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Comparison of WPAN Mesh Networking Approaches

This document compares the different approaches for a 802.15.5 WPAN mesh network MAC taken by the authors of this document, as seen in document 15-05-0552-02 and the proposal 15-05-0491-01.

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Comparison of WPAN Mesh Networking Approaches

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  1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Comparison of baseline document 15-05-0552-02 and proposal 15-05-0491-01] Date Submitted: [16 January, 2006] Source: [Sebastian Max, Guido R. Hiertz] Company [Philips Research Laboratories Aachen, ComNets, RWTH Aachen University] Address [Kopernikusstr. 16, 52074 Aachen, Federal Republic of Germany] Voice:[+49-241-80-25-82-9], FAX: [+49-241-80-22-24-2], E-Mail: [smx@comnets.rwth-aachen.de] Re: [] Abstract: [To aid discussion.] Purpose: [This documents compares the different approaches for a 802.15.5 WPAN mesh network MAC taken by the authors of this document, as can be seen in document 05-0552-02 and the author of the proposal 05-0491-01.] Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. S. Max, G.R. Hiertz

  2. Comparison of the baseline document 15-05-0552-02-0005-tg5-mesh-networking-baseline-document.doc and the proposal 15-05-0469-001-0005-mesh-networking-wpan.ppt Sebastian Max, Guido R. Hiertz Philips Research Laboratories & Chair of Communication Networks, RWTH Aachen Aachen, Germany S. Max, G.R. Hiertz

  3. As already mentioned, • We are open-minded to discuss and come to consensus with Mr. Michael Sim’s proposal. • We appreciate his work and efforts to bring forward the standardization process. • We esteem his very valuable ideas and thoughts on Mesh WPAN. • We believe that it would have been very helpful for the 802.15.5 process, if Mr. Michael Sim took the opportunity to contact the authors of the current 802.15.5 proposal to receive feedback and start discussion. S. Max, G.R. Hiertz

  4. In the following comparison, blue text is copied from Mr. Sim’s presentation 15-05-0469-001-0005-mesh-networking-wpan.ppt. Black text is copied from The baseline document 15-05-0552-02-0005-tg5-mesh-networking-baseline-document.doc The presentation 15-05-0247-00-0005-mesh-pan-alliance-mpa-mesh-wpan-proposal.ppt The presentation 15-05-0670-00-0005-mesh-pan-alliance-mpa-and-15-3-integration.ppt Comparison S. Max, G.R. Hiertz

  5. Channel time is partitioned into equal-sized Medium Slots (MSs) Channel time is partitioned into equal-sized Medium Access Slots (MAS) Comparison: Time partitioning S. Max, G.R. Hiertz

  6. A piconet uses a MS exclusively for its CS (beacon + CAP) to start and maintain a basic piconet Master devices include in their beacon the MS occupancy information Devices listen to all CS in the neighbourhood Provide 1-hop information to support network extension All master device to listen CSs in the neighborhood Master device informs nearby master devices of its presence by sending an announcement in the CSs (during CAP) of the nearby master devices Every mesh device transmits a mesh beacon, used for mesh coordination Synchronization information Transmission time of neighbor’s beacons Occupancy of MASs All mesh devices listen to neighbor’s beacons and disseminate information Beacon Period bundles beacon Improved predictability Special (cautious) medium access rules to avoid beacon collisions Mesh devices can transmit a legacy 802.15.3 beacon Only if legacy 802.15.3 device is associated Comparison: Beaconing S. Max, G.R. Hiertz

  7. Collision Detection 3rd parties exists: Local device not heard in neighbor’s MS occupancy information (CS Collision) Associated slave unable to heard beacon (CS Collision) Packet addressed to devices not associated with master device heard in CAP (CS Collision) Conflict heard in MS occupancy information (ES Collision) No 3rd parties exists: Random periodic scan Repeated communication failure CS Collision Resolution ES collision: Re-allocate ES CS collision: Relocate CS to a random FS Collision avoidance: Negotiation protocol Receiver acknowledges reservation Mitigation of “Hidden Node Problem” Collision Detection Occupancy information is relayed into 2-hop neighborhood Collision is detected by Tx or Rx with the help of Neighbor’s occupancy information Repeated communication failure Collision Resolution Both parties of the collision defer from transmission, reserve new MAS  Decisions are additionally based on the receiver’s viewpoint Comparison: Collisions • Collisions occur if two mesh devices have reserved the same MAS (MS) • Related to hidden node problem S. Max, G.R. Hiertz

  8. IEEE 802.15.3 DEV+ DEV+ shall not make secondary association with PNC PNC+ PNC+ may choose associate as child/neighbor of PNC PNC+ operate within Private CTA granted by PNC PNC+ may choose to stay as “parent PNC” for PNC PNC+ allocates 1 or more consecutive ESs for PNC IEEE 802.15.3 Mesh devices support Association Data transfer Data forwarding of legacy, non-mesh 802.15.3 devices Coexistence of the mesh traffic and PN traffic Ensured by mesh-enhanced PNC Comparison: Backward Compatibility S. Max, G.R. Hiertz

  9. Interference awareness Learning of mutual interference conditions Listening during Beacon Period Dissemination of RSSI in beacon Planning of successful concurrent transmissions Adaptive to environment, attenuating walls, neighbor’s transmissions  Improves capacity of mesh network in WPAN environment Comparison: Exposed Node Problem Medium is underutilized due to overly sensitive collision avoidance mechanism S. Max, G.R. Hiertz

  10. Multiband PHY – MAC enhancements Medium reservation protocol supports reservation in Time and Channel Comparison: Multiband Enhancements How are multiple (frequency/code/etc…) channels used? Does the network capacity scale with the number of channels? S. Max, G.R. Hiertz

  11. Conclusion • Similar concepts • Timing structure • Information exchange via beacons • Reservation of time slots, collisions resolving • Different aspects • Backward compatibility to non-mesh 802.15.3 devices • Our extensions • Planned concurrent transmissions, high frequency reuse • Multi-channel S. Max, G.R. Hiertz

  12. Mahalo for your attention! Questions? Discussion! S. Max, G.R. Hiertz

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