Current Projects
• Network Coding File System
– first NC-based data storage prototype
– hold the First Workshop on NC and Data Storage in HK (Jul
21-22, 2011)
• Physical-Layer Network Coding
– first realization on software radio (USRP)
• Wireless Network Coding Applications
– a demo of NC protocol on iPhones
• BATched Sparse Code (BATS Code)
– generalization of fountain code
– used in conjunction with network coding
– Can out perform fountain code in a multihop network
Network Coding File System
• NCFS: Network-coding-based distributed file system
– Use network coding to speed up repair while preserving fault tolerance of
storage
– No intelligence required on storage nodes
– Data is transparently striped across nodes. Clients only see a mount drive
NCFS
proxy
client
`
/mnt/ncfs
storage
nodes
Network
2
Network Coding File System
• Apply network coding in proxy to improve repair
throughput
NCFS
proxy
A
C=A+B
B
A
B
storage
nodes
C
new
node
3
failed
node
NCDS 2011
• First Workshop on Network Coding and Data
Storage
• Hosted by INC
• Hong Kong, July 21-22, 2011
• Free registration
• http://www.ncds2011.inc.cuhk.edu.hk/
Traditional Multi-hopping
S1
S1
1
3
S2
2
S2
Time slot 1
Time slot 2
Time slot 3
Time slot 4
Transmissions non-overlapping in time
Nov 2010
Soung Liew, CUHK
5
Symbol-Level Network Coding
S2  S3  S1
S1
S2
1
3
S3  S1  S2
S3  S1  S2
Time slot 1
S1  S3  S2
2
Time slot 2
Time slot 3
Node 3 uses one time slot to broadcast
Transmissions by nodes 1 and 2 still non-overlapping
Nov 2010
Soung Liew, CUHK
6
Physical-Layer Network Coding
S2  S3  S1
S1
S1  S3  S2
S2
1
3
S3  S1  S2
S3  S1  S2
Time slot 1
2
Time slot 2
Transmissions by nodes 1 and 2 are simultaneous!
Nov 2010
Soung Liew, CUHK
7
Wireless Network Coding Applications
Relay Network with Packet Loss
BATS Code
• Network coding at relay (Avalanche) can achieve
network capacity asymptotically.
• Network coding at relay destroys the structure of
the fountain code, i.e., fast decoding not possible.
• BATS code, a generalization of fountain code,
provides a solution.
• Advantages of BATS code:
– achieve network capacity asymptotically
– no delay at relay
– fast encoding and decoding, like fountain code