Roger kieckhafer rmkieckh@mtu edu for the pierre auger collaboration
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Roger Kieckhafer ([email protected]) 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

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Roger kieckhafer rmkieckh@mtu edu for the pierre auger collaboration

Roger Kieckhafer

([email protected])

for the Pierre Auger Collaboration

Hard Real-Time Wireless Communication in theNorthern Pierre Auger Observatory

RT2010 - Lisboa


Auger north and south

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


Hard real time wireless communication in the northern pierre auger observatory

Flourescence Detector (FD)Telescopes

Surface Detector (SD) Array

ObservatoryFunctionalOverview

H+

Shower of secondary particles

Timestamps+ other data

RT2010 - Lisboa


Sd wireless real time sequence

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


Auger north vs south

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


Auger north site

AugerSouthFootprint

AugerNorthFootprint

Auger North Site

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Auger south sd communication

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


Auger north communication problem

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


Only viable option peer to peer wsn

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


Wahren interconnection topology

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10

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10

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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


Turning corners

10’

9’

8’

Must be Preventedby Protocol

7’

Mobius Fold

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10

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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


Hybrid tdma csma mac protocol

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

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Systolic broadcast scheduling protocol

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Win-3

Win-1

Win-5

Win-0

Win-2

Win-4

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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


Adapting wahren to auger topology

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


Comm sequence in one sector

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


System throughput

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


Research development array rda

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


Summary

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


Questions

Questions?

RT2010 - Lisboa


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