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Communication Hardware

Communication hardware divided into three parts:-

Sender receiver hardware:- Sender and receiver hardware for handling communication messages, data transfer etc.
  • Node and workstation:- In communication networks, a node is a connection point. A physical network node is an active electronic device that is attached to a network, and is capable of sending, receiving, or forwarding information over a communications channel. The device used to communicate a data communication network is called workstations. These workstation may be terminal, printer, telephone in other communication devices. A workstation known as terminal, client or slave.
  • Multiplexer:- Multiplexing is a device which convert multiple input signals into a single signal for transmission. Multiplexer is a device that combines several input information signals into one output signal, which carries several communication channels. e.g A Telephone lines that use for our daily conversation can carry hundreds of conversation using multiplexing
  • De-multiplexer:- De-multiplexer is a device which divide single lines into a multiplex line.

Types of Multiplexer

  • Frequency Division Multiplexing (FDM):- combines two or more signals at the transmitter by frequency multiplying up the different signals by different amounts. This composite signal is then transmitted and the receiver separates the individual signals, frequency multiples down and produces the originals. FDM is still used with cable TV, some older analog cellular systems, and most commonly YOUR FM RADIO.
  • Time Division Multiplexing (TDM):- gives each signal a time slot for transmission e.g. A 10 micro-sec, B 10 micro-sec, C 10 micro-sec, A 10 micro-sec, B 10 micro-sec, C 10 micro-sec etc. There are two types of TDM, Synchronous TDM and Statistical TDM. Synchronous TDM is widely used with T carriers and ISDN. E.g T.V transmission
  • Wavelength Division Multiplexing (WDM):- WDM is a modification of TDM and FDM. It performs the same function of multiplexing data, but it uses different colored lasers to send multiple channels over the same physical line. WDM only runs over fiber optic lines but has an advantage because it can combine multiple connection types such as ATM (Asynchronous Transmission Mode), OC, etc into one physical fiber line.
  • Code division multiplexing (CDM):- An advanced technique that allows multiple devices to transmit on the same frequencies at the same time using different codes. It is used for mobile communication.
  • Communication Devices:- There are several types of communication devices or interface used in data communication. These devices are connection between receiver and sender hardware involved data communication. Some of these devices are:-
    • Modem:- Modem is a combination of two words ‘Mo+Dem’. Mo stand for Modulation and Dem stand for demodulation. Modem is a device which convert digital signals into analog signal and analog signal into digital signal. You can use modem with computer.
    • Codec:- Codec does opposite function as modem but cannot be used with computer.
  • Communication channels:- The most basic hardware is the media through which data is transferred. There are several types of media available and the choice of media depends on cost of transmission, efficiency of data transmission and transfer rate:
    • Two wire open line:- This is the simplest of all the transmission media. It consists of simple pair of metallic wires made of copper or aluminum of between 0.4 and 1 mm diameter. This is used for short distance, upto 50 m and can transfer upto 19,200 bps.
    • Twisted pair cable:- A twisted pair consists of insulated conductors that are twisted together. It is used for communication upto distance of 1 K.M and can achieve transfer rate of 1-2 mbps. Twisted pair cable widely used in telephone network.
    • Coaxial cable:- A coaxial cable consist of a solid conductor running coaxial inside a solid or braided outer annular conductor. A coaxial cable can be used over a distance about 1 KM and can achieve a transfer rate of upto 100 mbps. A coaxial cable is of two types:- a 75 ohm cable which is used by cable TV operator and the 50 ohm cable which is used in high speed broadband.
    • Fiber optics cable:- A fiber optics cable carries signals in the form of fluctuating light in a glass or plastic fiber. It has very high data transfer rates of about 1000 mbps. These are known as guided media.
    • Radiowave, microwave and satellite:- Radiowave, microwave, satellite channels use electromagnetic propagation in open space. It covers large geographical area. These are known as un-guided media.
Network:- A network is a way or means of transmitting or receive of information from one or more sources.


Networks can be broadly classified as using either a peer to peer or client/server Architecture.
  • Client Server Architecture:- Client/Server Architecture is one in which the client (PC or workstation) is the requesting machine and the server is the supplying machine, both of which are connected via a LAN or WAN. The client contain the user interface and may perform some or all of the application processing. Server can be high speed micro computer, minicomputers or even mainframes. A network architecture in which each computer or process on the network is either a client or a server. Servers are powerful computers or processes dedicated to managing disk drives (file servers), printers (print servers), or network traffic (network servers ). Clients are PCs or workstations on which users run applications.
  • Peer-to-peer Architecture:- A type of network in which each workstation has equal capabilities and responsibilities is called peer-to-peer network. Each workstation act as both client and server/ There is no central repository for information and there is no central server to maintain. Data and resources are distributed throughout the network and each user is responsible for sharing data and resources connected to their system. This is simpler and less expensive network but not perform under heavy loads. A peer to peer network known as distributed network.

Difference between Client-Server and Peer to Peer Network Architectures

The main difference between client-server and peer to peer systems is that in the client-server architecture, there are designated clients that request for services and servers that provide services, but in peer to peer systems, peers act as both service providers and service consumers. Further, client-server systems require central file server and they are expensive to implement than peer to peer systems. On the other hand, in the client-server system, a dedicated file server provides level of access to the clients, providing better security than peer to peer systems where security is handled by the end users.

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