L E C T U R E 1 0

CT1303 LAN

WIRELESS NETWORK

• Is any type of computer network that uses wireless data connections for connecting network nodes and sharing network resources.• So, it differs than previous network with, the type

of transmission media, wireless transmission media.• Microwave.• Infrared.• Laser.

WIRELESS NETWORK

• Wireless network based on its covered and its bandwidth used in its channel frequencies.• Wireless Personal Area Network (WPAN) الشخصية الشبكة

الالسلكية .المحلية• Wireless LAN الالسلكية المحلية . الشبكة• Wireless WAN الالسلكية الموسعة . الشبكة• Wireless Broadband النطاق عريضة المدنية الالسلكية . الشبكة• Wireless Cellular الجوالة الالسلكية .الشبكة

WIRELESS PERSONAL AREA NETWORK (WPAN)

• Used to link or connect personal devices (PDA Personal Data Assistant), printers, mobile devices embedded in computers.

• One hall, room

• Controlled by 1 person owned the network.

• Microwave, Infrared waves.

WIRELESS LAN

• Covers a building, or more.• Connects personal computers, Notebooks,

printers, storage devices wirelessly.• Controlled by 1 person or more.• Microwave, Infrared waves.

WIRELESS WAN

• Covered wider geographical area, cities, countries.

• Links and connects computers among different cities wirelessly by Satellite.

• Controlled by international organization or government or big telecommunication companies.

WIRELESS BROADBAND

• Covers a city.• Connects computers wirelessly.• Mainly used to transmit large amounts of data

very fast, • Ex: Video films, Photos, websites.

• Broadband microwaves, laser.

• Controlled by organization or government.

WIRELESS CELLULAR

• Used mostly for mobiles, but now can be used for data transmission.• Can connect computers, connect to Internet.• Can be used in a wide area.• Controlled by companies or government.

WIRELESS LAN APPLICATIONS

• To extend LAN.• Sometimes it is difficult to extend a wired LAN, so

wireless technologies can help. • To connect two to more LANs.

WIRELESS LAN APPLICATIONS

WIRELESS LAN APPLICATIONS

• Advantages:• Decrease cost of the new extension.• Easy to change.

WIRELESS LAN APPLICATIONS

• Serve mobile devices, laptops, notebooks.

WIRELESS LAN APPLICATIONS

•Build a temporary network.•Military camps.•Relief camps.•conferences.•Usually this type of temporary networks have a

changing topology ( not fixed or has a permanent topology).

CHALLENGES AND OBSTACLES OF WIRELESS NETWORKS

•Radio and microwaves and infrared waves is more prone to the interference.

•Data transmission is not %100 guaranteed.•Attenuation and fading of waves and signals may

occur.•Privacy security concerns .•The limitation of the bandwidth, and the huge

number of people connecting with this network demanding the need to manage and granting the

right to broadcast to eliminate interference if waves .

CHALLENGES AND OBSTACLES OF WIRELESS NETWORKS

• Usually transmission rate becomes lower (based on Nyqist rule) when huge number of Subscribers are there.• The limitation of the power that supplies wireless

devices , protocols should be made based on it.• “Hidden node” and “Exposed node” .

CHALLENGES AND OBSTACLES OF WIRELESS NETWORKS

MAIN STRUCTURE OF WIRELESS LANS

• Add-hoc WLAN الالسلكية العشوائية . الشبكة• Routers pass/forwards signals and data.• Service nodes.

• A network with a changing and random nature.• Topology cab change

• Basic Service Set (BSS) االساسي الخدمة مدى

MAIN STRUCTURE OF WIRELESS LANS

• Multicells wireless networks الخاليا متعددة . شبكة• Many access points AP connect computers.• These AP connected through channel or wired network “

Distributed Systems”• Extended Service Set ESS

MAIN STRUCTURE OF WIRELESS LANS

WIRELESS NETWORK STANDARDS

• Institute of Electrical & Electronic Engineers IEEE, The European Telecommunications Standards Institute ETSI, and forums of companies and factories that manufacture these network devices (ex: Bluetooth forum).• 204 GHz – 5 GHz frequencies.

WIRELESS NETWORK STANDARDS:BLUETOOTH WIRELESS NETWORK

• Bluetooth wireless network standards:• IBM, INTEL, NOKIA, Ericsson, Toshiba

• Connect PDAs, printers, mobile devices embedded in computers.• Covers 1 hall, room.• Controlled by 1 person won this network.• Microwave, infrared transmission channel.

WIRELESS NETWORK STANDARDS:WIRELESS LAN STANDARD

• IEEE, 802.11 project• 802.11a , 802.11b, 802.11g• It is called Wi-Fi ( commercial name)

•802.11 wireless LAN:• Transmission rate: 2 Mbps• Bandwidth: 2.4 GHz

•802.11b wireless LAN:• Transmission rate: 11 Mbps• Bandwidth: 2.4 GHz

WIRELESS NETWORK STANDARDS:WIRELESS LAN STANDARD

•802.11a wireless LAN:• Transmission rate: 54 Mbps• Bandwidth: 5 GHz

•802.11g wireless LAN:• Transmission rate: 54 Mbps• Bandwidth: 2.4 GHz• Compatible with 802.11b

WIRELESS NETWORK STANDARDS:WIRELESS MAN STANDARD

• IEEE, 802.16 project• 802.16:• Line of sight transmission rate: 134 Mbps

• Bandwidth: 10-66 GHz.

• Wi-MAX 802.16a:• Line of sight transmission rate: 70 Mbps

• Bandwidth: 2-11 GHz.

WIRELESS NETWORK STANDARDS:WIRELESS MAN STANDARD

WIRELESS SENSOR NETWORK

• For specific purposes, use sensing and digital controlling.• Used for Remote Sensing application, ex:

factories, radar application, hospitals.• 802.15.3 standards: • Transmission using: Ultra Wide Band (UWB),

transmission with lower power with a very high broadband.• No interference and noise.

WIRELESS NETWORK STANDARDS

WIRELESS LAN PROTOCOLS

• Due to noise, interference, hidden and exposed nodes; CSMA can’t be used effectively in wireless LANs.• Aloha can be used.• Multiple Access with Collision Avoidance MACA;

similar to CSMA/DA• Multiple Access with Collision Avoidance for

Wireless MACAW.• Collisions can be detected at receiver device.• Transmission by Request To Send” frame (RTS) and

Confirm To Send” frame (CTS).

WIRELESS LAN PROTOCOLS

• Waiting time after collision is equal with all waiting nodes. • ACK is used to confirm receiving the data

correctly.• RTS• CTS• DATA• ACK