Qiao Xiang Advisor Hongwei Zhang Outlines Introduction InNetwork Processing Methods QoSAssured INP in WCPS Open Issues Conclusion Outlines Introduction InNetwork Processing Methods QoSAssured INP in WCPS ID: 624561
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QoS-Assured In-Network Processing in Wireless Cyber-Physical Systems: A Survey
Qiao Xiang
Advisor: Hongwei ZhangSlide2
Outlines
Introduction
In-Network Processing Methods
QoS-Assured INP in WCPS
Open Issues
ConclusionSlide3
Outlines
Introduction
In-Network Processing Methods
QoS-Assured INP in WCPS
Open Issues
ConclusionSlide4
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 Aggregation
Packet Packing
Network Coding
Data Fusion
Query ProcessingSlide5
From WSN to WCPSWireless Cyber-Physical Systems:
Close-Loop vs. Open-Loop
INP in WCPS:
More emphasis on Quality of Service
e.g., latency and reliability
Slide6
Outlines
Introduction
In-Network Processing Methods
QoS-Assured INP in WCPS
Open Issues
ConclusionSlide7
In-Network Processing Methods
Data Aggregation
Packet Packing
Network Coding
Data Fusion
Query ProcessingSlide8
Data Aggregation
Aggregate/Compress Correlated Data
Most common INP mechanism
Different Design Goals:
Energy Efficiency
Collision Reduction
Scalability Network LifetimeSlide9
Data Aggregation
Current Research:
How to build efficient aggregation structure
Representative approaches:
Chain structure
Cluster structure
Tree structureStructure freeSlide10
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 guaranteeSlide11
Network Coding
Make use of the broadcast nature of wireless communication
Main Goal: improve throughput
Current Research:
Cooperation of random linear
network coding and routingSlide12
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
Slide13
Examples of Inter and Intra Flow CodingSlide14
Data FusionMain 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:
DFuseSlide15
Query ProcessingMain 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,
TinyDBSlide16
Outlines
Introduction
In-Network Processing Methods
QoS-Assured INP in WCPS
Open Issues
ConclusionSlide17
QoS-Assured INP in WCPS
Mission-Critical Real-Time WCPS
Latency-Guaranteed INP
Reliability-Guaranteed INPSlide18
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 metricSlide19
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 controlSlide20
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
Slide21
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 reliabilitySlide22
Outlines
Introduction
In-Network Processing Methods
QoS-Assured INP in WCPS
Open Issues
ConclusionSlide23
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 AlgorithmSlide24
Outlines
Introduction
In-Network Processing Methods
QoS-Assured INP in WCPS
Open Issues
Conclusion