What is DWDM

Before we learn about the DWDM first let it check out the full form of DWDM. DWDM stands for dense wavelength division multiplexing. Hence the dense means the wavelength channel is very narrow and also very close to each other. 

Dense wavelength division multiplexing(DWDM) is technology put data from different sources together in an optical fiber, which uses single-mode fiber to carry multiple light waves of different frequencies.

For 100 GHz dense WDM, the interval between the adjacent channel is only 100 GHz, for example, the adjacent channels could be 1533.33 nm, 1533,12 nm, 1531.90 nm.

 DWDM is widely used for the 1550 nm band so as to help the capabilities of EDFA full form. EDFA as are commonly used for the 1525 nm - 1565 nm.

 Dense wavelength division multiplexing is an important innovation in optical network and provides many benefits of DWDM. It can be used various applications like  utilize the existing thin fiber and building or expanding a network

DWDM system structure :

 DWDM system consists of transmitter, receiver, Multiplexer, optical amplifier (EDFA), demultiplexer. The figure shows a typical application of a DWDM system

Transmitter: Laser that transmits data with a very accurate wavelength each laser is configured to transmit in a certain wavelength.

Receiver: Component that receives the signal and transmits them into a de-multiplexer.

DWDM system
EDFA: Erbium-doped fiber amplifier. Optical repeater device that amplifies the optical signal, It is a silica-based optical fiber that doped with erbium that boosts the power of the wavelength.

Add and drop: Component that receives a fiber optic with some wavelength multiplexed, and can drop or add a certain lambda from the signal.

DWDM multiplexers: Receive many optical signals, each one is a different wavelength, and transmit the entire wavelength in one optic fiber.

DWDM de-multiplexer: Receive all the signal in one optic fiber, and transmit each wavelength in a different fiber.

DWDM applications:
  • It can be used for signal transmission
  • It is ready to make for long distance, Telecommunication operator that use either point to point or ring topology 
  • Utilize the existing thin fiber
  • Building or expanding network
  • The transparency of the DWDM system to  various bit-rate and protocols
  • Network wholesalers can lease capacity rather than entire fiber cable

Full form of DWDM

What is the full form of DWDM?

Answer :

  • Dense Wavelength Division Multiplexing

What does DWDM?

DWDM stand for dense wavelength division multiplexing. Hence dense means the wavelength channel is very narrow and close to each other.

 Dense wavelength division multiplexing is technology put data from different sources together in an optical fiber, which uses single-mode fiber to carry multiple light waves of different frequencies.

Dense wavelength division multiplexing is a data transmission technology having large capacity and efficiency.

A better is a solution is to use dense wavelength division multiplexing, which effectively increases the useable bandwidth in a system without electronic repeaters.

What is WDM

In this method, the scheme of combining a number of wavelength over a single fiber called wavelength division multiplexing. In this techniques fiber optic transmission using multiple light wavelength to send the data over the same medium or device. In fiber optic, two or more wavelength (colors) of light can travel on one fiber and several signals can be transmitted in optical waveguide at differing wavelengths. 

 So the combining a number of wavelengths over a single fiber called WDM full form is wavelength division multiplexing.

 In WDM each input generated by a separate optical source with a unique wavelength. An optical multiplexer couples light from individual sources to the transmitting fiber shown in the figure. 

 At the receiving station, an optical demultiplexer is required to separate the different carriers before photodetection of the individual signal.
WDM scheme
To prevent spurious signal to enter into receiving channel, the demultiplexer must have a narrow spectral operation with sharp wavelength cut-offs. The acceptable limit of cross talk is -30 dB. 

 Features of WDM :

 The following features of WDM are given below:
  • Capacity upgrade for the system - Each wavelength support independent data rate in Gbps.
  • Wavelength routing for the device - Link capacity and flexibility can be increased by using multiple wavelengths.
  • Transparency of the system - WDM can carry fast asynchronous, slow synchronous, synchronous analog and digital data.
  • Wavelength switching for the system - WDM can add or drop multiplexer, cross-connects and wavelength converters.
WDM has wide application in the communication system because of this useful feature details we show above. Other method called DWDM, it's different from WDM. The main difference between WDM and DWDM is DWDM has a greater overall capacity so DWDM spaces the wavelength more closely than WDM.

Application of WDM :
  • SONET network
  • Dense WDM allows to muxed and de-muxed numbers of channel closer to one another to achieve greater efficiency
  • FDM to an optical fiber
  • Optical transport network
  • Local exchange network
WDM driver:

WDM driver is classified into three types :
  • Bus driver
  • Function driver
  • Filter driver
Function driver :
  • A function driver is a specific individual device, such as a printer.
Bus driver :
  • Bus driver uses individual buses like PCI, SCSI, and USB, adapter or bridges. It is reported to the child device that is connected to the bus.
Filter driver :
  •  It is I/O request for a device, which is a class of device or bus device.

Full form of WDM

What is full form of  WDM  ?

 Answer :
  • Wavelength division multiplexing
The scheme of combining a number of wavelength over a single fiber called wavelength division multiplexing. In this techniques fiber optic transmission using multiple light wavelength to send the data over the same medium or device. In fiber optic, two or more wavelength (colors) of light can travel on one fiber and several signal can be transmitted in optical wave guide at differing wavelengths. 



Features of Bluetooth

Bluetooth technology is an open standard that provides an ad-hoc way for connecting devices in the 10 m range. Bluetooth in the 2.4 GHz band and uses a frequency hopping TDD method for each radio channel. Now let us check it out features of Bluetooth to know more details about Bluetooth. 
  • Better IOT
  • Quick data transfer
  • Better audio quality
  • Easy transport 
  • Greater flexibility
  • Available everywhere
  • Up to eight devices can be a network in the piconet
  • The device does not need to be a point at each other, as a signal is OMNI directional 
  • Increases numbers of advertising packets
  • Provide location-based services
  • Government  worldwide regular it, so it is possible to utilize the same standards wherever one travel
  • Sending the information between the two devices which are close to each other

Bluetooth architecture

Bluetooth architecture defines two types of structure :
  1. Piconet
  2. Scatternet
1. Piconet 
  • Eight devices are connected in a Bluetooth network called as a piconet, so the piconet has up to eight active nodes 
  • One of them acts as a master and others act as slaves.
  • In piconet communication between the primary and secondary can be one to one or one to many forms. 
  • All communication is done between master and slave. slave-slave or master-master communication is not possible
2. Scatternet
  • A scatternet is formed when two more piconets connect through a bridge node. 
  • It is combining various piconet.
  • In scattered addition to be seven active slaves, there can be up to 255 parked nodes in the net that can only respond to a beacon signal from the master.
  • The slaves are also dumb devices that do the task that the master tells them to do.
  • Mater controlling the clock and it is determining in which slave gets to communicate in which time slot.
  • All the communication is between the master and slave and but not between the slaves.
Bluetooth architecture

Bluetooth frame structure

Access code: It identifies the master so that slaves within the radio range of two masters can tell which is traffic for them. It is a 72-bit field, that contains synchronization bits.

Header: The 54-bit header contains an 18-bit header that is repeated 3 times for a total of 54 bits. It allows the receiver to remind all three copies of each beat and reject the ones that do not have a majority.

Address field: The address field in the header identifies which of the eight devices the frame is intended for.

Types field: Types field identifies whether it is an ACL, SCO, pull or null frame types, the types of error correction used in the data field and how many slots long the frame is

Flow bit: It is used for primitive types of flow control and is asserted by the slave when its buffer is full and cannot receive any more data.

ACK bit: ACK bit is used to piggyback an acknowledgment onto a frame

Sequence bit: It is used to number the frame to detect re-transmission in a stop and wait for a protocol. It is followed by an 8-bit checksum.

Bluetooth frame structure

Application of Bluetooth

Bluetooth system is an open standard that provides an ad-hoc way for connecting devices in the 10 m range. Bluetooth in the 2.4 GHz band and uses a frequency hopping TDD method for each radio channel. Let us now check it out the application of Bluetooth to know more details about Bluetooth. 
  • Medical requirement
  • Vending machines
  • Office requirement, faxes, PCs, laptops, handset, pager, etc
  • Bluetooth car kit
  • Vending machines
    DVD player cameras refrigerators
  • In the parking and vehicle communication system
  • Microwave ovens
  • Electronic payment system
  • Banking and other electronic systems
  • Headsets and pagers
  • Office and conference rooms with wireless devices

Zigbee topology

Zigbee is network technology. Here this article gives information about Zigbee topology to know more details about it. 

1. Star topology :

A star network has a central node, which is linked to all other nodes in the networks. All messages travel via the central node.

The star topology consists of a coordinator and several end devices as shown in the figure. In this topology, the end device communicates only with the coordinator. So any packet exchange between end devices must go through the ZigBee coordinator.

The advantages of the star topology are that it is simple and packet go through at most two hopes to reach their destination.

2. Tree topology :

A tree network has a top node with a branch like structure as shown in the figure. To reach its destination, a message travels up the tree and then down the tree.

As shown in the figure, the network terminal consists of a central node, which is a coordinator, several routers and end device.

So in this topology, the task of the router is to extend the coverage of the network. The end nodes connected to the routers or the coordinator are referred to as children. Only the coordinator and the routers can have children like that.

The coordinator and the routers can have children. Hence only they can be parents. A special case of tree topology is called as cluster tree topology. In it, a parent with its children is called a cluster, as shown in the figure.

One of disadvantages of tree topology is that if two nodes are located close to each other, they can not directly communicate.

3. Mesh topology :

A mesh topology look like a tree structure, in which some leaves are directly linked. Message can travel across the tree, when a suitable route is available.

It is also called peer to peer topology. It consist of one coordinator several routers , and end device as shown n figure. 

Following characteristics of a mesh topology

  • Dead zone eliminated in this topology
  • In this topology the device can be placed close to each other so that they use less power
  • Adding or removing a device is very easy in this topology
  • Any source device can communicate with any destination in the network
  • It uses a more complex routing protocol in comparison to the star topology
Zigbee topology



Application of Zigbee networks

Zigbee is a wireless protocol used for wireless networking technology and connectivity. Zigbee is the wireless language that every device used to connect to one another. It is the recently emerged technology of network communication based on the IEEE 802.15.4 standard where IEEE stands for Institute of electrical and electronic and communication engineers. Zigbee is a new standard developed by the Zigbee alliance for personal area network ( called PAN), Consisting of more than 270 companies. 

Now let us now check it out the application of the Zigbee network to know more details about the Zigbee network.

Home automation :
  • Heating, lighting
  • Cooling, door locking mechanisms
  • Home security system
  • Smoke detector
Telecom application :
  • Used to transmit and receive the message
  • Share ring tone, images, and contacts
  • Emergency services
Industrial automation :
  • Personal tracking
  • Livestock tracking
  • Record and transmit critical data like pressure, temperature, and also a vibration
Security :
  • Home security
  • Fire detection
Some other applications :
  • Health care
  • Smart energy
  • Remote control for consumer electronics 
  • Hotel room access
  • Smart metering

Advantages and disadvantages of Zigbee networks

Zigbee network technology is a wireless protocol used for wireless networking and connectivity. Zigbee is the wireless language that every device used to connect to one another. It is the recently emerged technology of network communication system based on the  IEEE 802.15.4 standard. Zigbee is a new standard developed by the Zigbee alliance for personal area network ( called PAN), Consisting of more than 270 companies. Let us now check it out advantages and disadvantages of  Zigbee network to know more details about the Zigbee network.

Advantages of Zigbee networks :
  • Zigbee has a flexible network structure
  • It has very long battery life
  • Zigbee has a mesh network topology with low cost, multi hope data transmission and is power effective
  • It is less complex than Bluetooth
  • It is easy to install
  • Zigbee support a large number of nodes 
  • Zigbee is more reliable 
  • It is a short working period result in power saving and power consumption of communication
Disadvantages of Zigbee networks :
  • Zigbee disadvantages mainly include short range
  • Low complexity, and low data speed
  • Its high maintenance cost, lack of total solution, and slow materialization,
  • Low transmission, as well as low network stability, are also some of its disadvantages that takes it a step back as compared to others
  • Replacement with Zigbee compliant appliances can be costly 
  • Zigbee is not secure like WiFi based secured system
  • It does not have end devices available yet
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Features of Zigbee network

We all know that Zigbee technology is a wireless protocol used for wireless networking and connectivity. Zigbee is the wireless language technology that every device used to connect to one another. It is the recently emerged technology of network communication based on the IEEE 802.15.4 standard where the standard IEEE stands for Institute of electrical and electronic engineers. Zigbee is a new standard developed by the Zigbee alliance for PAN stands called personal area network, Consisting of more than 270 or more companies. Here this article gives the basic features of the Zigbee network to know more details about the Zigbee network.

 Feature of Zigbee
  • Zigbee has incorporated power saving mechanisms for all device classes
  • Discovery mechanism with full application confirmation
  • Pairing mechanism with full application confirmation
  • Various transmission option included broadcast
  • It has a small packet compared with WiFi and Bluetooth
  • Low data rate
  • Low battery consumption
  • The maximum range of operation for a Zigbee device is  around 250 feet
  • Easy to implement
  • Low cost
  • It supports up to around 65000 nodes connected in a network
  • Support alliance standard or manufacturer specific profiles
  • It has used small packets compared with WiFi and Bluetooth
  • Multiple star topology and interpersonal area network communication
  • Zigbee can automatically establish its network

Features of WDM

The technology of WDM full meaning is wavelength division multiplexing. This technology widely used in optical transport networks so many application of WDM in the communication system. The technical requirement is only that the laser is of very specific and that the DWDM full form is capable of distinguishing each wavelength without cross-talk. This article gives some features of WDM to give more information about WDM.
  • Capacity upgrades - Since each wavelength support independent data rate in up to Gbps range.
  • Transparency - WDM can carry fast asynchronous, slow synchronous, synchronous analog and also provide digital data.
  • Wavelength routing - Link capacity and flexibility can be increased by using multiple wavelengths.
  • Wavelength switching - WDM can add and drop multiplexers, cross-connect and wavelength converters.

Application of WDM

The technology of WDM is nothing but wavelength division multiplexing the full form of WDM. This technology widely used in optical transport networks. The technical requirement is only that the laser is of very specific and that the DWDM full form is capable of distinguishing each wavelength without cross-talk. This article gives some application of WDM to give more information about WDM.

  • In SONET network
  • Dense WDM multiplexing allow to muxed and demuxed numbers of channel closer to one another to achieve greater efficiency
  • FDM to the optical fiber
  • Optical transport network
  • Local exchange network
You can also know the feature and applications of WDM.

Application of WiMAX

Wi-Fi and WiMAX offer complementary solutions with Wi-Fi being suitable for short range and WiMAX being suitable for long-range outdoor connection.
  • It is a wireless alternative to many existing wired and late miles coverage deployments such as cable modem, digital subscriber line, T and E-carrier system and optical carrier technologies.
  • The most important application offered by WiMAX technology is business, Multiplayer interactive gaming, backhaul, consumer connectivity, large area coverage access
  • It can offer broadband wireless access at data rates of multiple in Mbit/second to the end user and within a range of several kilometers. 
  • And also the same radio technology will also offer high-speed data services to all nomadic terminal like laptops. PDAs, etc
  • IEEE 802.16 - Fixed users
  • IEEE 802.16e - portable user
  • back-haul - Point to point antenna are used to connect base station located across a long distance
  • Last mile - Residential and business subscriber are connected to the base station using point to multi-point antennas
  • Large area coverage access - also offer broadband connectivity in larger areas

Advantages and disadvantages of WiMAX

WiMAX stands for Worldwide Interoperability for Microwave Acess services brings long time term evolution in the wireless sector. It is similar to the Wi-Fi both create hot-spots. Wi-Fi technology can cover several 100 meters while covering a range of 40-50 km. It can also provide a wireless alternative to cable, DSL, and broadband access. The main advantages of WiMAX are that it allows high-speed wireless internet connection over the broad coverage area, while main disadvantages of WiMAX is still much bigger installation coast and also operational cost. Now let us check it out the information about the advantages and disadvantages of WiMAX to know more details about it.

 Advantages of WiMAX :
  • A single location can serve hundreds of users
  • Single WiMax BS serves hundreds of users
  • Much faster deployment of the new user as compared to wired networks
  • It creates a volume opportunity for silicon suppliers
  • The speed of 10 Mbps at 10 kilometers with a line of sight
  • It is considered to be a cheaper alternative to broadband wired technologies viz. ADSL, cable modem etc
  • It is standardized, and also have same frequency equipment should work together
  • There exists a standard based, the stable platform upon which to rapidly add new capabilities so it is innovating more rapidly
  • Higher bandwidth
  • High coverage range
  • High speed can be achieve
  • Lower cost
  • Communication range up to 100 miles 
  • Does not require telephone lines
  • Provide mobility to a user with access to the internet
  • Design with better quality services
  • No SIM card requires
  • Non-line of sight connection
  • It works on an unlicensed frequency spectrum
  • Cellular like performance is achieved with mobile WiMAX
Disadvantages of WiMAX :
  • Big installation and operational cost
  • Multiple frequencies are used
  • A line of sight needed
  • Poor bandwidth when serving lots of clients
  • Higher latency
  • Unreliable service
  • Spectral limitation
  • Big delay
  • Big power consumption
  • Interference with other wireless signals
  • Hand over and roaming hard to achieve
  • Very power intensive technology  and  also have to require strong electrical support
  • Weather conditions like rain could cause interference
  • WiMAX is very power consuming
  • Multiple frequencies are used for WiMax deployment
  • WiMAX can offer up to 70 Mbps in the range of 70 miles with the moving station. So in practice, the situation is very different. So it is true that only in ideal circumstances with only one recipient
  • If there are many users in one sector, then they will have lower speed

WiFi technology

Wi-Fi network uses radio technologies to transmit and receive data at high speed. 

 These are governed by some set of the standard given below :
  1. IEEE 802.11b
  2. IEEE 802.11a
  3. IEEE 802.11g
1. IEEE 802.11b
  • It was formulated in the year 1999
  • It operates at 2.4 GHz radio spectrum
  • The actual speed is 4-6 Mbps
  • It supports a range from 100-500 feet
  • It is a very popular Wi-Fi technology and is the least expensive
  • It has a theoretical speed of 11 Mbps within 30 m range
2. IEEE 802.11a
  • It was introduced in 2001
  • It operates at 5GHz with theoretical speed 54 Mbps
  • It is the most expensive technology and hence reduce its popularity
  • It is actual speed varies from 15-20 Mbps in a range of 50-75 feet
  • It is not compatible with IEEE 802.11b
3. IEEE 802.11g
  • It was introduced in 2003
  • It was improved version with inherent advantages of 802.11a and 802.11b specification
  • It operates at 2.4 GHz radio frequency
  • It has a speed of 54 Mbps and covers a range of 100-150 feet
  • It is compatible with IEEE 802.11b

Advantages and disadvantages of WiFi

Wi-Fi is term full form of Wi-Fi is Wireless fidelity is an alternative to wired technology that is commonly used for connecting devices in wireless mode. Wi-Fi network device connects computers to each other to the internet and to the wired network. This article gives information about some advantages and disadvantages of Wi-Fi to know more details about Wi-Fi. 

Advantages of Wi-Fi :
  • Ease of installation
  • It is easy to add Wi-Fi client
  • Flexibility
  • Cost-effective, Reduce set up the cost
  • Reduce cable clutter
  • Avoid deterioration
  • Secure
  • VOIP facility
  • Flexible computing
  • Better coverage
  • Hotspots
  • Increase efficiency
  • Working inflexible
  • Eliminate re-configuring computer
  • Support roaming
  • Provide high-speed internet access
  • Use unlicensed part of the radio spectrum
  • Mobility facility
  • Cheaper than wired connection as no wires are required
  • Low cost of Implication
  • WiFi-enabled USB dongles are available at a very affordable rate from TP-link, D-link, Tenda, etc
  • Easy to integrate
  • No need to stick at one place
  • More than one device can be accessed wireless internet connection
Disadvantages of Wi-Fi :
  • Degradation in performance
  • Lesser range
  • Less speed
  • Lesser control
  • Less stable
  • Slower than cable
  • Effect of climatic condition
  • Unauthorized access
  • Compromising data
  • Denial of service
  • Data transfer rate decreases  when the number of clients
  • Limited range of network
  • Full security is difficult to achieve
  • Can generate radiation which can harm the human health
  • Installation problem
  • High power consumption
  • Limited range operation
  • Affected by interference
  • Limited lifetime
  • Risk of cancer
  • Effect of children and pregnant women
  • Sometimes bad weather slows down internet connection speed due to lack of proper WiFi signals
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Conclusion :
The conclusion is that a WiFi network is not perfect. There are many advantages and disadvantages to a WiFi network. However, it has a lot of advantages. Hence, every day, this modern technology is becoming popular and its uses are increasing on a large scale.

Application of WiFi

Wi-Fi fidelity is an alternative to wired technology that is commonly used for connecting devices in wireless mode. A Wi-Fi network connects to the computers to each other to the internet and the wired network. This article gives an application in Wi-Fi technology to gives more information in Wi-Fi.

Wi-Fi network finds a variety of application following below :

  • Home/residential areas
  • Health care
  • Travelers
  • Browsing the internet
  • Mobile application
  • Computerized application
  • Bank
  • Institutes
  • Educational
  • Stream audio to the wireless speaker
  • Sharing the files
  • Wireless ISP
  • Small business or SOHO
  • Large corporation and campuses
  • Video conference
  • Automotive segment
  • Mobile application
  • Business application
  • Video conference

Full form related to optical communication

Optical communication related full form :

AON - All-optical network
APD - Avalanche photodiode
ASE - Amplified spontaneous emission
ATM - Asynchronous transfer mode
BER - Bit error rate
BH - Buried heterostructure
CNR - Carrier to noise ratio
CVD - Chemical vapor deposition
DBR - Distributed Bragg reflector
DFB - Distributed feedback
EDFA - Erbium-doped fiber amplifier
FDDI - Fiber distributed data interface
FP - Fabry Perot
FWHM - Full width at half maximum
GVD - Group velocity dispersion
HBT - Heterojunction bipolar transistor
HFD - Hybrid fiber co-axial
IMD - Intermodulation distortion
IMP - Intermodulation product
ISI - Intersymbol interference
LEAF - Large effective area fiber
LED - Light-emitting diode
LO - Local oscillator
MCVD - Modified chemical vapor deposition
MEMS - Micro electro mechanical system
MOCVD - Metal-organic chemical vapor deposition
MONET - Multi-wavelength optical network
NA - Optical carrier
OTDM - Optical time division multiplexing
OVD - Outside vapor deposition
PIC - Photonic integrated circuit
PON - Passive optical network
RDF - Reverse dispersion fiber
RIN - Relative intensity noise
RMS  - Root mean square
RZ - Return to zero
SCM - Subcarrier multiplexing
SDH - Synchronous digital hierarchy
SONET - Synchronized optical network
STM - Synchronous transport module
STS - Synchronous transport signal
TDM -  Time division multiplexing
TE - Transverse electric
TW - Transverse magnetic
VAD - Vapor axial deposition
VPE - Vapor phase epitaxy
WDM - Wavelength division multiplexing
WDMA - Wavelength division multiple access
YAG - Yttrium aluminium garnet
YIG - Yttrium iron garnet
ZDWL - Zero-dispersion wavelength
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