awareness Contention between neighbors in carrier- sensing range - - PowerPoint PPT Presentation

Motivation: Contention- awareness



Contention between neighbors in carrier- sensing range (c- neighbors)



Transmission at a node may consume bandwidth at its c- neighbors



A new flow may affects the QoS of existing flows at its c-neighbors

Transmission range Carrier-sensing range A B C

Motivation: Contention- awareness

 Local achievable

bandwidth



Achievable, but may degrade c-neighbors’ QoS

 C-neighborhood

available bandwidth



Allowable bandwidth that does not affect c- neighbors’ QoS

Transmission range Carrier-sensing range A B C

D

Motivation: Contention- awareness

 Nodes have different

views of the wireless channel



A node only knows its local bandwidth



A node can not know the available bandwidth at its c- neighbors



C-neighborhood signaling

Transmission range Carrier-sensing range A B C

Motivation: Contention- awareness

 Multiple nodes on a

route contend at the same location

 Each node consumes

bandwidth that equals the flow rate

 Contention count (h)

A B C D E F

Carrier-sensing Range Transmission Range

Other Approaches



Existing Approaches



SWAN



Local achievable bandwidth = idle channel bandwidth



Insignia



Achievable bandwidth = unreserved bandwidth



VMAC



Idle channel bandwidth = achievable bandwidth 

Limitations: Not contention-aware



Only local free or achievable bandwidth is considered



No consideration of contention between nodes on the same route



No consideration of contention between realtime traffic and best effort traffic

Contention-aware Admission Control Protocol (CACP)

 Components

 Route discovery  Admission control  Resource reservation  Mobility and QoS violation management

Route Discovery

 Source Routing

 Pin a flow to a route with enough resources  Supports traffic splitting & load balancing

 Route request phase

 Route request messages flood the network

 Route reply phase

 Route reply messages sent along the

reversed route

Admission Control

 Admission control combined with route

discovery

 Route request phase

 Partial admission control on receiving a

route request message

 Route reply phase

 Full admission control on receiving a

route reply message

C-neighborhood Admission Control

 Broadcast an admission

request message to c- neighbors



Multihop: CACP-Multihop



Enhanced Power: CACP- Power

 Admission rejection if not

enough resources

 Timeout if no admission

rejection

A B C D E F G H

Carrier-sensing Range Transmission Range

Example: Route Request

 Example of CACP

Node A B C D C-neighbor set

A B C D

Rt-Req

Example: Route Request

 Partial admission control

Node A B C D C-neighbor set A

A B C D

Rt-Req

Example: Route Request

 Partial admission control

Node A B C D C-neighbor set B A A B

A B C D

Rt-Req

Example: Route Request

 Partial admission control

Node A B C D C-neighbor set B A A B C B C

A B C D

Rt-Reply

Example: Route Reply

 Full admission control

 Local admission control

Node A B C D C-neighbor set B A A B C B C D

A B C D

Ad-Req Ad-Req Ad-Req

Example: Route Reply

 Full admission control

 Local admission control  C-neighborhood admission control

(enhanced power)

Node A B C D C-neighbor set B A A B C C B C D

A B C D

Rt-Reply

Example: Route Reply

 Full admission control

 Local admission control

Node A B C D C-neighbor set B A A B C C B C D D

A B C D

Ad-Req Ad-Req Ad-Req

Example: Route Reply

 Full admission control

 Local admission control  C-neighborhood admission control

(enhanced power)

Node A B C D C-neighbor set B A A B C C B C D D

A B C D

Example: Route Reply

 Full admission control

 Local admission control

Node A B C D C-neighbor set B A A B C C B C D D

A B C D

Rt-Reply

CACP

Ad-Req Ad-Req

Example: Route Reply

 Full admission control

 Local admission control  C-neighborhood admission control

(enhanced power)

Node A B C D C-neighbor set B A A B C C B C D D

A B C D

Example: Flow Starts

 Periodically refresh resource reservation  Monitor link breaks



Reroute

 Monitor QoS violation events



Reroute or decrease QoS requirement

Node A B C D C-neighbor set B A A B C C B C D D

A B C D

Data Data Data

Evaluation

 Metrics

 Bandwidth violation



Throughput - packet generation rate at source



Throughput guarantees

 Total network throughput



Bandwidth utilization

 Control message overhead  Packet delay

Evaluation: Simulation Setting

 Compare CACP with



DSR



SWAN



No c-neighborhood admission control



bandwidth consumption=flow rate

Network Area 1000m  1000m # of nodes [20,180] Flow rate (pkts/s) [10,50] Packet size (Byte) [100,1000] Max speed (m/s) 5 Pause time (s) 10 # of flows 20

Evaluation: Throughput Guarantees

QoS violation

• 100
• 90
• 80
• 70
• 60
• 50
• 40
• 30
• 20
• 10

20 40 60 80 100 120 140 160 180

Number of nodes Bandwidth violation rate (pkts/s) CACP-Multihop CACP-Power SWAN DSR

 Bandwidth violation=Throughput- packet

generation rate at the source

Evaluation: Network Utilization

Total network throughput

40 50 60 70 80 90 100 110 120 130 140 20 40 60 80 100 120 140 160 180

Number of nodes Throughput (pkts/s) CACP-Multihop CACP-Power SWAN DSR