Internet of Things (IoT)

Transcription

1 Internet of Things (IoT) INF5050 February 19,

2 Outline Internet of Things (IoT) Key Technologies RFID Mobile Cloud Computing

3 Things A real/physical or digital/virtual entity that exists and moves in space and time Examples computers, sensors, people, actuators, refrigerators, TVs, vehicles, mobile phones, clothes, food, medicines, books, passports, luggage,.. 3

4 Explosion of connected things (devices/terminals/phones/sensors) 4

5 Internet of Things (IoT) Visions IoT allows people and things to be connected Anyone can use anything to access any service and any network at anytime any place Q: is it challenging to make one sentence to include all these Any* words? 5

6 IoT development ITU Internet Report 2005:The Internet of Things Internet of Things action plan for EU IoT concept U-Japan U-Korea IBM: Smart Planet Sensing China future

7 IoT Application: Connected Vehicles for driving safety road slippery message can be transmitted from the first car to the last white car View for the driver in the 2 nd yellow car

8 Connected Road: addressable sensors on the road and can be networked Increase safety Road surface temperature Road condition ice/snow/rain/dry/wet Tyre pressure monitoring Estimate traffic Number of vehicles passed in 15 minutes Sensors on the road 8

9 Outline Internet of Things (IoT) Key Technologies RFID Mobile Cloud Computing

10 KEY TECHNOLOGY: RFID 10

11 RFID (Radio Frequency Identification) In IoT, normally the first question is to identify whom you are. RFID can answer this question. RFID principle: devices are wireless microchips used for tagging objects for automatic identification RFID can identify objects wirelessly line-of-sight or non line of sight Line-of-Sight (LoS) transmitter Non Line-of-Sight (NLoS) receiver 11

12 RFID systems RFID systems consist of Readers: read and write tag data Tags: carry object identification data Back-end database: to manage and deal with data Reader Tag 12

13 RFID Frequency Source: centrenational-rfid LF (low frequency): Reading range is limited Can penetrate thin metal Work well with high-water content (e.g., fruit) Application: animal tagging HF (High frequency): work well on metal Application: tracking library books, patient flow tracking UHF (Ultra-high Frequency): Long range, high data rate Cannot penetrate metal or water Application: electronic toll collection; parking access control. 13

14 Tags Passive tags Semi-passive tags Active tags Energy resource No Battery Battery Communication range Communication mode Short, 10meters Long, 100m+ Long, 100+ Response only Response only Response or Initiate Price Low Medium high ❶ ❷ ❶ ❷ Communication mode: Response Tag waits for reader s signal and sends feedback Communication mode: Initiate Tag sends signal to reader instead of waiting 14

15 Which tags are used in the applications? Applications Reisekort Active, Semi-passive or Passive Tags Passive Shipping containers Active Large assets tracking Active 15

16 Which tags are used in the applications? Applications Electronic toll Active, Semi-passive or Passive Tags Semi-Passive Tracking components like automobile parts during manufacture Semi-Passive electronic product code Passive 16

17 Reader s reading range Tag 1 Tag 3 Tag 2 reader Reading range Q: what can affect the reading range? 17

18 Tags collision problem Collision occurs when multiple tags respond to the same reader at the same time. The reader is unable to differentiate these signals. Tag collision results in wastage of energy, increases identification delays. Readers must use an anticollision protocol to minimize collisions and help reduce identification delays Tag Reader Reading range 18

19 RFID anti-collision protocols: Aloha Pure Aloha based protocols Slotted Aloha Framed Slotted Aloha 19

20 RFID anti-collision: Pure Aloha Easy to implement If a tag has data to send, send the data If the message collides with another tag, try resending "later On collision, sender waits random time before trying again Tag10 Tag9 Tag8 Tag7 Tag6 Tag5 Collision A tag responds after a random delay, and continues until identified. Tag4 Tag3 Tag2 Collision Efficiency: 18.4% Tag1 An example of ALOHA time Q: have we seen ALOHA in other networks? 20

21 RFID anti-collision: Slotted Aloha S-ALOHA divides time into timeslots. Each tag can send out data at the beginning of a timeslot. A tag responds in synchronized slots after random delay Tag10 Tag9 Tag8 Tag7 Tag6 Tag5 Tag4 Tag3 Tag2 Collision Collision Efficiency: 36.8% Tag1 S1 S2 S3 S4 S5 S6 S7 S8 S9 S10 S11 An example of slotted ALOHA protocol S: time slot 21

22 RFID anti-collision: Frame-Slotted Aloha A tag randomly selects a slot to respond only once in a frame. If there is a collision, tags respond in the next frame Tag 1 Tag 2 Tag 3 collision channel Frame 1 Frame 2 Frame 3 22

23 Collisions Tags collision Q: Readers have collision problem?

24 RFID readers collision (I) Reader-to-Tag When a tag enters an overlapping area of two readers, transmitted signals will collide and tags will be unable to answer readers queries Reader A s reading range A Tag B Reader B s reading range

25 RFID readers collision (II) Reader-to-Reader Reader B s interference range R i = (1 + α)r r Reader A s reading range Tag A B Reader B s reading range R r

26 Coverage based approach for Readers Anti-collision The reading ranges of readers are adapted dynamically to reduce the overlapped areas between adjacent readers Advantage: increases the space re-used ratio Disadvantage: needs a central node to calculate the distance between two readers and adjust their reading ranges, which will increase the complexity of realization and cost of the system Reader A s reading range A Tag B Reader B s reading range Rr 26

27 Scheduling based Readers Anticollision Resources (e.g., frequencies and time) are allocated properly among readers to prevent readers from transmitting simultaneously Advantage: reduce readers collision effectively Disadvantage: requires the system to maintain information over the network, which will be time and energy consuming A Tag B -Reader A transmits -after some time, e.g., 1sec -Reader B transmits 27

28 KEY TECHNOLOGY: MOBILE CLOUD COMPUTING 28

29 MCC = Mobile + Cloud Computing Cloud computing Mobile network Cloud Q: can you name some MCC services that we use everyday? 4G/wifi

30 Motivations for MCC Internet traffic explosion; while smart phones generate more than half of mobile data traffic Internet-of-Things Vision of anything connected Mobile devices still lack in resources compared to a conventional device such as laptops or powerful servers in cloud battery lifetime network bandwidth storage capacity processor performance

31 Mobile Devices/Terminals/Machines Smart phones Laptops Tablet (e.g., Apple ipad, Samsung Galaxy Tab, Sony Xperia) Sensors, actuators, robots Embedded systems (e.g., RFID readers and tags) Vehicles Glasses Satellites and many more

32 MCC definition According to Mobile Cloud Computing Forum Mobile Cloud Computing at its simplest refers to an infrastructure where both the data storage and the data processing happen outside of the mobile device. Mobile cloud applications move the computing power and data storage away from mobile phones and into the cloud, bringing applications and mobile computing to not just smart phone users but a much broader range of mobile subscribers In plain language MCC moves data processing and storage from mobile phones to cloud

33 MCC 1 st Perspective: using mobile devices to access cloud Infrastructure mode Application Offloading Mobile Clone Task Delegation Execution Engine Data Storage Mobile Device Application Server Example: using your mobile phone to access gmail, dropbox, facebook etc.

34 MCC 2 nd Perspective: mobile devices are cloud Ad hoc mode: use mobile devices for a self-organized cloud Share resources (computation, storage) among devices Run cloud services by mobile devices Q: any example? Online Services Mobile Media Urgent Tasks

35 Vehicular Cloud: example Hundreds cars unused for hours on a typical workday Vehicles can share computation/storage resources Storage resource sharing (e.g., Storage as a Service) Computers in cars have onboard storage Data center in airport parking lot

36 MCC advantages Extending battery lifetime Voice recognition, e.g., Siri, is computation intensive Improving data storage capacity and computation capability Improving data reliability and security

37 MCC challenges Device side Limited energy Wireless Communication side Limited radio bandwidth Network latency Availability Computation side Computation offloading Data access efficiency Context-aware cloud services

38 OFFLOADING FOR MOBILE CLOUD

39 Computation Offloading Offloading: sending heavy computation to resourceful servers and receiving the results from these servers. Cloud ❷Computation in cloud Q: do you believe: using WiFi in IFI instead of 4G is offloading? Result: 6 ❸ ❶ Computation request

40 Offloading schemes for energy-saving Energy usage when computing is done in mobile phones in mobile phones P c : the energy cost when the mobile phone is doing computing C: the computation needs C instructions M: the speed of mobile device to compute Energy usage when computing is done in cloud P i : energy cost when the mobile phone is idle. P tr : energy cost when the mobile transmits the data S: the speed of cloud to compute D: the data need to transmit B: the wireless bandwidth Saved energy by using offloading

41 Energy-efficiency in offloading schemes Suppose the cloud is F times faster i.e., S = F M. Then, saved energy is Energy is saved when this formula produces a positive number. The formula is positive if

42 Observations Offloading is beneficial when a task needs large computation C relatively small communication D Large C Small D K. Kumar and Y. Lu: Cloud Computing for Mobile Users: Can Offloading Computation Save Energy?. IEEE Computer 43(4): (2010)

43 But, offloading does not help when wireless channel has low quality Service areas in Tunnel Subway Q: other examples? In these scenarios, the bandwidth B is very small, D/B approaches infinite. cloud computing does not save energy. B 0; then, D/B

44 Application may benefit from offloading: photo retrieval as an example Search and retrieve images in photo sharing databases D is large since considerable data must be sent; hence D/B might be too large Condition Only if the bandwidth B is very large, offloading saves energy (Q: why?)

45 Real-time Navigation When D is very large, offloading may not save energy Partitioning computation between the mobile phone and the cloud may reduce energy consumption. Q: what should be considered to use partitioning computation?

46 Partitioning Computation We need to determine whether to offload which units of computation should be moved to the cloud We need to consider Computation cost Communication cost Energy consumption Communications quality: data between devices and cloud may be lost Cloud 70% tasks moved to cloud 30% tasks done in mobile phone

47 Contact or Mobile: