Cooperative and OpportunisticWireless Network

Behnaam AazhangUniversity of Oulu

Wireless Network

• Infrastructure• Ad hoc• Mesh network

Engineering Wireless Network

• Wireless links– Per link design

Wireless Network

• Collection of links– Interference– Resource allocation

• Orthogonal?

Scalability

• Number of users– Active flows

• Throughput• Delay• Energy

Wireless Network

• Improve scalability– Exploit network topology– Location

At the Physical Layer

• Architecture examples• Gains

– Achievable rates– Outage

R1

R2

D

S D

R

DataData S

Relay Channels

• Practice of multiuser information theory– 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

Applications

• “Edge” solutions• Mesh networks• Sensor networks