Adaptive QoS Control of Multimedia Transmission Over Band-limited Networks. G.Y.Hong 1 , Member, IEEE, A.C.M.Fong 1 , Member, IEEE, B.Fong 2 , Member, IEEE 1 IIMS, Massey University, 2 Auckland University of Technology. Presenter : Hu Huang Nov. 2002.
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G.Y.Hong1, Member, IEEE, A.C.M.Fong1, Member, IEEE, B.Fong2, Member, IEEE
1IIMS, Massey University, 2Auckland University of Technology
Presenter: Hu Huang
IEEE Transactions on Consumer Electronics, Vol.48, No.3, AUGUST 2002
Application-layer QoS control Band-limited Networks
(sender and /or receiver)
Channel-based FECCurrent Application-Layer QoS Control Techniques(for multimedia data transmission over band-limited networks)
Fig. 1 Application-layer QoS control (transport perspective)
An adaptive QoS control mechanism that adapts to network conditions as perceived by each receiver has been proposed.
Model-based control (Bernoulli model)
packet loss detection: threshold =3
packet loss ratio r = nL/n (within one sampled period)
smoothed loss ratio j=j-1+(1-)rj(=0.33)
AIMD (Additive Increase and Multiplicative Decrease) rate adjustment:
Appropriately loaded transmission rate to that receiver is not changed
Heavily loaded transmission rate is aggressively decreased
Lightly loaded transmission rate is gradually increased
depending on j
Purpose:produce scalable multimedia data streams for different transmission rates for different receivers at different times, achieving optimal match between network resources, devices capabilities and transmission rate.
Transformed Data --
Fig. 4 Rate shaping with multiple QP
In the proposed approach, N =3 to obtain three bitstreams of different quality (Bitstream3 is the highest quality while Bitstream1 is the least).
………………… Band-limited Networks
Adaptive QoS Control (Cont.)
Each block of Kprimary data packets has a parity packet P appended to it, which is used for recovering lost packets.
Fig.5 Transmitted data stream
P=d1 d2d3 …dk
K= (, 16, 8, 4, 2) depending on the prevailing network condition.
(e.g. K= indicates Pis not employed at all due to good network condition).
jis used to determine the appropriate degree of protection.
(PSNR: peak signal-to-noise ratio; RMSE: root mean squared error)
The results indicate that the new scheme consistently outperformed the standard MPEG codec with fewer fluctuations. Average improvement of 0.5dB PSNR can be achieved over standard MPEG implementation.