communication network

ANAND SRIVASTAVA

Communication Network

What is Communication ?

Communication activity of exchanging information across space and time using various methods.

Communications is the physical transfer of data a digital bit stream or a digitized analog signal over a point-to-point or point-to-multipoint communication channel.

Why It Is Needed ?

Every day, in our work and in our leisure time, we come in contact with and use a variety of modern communication systems.

Through these systems we are able to communicate instantaneously with people on different continents, transact our daily business, and receive information about various developments and events of note that occur all around the world.

How It Started ?

Most of these modern-day communication systems were invented and developed during the past century.

One of the earliest inventions of communications was the invention of the electric battery by Alessandro Volta in 1799.

This invention made it possible for Samuel Morse to develop the electric telegraph in 1837.

Continued…

Electrical communications that was developed by Morse, namely telegraphy, was a binary digital communication system in which the letters of the English alphabet were efficiently encoded into corresponding variable-length code.

Nearly forty years later, in 1875, Émile Baudot developed a code for telegraphy in which each letter was encoded into fixed-length binary code words of length 5.

Continued…

Alexander Graham Bell patented his invention of the telephone in 1876.

Significant advances in the quality and range of service during the first two decades of the 20th century allowed the telephone signal transmission over great distances.

During the past thirty years there have been numerous significant advances in telephone communications.

Communication Through The Ages

Communication in Ancient Human Voice Writing

Communication 1500-1800 Printed Material Postal Service

Communication in the 19th Century Telegraph Fax Telephone

Communication Through The Ages

Communication in The 20th Century Radio Satellites Television Cell Phone

Communication in The 21st Century Internet Wireless

The Basic Communication Classification

The Wired Communication

The Wireless Communication

The wired Communication

Why Wired ?

The equipment is inexpensive.Many computers have a wired network

adapter.Wired networks transfer information more

swiftlyWired networks are generally more secure

than wireless networks

Wired Network

Consider Cable Television Service

Wired Network Protocols

Sender - Initiated Protocols

Receiver - Initiated protocols


Sender-initiated protocols have been characterized as placing the responsibility of reliable delivery at the sender.

A sender-initiated protocol is one that requires the source to receive ACK from the receiver before it is allowed to release memory for the data associated with the ACK.

The source is required to know the receiver set, and that the scheme suffers from the ACK implosion problem.

Limitation

Error recovery is selective repeat, only packets that are suspected to be lost or corrupted are retransmitted,

Limitation in processing the ACK of receiver set.

The known methods that address this limitation is using NAKS instead of ACK.


Receiver-initiated protocols are characterized as placing the responsibility for ensuring reliable packet delivery at each receiver.

The critical aspect of these protocols is that no ACK are used. The receivers send NAK back to the source when a retransmission is needed, detected by either an error, a skip in the sequence numbers used, or a timeout.

The source is unable to ascertain when it can safely release data from memory.

Limitation

Receivers communicate NAK back to the source, receiver-initiated protocols have the possibility of experiencing NAK implosion problem at the source.

The source is unable to ascertain when it can safely release data from memory as NAK is send back only on errors.

Receiver-initiated with NAK avoidance (RINA) protocols would be helpful to overcome this limitation.

The Wireless Communication

Why Wireless ?

To span a distance beyond the capabilities of typical cabling.

To provide a backup communications link in case of normal network failure.

To link portable or temporary workstations.To overcome situations where normal cabling

is difficult or financially impractical.To remotely connect mobile users or

networks.

Wireless Network Communication

Consider Satellite Television Service.

Wireless Network Protocols

LEACH (Low Energy Adaptive Clustering Hierarchy)

SPIN

LEACH

LEACH(Low Energy Adaptive Clustering Hierarchy)

LEACH is a protocol in which most nodes transmit to cluster heads, and the cluster heads aggregate and compress the data and forward it to the base station.

Each node uses a stochastic algorithm at each round to determine whether it will become a cluster head in this round.

LEACH assumes that each node has a radio powerful enough to directly reach the base station.

LEACH (Advantages & Disadvantages)

It utilizes TDMA making is more power efficient.

Cluster Heads are chosen ones any node can be chosen as cluster head based on rounds.

Cluster Head is the one which compress and packs the data and forwards it to the Base Station.

LEACH assumes that each node has a radio powerful enough to directly reach the base station or the nearest cluster head, but that using this radio at full strength all the time would waste energy.

SPIN

SPIN is a family of adaptive protocols that use data negotiation and resource-adaptive algorithms.

SPIN is a data centric routing protocol assuming all nodes in the network are base stations & nodes in close proximity have similar data.

All nodes can be assumed as base stations all information is broadcasted to each node in the network.

User can query to any node and can get the information immediately.

SPIN (Advantages & Disadvantages)

Before transmission, meta-data are exchanged among sensors nodes (meta-data negotiation) via a data advertisement procedure avoiding transmission of redundant data.

After receiving the data each node advertises it to its neighbors and interested neighbors get this data by sending a request message.

SPINs data advertisement mechanism cannot guarantee the delivery of data.

Questions ???

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