Wi-fi and Wi-max Systems

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ASSIGNMENT NO: 01

WI-FI & WI-MAX

COURSE NAME: FUNDAMENTALS OF TELECOMMUNICATION ENGG.

COURSE CODE: EC-2101

SUBMISSION DATE: 23/10/09

SESSION: JULY-DEC 2009

SUBMITTED BY:

BIGYAMAN MAHANTA (BA/08/EC/009)

SUSHIL KR. JOSHI (BA/08/EC/011)

BARNAJIT GHOSH (BA/08/EC/017)

MANISH GUPTA (BA/08/EC/021)

ASHISH BHANDARI (BA/08/EC/027)

North Eastern Regional Institute of Science and Technology

(Under the Ministry of Human Resource Development, Govt. of India)

(Deemed University u/s 3 of UGC Act, 1956) Nirjuli-791109, Arunachal Pradesh, India


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WI-FI

1. NAMING

The term Wi-Fi suggests Wireless Fidelity, compared with the long-established audio

recording term High FidelityorHi-FiWireless Fidelity has often been used in an informal

way, even by the Wi-Fi Alliance itself, but officially the term Wi-Fi does not mean anything.

The term Wi-Fi, first used commercially in August 1999, was coined by a brand consulting

firm called Interbrand Corporation that had been hired by the Alliance to determine a name

that was "a little catchier than 'IEEE 802.11b Direct Sequence'." Interbrand invented Wi-Fi as

a play on words withHi-Fi, and also created the yin yang-style Wi-Fi logo.

The Wi-Fi Alliance initially complicated matters by stating that it "actually stoodfor" Wireless Fidelity, as with the advertising slogan, "The Standard for Wireless

Fidelity," but later removed the phrase from their marketing. The Wi-Fi Alliance's

early White papers still held on their website say: "a promising market for wireless fidelity

(Wi-Fi) network equipment." and "A Short History of WLANs." The yin yang logo indicates

that a product had been certified for interoperability.

2. USES

Figure 1 A roof mounted Wi-Fi antenna
http://en.wikipedia.org/wiki/File:WIFI_Amp_Setup.JPG


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Figure 2 A Wi-Fi antennas

A Wi-Fi enabled device such as a PC, video game console, mobile phone, MP3

player or PDA can connect to the Internet when within range of a wireless networkconnected

to the Internet. The coverage of one or more interconnected access points called

a hotspotcan comprise an area as small as a single room with wireless-opaque walls or as

large as many square miles covered by overlapping access points. Wi-Fi technology has

served to set up mesh networks, for example, in London. Both architectures can operatein community networks.

Wi-Fi also allows connectivity in peer-to-peer (wireless ad hoc network) mode, which

enables devices to connect directly with each other (this is being formalized through a new

spec called Wi-Fi Direct. This connectivity mode can prove useful in consumer

electronics and gaming applications.

Many consumer devices use Wi-Fi. Amongst others, personal computers can network to each

other and connect to the Internet, mobile computers can connect to the Internet from any Wi-

Fi hotspot, and digital cameras can transfer images wirelessly.

Figure 3 A keychain sizes Wi-Fi detector
http://en.wikipedia.org/wiki/Personal_computerhttp://en.wikipedia.org/wiki/Video_game_consolehttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/MP3_playerhttp://en.wikipedia.org/wiki/MP3_playerhttp://en.wikipedia.org/wiki/Personal_digital_assistanthttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Wireless_networkhttp://en.wikipedia.org/wiki/Wireless_access_pointhttp://en.wikipedia.org/wiki/Hotspot_(Wi-Fi)http://en.wikipedia.org/wiki/Wireless_mesh_networkhttp://en.wikipedia.org/wiki/Wireless_community_networkhttp://en.wikipedia.org/wiki/Peer-to-peerhttp://en.wikipedia.org/wiki/Wireless_ad_hoc_networkhttp://en.wikipedia.org/wiki/Consumer_electronicshttp://en.wikipedia.org/wiki/Consumer_electronicshttp://en.wikipedia.org/wiki/Personal_computerhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Mobile_computerhttp://en.wikipedia.org/wiki/Digital_camerahttp://en.wikipedia.org/wiki/File:WiFi-detector.jpghttp://en.wikipedia.org/wiki/File:Patras_Wireless_Network_1.jpghttp://en.wikipedia.org/wiki/Digital_camerahttp://en.wikipedia.org/wiki/Mobile_computerhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Personal_computerhttp://en.wikipedia.org/wiki/Consumer_electronicshttp://en.wikipedia.org/wiki/Consumer_electronicshttp://en.wikipedia.org/wiki/Consumer_electronicshttp://en.wikipedia.org/wiki/Wireless_ad_hoc_networkhttp://en.wikipedia.org/wiki/Peer-to-peerhttp://en.wikipedia.org/wiki/Wireless_community_networkhttp://en.wikipedia.org/wiki/Wireless_mesh_networkhttp://en.wikipedia.org/wiki/Hotspot_(Wi-Fi)http://en.wikipedia.org/wiki/Wireless_access_pointhttp://en.wikipedia.org/wiki/Wireless_networkhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Personal_digital_assistanthttp://en.wikipedia.org/wiki/MP3_playerhttp://en.wikipedia.org/wiki/MP3_playerhttp://en.wikipedia.org/wiki/MP3_playerhttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Video_game_consolehttp://en.wikipedia.org/wiki/Personal_computer


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3. ADVANTAGES AND CHALLANGES

Wi-Fi allows local area network (LANs) to be deployed without wires for client devices,

typically reducing the costs of network deployment and expansion. Spaces where cables

cannot be run, such as outdoor areas and historical buildings, can host wireless LANs.

Wireless network adapters are now built into most laptops. The price ofchipsets for Wi-Fi

continues to drop, making it an economical networking option included in even more devices.

Wi-Fi has become widespread in corporate infrastructures.

Different competitive brands of access points and client network interfaces are inter-operable

at a basic level of service. Products designated as "Wi-Fi Certified" by the Wi-Fi Alliance are

backwards compatible. Wi-Fi is a global set of standards. Unlike mobile phones, any standard

Wi-Fi device will work anywhere in the world.

4. MOBILITY

Figure 4 Speed vs. Mobility of wireless systems: Wi-Fi, HSPA,UMTS, GSM

Because of the very limited practical range of Wi-Fi, mobile use is essentially confined to

such applications as inventory taking machines in warehouses or retailspaces, barcode reading devices at check-out stands or receiving / shipping stations. Mobile

use of Wi-Fi over wider ranges is limited to move, use, as for instance in an automobile

moving from one hotspot to another (known as Wardriving). Other wireless technologies are

more suitable as illustrated in the graphic.
http://en.wikipedia.org/wiki/Chipsethttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/High_Speed_Packet_Accesshttp://en.wikipedia.org/wiki/UMTShttp://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/Barcodehttp://en.wikipedia.org/wiki/Wardrivinghttp://en.wikipedia.org/wiki/File:Wimax.svghttp://en.wikipedia.org/wiki/Wardrivinghttp://en.wikipedia.org/wiki/Barcodehttp://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/UMTShttp://en.wikipedia.org/wiki/High_Speed_Packet_Accesshttp://en.wikipedia.org/wiki/Mobile_phonehttp://en.wikipedia.org/wiki/Chipset


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5. NETWORK SECURITY

The main issue with wireless network security is its simplified access to the network

compared to traditional wired networks such as Ethernet. With wired networking it is

necessary to either gain access to a building, physically connecting into the internal network,

or break through an external firewall. Most business networks protect sensitive data and

systems by attempting to disallow external access. Thus being able to get wireless reception

provides an attack vector, if encryption is not used or can be defeated.

Attackers who have gained access to a Wi-Fi network can use DNS spoofing attacks very

effectively against any other user of the network, because they can see the DNS requests

made, and often respond with a spoofed answer before the queried DNS server has a chance

to reply.
http://en.wikipedia.org/wiki/Ethernethttp://en.wikipedia.org/wiki/Ethernet


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WI-MAX

1. NAMINGWi-Max, meaning Worldwide Interoperability for Microwave Access, is

a telecommunications technology that provides wireless transmission of data using a varietyof transmission modes, from point-to-multipoint links to portable and fully mobile internet

access. The technology provides up to 10 Mbit/s broadband speeds without the need for

cables. The name "WiMAX" was created by the WiMAX Forum, which was formed in June

2001 to promote conformity and interoperability of the standard. The forum describes

WiMAX as "a standards-based technology enabling the delivery oflast mile wireless

broadband access as an alternative to cable and DSL".

Figure 5 WiMAX base station equipment with a sector antenna and wireless modem on top

2. USES

The bandwidth and range of WiMAX make it suitable for the following potential

applications: Connecting Wi-Fi hotspots to the Internet. Providing a wireless alternative to cable and DSL for "last mile" broadband access. Providing data and telecommunications services. Providing a source of Internet connectivity as part of a business continuity plan. That is, if

a business has both a fixed and a wireless Internet connection, especially from unrelated

providers, they are unlikely to be affected by the same service outage.

Providing portable connectivity.
http://en.wikipedia.org/wiki/Telecommunicationhttp://en.wikipedia.org/wiki/Transmission_(telecommunications)http://en.wikipedia.org/wiki/Point-to-multipoint_communication_(telecommunications)http://en.wikipedia.org/wiki/WiMAX#WiMAX_Forumhttp://en.wikipedia.org/wiki/Last_milehttp://en.wikipedia.org/wiki/Base_stationhttp://en.wikipedia.org/wiki/Sector_antennahttp://en.wikipedia.org/wiki/Wireless_modemhttp://en.wikipedia.org/wiki/Hotspot_(Wi-Fi)http://en.wikipedia.org/wiki/Digital_subscriber_linehttp://en.wikipedia.org/wiki/Last_milehttp://en.wikipedia.org/wiki/File:WiMAX_equipment.jpghttp://en.wikipedia.org/wiki/Last_milehttp://en.wikipedia.org/wiki/Digital_subscriber_linehttp://en.wikipedia.org/wiki/Hotspot_(Wi-Fi)http://en.wikipedia.org/wiki/Wireless_modemhttp://en.wikipedia.org/wiki/Sector_antennahttp://en.wikipedia.org/wiki/Base_stationhttp://en.wikipedia.org/wiki/Last_milehttp://en.wikipedia.org/wiki/WiMAX#WiMAX_Forumhttp://en.wikipedia.org/wiki/Point-to-multipoint_communication_(telecommunications)http://en.wikipedia.org/wiki/Transmission_(telecommunications)http://en.wikipedia.org/wiki/Telecommunication


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3. MAC LAYER/DATA LINK LAYERIn Wi-Fi the media access controller (MAC) uses contention accessall subscriber stations

that wish to pass data through a wireless access point (AP) are competing for the AP's

attention on a random interrupt basis. This can cause subscriber stations distant from the APto be repeatedly interrupted by closer stations, greatly reducing their throughput.

The time slot can enlarge and contract, but remains assigned to the subscriber station, which

means that other subscribers cannot use it. In addition to being stable under overload and

over-subscription, the 802.16 scheduling algorithm can also be more bandwidth efficient. The

scheduling algorithm also allows the base station to control QoS parameters by balancing the

time-slot assignments among the application needs of the subscriber stations.

4. DEPLOYMENT

Modulation is chosen to be spectrally more efficient (more bits

per OFDM/SOFDMA symbol). That is, when the bursts have a high signal and a carrier to

noise plus interference ratio (CINR), they can be more easily decoded using digital signal

processing (DSP). In contrast, operating in less favourable environments for RF

communication, the system automatically steps down to a more robust mode (burst profile)

which means fewer bits per OFDM/SOFDMA symbol; with the advantage that power per bit

is higher and therefore simpler accurate signal processing can be performed.

Burst profiles are used inverse (algorithmically dynamic) to low signal attenuation; meaning

throughput between clients and the base station is determined largely by distance. Maximumdistance is achieved by the use of the most robust burst setting; that is, the profile with the

largest MAC frame allocation trade-off requiring more symbols (a larger portion of the MAC

frame) to be allocated in transmitting a given amount of data than if the client was closer to

the base station.

The client's MAC frame and their individual burst profiles are defined as well as the specific

time allocation. However, even if this is done automatically then the practical deployment

should avoid high interference and multipath environments. The reason for which is

obviously that too much interference causes the network function poorly and can also

misrepresent the capability of the network.

The system is complex to deploy as it is necessary to track not only the signal strength and

CINR (as in systems like GSM) but also how the available frequencies will be dynamically

assigned (resulting in dynamic changes to the available bandwidth.) This could lead to

cluttered frequencies with slow response times or lost frames.

As a result the system has to be initially designed in consensus with the base station product

team to accurately project frequency use, interference, and general product functionality.
http://en.wikipedia.org/wiki/Wi-Fihttp://en.wikipedia.org/wiki/Media_Access_Controlhttp://en.wikipedia.org/wiki/Contention_(telecommunications)http://en.wikipedia.org/wiki/Wireless_access_pointhttp://en.wikipedia.org/wiki/Bandwidth_(computing)http://en.wikipedia.org/wiki/Quality_of_servicehttp://en.wikipedia.org/wiki/Orthogonal_frequency-division_multiplexinghttp://en.wikipedia.org/wiki/Orthogonal_frequency-division_multiple_accesshttp://en.wikipedia.org/wiki/Carrier_to_Noise_Ratiohttp://en.wikipedia.org/wiki/Carrier_to_Noise_Ratiohttp://en.wikipedia.org/wiki/Digital_signal_processinghttp://en.wikipedia.org/wiki/Digital_signal_processinghttp://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/GSMhttp://en.wikipedia.org/wiki/Digital_signal_processinghttp://en.wikipedia.org/wiki/Digital_signal_processinghttp://en.wikipedia.org/wiki/Digital_signal_processinghttp://en.wikipedia.org/wiki/Carrier_to_Noise_Ratiohttp://en.wikipedia.org/wiki/Carrier_to_Noise_Ratiohttp://en.wikipedia.org/wiki/Carrier_to_Noise_Ratiohttp://en.wikipedia.org/wiki/Orthogonal_frequency-division_multiple_accesshttp://en.wikipedia.org/wiki/Orthogonal_frequency-division_multiplexinghttp://en.wikipedia.org/wiki/Quality_of_servicehttp://en.wikipedia.org/wiki/Bandwidth_(computing)http://en.wikipedia.org/wiki/Wireless_access_pointhttp://en.wikipedia.org/wiki/Contention_(telecommunications)http://en.wikipedia.org/wiki/Media_Access_Controlhttp://en.wikipedia.org/wiki/Wi-Fi


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5. SPECTRAL EFFICIENCYOne of the significant advantages of advanced wireless systems such as WiMAX is spectral

efficiency. For example, 802.16-2004 (fixed) has a spectral efficiency of 3.7(bit/s)/Hertz, and

other 3.54G wireless systems offer spectral efficiencies that are similar to within a few

tenths of a percent. The notable advantage of WiMAX comes from combining SOFDMA

with smart antenna technologies. This multiplies the effective spectral efficiency through

multiple reuse and smart network deployment topologies. The direct use of frequency domain

organization simplifies designs using MIMO-AAS compared to CDMA/WCDMA methods,

resulting in more effective systems.

6. LIMITATIONS

Typically, fixed WiMAX networks have a higher-gain directional antenna installed near theclient (customer) which results in greatly increased range and throughput. Mobile WiMAX

networks are usually made of indoor "Customer-premises equipment" (CPE) such as desktop

modems, laptops with integrated Mobile WiMAX or other Mobile WiMAX devices. Mobile

WiMAX devices typically have unidirectional antennae which are of lower-gain compared to

directional antennas but are more portable. In current deployments, the throughput may reach

2 Mbit/s symmetric at 10 km with fixed WiMAX and a high gain antenna. It is also important

to consider that a throughput of 2 Mbit/s can mean 2 Mbit/s, symmetric simultaneously,

1 Mbit/s symmetric or some asymmetric mix (e.g. 0.5 Mbit/s downlink and 1.5 Mbit/s uplink

or 1.5 Mbit/s downlink and 0.5 Mbit/s uplink), each of which required slightly different

network equipment and configurations. Higher-gain directional antennas can be used with a

WiMAX network with range and throughput benefits but the obvious loss of practical

mobility.

Like most wireless systems, available bandwidth is shared between users in a given radio

sector, so performance could deteriorate in the case of many active users in a single sector. In

practice, most users will have a range of 2-3 Mbit/s services and additional radio cards will

be added to the base station to increase the number of users that may be served as required.

Because of these limitations, the general consensus is that WiMAX requires various granular

and distributed network architectures to be incorporated within the IEEE 802.16task groups.This includes wireless mesh, grids, network remote station repeaters which can extend

networks and connect to backhaul.

7. COMPARISON WITH WI-FIComparisons and confusion between WiMAX and Wi-Fi are frequent because both are

related to wireless connectivity and Internet access.

WiMAX uses is a long range system, covering many kilometres, that uses licensed orunlicensed spectrum to deliver a point-to-point connection to the Internet.
http://en.wikipedia.org/wiki/Spectral_efficiencyhttp://en.wikipedia.org/wiki/Spectral_efficiencyhttp://en.wikipedia.org/wiki/Spectral_efficiencyhttp://en.wikipedia.org/wiki/Smart_antennahttp://en.wikipedia.org/wiki/Customer-premises_equipmenthttp://en.wikipedia.org/wiki/IEEE_802.16http://en.wikipedia.org/wiki/Wireless_mesh_networkhttp://en.wikipedia.org/wiki/Wi-Fihttp://en.wikipedia.org/wiki/Wi-Fihttp://en.wikipedia.org/wiki/Wireless_mesh_networkhttp://en.wikipedia.org/wiki/IEEE_802.16http://en.wikipedia.org/wiki/Customer-premises_equipmenthttp://en.wikipedia.org/wiki/Smart_antennahttp://en.wikipedia.org/wiki/Spectral_efficiencyhttp://en.wikipedia.org/wiki/Spectral_efficiencyhttp://en.wikipedia.org/wiki/Spectral_efficiencyhttp://en.wikipedia.org/wiki/Spectral_efficiency


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Different 802.16 standards provide different types of access, from portable (similar to acordless phone) to fixed (an alternative to wired access, where the end user's wireless

termination point is fixed in location.)

Wi-Fi uses unlicensed spectrum to provide access to a network.

Wi-Fi is more popular in end user devices. WiMAX and Wi-Fi have quite different quality of service (QoS) mechanisms. WiMAX uses a mechanism based on connections between the base station and the user

device. Each connection is based on specific scheduling algorithms.

Wi-Fi has a QoS mechanism similar to fixed Ethernet, where packets can receivedifferent priorities based on their tags. For example VoIP traffic may be given priority

over web browsing.

Wi-Fi runs on the Media Access Control's CSMA/CA protocol, which is connectionlessand contention based, whereas WiMAX runs a connection-oriented MAC.
http://en.wikipedia.org/wiki/Voice_over_Internet_Protocolhttp://en.wikipedia.org/wiki/Media_Access_Controlhttp://en.wikipedia.org/wiki/Media_Access_Controlhttp://en.wikipedia.org/wiki/Voice_over_Internet_Protocol

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