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Optimizing On-Demand Data Streaming with UEP Codes

Explore efficient and scalable data streaming using Unequal Error Protection codes for optimal resource consumption and network bandwidth utilization. Learn how to enhance client's buffer space and reduce initial playout delay for seamless streaming.

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Optimizing On-Demand Data Streaming with UEP Codes

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  1. Efficient and Scalable On-Demand Data Streaming Using UEP Codes Lihao Xu Washington University in St. Louis ACM Multimedia 2001 Sept. 30 – Oct. 5, 2001 Sheng-Feng Ho

  2. Outline • Introduction • Unequal Error Protection Codes • UEP Codes Example • Theorem • The Scheme • Resource Consumption • Network Bandwidth • Client’s Buffer Space • Client’s Network Bandwidth • Additional Initial Playout Delay • Conclusion Sheng-Feng Ho

  3. Introduction • Streaming Method • Unicast：Point-to-point • Resource consumption is proportional to the number of requests. • Multicast：Pyramid or Skyscraper • The lowest resource consumption with no initial data playout delay is proportional to logarithm of the average request arrival rate. • The reliability：Automatic-Repeat-Request、 Forward Error Correction Sheng-Feng Ho

  4. Unequal Error Protection Codes • (N,K) block code encodes an original message of K symbols into a codeword of N data symbols of the same size. • A data symbol is a general data unit of certain size：a bit, a byte, a packet or a frame. • Original K data symbols can be recovered from any M data symbols of its codeword. (M≧K) Sheng-Feng Ho

  5. Unequal Error Protection Codes • For a UEP code, certain data symbols of its codeword are protected against a greater number of errors than others. • For a message m with n data symbols, if the error protection degree of its i-th symbol is Li (i≦1 ≦n), and it is encoded with a UEP code C of N symbols, then any Li symbols of its codeword are sufficient to retrieve the i-th symbol in the original message m. Sheng-Feng Ho

  6. UEP Codes Example (1) • Message m has 3 symbols of equal size：a, b and c. (m=abc) • Partition symbol • a into 6 sub-symbols of equal size：a=a1..a6, • b into 9 sub-symbols：b=b1..b9 • c into 6 sub-symbols：c1..c6 Sheng-Feng Ho

  7. UEP Codes Example (2) • Apply the (6,2) B-Code on a to get a codeword of a：A=A1..A6 (Ai is ½ size of a) • A1 = a1, a2+a3, a4+a6, • A2 = a2, a3+a4, a5+a1, • A3 = a3, a4+a5, a6+a2, • A4 = a4, a5+a6, a1+a3, • A5 = a5, a6+a1, a2+a4, • A6 = a6, a1+a2, a3+a5, • and + is the simple bit-wise binary exclusive or (XOR) operations Sheng-Feng Ho

  8. UEP Codes Example (3) • Apply a modified (6,3) RS-Code on b to get a codeword of b：B=B1..B6 (Bi is 1/3 size of b) • B1 = b1, b2, b3, • B2 = b1+b3+b4, b2+b4+b5, b2+b3+b6, • B3 = b6+b7, b4+b6+b8, b5+b9, • B4 = b3+b6+b7, b1+b4+b7+b8, b2+b5+b9 • B5 = b4+b6+b9, b4+b7,？ • B6 = b7, b8, b9 • “+” is the XOR operation • Let Ci = ci for i = 1 to 6, thus each Ci is 1/6 size of c. Sheng-Feng Ho

  9. UEP Codes Example (4) • Construct a UEP codeword of the original message m：U = U1..U6, where Ui = AiBiCi for i = 1 to 6. • The protection degrees of the original data symbols a, b and c are La=2, Lb=3 and Lc=6 respectively. • 1/La+1/Lb+1/Lc=1 Sheng-Feng Ho

  10. UEP Codes Example (5) Original Messagem=abc Original Messagem=abc UEP CodewordU=U1U2U3a=a1..a6,b=b1.. UEP CodewordU=U1U2U3U1=A1B1C1,U2=.. Network Transmit Server Multicast Client Receive Sheng-Feng Ho

  11. Theorem • For a message m with n symbols, if there exists a UEP code such that the error protection degree of the i-th symbol in the original message m is Li (i≦1 ≦n), then Sheng-Feng Ho

  12. The Scheme (1) • Encoding the original data of n symbols into a UEP codeword of N symbols. • Multicast the UEP codeword in a cyclic fashion. • Once the number of data symbols in user’s buffer space reaches Li, the user retrieves the i-th symbol of the original data stream and plays it out. Sheng-Feng Ho

  13. The Scheme (2) • B：normal playout unicast network bandwidth • d：the initial playout number of original data symbols • The peak network bandwidth needed：rpeakB, where rpeak = max(Li/(i+d)) • The average network bandwidth is raveB, where raveB = Ln/(n+d) Sheng-Feng Ho

  14. The Scheme (3) Resource Consumption vs. Initial Playout Delay for Multicasting a 2-hour Video. d：initial playout delay in seconds R：normalized backbone network bandwidth C：normalized client buffer space needed Sheng-Feng Ho

  15. R≒αlog2(1+n/d), where ½≦α≦1 Resource Consumption (1) • The peak network bandwidth needed：rpeakB, where rpeak = max(Li/(i+d)) • Minimize rpeak, set Li/(i+d) = R for all i’s • R=Hn+d-Hd≒αlog2(1+n/d), where ½≦α≦1 Sheng-Feng Ho

  16. Resource Consumption (2) • Let Si be the buffer space needed between the retrieval of the i-th and the (i+1)th original data symbols, then • Client’s Buffer Space： Sheng-Feng Ho

  17. Resource Consumption (3) • The normalized network bandwidth a client needs to consume between the retrieval of the i-th and (i+1)th original data symbols is Sheng-Feng Ho

  18. Additional Initial Playout Delay • d：additional initial playout delay • ：normalized backbone network bandwidth • W：client’s normalized incoming network badnwidth Sheng-Feng Ho

  19. Conclusion • Our scheme utilizes nice properties of error control codes, particularly UEP codes. • The scheme also tolerates packet loss during transmission, thus further reduces multicast cost. • Problem：Fast Seek Sheng-Feng Ho

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