Advantages And Disadvantages Of Wifi PDF

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Advantages And Disadvantages Of Wifi...

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Advantages And Disadvantages Of Wifi 1. INTRODUCTION

Figure: Wi-Fi logo

Wi-Fi stands for wireless fidelity. Wi-Fi is the wireless network that used to connect the internet without wires. It’s based upon the radio technology. Many computers can be connected to each other through Wi-Fi and we can share files data and many of the other things through Wi-Fi. A Wi-Fi network operated just like a wired network, but without the restriction of wires, it not only enable user to share the data but it also provide easy connection to the internet and business network while travelling. It is the best wireless technology so far in the world. It is fairly easy to set up a Wi-Fi enable network at home or at office.

2. HISTORY AND DISCOVERY OF WIFI

Figure: Wi-Fi trademark

In 1997, the institute of electrical and electronics engineers (IEEE) develop a set of standards required to setup the wireless communication between computers and pre existing networks including networks at home and office. Wi-Fi has mature and grown immensely fast changing the face of computing and communication in the world. First let we look out the history of 802.11 standards (the radio frequency) used for broadcasting a Wi-Fi signal. Secondly we have to look at the electronic equipments involved in sending and receiving the signals, and not surprisingly there are many patents connected with Wi-Fi technology however one important patent stands out.

2.1. The history of 802.11 standard and Vic Hayes

Figure: Vic Hayes

Vic Hayes is known as the “father of Wi-Fi” because he chaired the IEEE committee that is established the 802.11 standard in 1997.Before the world even heard Wi-Fi. He was born on July 31, 1941 at Surabaya, Dutch East Indies. Vic Hayes established the standards that would make Wi-Fi feasible. The 802.11 standard was established in 1997. Many, improvements were added to the 802.11 standard. That’s what the letters represent; 802.11 a, 802.11b, and more.

2.2. WLAN patent

Figure: commonwealth Scientific and industrial research organization

One of the key patents for Wi-Fi technology that has won patent litigation lawsuits and does deserve credit belongs to the commonwealth Scientific and industrial research organization (CSIRO) of Australia. CSIRO invented a chip which improves the signal quality of Wi-Fi. “The inventions done by the CSIRO’s & pioneering work in radio astronomy, with a team of CSIRO’s scientists which was led by Dr. John o Sullivan cracking the problem of radio waves bouncing off surface indoors, causing an echo effect that distorts the signal. They solve this problem by building a fast chip that could transmit the signal while reducing the echo.” CISRO consists of the following inventor’s: Dr. John o Sullivan, Dr. Terry Percival, Mr. Graham Daniels, Mr. Diet Ostry and Mr. John Dean that create this technology.

3. HOW WI-FI WORKS.

Wi-Fi works with no physical connection of wires between sender and receiver by using the technology of radio frequency, a frequency associated with radio wave propagation. When a current is supplied to the antenna, an electromagnetic field is created that then able to propagate through space. The important quality of any wireless network is a space point. The primary job of an access point is to broadcast a wireless signal that computer can detect and “tune” into. In order to connect to an access point and join a wireless network, computer and device must be equipped with wireless network adapters.

Figure: Wi-Fi Router

Many of the laptop comes with the build in Wi-Fi card in them. Wi-Fi card can be internal or external. Meaning that if the system does not have pre installed Wi-Fi card, then one can purchase a USB antenna attachment and have it externally connect to the USB port, or have a pre installed Wi-Fi card in the computer.

4. Wi-Fi HOT SPOTS

Figure: Hotspot

A Hot spot is an area where one can access to the internet over a WLAN with a use of a router connection. Wi-Fi network around the world is creating hot spots in cities where anyone with a laptop can wirelessly plug into the internet. A hotspot is a connection point for a Wi-Fi network. It is a box that is hardwired into the internet. There are many Wi-Fi hotspots now available in public places like restaurants, colleges, schools, malls, hotels, libraries, airports metros etc. the first attempt to create a public local area network was founded in Richardson, Texas known as PLANCOM ( Public local area network Communications ).the founders of this technology Greg Jackson, Mark Goode and Brett Stewart dissolve the firm in 1998.

Figure:- Wi-Fi growth

5. THE RADIO FREQUENCY

Figure: Radio Frequency The device used for Wi-Fi communication can transit and receives radio waves, and they can convert 1s and 0s into radio waves and convert the radio waves back into 1s and 0s. Wi-Fi radios have a few notable differences from other radios: • They transmit at frequency of 2.4 GHz or 5 GHz. This frequency is higher as compare to the frequencies used for cell phones, televisions and wacky- talkies. Higher the transmission of the data if there is higher frequency. • They use 802.11 networking standards. • Wi-Fi radios can transmit on any of three frequency bands. Or, they can “frequency hop” rapidly between the different bands. Frequency

hopping help reduces interference and lets multiple long as they all have wireless adapters; one router is used by several users to connect to the internet through Wi-Fi. This connection is convenient and physically invisible, and it’s fairly reliable. If the router fails or if too many people try to use high bandwidth applications at the same time, in this case users can experience interference or loose there connection. Currently there are three forms of the 802.11 standard proposed by the Institute of electrical and electronics engineering. 802.11b, 802.11a and the last is 802.11g

6. 802.11b –THE RADIO FRQUENCY

Wi-Fi uses the IEEE 802.11b a type of radio technology to provide secure, fast, reliable, wireless connectivity. In the 802.11b the 11bdefine the physical layer and the media access control sub layer for communications across a shared WLAN. The 802.11b operates the frequency of 2.45 GHz with the bit rate of about 11 Mbps. It uses the direct sequence spread spectrum (DSSS)) transmission technique. At

the MAC sub layer of the Data sub layer, 802.11b uses the carrier sense multiple access with collision avoidance media access control protocol.

6.1. Direct Sequence Spread Spectrum

Figure: DSSS working

Direct Sequence is also known as Spread Spectrum Technique. A DSSS converts the incoming data into the symbols, where every symbol is the group of bits. With the help of the phase

varying modulation technique, DSSS transmitter modulates multiplies each symbol with code called “chip” sequence. This is known as processing gain. The multiplication transmitter artificially increase the

used bandwidth based on the length of the chip sequence in a DSSS transmitter. Distribution coordination function is the basic access method for 802.11 which uses carrier sense multiple accesses. This required each user to listen to the other users. If the channel is idle, the station may transmit. However if the station is busy each station wait till the transmission stops, and then enter the random off procedure. This prevents the multiple stations from seizing the medium immediately after the preceding transmission completes.

6.2. Operation Basics

When we turn the wireless adapter on, it starts scanning across the wireless frequencies. Assuming that the wireless clients are configured to operate in infrastructure mode, the wireless adapter chooses an AP to connect. By using the SSID the selection make automatically, signal strength and frame error rate information. Next,

wireless adapter switch to assigned channel of the selected AP and negotiate the use of port. This is known as establishing an association. If the signal strength is too low of the wireless AP, the error rate too high, if instruction by the operating system (in case of windows XP), the wireless adapter scan for the other wireless APs to determine whether a different wireless AP can provide a strong signal. The wireless adapter switches to the channel of the wireless AP if such wireless AP is located and negotiates the use of a port. This is known as re-association

7. RANGE OF WI-FI NETWORKS

Figure: Range

Like all the networks the Wi-Fi network has a limited range. A normal wireless network have a range of 35m (115 ft) in indoors an about 100m (330 ft) in outdoor. Range of a Wi-Fi network depends upon the

frequency band also. The Wi-Fi of the 2.4 GHz frequency has better range as compare to the Wi-Fi of 5 GHz frequency band. It is possible to improve the range of the wireless network but it is only possible with wireless router having detachable antenna which have higher gain in particular direction. In outdoors the high gain directional antennas are used to improve the signal strength to many kilometers. Wi-Fi has quit high power consumption as compare to other slandered; it is due to the reach requirement of wireless LAN applications. The technologies which have lower range also generally have lower power consumption for example Bluetooth (range between 1 to 100m). Other lower power consumption technologies such as ZigBee have very long range, but low data rate. The high power consumption of the Wi-Fi technology makes the battery of the mobile low very fast. Researchers are developing the new wireless technologies to provide an alternative of the Wi-Fi. For example ITU-T G.hn slandered for high speed local area networks. Although G.hn does not provide some of the advantages that Wi-Fi provides.

8. NETWORK SECURITY

The main issue of the wireless network is its security, as it is easily accessible to any user as compare to the wired network such as Ethernet, in the wired network one should gain the network to access to building the external firewall. One if want to make access through Wi-Fi, he/she must have to bring the device in the Wi-Fi network range. An attacker who has gained the access to the wireless network can implement the DNS spoofing attack against other user using the same wireless network.

9. SECURING METHOD

The common way to deter the unauthorized user is hiding the access point’s name by disabling the SSID broadcast. While this method is useful for casual user but it is not effective as a security method

because the SSID is broadcast in the clear in response to a client SSID query. Another way is to only access the user with the MAC addresses registered.

9.1. Wired equivalent privacy (WEP)

The Wired Equivalent Privacy (WEP) encryption is made for the protection of the system from snooping but it is no longer considered as secured. Another way to secure the Wi-Fi network is WPA; WPA was design to work with older equipments usually through a firmware upgrade. The WPA has known as the vulnerabilities because WPA is more secure then the WEP. A flow in the feature is added to Wi-Fi in 2007, called Wi-Fi protection setup.

9.2. Virtual private networks (VPNs)

Since 1990 the virtual networks technologies has been used to secure communication among the remote locations with the help of the internet. It is the familiar and widely used technology in the world, it can either be used in the wireless networks or we can use it in the wired networks also. VPN was design to provide pint-to-point encryption for long internet connections between remote user and there user. Whenever the VPN tunnel is use by the WLAN client, until the communication data reaches the VPN gateway it remain encrypted, which site behind the wireless AP. Thus, from intercepting all the network communication the intruders are effectively block the network communication. Since in the heart of the corporate network the VPN encrypts the entire link from the PC to the VPN, the wireless network segment between the PC and the AP is also encrypted. This is why the VPN have been recommended to help Wi-Fi secure.

9.3. Wi-Fi Protected Access

Wi-Fi Protected Access is a specification of standards, it strongly increase the level of data protection. It is design to run on the hardware that is currently installed in the system as a software upgrade. The Wi-Fi protection access is derived from IEEE 802.11i standards and will be forward – compatible with the upcoming same. If installed correctly it will give the high level of protection to the data and will allow only the authorized network user to access. The Wi-Fi protection access has some of its goals to make Wi-Fi more protective, that is be a strong interoperable, be software upgradeable, be easily used by both home and large enterprise user etc. two primary security enhancements need to be made for the achievement of the goals.

10. Wi-Fi SIGNAL INTERFERENCE

Wi-Fi signal interferences’ can be broke down into 2 categories. The very first interference is easy to understood physical interference.

Second is electromagnetic interference. Let us study about each of them briefly:-

1. Physical interference Like the cellular towers, the Wi-Fi transducer emits signals in 360 degree. Making a large sphere, in this sphere closer you are from the center, the stronger and better the signal. But when some physical interruptions occur in the transmission of this signal this is known as physical interference. This physical interruption includes wall, trees, etc. 2. Electromagnetic interference This type of interference is due to the other devices that usually come in two forms that are the interference due to magnetic field from devices that run on electricity and interference due to the radio signals coming from other electronics devices. 1. Magnetic interference from electrical devices-

Magnetism and electricity are closely related to each other, as we know every electric field correspond with the magnetic field. Magnetic fields, regardless of their source, can interfere with the radio wave. Any device which use electricity generate the magnetic field and the magnetic field will depend largely upon the power of the device, all the devices like an AC, a microwave, etc. this magnetic field interferes the Wi-Fi signal. 2. Interference due to Radio wave In addition to electricity and magnetism, the interfering with other radio waves is important to understand. There are two main reasons. One is old friend magnetism, and the other is a phenomenon known as "phasing."

11. ADVANTAGES AND FUTURE OF Wi-Fi TECHNOLOGY

Wi-Fi is very chipper and allows easy development of the local area network. Wi-Fi is independent of wires, that’s why it is best to build

Wi-Fi enable area anywhere specially at outdoors and historical buildings. Companies are making the laptops that have wireless network adapter in it and the prices of such laptops are very low, making the Wi-Fi an economical networking option. User connected to the Wi-Fi network can maintain a nearly constant affliction with their own network as they move from one place to another. In wireless network we can add more clients to the network easily without any wastage of money and material, where as in the wired network more wire required to connect more clients. The popularity of wireless LANs is a testament primarily to their convenience, ease of integration with other networks and network components and cost efficiency. All the computers today come with all the wireless technologies built like Wi-Fi, Bluetooth, etc.

What is next?

Now the main focus of the Wi-Fi is to increase its range as far as possible so that at a time many users can use the Wi-Fi technology. WiMax which also be called as the Worldwide Interoperability for Microwave Access. Is define in IEEE802.16 standard is design to delivers a metro area broadband wireless access service. WiMax is same as the Wi-Fi technology. But deliver much higher speed as compare to the Wi-Fi technology, on a much larger scale.

12. DISADVANTAGES OF THE Wi-Fi TECHNOLOGY

As we know the most beneficial technology has some of its disadvantage the same is for the Wi-Fi technology let us look some of the disadvantages of the Wi-Fi:1. The Wi-Fi band that is used in Wi-Fi is 2.4GHz does not required any license in most of the countries provide that it stay below the limit of

2. 100mW and one accept interference from other device; including interference which cause the user device to no longer function.

3. Power consumption in the Wi-Fi technology is quite high as compare to other device that led to use the excess battery and liberation of heat.

4. The Wi-Fi has unlicensed 2.4GHz spectrum which may cause degradation in performance because it often crowed with other device such as Bluetooth, microwave ovens, cordless phone etc.

5. Wi-Fi network also have a very limited range. A home Wi-Fi router might have a range of45m indoors and 90m outdoors.

6. The most common wireless encryption standard, WEP has been showed to be breakable even after correctly configured.

7. The Wi-Fi modem use dangerous electromagnetic radiation to send the signals to your computer through walls. This electromagnetic radiation can harm you and cause many of the disease.

13. CONCLUSION

Wi-Fi is the technology that provides you the freedom, freedom to share the data, freedom to connect to the internet, freedom to grow and move the business without installing new cables and wires, freedom to connect while travelling. Wireless hotspots are installed worldwide. That is helping us to stay connected to the internet and with each other all the time. As Wi-Fi is the wireless technology it is very cheap as compared to the wired network technology. Nowadays every device like mobile, laptops etc are coming with Wi-Fi pre

installed in it, and a very large population of the world use internet through mobiles which make it very popular among users. Security of the Wi-Fi network is the big issue for the user but now many of the software are available that make the Wi-Fi network super secure. Wi-Fi technology is growing immensely fast in public access area, home and businesses both large and small. The Wi-Fi alliance is working with many of the industry organization to make the devices which can be compatible with wireless technology building in the future.

14. REFERENCE

Wikipedia.org

Computer.howstuffworks.com

Webopedia.com

Techterms.com

Bbc.co.uk

Compnetworking.about.com

Tutorialspoint.com...