Qos provisioning in wireless mesh networks
This presentation is the property of its rightful owner.
Sponsored Links
1 / 23

QoS Provisioning in Wireless Mesh Networks PowerPoint PPT Presentation


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

QoS Provisioning in Wireless Mesh Networks. Ali Hamidian and Ulf Körner. Fourth EuroNGI/FGI Workshop on Wireless and Mobility January 16-18 2008, Barcelona, Spain. Outline. Overview of IEEE 802.11e EDCA with Resource Reservation (EDCA/RR) Multi-hop resource reservation in EDCA/RR Summary.

Download Presentation

QoS Provisioning in Wireless Mesh 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


Qos provisioning in wireless mesh networks

QoS Provisioning in Wireless Mesh Networks

Ali Hamidian and Ulf Körner

Fourth EuroNGI/FGI Workshop on Wireless and Mobility

January 16-18 2008, Barcelona, Spain


Outline

Outline

  • Overview of IEEE 802.11e

  • EDCA with Resource Reservation (EDCA/RR)

  • Multi-hop resource reservation in EDCA/RR

  • Summary


Ieee 802 11e and hcf

IEEE 802.11e and HCF

  • 802.11e introduces hybrid coordination function (HCF), which has 2 medium access methods:

    • enhanced distributed channel access (EDCA)

    • HCF controlled channel access (HCCA)

  • HCF introduces 2 new concepts:

    • transmission opportunity (TXOP): A bounded time interval during which a station may transmit multiple frames

    • traffic specification (TSPEC): Contains information about the QoS expectation of a traffic stream (frame size, service interval, data rate, burst size, delay bound, etc.)


Edca hcca

EDCA HCCA

  • Contention-based

  • “Enhanced DCF”

  • Distributed

  • Service differentiation

  • Contention-free

  • “Enhanced PCF”

  • Centralized

  • Resource reservation


Motivation of edca rr qos limitations in 802 11e

Motivation of EDCA/RR: QoS Limitations in 802.11e

  • Problem with EDCA

    • Contention-based medium access & no distributed admission control ==> not possible to guarantee QoS

  • Problem with HCCA

    • Centralized infrastructure requirement ==> HCCA not useful in ad hoc/mesh networks

  • We need a solution which is

    • Contention-free (unlike EDCA)

      • Remove the random medium access delays

    • Distributed (unlike HCCA)

      • Remove the need of an access point


Outline1

Outline

  • Overview of IEEE 802.11e

  • EDCA with Resource Reservation (EDCA/RR)

  • Multi-hop resource reservation in EDCA/RR

  • Summary


Edca rr operation

EDCA/RR Operation

EDCA/RR is similar to EDCA as long as the stations are sending LP-frames (which do not need resource reservation).

destination

source


Edca rr operation1

EDCA/RR Operation

When an HP-stream needs to reserve resources, EDCA/RR in the source checks whether its own new stream can be admitted.

destination

source


Edca rr operation2

EDCA/RR Operation

  • If admission control OK:

  • schedule the new stream

  • broadcast ADDTS request containing TSPEC

  • wait for ADDTS response

destination

source

ADDTS request


Edca rr operation3

EDCA/RR Operation

Once all ADDTS responses are received by the source, it waits until its first reserved TXOP at service start time & starts transmitting.

destination

source

ADDTS response


Edca rr operation4

EDCA/RR Operation

Now the source has periodic and contention-free access to the medium.

destination

source

HP data frames


Simulation setup

Simulation Setup

  • EDCA/RR implementation in ns-2.26 based on Mike Moreton’s enhanced 802.11/802.11e implementation

  • EDCA vs. EDCA/RR

  • The impact of (hidden) LP-streams on an HP-stream

  • HP stream (AC_VO): G.711, 180 B, UDP datagrams every 20 ms

  • LP stream (AC_BE): FTP, 1000 B, TCP segments


Average end to end delay 0 packet error

Average End-to-End Delay - 0 % packet error


Outline2

Outline

  • Overview of IEEE 802.11e

  • EDCA with Resource Reservation (EDCA/RR)

  • Multi-hop resource reservation in EDCA/RR

  • Summary


Motivation why edca rr for wireless mesh networks wmns

Motivation: Why EDCA/RR for Wireless Mesh Networks (WMNs)?

  • EDCA/RR (with multi-hop capability) is especially well-suited for static wireless networks, like WMNs

  • IEEE 802.11s for mesh networks is based on EDCA, so it is not too difficult/unrealistic extending 802.11s to support EDCA/RR


Motivation why edca rr for wireless mesh networks wmns1

Motivation: Why EDCA/RR for Wireless Mesh Networks (WMNs)?

  • Results from a 4-hop 802.11g WMN

CS = Counter Strike

server to clients: (50.4+6.15×n) B every 60 ms

clients to server: 42 B every 50 ms


Multi hop resource reservation in edca rr

Multi-hop Resource Reservation in EDCA/RR

  • Combined route discovery (AODV) and resource reservation (EDCA/RR)

    • search for route fulfilling the QoS requirements

    • faster route discovery/resource reservation

  • Why AODV? Because it will be part of HWMP (Hybrid Wireless Mesh Protocol), which is the default routing protocol suggested in 802.11s

    • reactive part: RM-AODV (Radio Metric AODV)

    • proactive part: tree-based routing


Multi hop resource reservation in edca rr1

Multi-hop Resource Reservation in EDCA/RR

  • Copy TSPEC from HP-packet to RRQ

  • Do admission control

  • Temporarily mark resources as reserved and broadcast RRQ

RRQ (route and reservation request) is a RREQ extended with some TSPEC fields.

A

B

C

An HP-packet is sent down the protocol stack and reaches the routing protocol (AODV).


Multi hop resource reservation in edca rr2

Multi-hop Resource Reservation in EDCA/RR

  • Copy TSPEC from RRQ

  • Do admission control

  • Temporarily mark resources as reserved and rebroadcast RRQ

A

B

C


Multi hop resource reservation in edca rr3

Multi-hop Resource Reservation in EDCA/RR

  • Copy TSPEC from RRQ

  • Do admission control

  • Schedule the traffic request and send a RRP

A

B

C


Multi hop resource reservation in edca rr4

Multi-hop Resource Reservation in EDCA/RR

Schedule traffic and forward RRP

A

B

C


Multi hop resource reservation in edca rr5

Multi-hop Resource Reservation in EDCA/RR

Schedule traffic; TXOP reservation done

A

B

C


Summary

Summary

  • EDCA/RR

    • is a MAC scheme with distributed admission control and scheduling

    • allows stations to reserve TXOPs for periodic and contention-free medium access

    • suites well for WMNs


  • Login