1 / 18

Cluster-based Multihop Networking with controlled Quality of Service

Cluster-based Multihop Networking with controlled Quality of Service. Joerg Habetha, Wolfgang O. Budde Philips Research, Aachen, Germany joerg.habetha@philips.com. Outline. The need for multi-cluster multi-hop communication in QBSSs Coverage area extension of a QBSS:  forwarding mechanisms

tammypittman
Download Presentation

Cluster-based Multihop Networking with controlled Quality of Service

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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Cluster-based Multihop Networking with controlled Quality of Service Joerg Habetha, Wolfgang O. Budde Philips Research, Aachen, Germany joerg.habetha@philips.com

  2. Outline • The need for multi-cluster multi-hop communication in QBSSs • Coverage area extension of a QBSS:forwarding mechanisms • Interconnection of QBSSsmulti-hop ad hoc networking • Conclusions • Next steps

  3. The need for multi-cluster multi-hop QoS-controlled W-LANs • QBSSs’ coverage area is limited to the radio range of the Hybrid Coordinator (HC) • Overall capacity for QoS-controlled traffic is given by the capacity of a single channel • Multi-cluster multi-hop communication is a necessity for QoS-enhanced wireless networks • Standardization needs to be started now!

  4. Benefits of multi-cluster multi-hop QoS-controlled W-LANs • Coverage Extension of QBSSs • Capacity Increase due to clustering • Wireless interconnection of QBSSs • More efficient use of spectrum in case of multi-hop connections (no collisions) • Builds upon existing IEEE802.11 extensions • 802.11e: QoS enhancements • 802.11h: Frequency agility

  5. Problem: Limited coverage area of QBSSs • The higher the frequency • the more ray-like the propagation, • the higher the free-space loss, • the higher the attenuation due to walls and other obstacles • thus, the smaller the coverage area

  6. FN FN HC Solution: Extension of coverage area by means of forwarding • Coverage area of HC’s QoS management increased through forwarding of control information • QBSS coverage area increased through forwarding of user traffic City scenario: FN: Forwarding Node

  7. Problem: Interconnection of QBSSs • As of today, QBSSs can only be connected through wired infrastructure • A-priori network planning required • Rather limited ad-hoc capabilities • No multi-hop mode defined for QBSSs

  8. Solution: Multi-channel Cluster Bridges • A cluster bridge (CB) associates with overlapping QBSSs operating in different channels • Part-time presence in either of the two BSSs • Throughput optimization by predefined medium access opportunities • Requires some buffer space for transportation of packets from one BSS into the other

  9. Properties of clustered wireless networks • The smaller the clusters, the more channels can be used in a given area (re-use). • Advantage: offered traffic per channel decreases • Option: spatial diversity improves re-use factor • The smaller the cluster, the higher modulation/coding can be used. • Advantage: increased channel capacity • The smaller the cluster, the more hops needed • Dynamic clustering helps to maintain efficiency

  10. Capacity increase over # clusters = Number of Clusters

  11. Clustering in 802.11 • Applicable diversity techniques • Frequency (channel) • Space • Code • Compliant with latest extensions • 802.11h: frequency agility • 802.11e: QoS enhancements (periodic beacons, reserved TXOPs)

  12. Coverage extension • FQSTA is transparent representative of HC. • Selection and hand-off of FQSTA and HC. • QoS is guaranteed. • Bandwidth-efficient. FQSTA HC

  13. Wireless Inter-connection of BSSs Cluster 1 (frequency 1) HC CB HC Cluster 2 (frequency 2) CB: Cluster Bridge HC: Hybrid Coordinator

  14. Proposal for extended MAC frame structure with additional TXOP Sub-MAC frame structure CFP CP TXOP for FQSTAand CBs Cont. free per. (CFP) CP Beacon CFP/CP, CFBs Beacon

  15. Multi-frequency forwarding solution • PCs/HCs operate on different frequencies • FQSTAs/CBs switch from one frequency to the other • FQSTAs/CBs switch during (E)DCF-phase • Switching Times TS and Waiting Times TW will occur f1 f2 f2 f1 f1 FQSTA/CB T T T T S W S W

  16. T7 T8 T9 T11 T10 T12 T13 T16 T15 T14 Work items to be tackled T4 T5 T6 HC1 T3 • Dynamic clustering • Signalling procedures • Membership management • Interconnection of clusters • Forwarding procedure • Choice of forwarding stations • CB-installation and hand-off • Routing of packets • Type of algorithm • Address resolution T2 T1 HC2 HC3

  17. Conclusions • Multi-cluster multi-hop communication is a necessity for QoS-enhanced wireless networks. • Centralized solutions based on PC/HC and Forwarding Stations / Cluster Bridges have been sketched • Compliance with current 802.11 features and extensions shown • Coverage extension and capacity increase for QoS-controlled networks is feasible

  18. Next steps • Discussion and standardization has to be started now • 802.11a is in initial deployment • 802.11e/h are settling these days • The road towards coverage extension and capacity increase must be presented in short term • Experience from simulation exists • Partners needed!

More Related