1. Performance Analysis of MPEG-4 Video Stream with FEC Error Recovery over IEEE 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. 2 Outline Introduction Proposed Analytical Model Numerical Results Conclusion WiOpt - WiVid 2013

3. 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. 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. 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. 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 1.Performance analysis of IEEE 802.11 DCF WLANs The loss of a transmission frame can be caused by:  Congestion loss (P C )  Wireless loss (P E ) The probability of frame transmission failure WiOpt - WiVid 2013

9. Proposed Analytical Model Wireless loss (P E )  Loss probability of data frame (P E_data )  Loss probability of ACK frame (P E_ACK ) WiOpt - WiVid 2013

10. Proposed Analytical Model Congestion loss (P C )  The collision probability for any station competing for channel access  The probability of 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 T max : maximum number of frame retransmission WiOpt - WiVid 2013

12. Proposed Analytical Model 2.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 S I, S P, S B Numbers of MAC I-, P-, and B-frames. S IR, S PR, S BR Numbers of FEC redundant I-, P-, and B- frames.

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. R I, R P, R B Playable frame rates of I-, P-, and B-frames over entire video sequence.

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  R F : the encoding frame rate per second  N P and N B : 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 Packet payload (L data )8184 bitsSlot time50 μs ACK (L ACK )240 bitsDIFS128μs MAC header272 bitsSIFS28μs PHY header128 bitsCW min 32 Channel Data Rate1 MbpsT max 5 BEP (P E_bit )10 -5 CICI 3.91 NPNP 3CPCP 2.05 NBNB 8CBCB 1.52

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