Performance Analysis of MPEG-4 Video Stream with FEC Error Recovery over IEEE 802.11 DCF WLAN

1. Performance Analysis of MPEG-4 Video Stream with FEC Error Recovery overIEEE 802.11 DCF WLAN Cheng-Han Lin, Huai-Wen Zhang, Ce-Kuen Shieh Department of Electrical Engineering, National Cheng Kung University, Taiwan Wen-Shyang Hwang* Department of Electrical Engineering, National Kaohsiung University of Applied Sciences, Taiwan WiOpt - WiVid 2013

2. Outline • Introduction • Proposed Analytical Model • Numerical Results • Conclusion WiOpt - WiVid 2013

3. Introduction • Wireless Local Area Network (WLAN) • Convenience of wireless access • The use of mobile devices is increasing • The data rates and bandwidth are increasing • Internet-based video streaming applications is popular • The performance analysis of video streaming over wireless networks has emerged as an important issue in the multimedia communications field. WiOpt - WiVid 2013

4. Introduction • The literature contains many models based on a two-dimensional Markov chain for analyzing the performance of IEEE 802.11 DCF networks [7-10]. [7] The model assumed that the number of retransmissions of a lost frame is unlimited. [8] The frame retransmission limit is taken into consideration. The effects of wireless bit errors on the frame loss are ignored. [9] The wireless bit errors is taken into consideration. The frame retransmission limit is ignored. [10] A model analyzes the effects of both the frame retransmission limit and wireless bit errors. WiOpt - WiVid 2013

5. Introduction • The [7-10] focus on the system performance, but do not enable the video quality over IEEE 802.11 DCF WLANs to be directly assessed. [13] Decodable Frame Rate (DFR), for analyzing the video quality of MPEG-4 video streaming over WLANs. The assumptions regarding the wireless transmission were overly simple. [14] A more realistic model in which the effects on the frame losses of wireless channel errors and transmission collisions were both taken into account. However, the models in [13-14] did not consider the effects of error recovery on the MPEG video streaming quality. WiOpt - WiVid 2013

6. Introduction • This paper proposes an analytical model for evaluating the performance of MPEG-4 video streaming over IEEE 802.11 DCF WLANs with FEC error protection. • The model considers both congestion losses and wireless channel losses. • The model enforces the frame retransmission constraint prescribed in IEEE 802.11. • The model takes account of the FEC error recovery performance in improving the perceived video quality at the receiver end. WiOpt - WiVid 2013

7. Outline • Introduction • Proposed Analytical Model • Numerical Results • Conclusion WiOpt - WiVid 2013

8. Proposed Analytical Model • Performance analysis of IEEE 802.11 DCF WLANs • The loss of a transmission frame can be caused by: • Congestion loss (PC) • Wireless loss (PE) • The probability of frame transmission failure WiOpt - WiVid 2013

9. Proposed Analytical Model • Wireless loss (PE) • Loss probability of data frame (PE_data) • Loss probability of ACK frame (PE_ACK) WiOpt - WiVid 2013

10. Proposed Analytical Model • Congestion loss (PC) • The collision probability for any station competing for channel access • The probabilityof an station transmits a frame [1] • m: maximum backoff stage [1] “Saturation throughput analysis of error-prone 802.11 wireless networks,” Wiley Journal of Wireless Communications and Mobile Computing 2005

11. Proposed Analytical Model • The probability of a frame transmission failure • The effective failure probability of each frame • Tmax: maximum number of frame retransmission WiOpt - WiVid 2013

12. Proposed Analytical Model • Analytical model for MPEG-4 video streaming with FEC error recovery • The probability of a successful frame transmission • n: the total number of source frame (k) and redundant frame (h) • k: the number of source frame WiOpt - WiVid 2013

13. Proposed Analytical Model • The successful transmission probabilities of the I-, P- and B-frames in the GOP WiOpt - WiVid 2013

14. Proposed Analytical Model • Playable Frame Rate (PFR) • A performance metric for evaluating the quality of video streaming over lossy network. • The ratio of the expected number of decodable video frames at the receiver to the total number of video frames transmitted by the sender.

15. Proposed Analytical Model • The PFR for I-frames • The effective GOP transmission rate • Note that the PFR is computed on a per-second basis • RF : the encoding frame rate per second • NP and NB : the number of P- and B-frames in the GOP

16. Proposed Analytical Model • The playable frame rate for P-frame

17. Proposed Analytical Model • The playable frame rate for B-frame

18. Proposed Analytical Model • The overall PFR for a FEC-Protected MPEG video stream is equal to the sum of the PFRs of the I-, P- and B-frames, respectively

19. Outline • Introduction • Proposed Analytical Model • Numerical Results • Conclusion WiOpt - WiVid 2013

20. Numerical Results • Simulation topology • Parameter settings WiOpt - WiVid 2013

21. Numerical Results • Variation of Playable Frame Rate with number of active stations Bit Error Probability (BEP) = 10-4 Bit Error Probability (BEP) = 10-6 WiOpt - WiVid 2013

22. Numerical Results • Variation of Playable Frame Rate with number of active stations The maximum backoff stage (m) = 4 The maximum backoff stage (m) = 6 WiOpt - WiVid 2013

23. Outline • Introduction • Proposed Analytical Model • Numerical Results • Conclusion WiOpt - WiVid 2013

24. Conclusion • This paper has proposed an analytical model for evaluating the video quality of MPEG-4 video streaming over FEC-protected IEEE 802.11 DCF WLANs. • The proposed model considers • the effects of congestion and wireless frame losses • the performance of the FEC error recovery mechanism • The proposed model has been validated by comparing • the predicted results • the results obtained from NS-2 simulations • two existing analytical models [8, 9]. WiOpt - WiVid 2013