Improving Communication Quality with Reed Solomon Code in Internet Voice Broadcasting System

1
Improving Communication Qualitywith Reed Solomon
Codein Internet Voice Broadcasting System

• Shingo Kashima
• Kyushu University, Japan

Asia-Pacific Advanced Network 2003 January 21-24,
2003 Fukuoka, Japan
2
Plan of Presentation

• Background (Existing Issue)
• Objective
• Icecast
• Solution of Issue
• FEC and Reed Solomon Code
• Proposal of System
• Evaluation
• Future Work
• Summary

3
Background 1 of 2

• Music Delivery in Real Time
• 1 to 1 communication using client-server model

4
Background 2 of 2

• Issues in the Current Model
• A heavy load is applied at the network between
  client and server.
• The number of clients is limited by bandwidth of
  network between client and server.
• Sound is interrupted or noise occurs.

• Solution

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Objective

• Improve the communication quality ofa large
  scale real time voice broadcasting on the
  Internet without modifying the existing
  applications.

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Icecast

• Audio streaming server
• Developed under the GNU General Public License
• Support MP3, HTTP / TCP
• Support many client applications
• ex. WindowsMediaPlayer, Winamp, XMMS, etc
• Relay function (described later)

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Issues in the Current Model

1. A heavy load is applied at the network between
   client and server.
2. The number of clients is limited by bandwidth of
   network between client and server.
3. Sound is interrupted or noise occurs.

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Issues in the Current Model

1. A heavy load is applied at the network between
   client and server.
2. The number of clients is limited by bandwidth of
   network between client and server.
3. Sound is interrupted or noise occurs.

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Solution of Issues I, II

• Distributed Delivery by Relay Server
• The load of network is reduced.
• The number of clients increases.

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Issues in the Current Model

1. A heavy load is applied at the network between
   client and server.
2. The number of clients is limited by bandwidth of
   network between client and server.
3. Sound is interrupted or noise occurs.

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Solution of Issue III 1 of 5

• Factor of Issue III

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Solution of Issue III 2 of 5

• The Communication with TCP

Client has received the packet.
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Solution of Issue III 3 of 5

• The Communication with TCP

Ack nowledgement ??
Ack nowledgement ??
Ack nowledgement ??
Ack nowledgement ??
Ack nowledgement ??
When a packet is lost.
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Solution of Issue III 3 of 5

• The Communication with TCP

Retransmission
No ack nowledgement!
When a packet is lost.
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Solution of Issue III 4 of 5

• Delay by Retransmission Control of TCP

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Solution of Issue III 5 of 5

• UDP is not reliable for arrival of packet

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FEC
Code Error Usage
Hamming code Ramdom Error semiconductor memory storage of computers
BCH code Ramdom Error satellite broadcasting
Fire code Burst Error magnetic memory storage of computers
Reed Solomon code Burst Error audio compact disk



Burst Error
Reed Solomon code
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Reed Solomon Code

• 4bit (8, 4) RS code

available in the network with knowing packet loss
rate
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Proposal of System 1 of 4

• Provide Gateways

Existing System
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Proposal of System 2 of 4

• The Stream of Sound Data

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Proposal of System 3 of 4

• RS encoding and division into packets

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Proposal of System 4 of 4

• Packet Format
• block number
• position of the packet
• number in a block
• position of the packet in a block
• real data size
• date size of a block brefore encoding(generally
  4096 bytes)

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Evaluation 1 of 5

• Compare the communication quality in the proposed
  model with the existing model
• Interruption and Noise
• Connect-able Time

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Evaluation 2 of 5

• Evaluating environment
• server ??? Internet Radio Station FOR (in IPU)
• router ??? 20
• MP3 bitrate ??? 32kbps
• Reed Solomon code ??? 8 bits (32, 16) RS
• packet loss rate ??? unknown

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Evaluation 3 of 5

• Interruption and Noise

experimental time 300 seconds
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Evaluation 4 of 5

• Connect-able Time(connection between client and
  relay server)
• Existing model
• 5 minutes at the worst
• proposed model
• never disconnect (300 minutes)

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Evaluation 5 of 5

• Interruption and Noise
• decreased
• Connect-able Time
• increased
• Communication quality improved in the real
  network
• without knowing packet loss rate.

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Future Work

• Value-added services provided between a server
  and relay servers
• bitrate conversion for bandwidth constraint
  environment (ex. PHS, mobile user)
• different Commercial Message for each relay server

Value-added Servive
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Summary

• The issue of Interruption and Noise
• UDP and Reed Solomon code
• Provided gateways using Reed Solomon code into
  the existing system.
• Not modify the existing applications.
• The communication quality improved in the
  proposed system than the existing system
• In the real network without knowing packet loss
  rate

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Thank You!