1. SPEED: A Stateless Protocol for Real-Time Communication in Sensor Networks RAP: A Real-Time Communication Architecture for Large-Scale Wireless Sensor Networks
CS851 Presentation
By: Gary Zhou
Computer Science Department
University of Virginia
11/15/2018

2. Outline Comparison: SPEED vs. RAP Background: SPEED and Its Family
SPEED Details
RAP Details
Critiques and Discussion
11/15/2018

3. SPEED vs. RAP Similarities Differences Soft real-time No guarantees
Ad hoc deployment
Dynamic traffic
Homogeneous platform
Motes
Differences
No priority, ordinary MAC
SPEED=Distance/Delay
Distance (node, neighbor)
Reflect communication capacity
Traffic Control
SNGF
MAC Layer adaptation
Back-Pressure Rerouting
Provide priority, need prioritized MAC
Velocity=Distance/Deadline
Distance (Source, Destination)
Reflect local emergency
VMS?? (No)
11/15/2018

4. Can we combine SPEED & RAP ??
SPEED talks about the real-time scheduling between nodes. It decides the candidate node to forward the packet to.
RAP talks about the real-time scheduling within a single node. It decides the candidate packet to send out.
So they talk about real-time in different spaces:
between nodes vs. within a node.
So they talk about real-time in different time segments during the whole period the packet is forwarded from the source to the destination.
The time series is "SPEED - RAP - SPEED - RAP - SPEED - RAP "
So to combine (integrate) them together is reasonable and feasible.
11/15/2018

5. SPEED and Its Family (important members only)
Reverse Path
AODV
DSR DD
LAR
Neighbor Table GF
GPSR
SPEED
IGF
GF, DSR and AODV are used in evaluations of SPEED and RAP
11/15/2018

6. Background – GF
GF always chooses the node that is closest to the destination in FS. s d
11/15/2018

7. Background – Route Requests in AODVY Z S E F B C M L J A G H D K I N
Represents a node that has received RREQ for D from S
11/15/2018

8. Background – Route Requests in AODVY Z S E F B C M L J A G H D K I N
Represents transmission of RREQ
11/15/2018

9. Background – Route Requests in AODVY Z S E F B C M L J A G H D K I N
Represents links on Reverse Path
11/15/2018

10. Background – Reverse Path Setup in AODVY Z S E F B C M L J A G H D K I N
Node C receives RREQ from G and H, but does not forward
it again, because node C has already forwarded RREQ once
11/15/2018

11. Background – Reverse Path Setup in AODVY Z S E F B C M L J A G H D K I N
11/15/2018

12. Background – Reverse Path Setup in AODVY Z S E F B C M L J A G H D K I N
Node D does not forward RREQ, because node D
is the intended target of the RREQ
11/15/2018

13. Background – Forward Path Setup in AODVY Z S E F B C M L J A G H D K I N
Forward links are setup when RREP travels along the reverse path
Represents a link on the forward path
11/15/2018

14. Background – Route Discovery in DSRZ S E F B C M L J A G H D K I N
Represents a node that has received RREQ for D from S
11/15/2018

15. Background – Route Discovery in DSR
Broadcast transmission Z
[S] S E F B C M L J A G H D K I N
Represents transmission of RREQ
[X,Y] Represents list of identifiers appended to RREQ
11/15/2018

16. Background – Route Discovery in DSRZ S
[S,E] E F B C M L J A G
[S,C] H D K I N
11/15/2018

17. Background – Route Discovery in DSRZ S E F B
[S,E,F] C M L J A G H D K
[S,C,G] I N
Node C receives RREQ from G and H, but does not forward
it again, because node C has already forwarded RREQ once
11/15/2018

18. Background – Route Discovery in DSRZ S E F
[S,E,F,J] B C M L J A G H D K I N
[S,C,G,K]
11/15/2018

19. Background – Route Discovery in DSRZ S E
[S,E,F,J,M] F B C M L J A G H D K I N
Node D does not forward RREQ, because node D
is the intended target of the route discovery
11/15/2018

20. Background – Route Reply in DSRZ S
RREP [S,E,F,J,D] E F B C M L J A G H D K I N
Represents RREP control message
11/15/2018

21. Background – Data Delivery in DSRZ
DATA [S,E,F,J,D] S E F B C M L J A G H D K I N
Packet header size grows with route length
11/15/2018

22. SPEED Goals Soft real-time: predictable e2e delay High Scalability
Uniform communication speed
High Scalability
Stateless Architecture
Localized Behavior
Load Balancing
Traffic Control
MAC Layer Adaptation
Network Layer Adaptation
Void Avoidance
11/15/2018

23. SPEED Architecture
11/15/2018

24. Last Mile Process
SNGF
Backpressure
Rerouting
NFL
Beacon
Exchange
API
UniCast
MultiCast
AnyCast
MAC
Delay
Estimation
Neighbor
Table
API & Last Mile Process
AreaMulticastSend(Center position, radius, deadline, packet)
AreaAnyCastSend(Center position, radius, deadline, packet)
UnicastSend(Global_ID,deadline,packet)
SpeedReceive()
11/15/2018

25. SNGF – 1 (NS & FS) Neighbor Set of Node i Forwarding Set of Node i
Last Mile Process
SNGF
Backpressure
Rerouting
NFL
Beacon
Exchange
API
UniCast
MultiCast
AnyCast
MAC
Delay
Estimation
Neighbor
Table
SNGF – 1 (NS & FS)
Neighbor Set of Node i
NSi = {node | distance(node , node i )  R }
Forwarding Set of Node i
FSi (Destination) = {node  NSi | L – L_next > 0 }  NSi
11/15/2018

26. SNGF -2 (SPEED Calculation)
Lec
Lac
11/15/2018

27. SNGF - 3 (Example) Destination Source Boo Packet Node 5's NT Packet
Delay
0.5s
0.1s
0.4s ID 9 7 10 3
SPEED 20
110 30
115 7 11
Packet
Destination 5
Packet 9 2
Delay 3 10
Source
Boo
11/15/2018

28. SNGF – 4 (Some Definitions)
Speed Set Point: A desired smallest speed towards the destination
So e2e delay is bounded by (Distance/Speed Set Point)
Speed Miss: a single hop relay speed violates the set point.
Miss Ratio: the percentage of packet miss over a certain time window.
11/15/2018

29. NFL & Back-Pressure Rerouting
Last Mile Process
SNGF
Backpressure
Rerouting
NFL
Beacon
Exchange
API
UniCast
MultiCast
AnyCast
MAC
Delay
Estimation
Neighbor
Table
NFL & Back-Pressure Rerouting
Delay Estimation: Delay=Round Trip Time–Receiver Side Processing Time
Relay Ratio Control
On/Off Switch
Back-Pressure Rerouting
11/15/2018

30. Back-Pressure Rerouting (Example)
ID Delay S S
Node 6's NT
Packet (to 4) 6
Beacon 7
ID Delay S S S
Node 3's NT
Boo
Delay 1 3 5
Packet 2
Packet 1 9 2
Packet 1
Packet 2 3 10
Packet 2 12
Packet 2 4
Packet 2 11
11/15/2018

31. Void Avoidance In a similar way it deals with traffic congestion.
Last Mile Process
SNGF
Backpressure
Rerouting
NFL
Beacon
Exchange
API
UniCast
MultiCast
AnyCast
MAC
Delay
Estimation
Neighbor
Table
Void Avoidance
In a similar way it deals with traffic congestion.
Backpressure beacon (ID, Destination, Positive Infinity)
Only guarantee a greedy path 1 2 5 4 3
11/15/2018

32. Evaluations: Simulation Setup -1
Components
Setting
Simulator & TestBed
GloMoSim & Berkeley Motes
Routing
SPEED, AODV, DSR, GF (Max Progress )
SPEED-S (Max Speed ), SPEED-T ( minimum delay)
MAC Layer
( Simplified DCF)
Radio Layer
RADIO-ACCNOISE
Propagation
TWO-RAY
Bandwidth
200Kb/s
Payload size
32 Byte
TERRAIN
(200m, 200m)
Node number
100
Node Placement
Uniform
Radio Range
40m
Runs 16
11/15/2018

33. #E2E Delay vs. Congestion-Level
Congestion Avoidance
(Heavy Congestion) Delay: SPEED performs best
Delay: SPEED-T > GF,SPEED,SPEED-S
Delay: AODV>DSR>SPEED
#E2E Delay vs. Congestion-Level
11/15/2018

34. #Control Packets vs. Congestion-Level
Control Overhead
(Heavy Congestion) #Packets: DSR>SPEED>GF=SPEED-T=SPEED-S
(Light Congestion) #Packets: DSR<GF,SPEED,SPEED-S,SPEED-T
#Packets: AODV>SPEED
#Control Packets vs. Congestion-Level
11/15/2018

35. Energy Consumption for Transmission
When Rate<60, SPEED has more Control Packets than DSR
But consumes less energy than DSR. Why???
(Light Congestion) Energy Consumed: SPEED=GF=SPEED-S
Energy Consumed: AODV>DSR>SPEED,GF,SPEED-S,SPEED-T
(Heavy Congestion) Energy Consumed: SPEED>GF,SPEED-S
Energy Consumed vs. Congestion-Level 5 10 15 20 25 30 35 40 50 60 70 80 90
100
Rate (P/S)
AODV
DSR
SPEED GF
SPEED-S
SPEED-T
Energy Consumption
11/15/2018

36. Density (nodes per radio circle)
Void Avoidance
70%
75%
80%
85%
90%
95%
100%
15.5
13.9
12.6
11.4
10.4
9.5
8.7
8.0
Density (nodes per radio circle)
DSR
SPEED GF
SPEED-S
SPEED-T
Delivery Rate
Delivery Rate: DSR>SPEED>SPEED-S=GF=SPEED-T
Delivery Ratio vs. Node Density
11/15/2018

37. RAP Goals Minimize e2e deadline miss ratio
Provide high-level services APIs (similar to SPEED)
High scalability
Minimize communication and processing overhead
11/15/2018

38. RAP Architecture Sensing/Control Application Query/Event Service
Query/Event Service APIs
Query/Event Service
Coordination Service
Location-Addressed Protocol
Geographic Routing
Velocity Monotonic Scheduling
Prioritized MAC
11/15/2018

39. Query/Event API Example: register_event {
Velocity Monotonic Scheduling
Prioritized MAC
Query/Event Service
Coordination Service
Location-Addressed Protocol
Geographic Forwarding
Query/Event API
Example:
register_event {
virusFound(0,0,100,100), // area to post event
query { // query to be triggered
virus.count, // attribute
area=(x-1,y-1,x+1,y+1), // query area
period=1.5, deadline=5, // timing info
base=(100,100) // base station location }
11/15/2018

40. Velocity Monotonic Scheduling
Prioritized MAC
Query/Event Service
Coordination Service
Location-Addressed Protocol
Geographic Forwarding
Velocity
Time constraint: deadline
Location constraint: distance to destination
Requested Velocity
Embody both constraints
Velocity = Distance/Deadline (Difference with SPEED ?)
Reflect local urgency
Velocity Monotonic Scheduling (VMS)
Priority is set based on Requested Velocity
11/15/2018

41. Example D E A C B dis = 90 m; D = 2 s V = 45 m/s HIGH Priority
LOW Priority
11/15/2018

42. Velocity Monotonic Scheduling
Static VMS
Fixed velocity on each hop
V=dis(x0,y0,xd,yd)/D
Dynamic VMS
Adapt velocity at intermediate node
Vi = dis(xi,yi,xd,yd)/ Si
Si = D - elapseTime
11/15/2018

43. Velocity Monotonic Scheduling
Prioritized MAC
Query/Event Service
Coordination Service
Location-Addressed Protocol
Geographic Forwarding
Prioritized MAC
Collision Avoidance (CA)
Channel idle  wait for
(IEEE (DCF) ) Rand*DIFS
(RAP) Rand*DIFS*Prio
Contention
Collision (No CTS or No ACK) 
(IEEE (DCF) ) CW=CW*2
(RAP) CW=CW*(2+(Prio-1)/MAX_Prio)
11/15/2018

44. Overall Deadline Miss Ratios with deadlines(5,10)
Deadline Miss Ratio: FCFS>DS>DVM,SVM
Why SVM better than DVM ??
Overall Deadline Miss Ratios with deadlines(5,10)
11/15/2018

45. SVM provides “fairer” service to remote sensors (Obvious??)
Distance Fairness
SVM provides “fairer” service to remote sensors (Obvious??)
11/15/2018

46. Critiques & Discussion - SPEED
It is a very good paper. (Many issues and ideas)
No prioritization: uniform speed may not be what applications want
The uniform speed is not guaranteed (soft real-time)
Need periodical beacon to maintain neighbor table
Back-pressure Rerouting is good, but maybe not the only choice
Needs symmetric communication
11/15/2018

47. Critiques & Discussion - RAP
A very early paper to provide soft real-time in sensor network
Provides Real-Time communication architecture
Provides VMS (Set Priority based on Velocity)
As SPEED, only soft real-time, no admission control, no guarantee
In the issue of “Distance Fairness”, it is not obvious.
Continuous priority rather than discrete priority
11/15/2018

48. Thanks! The End!
11/15/2018