1 / 11

1-PREQ : n-Targets versus n-PREQ : 1-Target

1-PREQ : n-Targets versus n-PREQ : 1-Target. Authors:. Date: 2009-01-22. Abstract.

vlora
Download Presentation

1-PREQ : n-Targets versus n-PREQ : 1-Target

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. 1-PREQ : n-Targets versus n-PREQ : 1-Target Authors: Date: 2009-01-22 Michael Bahr, Siemens AG

  2. Abstract This presentation list several reasons for having multiple targets in a single PREQ. Furthermore, it shows that the concept of having multiple PREQs with a single target in the same Mesh Path Selection frame has the potential of erroneous processing. The presentation recommends to keep the currently specified mechanism of having multiple targets in a single PREQ. Michael Bahr, Siemens AG

  3. PREQ with multiple Targets (I)1:n-PREQ • used in Path Maintenance • path maintenance necessary due to changing link qualities • path maintenance updates path metric and finds better paths than the existing ones • keeps paths current • used for simultaneous discovery of multiple destinations • Low number of octets • 28 + N*11 • minimum is 39 • all destinations have same HWMP SN and PREQ ID • order of targets is not important • all targets are processed for the same HWMP SN (same point in time) Michael Bahr, Siemens AG

  4. PREQ with multiple Targets (II)1:n-PREQ • simple generation • processing • the freshness of all targets is defined by the same condition, that is, the freshness or improvement of the reverse path to the originator • the path to the originator is updated only once • processing of targets is a for-loop from 1 to n over all targets • processing of all targets happens in a single “IE processing function”, that is, the IE processing routine is entered only once • completely described in draft • more complex description but complete and implementable and “processable” Michael Bahr, Siemens AG

  5. Multiple PREQ with single Target (I)n:1-PREQ • simultaneous discovery of multiple destinations has to be done with multiple PREQs with a single target in the same Mesh Path Selection frame • Increased number of octets • N * 38, minimum is 38 Michael Bahr, Siemens AG

  6. Multiple PREQ with single Target (II)n:1-PREQ • all destinations have different HWMP SN and PREQ ID • order of PREQs is important! • PREQs have to be ordered with ascending HWMP SN • all targets are processed for different HWMP SN (different points in time) • increased overhead and complexity for the compilation of the mesh path selection frame • Problem with HWMP SN number ordering • if a PREQ IE of higher order in the mesh path selection frame has a lower HWMP SN than a PREQ IE of lower order, it will not be processed, that is, no generation of PREP and no propagation. • if the same HWMP SN is used for all PREQs, the problem is simply pushed to the PREQ ID Michael Bahr, Siemens AG

  7. Multiple PREQ with single Target (III)n:1-PREQ • complex generation due to necessary ordering based on HWMP SN • processing • the freshness of all targets, that is, the freshness or improvement of the reverse path to the originator is defined by the different conditions due to the sequential processing of independent PREQs • the path to the originator is updated multiple times • processing of targets is the same as for 1:n-PREQ except for the repeated processing of the targets • processing of all targets happens in multiple (n) “IE processing function” calls, that is, the IE processing routine is entered multiple (n) times • simpler description Michael Bahr, Siemens AG

  8. Byte Overhead Michael Bahr, Siemens AG

  9. 1:n-PREQ vs. n:1-PREQ Michael Bahr, Siemens AG

  10. Summary • path maintenance is necessary in wireless mesh network with radio-aware link metrics • need efficient mechanism (overhead, processing, correctness) • PREQs with multiple targets • have less overhead, • can be implemented and processed effiently • provide no potential pitfalls for erroneous processing • multiple PREQs with single target • increase byte overhead • require a more complex generation (ordering of PREQ IEs based on HWMP SN) • result in processing errors if order of HWMP SN is not correct • have as major advantage an easier specification only • recommendation: keep the multiple targets in the PREQ Michael Bahr, Siemens AG

  11. References • IEEE 802.11s Draft 2.06 • 11-09/0149r1 „Action frames and addressing“ Michael Bahr, Siemens AG

More Related