network )– WiFi network (course project focus on 802.11g)

• Video over PAN (Personal area network)– Bluetooth/UWB network

IPTV over WLANIPTV over WLAN

802.11g Connectivity issues and solutions802.11g Connectivity issues and solutions

• Quality of Service (QoS) issue: Delay/delay jitter/Packet loss --solution: prioritized access and scheduled access for WiFi Multimedia

(WMM), presented in 802.11e

• Security issue: --Solution: Wi-Fi Protected Access (WPA/WPA2) addressed by 802.11i

• Bandwidth issue: although 802.11a/g achieve the maximum datarate at 54Mbps, their throughput are around 22Mbps. What’s more, the performance will drop-off while multi-users access at the same time

--solution: Multiple In Multiple Out (MIMO) presented in 802.11n

• Other issues should be considered: --Interference from other radio: Microwave, cordless phone, bluetooth,

etc--Roaming between two APs.…

• Platform and CPU capability– Intel xscale platform: Xscale CPU, high performance– TI PMP platform: ARM9+DSP architecture– Samsung platform: ARM9, relatively lower performance

• Operation system and compiler environment– Embedded Linux: open source but limited resources for

wireless multimedia– WinCE: not open source but plentiful board support

package for wireless multimedia application

System considerationsSystem considerations

REFERENCESREFERENCES

• [1] L. Yang, K. Yu, J. Li, and S. Li, “An Effective Variable Block-Size Early Termination Algorithm for H.264 Video Coding,” in IEEE RANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY, VOL. 15, NO. 6, JUNE 2005

• [2] T. STOCKHAMMER, and T. WIEGAND, “H.264/AVC for Wireless Applications”

• [3]A. Leon-Garcia, and I. Widjaja, “Communication Networks Fundamental Concepts and Key Architectures,” 2nd edition

• [4] http://en.wikipedia.org/wiki/IPTV• [5]http://www.masternewmedia.org/2005/06/04/

iptv_vs_internet_television_key.htm