Joint Source-Channel Coding for MPEG-4 Streams Transmission Over 3G Networks

1. Joint Source-Channel Coding for MPEG-4 Streams Transmission Over 3G Networks Fang Zhijun, Xu Shenghua, Wan Changxuan Wu Shiqian, Wang Zhengyou, Zeng Weiming Wireless Communications, Networking and Mobile Computing, 2005. Lee, Ick-Soo

2. Contents • Introduction • System Architecture • Joint Source-Channel Coding Scheme • TCP and UDP Protocol • 3GPP/3GPP2 Turbo Codes • Turbo Coder • Turbo Decoder • Data Partitioning and UEP • Simulation & Result • Conclusion

3. Abstract • The critical important MPEG-4 streams such as the BIFS (Binary Format for Scenes), OD (Object Descriptors) and IOD (Initial Object Descriptors) streams are transmitted by using TCP (Transmission Control Protocol) • MPEG-4 audio/video ES (Elementary Streams) are transmitted by using UDP (User Datagram Protocol) over 3G channels. • Transmission UDP packets is adopted UEP (Unequal Error Protection) Turbo codes according to MPEG-4 audio/video data partitioning. • Only video ES have been discussed.

4. Introduction • 3rd Generation Partnership Project (3GPP) & 3GPP2 • New worldwide standards for the creation • Delivery • Playback of multimedia over new • High-speed wireless networks • The aim of the 3rd generation networks • Combine the multimedia services of the Internet and provide multimedia services over wireless mobile platforms.

5. Introduction • The stability, interoperability and robustness offered by MPEG-4 make it an ideal solution for mobile networks and it has been selected by 3GPP and 3GPP2 for applying on 3G phones. • Some of MPEG-4 new techniques suitable for wireless such as scalable and error-resilient video coding techniques • MPEG-4 system streams have not considered • This paper present a new joint source-channel coding (JSCC) scheme of transmitting MPEG-4 streams over 3G systems.

6. System Architecture • 3G phones system can be divided as three layers, namely physical layer, link layer and upper layer.

7. System Architecture • Physical layer • Provides data transfer service to higher layers. • Main purpose is to convert data bit stream into a format suitable to traverse the media. • Link layer • Composed of media access control (MAC) and link access control (LAC) sub-layers. • MAC sub-layer administers and controls the material of physical layer according to the requests of different service objects from LAC, and provides levels of quality of service (QoS) for them. • LAC is in charge of providing higher level QoS control over MAC, which is to meet the requests from objects above, normally realized through the method of ARQ.

8. System Architecture • Upper Layer • Integrates the functions of network, transport, session, presentation and application layers in open system interconnect (OSI) reference model. • Deals with the signaling for multiple services, the control and processing on voice service (circuit and package types) and data service (IP service, data in circuit or package, short message service). • CDMA2000 uses correlation code or Turbo code in channel encode • Connection-oriented TCP transfer mode is used for critical system streams such as BIFS, OD and IOD streams, while UDP is applied for MEPG-4 video streams.

9. Joint Source-Cannel Coding Scheme • TCP and UDP Protocol • MPEG-4 streams have to be converted into packets for transport over the wireless network, TCP and UDP are the basic transport protocols for media streaming. • Multiplexing, error control, and flow control • The main objective of transmitting video over mobile networks is to provide interactive and conversational services. • The MPEG-4 critical important streams, such as BIFS, OD and IOD, are transmitted by using TCP. • This implies that all the video services offered over 3G for instance must run in real time with one-way delay not exceeding 200 ms per service. In order to meet these delay requirements, it is not possible to use retransmissions or ARQ

10. Joint Source-Cannel Coding Scheme • On the end-to-end level, UDP is typically employed as the transport protocol for the MPEG-4 video ES. However, since the UDP does not guarantee packet delivery, a UEP Turbo codes has applied to provide the error protection in this work.

11. 3GPP/3GPP2 Turbo Codes • Turbo Codes • Gaining increasing acceptance as the viable commercial FEC code for broadband wireless applications. • Performs well under the high noise environment • Good anti-fading, anti-jamming • 3G standards and digital video broadcast (DVB) adopted Turbo codes as one of their error correction schemes.

12. Turbo Codes • Parallel concatenated by two or more feedback systematic convolutional encoders through a random interleaver.

13. Turbo Decoder • Because Turbo code is encoded by interleaving two or more component codes of the same information sequences, its decoder is usually composed of two or more component coding units and deinterleaver.

14. Turbo Decoder • Derived from convolution code decoder, Turbo decoder use soft decision • With binary phase shift keying (BPSK, m = 1) or quadrature phase shift keying (QPSK, m = 2) modulation the decoder constant C should be adjusted • A: the signal amplitude • σ2: the normalized noise variance

15. Turbo Decoder • σ2: the normalized noise variance • Eb / N0 : the ratio of energy per bit to single sided noise density • For fading channels, the values of A and σ 2 should be averaged across the block to determine the average value of C

16. Data Partitioning and UEP • The importance of the data in different parts of the video streams is not same. • Motion Maker is decoded correctly yet texture-coding DCT is wrong, MV is used and DCT is dropped

17. Data Partitioning and UEP • Transported using connectionless-oriented UDP • coded at high bit rate as unimportant information. • Transported using connection-oriented TCP • consider the MB header, MV and shape coding information as important data • coded with low bit rate Turbo codes. • important data in MPEG-4 streams such as BIFS, OD, and IOD

18. Simulation & Result • Six times iterative 1/3 low bit rate Turbo code is adopted for the important information in the MEPG-4 stream, while four times iterative 1/2 high bit rate Turbo code is used for the parts with less importance.

19. Simulation & Result • The comparison of the error probability between no error protection (NEP) and Turbo error resilient coded situations under various Eb / N0 .

20. Simulation & Result • The PNSR of the images under various Eb / N0 for the first 100 frames of the sequence.

21. Simulation & Result • The comparison of average PSNR under various Eb / N0 and different error protection for the first 100 frames.

22. Conclusion • A novel joint source-channel coding technique that provides robustness to error from fading channel has been described in this paper. • MPEG-4 streams, the BIFS, OD, and IOD are critical important streams. Therefore, these key streams have been transmitted by using TCP. • The audio/video ESs are transmitted by UDP over 3G channels, then according to MPEG-4 data partitioning, we transport the UDP packets by using UEP turbo codes. • Simulation results show that low bit error rates can be obtained effectively over the 3G wireless channels by using our provided method.