1 / 19

Hard Real-Time Wireless Communication in the Northern Pierre Auger Observatory

Roger Kieckhafer (rmkieckh@mtu.edu) for the Pierre Auger Collaboration. Hard Real-Time Wireless Communication in the Northern Pierre Auger Observatory. Auger North and South. From the beginning: two sites were planned Northern and Southern Hemispheres Auger North: Planning Stages

isi
Télécharger la présentation

Hard Real-Time Wireless Communication in the Northern Pierre Auger Observatory

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. Roger Kieckhafer (rmkieckh@mtu.edu) for the Pierre Auger Collaboration Hard Real-Time Wireless Communication in theNorthern Pierre Auger Observatory RT2010 - Lisboa

  2. Auger North and South • From the beginning: two sites were planned • Northern and Southern Hemispheres • Auger North: • Planning Stages • Lamar, Colorado USA • Auger South: • Fully Operational • Malargue, Argentina RT2010 - Lisboa

  3. Flourescence Detector (FD)Telescopes Surface Detector (SD) Array ObservatoryFunctionalOverview H+ Shower of secondary particles Timestamps+ other data RT2010 - Lisboa

  4. T2 Trigger Message(Timestamps of promising events) T3 Trigger Message(Req. data on correlated timestamps) T3 Response Message Stream(Return data on req. timestamps) SD Wireless – Real-Time Sequence SD Station(in the field) CDAS(ObservatoryCampus) Record andfiltertimestamps CorrelateTimestampsAcross Stations Access Dataon requestedtimestamps Conductfurther analysis RT2010 - Lisboa

  5. Auger North vs South. • Auger North puts greater demands on the wireless net • Auger North will be much larger • Auger North will have higher data rates • Auger North will have roughly the same real-time deadlines RT2010 - Lisboa

  6. AugerSouthFootprint AugerNorthFootprint Auger North Site RT2010 - Lisboa

  7. Auger South SD Communication • Wide area wireless net • Microwave towers form a communication backbone • 4 Collector Towers on periphery of array • 1 Destination Tower at Malargue campus • 1-hop station-to-tower link for each station • Remarkably flat topography in the interior • Sizable hills on the periphery of the array • Easy to give each station a clear line-of-sight to a tower RT2010 - Lisboa

  8. Auger North Communication Problem • Array is 7 x Bigger than South • Need > 30 towers @ 45 mto stay within radio range • Terrain is Rougher than South • No convenient peripheral hills • Many small internal hills & ridges • Can not get reliable line-of-sight over that terrain • Bottom line: • 1-hop Station-to-Tower comm.does not work • >10% of stations incommunicado Lamar Springfield RT2010 - Lisboa

  9. Only Viable Option: Peer-to-Peer WSN • Auger North uses a new paradigm called “WAHREN” • WAWireless Architecture • Infrastructure Nodes (INs) = the dominant feature • Non-Infrastructure Nodes (NINs) = optional “guest” nodes • HRHard Real-time • Time-Bounded  subject to hard real-time deadlines • Deterministic  not subject to stochastic-timing • ENEmbedded Networks • Fault-Tolerant  Fully Redundant Comp. & Comm. • Fully Distributed  No leaders, coordinators, masters RT2010 - Lisboa

  10. 1 2 3 4 5 6 7 8 9 10 2 4 6 8 10 1 3 5 7 9 WAHREN Interconnection Topology • Uses 2nd Order Power chains (“Braided Chain”) • Graph Topology: • Start with a basic chain – nearest neighbor comm only • Extend range to reach second-nearest neighbors • Useful Physical Realization = 2D Triangular Mesh q RT2010 - Lisboa

  11. 10’ 9’ 8’ Must be Preventedby Protocol 7’ Mobius Fold 2 4 6 8 10 1 3 5 7 9 Turning Corners • Our Target Infrastructures are not always straight lines • Gentle curves are no problem • But what aboutsharp corners? • Existence of Mobiusfold is transparentto the topology RT2010 - Lisboa

  12. TDMA CSMA NIN Trans IN Transmissions Hybrid TDMA/CSMA MAC Protocol • Hybrid Window Combines TDMA & CSMA slots • Enough TDMA slots for all INs within interference range • Enough CSMA slots for expected/desired number of NINs • Auger North-Specific Comm Window • 8 TDMA slots – for neighboring Infrastructure Nodes • Based on predicted interference range, and • Alternating use of 2 RF channels • 1 CSMA slot – expecting few non-infrastructure nodes Window RT2010 - Lisboa

  13. 1 3 5 Win-3 Win-1 Win-5 Win-0 Win-2 Win-4 2 4 6 Systolic Broadcast Scheduling Protocol • Unidirectional Single-Source Broadcast: • Window 0: Node 0 originates a message • Window w: Node w forwards node 0’s message • Redundancy: Node Red = Path Red = Time Red = 2 • Unidirectional Multi-Source Broadcast • Window 0: All nodes originate a message • Window w: Node k forwards node (k-w)’s message 0 RT2010 - Lisboa

  14. Sector Service Area Adapting WAHREN to Auger Topology • Array is partitioned into “service areas” • Each served by one Concentrator Station • Each Service Area is partitioned into “sectors” • Sectors can be triangular, rectangular, or quite amorphous RT2010 - Lisboa

  15. Comm Sequence in One Sector • Auger North SD is a 2 mi square array tilted 45 degrees • Any adjacent pair of E-W rows or N-S columns naturally forms a 2nd order power chain • Can easily be organized into Backbones & Side Chains • Linked at Mobius Folds Side Chains Concentrator Station Fiber to Campus PCHost Backbone RT2010 - Lisboa

  16. System Throughput • Can Meet all required deadlines: • With up-to 128 stations / sector • 4,400 stations  35 sectors • 8 sectors/concent.  5 concents. • IF they are all centrally located. • Current Proposal is to put concentrators at the 5 FDs • Power, fiber & bldgs already exist • But, some FDs are on Periphery • They serve fewer sectors • May need 6-7 Concentrators • 5 at FDs + 1-2 standalone • That is still much cheaper than 30 tall towers RT2010 - Lisboa

  17. Research & Development Array (RDA) • Being built Near Lamar, CO • Goal: to test the riskier new technologies • Station Configuration • 10 fully functional stations • 10 comms-only stations • 1 concentrator • Array Layout • 1 backbone (A-J) • 1 side chain (K-O) • 6 off-grid “infill” stations (L-T) Lamar RT2010 - Lisboa

  18. Summary • WAHREN paradigm is well suited to Auger North: • Power Chain Architecture  path & node redundancy • Hybrid TDMA/CSMA MAC  real-time stability • Systolic Broadcast Sched  time redundancy & efficiency • Deadlines and throughput can be satisfied: • With a handful of concentrators • Much more cheaply than tall towers • Some items we had to skip today: • Formal validation & verification of the protocol – done • Detailed Markov Reliability modeling of a sector – done • Multimodal Performability modeling of a sector – in progress • Station radio hardware/software development – in progress RT2010 - Lisboa

  19. Questions? RT2010 - Lisboa

More Related