Dynamic channel allocation in wireless ad hoc networks
This presentation is the property of its rightful owner.
Sponsored Links
1 / 26

Dynamic channel allocation in wireless ad-hoc networks PowerPoint PPT Presentation


  • 53 Views
  • Uploaded on
  • Presentation posted in: General

Dynamic channel allocation in wireless ad-hoc networks. Anup Tapadia Liang Chen Shaan Mahbubani. Background. 802.11 networks have experienced a tremendous growth in last few years Access points work on a single static channel Contention & congestion

Download Presentation

Dynamic channel allocation in wireless ad-hoc networks

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Dynamic channel allocation in wireless ad hoc networks

Dynamic channel allocation in wireless ad-hoc networks

Anup Tapadia

Liang Chen

Shaan Mahbubani


Background

Background

  • 802.11 networks have experienced a tremendous growth in last few years

  • Access points work on a single static channel

  • Contention & congestion

  • Low throughput due to inefficient channel allocation

  • Presence of other interfering networks impacts performance


Channel variations

Channel variations

Traffic on Thursday 26th April at Calit2 6th floor


Cognet testbed setup at calit2

CogNet testbed setup at Calit2

CogNet is supported by

NSF SGER-CogNet


Calnode

CalNode

  • Seokris 4521

  • Linux 2.6

  • Iperf

  • Monitor Card

    • Atheros w/ Mad Wifi

  • Data Card

    • Prism 2.5 802.11b

  • Wired to UCSD network


What may affect the channel performance

What may affect the channel performance?

  • Interfering 802.11 Traffic

    • Packet count

    • 802.11 Rate

    • RSSI

  • Other interference

    • Bluetooth

    • Cordless phones

    • Microwaves

Our Focus


Challenge

Challenge

  • How do we select the channel that permits maximum throughput in an ad-hoc network ?


Channel controller java c

AP

Towards Nodes

Connection

Stub

iwlib

WiFi

NIC

WiFi

NIC

Channel Controller (Java & C++)

SQL Query

Decision Logic

CogNet

DB

Channel

Switcher

Iperf Test

Scheduler


Software architecture

AP

AP

AP

AP

Connection

Stub

Connection

Stub

Connection

Stub

Connection

Stub

iwlib

iwlib

iwlib

iwlib

WiFi

NIC

WiFi

NIC

WiFi

NIC

WiFi

NIC

WiFi

NIC

WiFi

NIC

WiFi

NIC

WiFi

NIC

Software Architecture

Channel Controller

Decision Logic

Channel Switcher


Channel switch

Channel Switch

Channel Controller

Decision Logic

Channel Switcher

Channel Switch Message

Channel Switch Message

Connection

Stub

Connection

Stub

iwlib

iwlib

802.11

Driver

802.11

Driver

Switch

Channel

Switch

Channel

Probe

802.11 H/W

802.11 H/W

Reply


Factors selection test

Factors selection test

Tx

Tx

Tx

15 sec silence

15 sec silence


Factors affecting throughput rssi

Factors affecting throughput :RSSI


Effect of our transmission rate on others rssi

Effect of our transmission rate on others RSSI


Factors affecting throughput rate

Factors affecting throughput : Rate


Factors affecting throughput packets

Factors affecting throughput :Packets


Channel selection algorithm

Channel Selection Algorithm

  • We select the least interference channel dynamically

    • Channel interference metric

      where Ci is the interference metric of channel i, Nip, Niq are the number of other packets captured at node p and q on channel i in a 120s window.

    • Selected channel j, s.t.


Experiment process

120 sec query window

S

R

D

15 sec silence

15 sec silence

Experiment: Process

  • Send a 3MB file using each scheme

  • 15s pause interval in betweeneach transfer

  • Repeat


Background traffic

Background Traffic


Results dynamic v static

Results: Dynamic v. Static


Results dynamic v random

Results: Dynamic v. Random


Results random v static

Results: Random v. Static


Channels picked

Channels picked


Results summary

Results: Summary


Effect of channel switching time

Effect of channel switching time

Our implementation

td = Tx time on dynamic channel

ts = Tx time on static channel

tc = Time to change

rd = Rate on dynamic channel

rs = Rate on static channel

f = Size of file


Future work

Future work

  • Multi hop links

  • More complex allocation schemes

  • Finer data granularity and patterns

  • Improve channel switching time

  • Effect of frequency of channel switching


Conclusions

Conclusions

  • Dynamic performed better than Static and Random

  • Static on a free channel provides upper bound on Dynamic performance; improvements come when static channel is loaded (channel usage varies over time)


  • Login