QoS-Assured In-Network Processing in Wireless Cyber-Physical Systems: A Survey Qiao Xiang Advisor:...
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QoS-Assured In-Network Processing in Wireless Cyber- Physical Systems: A Survey Qiao Xiang Advisor: Hongwei Zhang
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Transcript of QoS-Assured In-Network Processing in Wireless Cyber-Physical Systems: A Survey Qiao Xiang Advisor:...
QoS-Assured In-Network Processing in Wireless Cyber-Physical Systems: A Survey
Qiao Xiang
Advisor: Hongwei Zhang
Outlines
Introduction
In-Network Processing Methods
QoS-Assured INP in WCPS
Open Issues
Conclusion
Outlines
Introduction
In-Network Processing Methods
QoS-Assured INP in WCPS
Open Issues
Conclusion
Introduction
Wireless Sensor Networks:
Highly Resource- (Energy-) and Environment- Constrained
In-Network Processing:
Reduce Traffic Flow → Resource (Energy) Efficient
Category:
Application Independent Application Dependent
Data AggregationPacket PackingNetwork Coding
Data FusionQuery Processing
From WSN to WCPS
Wireless Cyber-Physical Systems:
Close-Loop vs. Open-Loop
INP in WCPS:
More emphasis on Quality of Service
e.g., latency and reliability
Outlines
Introduction
In-Network Processing Methods
QoS-Assured INP in WCPS
Open Issues
Conclusion
In-Network Processing Methods
Data Aggregation
Packet Packing
Network Coding
Data Fusion
Query Processing
Data Aggregation
Aggregate/Compress Correlated Data
Most common INP mechanism
Different Design Goals:
Energy Efficiency
Collision Reduction
Scalability
Network Lifetime
Data Aggregation
Current Research:
How to build efficient aggregation structure
Representative approaches: Chain structure Cluster structure Tree structure Structure free
Packet Packing
Assemble small packets into larger ones (No aggregation)
Data correlation is not important
Current Research:
Schedule small packets to transmit or wait.
Approaches: Opportunistic,
Pre-defined waiting time
Greedy
Drawbacks: No hard latency guarantee
Network Coding
Make use of the broadcast nature of wireless communication
Main Goal: improve throughput
Current Research:
Cooperation of random linear
network coding and routing
Network Coding
Inter-flow coding: COPE
Only packets with different destinations can be coded together
Intra-flow coding: MORE, Pacifier
Only packets with the same destination get coded together
Hybrid coding:
First do inter-flow coding, then do intra-flow coding
Examples of Inter and Intra Flow Coding
D
C
A
B
P1, P3
P1, P4
P3, P4
P1, P2, P3, P4
DC
A
B
P1, P2 P2, P3 P3, P4
P1, P2, P3, P4
Data Fusion
Main Goal: Assure data accuracy
More complex than aggregation/compression
Data is processed by sensors before the transmission
Data can be further processed at intermediate sensors during the transmission
Sensors’ roles are more flexible.
Representative works: DFuse
Query Processing
Main Goal: Data Accuracy and energy efficient
Data is only collected when there is a query request.
Requests are optimized before being sent to sensors.
Depending on different query requests, data is processed during the transmission.
Not every sensor need to response to a query request.
Representative works: TAG, CAG, TinyDB
Outlines
Introduction
In-Network Processing Methods
QoS-Assured INP in WCPS
Open Issues
Conclusion
QoS-Assured INP in WCPS
Mission-Critical Real-Time WCPS
Latency-Guaranteed INP
Reliability-Guaranteed INP
Latency-Guaranteed INP
Data Aggregation:
Only Soft-Latency guarantee is provided
End-to-End Latency One-hop Latency
Feedback control Define rewards function
Evenly divide the spare time Semi-Markov chain
Define new metric
Latency-Guaranteed INP
Packet Packing
Only Soft-Latency guarantee is provided
End-to-End Latency One-hop Latency
Grouping packets Pre-defined packet size
Opportunistic
Feedback control
Latency-Guaranteed INP
Network Coding
Network Coding can improve average end-to-end delay
Individual delay of each packet is still an unexplored area
Data Fusion
Latency constraints can be achieved by adjusting network density
Reliability-Guaranteed INP
Data Aggregation, Data Fusion, and Query Processing
Traffic load reduced → Collision and Interferences reduced → Reliability is assured
Packet Packing
Packet size is controlled to ensure the reliability
Network Coding
Similar to packet packing, coding degree can be controlled to ensure the reliability
Outlines
Introduction
In-Network Processing Methods
QoS-Assured INP in WCPS
Open Issues
Conclusion
Open Issues
Systematic Modeling and Complexity Analysis
Joint Optimization of QoS and WCPS-specific INP
Cooperation of Different INP Methods in WCPS
Theoretical Foundations of Algorithm
Outlines
Introduction
In-Network Processing Methods
QoS-Assured INP in WCPS
Open Issues
Conclusion
