Cooperative and OpportunisticNetwork

Behnaam Aazhangand

Ashutosh Sabharwal

Cooperative and OpportunisticNetwork

Behnaam Aazhangand

Ashutosh Sabharwal

Credits

• Brett Kaufman• Gareth Middleton• Funding

– NSF– Nokia– TI

Scalability

• Throughput/number of users• Optimization of each layer

– Almost done• Cross layer

– Exploit network topology?– Location?

At the Physical Layer

• Great examples• Gains

– Achievable rates– Outage

U1U1

U2

D

S D

R

DataData

Relay Channels

• Information theoretic analysis– Distributed coding– Finite feedback

• Relay selection• Hardware implementation

– Amplify and forward– Detect and forward

S D

R

Data

Wireless “Cooperative” Network

• Gains– Throughput– Power– Outage

• Overhead– Discovery– Access– Latency– Interference 2 8

1

3

5 7

D

S

6

4Data

Multiple Flows

• Distributed resource management– Access– Interference

• Priorities– Primary– Secondary

2 8

1

3

5 7

D2S1

6

4

S2D1

Data

Data

Research Agenda

• Distributed node discovery– Source initiated– State information

• Nodes and channels– Inspired by

• 802.11 RTS/CTS• Multihop route discovery (e.g., DSR)• Timer based relay selection

Research Agenda

• Cooperative path construction– Trellis– Graph theory

Example 1

• Two competing flows• Complete network state information

– Managing data with a trellisData

S2 D2

R

Data

D1S1

TrellisFlow 1

Flow 2

Meta node

Interference

Discovery

• The discovery for flow 1 is standard• R in the range of D1 receives D1’s CTS

and AckData

S2 D2

R

S1 D1

RTSRTS CTSCTS DataData AckAck

Discovery

• The discovery for flow 2– S2 sends RTS– R in the range of D1 will interfere with flow 1– D2 sends CTS– A noncooperativeflow 2 begins

Data

S2 D2

R

Data

S1 D1

Discovery

• If flow 2 is high priority– S2 sends RTS– R sends RTS– D2 sends CTS– R sends CTS torelay in half duplex

• Flow 1 will reducerate to half

Data

S2 D2

R

Data

S1 D1

Cooperative Network

• Developed protocols• Initial simulations• “In scale” experimental validation

– Throughput– Overhead– Complexity

Example 2

• Opportunistic network• Primary users

– Cellular, WiMax• Secondary users

– Share primary’s bandwidth– Meet primary service’s target SINR– Multi hop

Strategy

• Downlink

Strategy

• Downlink?

Strategy

• Uplink• Determine distanceto BS duringdownlink• Set secondarytransmissionpower during uplink

Route Discovery

• Secondary users discover– Multi hop route– Prescribed power

Applications

• “Edge” solutions• Mesh networks• Sensor networks