Delay-Aware Big Data Collection Strategies for Sensor Cloud Services Dr. Chi-Tsun (Ben), Cheng

Transcription

1 Delay-Aware Big Data Collection Strategies for Sensor Cloud Services Dr. Chi-Tsun (Ben), Cheng

2 An Overview Introduction Wireless Sensor Networks A Military Application (SASNet) Delay-Aware Data Collection Strategies Single Data Stream with Data Compression 2

3 An Overview (cont ) Delay-Aware Data Collection Strategies (cont ) Multiple Data Streams with Data Compression Conclusions 3

4 Introduction 4

5 Wireless Sensor Networks Large numbers of wireless sensor nodes Battery-powered (2x AA batteries) Low data rate (250 kbps) Limited processing power (AT Mega1281) Low-cost Limited communication range (<500m) MEMSIC IRIS MOTE ARDUINO UNO + XBEE 5

6 Wireless Sensor Nodes Micro-controller Transceiver Sensors Batteries 6

7 Sensors Microphone and Buzzer Ranging measurement MEMSIC MTS-310CB Temperature and Light Detection Accelerometer Magnetometer GPS module MEMSIC MTS-400 7

8 Wireless Sensor Networks (cont ) Many-to-one routing schemes Tree topologies A base station is often located at the root of a tree Individuals are aiming for the same objectives Fairness among individuals is often ignored 8

9 A Military Application (SASNet) 9

10 Project Background GEOmatics for Informed DEcisions Network GEOIDE ( ) [SII-PIV-70] Integrating Developmental Genetic Programming and Terrain Analysis Techniques in GIS-based Sensor Placement Systems Université Laval, Quebec, Quebec, Canada University of Calgary, Calgary, Alberta, Canada Defence Research and Development Canada (DRDC) 10

11 SASNet Self-healing Autonomous Sensing Network L. Li, Localization in Self-healing Autonomous Sensing Network (SASNet), Technical Report, DRDC Ottawa, Jan

12 Sensor Nodes used in SASNet Acoustic sensor Seismic sensor Magnetic sensor PIR motion detectors A.-L. Jousselme et al., Same world, different words: augmenting sensor output through semantics, 14 th Int. Conf. Info. Fusion, Chicago, July

13 Object Identification P. Maupin and A.-L. Jousselme, Representation and evaluation of sensor network performance, May

14 Delay-Aware Data Collection Strategies 14

15 Objectives? Optimization Objectives Delay in a data aggregation process The duration for a base station to collect information from all wireless sensor nodes in a network Target tracking Energy Consumption Data Transactions, Sensing, Processing and other Overheads 15

16 Delay-Aware Data Collection Strategies? Single Data Stream Multiple Data Streams With Data Compression Without Data Compression With Data Compression Without Data Compression 16

17 Delay-Aware Data Collection Strategies Single Data Stream with Data Compression 17

18 Problem Definition Typical wireless sensor nodes are half-duplex communication devices CH CM 1 CM 2 CM 3 T=1 T=2 T=3 18

19 Problem definition (cont ) Suppose multiple packets can be compressed into one CH CM 1 CM 2 CM 3 T=3 T=2 T=1 19

20 Problem Definition (cont ) What if? CH CM 1 CM 2 CM 3 T=1 T=2 T=1 20

21 Advantages of such modifications Shorten the duration of a data aggregation process Cluster members need smaller buffers to handle incoming data while waiting for their cluster head to become available 21

22 A Delay-Aware Data Collection Network Structure for Wireless Sensor Networks* Characteristics A tree structure Most efficient for networks with N = 2 p nodes *Cheng, C.-T.; Tse, C.K.; Lau, F.C.M.;, "A Delay-Aware Data Collection Network Structure for Wireless Sensor Networks," Sensors Journal, IEEE, vol.11, no.3, pp , March

23 Characteristics (cont ) Each node is given a rank, which is an integer between 1 and p+1 A node with a rank k will form k-1 data links with k-1 nodes, while these k-1 nodes are with different ranks starting from 1 up to k-1 These k-1 nodes will become the child nodes of the node with a rank k The node with a rank k will form a single data link with a node with a higher rank 23

24 Characteristics (Cont ) A graphical representation

25 Characteristics (Cont ) The cluster head is the one with the highest rank in the network. Instead of forming a data link to a node with a higher rank, it forms a data link with the base station BS RANK CH RANK 10 25

26 Characteristics (cont ) Rank distribution The distribution of the rank follows an inverse exponential base-2 function 1 node with a rank = log2n +1 26

27 Example A network with N=16 BS

28 Data Aggregation Duration Consider a network with N = 2 p. By adopting the proposed network structure, the number of time slots t(n) required for the base station to collect data from the whole network is given by 28

29 Delay-Aware Data Collection Strategies Multiple Data Streams with Data Compression 29

30 Problem Definition The delay-aware data collection network structure (Single Data Stream with Data Compression) is designed for scenarios which a data collection will be invoked occasionally, but once invoked, it should complete within a short duration A typical example is an event detecting application, in which an event may rarely happen, but once detected, data should be reported to the base station with a minimum delay 30

31 Problem Definition (Cont ) Consider a network with N=7 BS

32 Problem Definition (Cont ) A single data collection process will last for 3 time-slots There will be 7, 3, and 1 nodes involved in data transactions in the first, second, and third time-slot, respectively 32

33 Problem Definition (Cont ) Since all nodes will be utilized in the first time-slot, the next data collection process can only be invoked at or after the fourth time-slot. 33

34 Problem Definition (Cont ) It takes at least q x 3 time-slots to complete q data collection processes 34

35 Problem Definition (Cont ) For applications which require continuous monitoring, it is preferable to minimize the delays among consecutive data collection processes BS

36 Problem Definition (Cont ) Two clusters will be formed instead of three A single data collection process will last for 4 timeslots 36

37 Problem Definition (Cont ) There will be 4, 4, 3, and 1 nodes involved in data transactions at the first to fourth time-slots, respectively 37

38 Problem Definition (Cont ) Note that not all nodes are involved at the first and second time-slots, the next data collection process can begin at the third time-slot 38

39 Advantages of Such Modifications Although the duration of a data collection process is extended by 1 time-slot, by having the transmission schedules overlap, it takes only (q-1) x timeslots to complete q data collection processes 39

40 A Delay-Aware Network Structure for wireless sensor Networks with Consecutive Data Collection Processes ^ Characteristics Still, a tree structure Based on the Delay-Aware Data Collection Network Structure (Single Data Stream with Data Compression) ^Cheng, C.-T.; Tse, C.K.;, "A Delay-Aware Network Structure for Wireless Sensor Networks with Consecutive Data Collection Processes," Sensors Journal, IEEE, vol. 13, no. 6, June 2013, pp

41 Characteristics (Cont ) Let TDCP be the duration of a data collection process and TOL be the overlapping duration of 2 consecutive data collection processes. The duration for q consecutive data collection processes (Tq) is expressed as 41

42 Conflicts! By setting TOL=1, the next data collection process will begin at the last time-slot of the current data collection process A node with rank = TDCP will need to make a transmission to its parent node (i.e. the base station). Nevertheless, if such node has a child node with rank =1, it will need to receive a data packet simultaneously To resolve such conflicts, nodes with rank = TDCP should not connect to nodes with rank =1 42

43 Rules Rule - 1: A node with a rank = TDCP-Ƭ+1, where Ƭ=1,...,TOL, can have at most TDCP-TOL-1 child nodes and must not connect to a child node with a rank = Ƭ Rule - 2: A node with a rank = TDCP-Ƭ+1, where Ƭ=1,...,TOL, must not share the same parent node with another node with a rank =Ƭ 43

44 Rules (Cont ) Rule - 3: A node with a rank =Ƭ, where Ƭ=1,..., TOL, must connect to a parent node with a rank >Ƭ and TDCP-Ƭ and may connect to at most Ƭ-1 child nodes with their ranks ranging from 1 to Ƭ-1 Rule - 4: A node with a rank =Ƭ, where TOL< Ƭ TDCP-TOL, must connect to a parent node with a rank >TDCP-TOL and may connect to at most Ƭ-1 child nodes with their ranks ranging from 1 to Ƭ-1 44

45 TDCP=4, TOL=2 Example 4 2 BS

46 X X Example TDCP=4, TOL= BS

47 Network Formation Algorithm The energy consumption of an ordinary wireless sensor node is a function of its communication distance The objective of the network formation algorithm is to construct the proposed network structure while keeping communication distances among connected nodes short The proposed network formation algorithm is a multistage optimization process based on Dynamic Programming and Hungarian method. 47

48 Example 48

49 Example 49

50 Example 50

51 Example 51

52 Example 52

53 Example 53

54 Example 54

55 Example 55

56 Example 56

57 Evaluations 57

58 Evaluations 58

59 Evaluations 59

60 Conclusions 60

61 Conclusions Sensor networks act as interfaces for clouds to interact with the environment Two delay-aware data collection strategies are introduced Minimize the duration of a data collection process Keep the total communication distance short Reduce durations of consecutive data collection processes^ Does not introduce extra delay to a single data collection process^ 61

62 Thank You! 62