IOT(internet of Things) Notes

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Presentation layer defines the format in which the data is to be
exchanged between the two communicating entities.
• Also handles data compression and data encryption (cryptography).#Basic frequencies you should know#######
  • satellite communication uses ku band for communication its freq. is (12 to 18)GHz
  • ///////4G////////////
  • Currently in INDIA, 4G LTE band-40 having 2300 to 2400 MHz (TD-LTE) frequency range is active (online) and offered by the operators in indian territory. The other LTE band in 1800 MHz (FDD-LTE) frequency is also auctioned by the INDIA government. But this LTE band is not offered for LTE by any telecom operators. 

  • As we know there are two topologies exist in LTE technology viz. LTE TDD(or TD-LTE) and LTE FDD. TDD is the time division duplex and FDD is Frequency division duplex. In TDD one frequency is used at different times by both uplink and downlink. In FDD, two separate frequencies are allocated one each to uplink and downlink. Hence in FDD simulateneous transmissions in both uplink and downlink can exist. Refer FDD vs TDD.

  • in short in India we use band 40 and 2.3GHz to 2.4GHz Freq in which 1GHz is for uplink and downlink frequencies 
  • WIFI freq 2.4GHZ its standards is 802.11b/g/n currently we uses 802.11ac which is 3X times faster than 802.11n that is 1300Mbps i.e. 162.5MBps.

  • Blutooth frquency is 2.45GHz.

  • For 3G frequency is 1.8 GHz to 2.5 GHz/////data rate upto 2Mhz//WideBand CDMA

  • For 4 G frequency is 2 GHz to 8 GHz ////////data rate is upto 20Mbps or more//Multicarrier CDMA or TDMA

  • 3g and 4g band width is 5 to 20 MHz
##IOT
  • Blutooth has Basic Rate and low energy
  • it uses one Master one slave or One Master to multiple slaves(max 7 slaves)
  • this connection is known as piconet
  • Each piconet is defined by a different hopping channel
  • to which users synchronize to
  • Each piconet has max capacity (1 Mbps)
  • Socket address => IP address + Port number
  • UDP is  datagram protocol it is  connectionless, unreiable transport protocol instead of host to host it uses process to process communication 
  • its header part is 8 bytes(64 bit) 16bit--->source add.,16bit--->destination address,16-->checksum,16bit-->total length
  • TCP is a connection-oriented protocol; it creates a
  • virtual connection between two TCPs to send data. In
  • addition, TCP uses flow and error control mechanisms
  • at the transport level.
  • 16bit--->source add.,16bit--->destination address,16bit--->sequence number,16bit--->ack number
  • main network is that is net id converted into sub networks(0 to 255) and each sub nets have there access for connecting 256 devices(0 to 255)
  • Characteristics of physical layers are:
  • Voltage levels
  • • Timing of voltage changes
  • • Physical data rates
  • • Maximum transmission distances
  • • Physical connectors

  • Characteristics of Data link layers
  • it converts data into frames also resembles it for receiving data 
  • flow control check
  • Data link layer attempts to provide reliable communication over the
  • physical layer interface.
  • • Breaks the outgoing data into frames and reassemble the received
  • frames.
  • • Create and detect frame boundaries.
  • • It provides the physical addressing to the frames distributed over the
  • different networks.
  • • Handle errors by implementing and
  • retransmission scheme. an acknowledgement
  • • Implement flow control.
  • • Supports points-to-point as well as broadcast communication.
  • • Supports simplex, half-duplex or full-duplex communication.

  • Characteristics of Network layers are:
  • it implement routing for frames(packets) through the nework.
  • defines most optimum path for reach at destination 
  • Defines logical addressing so that any endpoint can be identified.
  • • Handles congestion in the network.
  • • Facilitates interconnection
  • (Internetworking).
  • between
  • heterogeneous
  • networks
  • • The network layer also defines how to fragment a packet into
  • smaller packets to accommodate different media.

  • Characteristics of Transport layers are:
  • Purpose of this layer is to provide a reliable mechanism for the
  • exchange of data between two processes in different computers.
  • • Ensures that the data units are delivered error free.
  • • Ensures that data units are delivered in sequence.
  • • Ensures that there is no loss or duplication of data units.
  • • Takes care of segmentation and reassembly with sequence number.
  • • Provides connectionless or connection oriented service.
  • • Provides for the connection management.
  • • Multiplexes multiple connections over a single channel.

  • Characteristics of Session Layer:
    •  
  • Session layer provides mechanism for controlling the dialogue
  • between the two end systems. It defines how to start, control and end
  • conversations (called sessions) between applications.
  • • This layer requests for a logical connection to be established on an
  • end-user’s request.
  • • Any necessary log-on or password validation is also handled by this
  • layer.
  • • Session layer is also responsible for terminating the connection.
  • • This layer provides services like dialogue discipline which can be
  • full duplex or half duplex.
  • • Session layer can also provide check-pointing mechanism such that
  • if a failure of some sort occurs between checkpoints, all data can be
  • retransmitted from the last checkpoint.


  • Characteristics of Presentation layer:
  • Presentation layer defines the format in which the data is to be
  • exchanged between the two communicating entities.
  • • Also handles data compression and data encryption (cryptography).


  • Characteristics of Application layer:
  • Application layer interacts with application programs and is the
  • highest level of OSI model.
  • • Application layer contains management functions to support
  • distributed applications.
  • • Examples of application layer are applications such as file transfer,
  • electronic mail, remote login etc.

10Base2===>10Mbps,200meter
10BaseT and 100BaseT

10/100 Mbps rate

• T stands for Twisted Pair
• Hub(s) connected by twisted pair facilitate “star topology”
– Distance of any node to hub must be < 100M


Ethernet Frames
Preamble is a sequence of 7 bytes, each set to “10101010”
– Used to synchronize receiver before actual data is sent
Local-area networks use a 48-bit (6-byte) physical address
written as 12 hexadecimal digits; every byte (2
hexadecimal digits) is separated by a colon,
  • routing algorithm used in internet are:
  • Dynamic global link state algorithm
  • vector algorithm
  • IP provides unreliable delivery
  • 802.11a uses 5GHz frequency




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