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A Robust Luby Transform Encoding Pattern-Aware Symbol Packetization Algorithm for Video Streaming Over Wireless Network

Dongju Lee and Hwangjun Song

IEEE TRANSACTIONS ON MULTIMEDIA, VOL. 13, NO. 4, AUGUST 2011

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Outline

•Introduction•LT Encoding Pattern-Aware Symbol

Relationship Analysis•Packetization Algorithm of LT Encoded

Symbols•Performance Analysis•Experimental Results•Conclusion

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Introduction• To minimize the quality degradation of video

streaming service caused by packet losses over wireless network.

• Minimize packet loss effects by reducing the dependency among packets conveying Luby transform encoded symbols.

• The LT decoding success rate can be improved at the receiver by minimizing the effect of a lost packet.

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Introduction

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LT Encoding Pattern-Aware Symbol Relationship Analysis

and the element of have a strong dependency on each other.

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LT Encoding Pattern-Aware Symbol Relationship Analysis• Property1 ： The decoding success rate of the

root can be improved by assigning {, 1 } to different packets.

• Property2 ： The decoding success rate of the source symbols in can be increased if more symbols of are available.

• Property3 ： The decoding success rate of the root can be enhanced by packetizing and the elements of its into the same packet.

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Packetization Algorithm of LT Encoded Symbols•The proposed packetization algorithm is

designed to insert more elements of and into the same packet.

： the subset of are put into the same packet with

： determine the number of elements of that are packetized with min{() , ||} and

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Packetization Algorithm of LT Encoded Symbols• Step 0 : Select the first source symbol as a root.• Step 1 : Select a with in { ,1} of the root that

has not been assigned to any packet until now (if all , 1 are already packetized, go directly to Step 4).

• Step 2 : Put the into the target packet chosen by the following rules (Rule i has a higher priority than Rule (i+1)). If any packet is not chosen by the rules below, go to Step 4.

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Packetization Algorithm of LT Encoded Symbols

▫ Rule 1: If an empty packet exists, choose the packet as the target packet.

▫Rule 2: If the available space at a packet is not less than (e.g., if and elements of can be inserted into the same packet), then choose the packet as the target packet.

▫Rule 3: when and elements of cannot be inserted into the same packet, if is less than and the available space at a packet is not less than , then choose the packet as the target packet with = in order to insert and elements in into the same packet as the best alternative policy of Rule 2

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Packetization Algorithm of LT Encoded Symbols• Step 4 : Sequentially selected next source

symbol as a root and repeat Step 1-3 with new root and the initial until no more root exist, go to Step 5.

• Step 5 : Randomly distribute the remaining encoded symbols into residual spaces of the packets.

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Packetization Algorithm of LT Encoded Symbols• Step 3: Determine a by randomly choosing

elements in . Put into the target packet as shown in Fig. 3.

• Step 4: Select source symbol sequentially as a root and repeat Step 1–3 with the new root and the initial until no more root exit, go to Step 5.

• Step 5: Randomly distribute the remaining encoded symbols into the residual spaces of the packets.

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Performance Analysis• Performance measure ： The number of the

successfully received elements of with .• Claim ： || > ||

： the number of transmitted packets (> )： the number of encoded symbols the average number of symbols in the target packet when the remaining symbols are randomly allocated to packet.

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Performance Analysis• To guarantee || > ||： > - (4)• Combining (3) and (4) > (5) then, = , for (6) (7)

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Experimental Results-setup

• Implemented by using Java and C/C++.

• H.264/AVC JM Software is used as a video codec.

• Test video sequences ： Harbour and Soccer of CIF size and 15 fps.

• The GOP structure is set to include one I-frame and 29 P-frames.

• Every simulation is repeated 1000 times and averaging values of

the repeated simulations

• LT codes ： robust soliton distribution and two parameters of this

degree probability distribution are set to 0.03 and 0.5,

respectively

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Performance Verification of the Proposed Packetization Algorithm

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Performance Verification of the Proposed Packetization Algorithm

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Performance Verification of the Proposed Packetization Algorithm

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Video Quality Comparison When Packet Loss Pattern Is Random

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Video Quality Comparison When Packet Loss Pattern Is Random

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Video Quality Comparison When Packet Loss Pattern Is Random

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Video Quality Comparison When Packet Loss Pattern Is Burst

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Video Quality Comparison When Packet Loss Pattern Is Burst

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Video Quality Comparison When Packet Loss Pattern Is Burst

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Video Quality Comparison When Packet Loss Pattern Is Burst

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Video Quality Comparison When Packet Loss Pattern Is Burst

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Conclusion• An efficient LT encoding pattern-aware

packetization algorithm for LT encoded symbols to provide a robust video streaming service over error-prone wireless network.

• The basic concept of the proposed packetization algorithm may be extended to other fountain codes with some modifications.