Chapter 1:Chapter 1: Wireless Wireless

Networking/TechnologyNetworking/Technology

Wireless NetworkingWireless Networking

Definition:Definition:– the technologies that enable computers to the technologies that enable computers to

communicate using standard network communicate using standard network protocols broadcasted on a radio frequency protocols broadcasted on a radio frequency rather than on cable.rather than on cable.

Nowadays has grown with various Nowadays has grown with various products and very popular with homes, products and very popular with homes, businesses and schools, and handheld businesses and schools, and handheld equipment.equipment.

Wireless NetworkingWireless Networking

Wireless NetworkingWireless Networking

Two kinds of wireless networks:Two kinds of wireless networks:– ad-hoc or peer-to-peer networkingad-hoc or peer-to-peer networking– infrastructure networkinginfrastructure networking

Ad-hoc or peer-to-peer networkingAd-hoc or peer-to-peer networking

Consists of a number of computers that each Consists of a number of computers that each equipped with wireless networking interface card equipped with wireless networking interface card ((figure 1).).

Each computer can communicate directly with Each computer can communicate directly with the other entire wireless enabled computer but the other entire wireless enabled computer but may not be able to access wired resources.may not be able to access wired resources.

Fixable if one of the computers acts as a bridge Fixable if one of the computers acts as a bridge to the wired LAN using special software and/or to the wired LAN using special software and/or additional hardware to connect to the wired LAN.additional hardware to connect to the wired LAN.

Figure 1: Wireless Network ICFigure 1: Wireless Network IC

Ad-hoc or peer-to-peer networkingAd-hoc or peer-to-peer networking

Infrastructure networkingInfrastructure networking

A wireless network can also use an access A wireless network can also use an access point, or base station.point, or base station.Two types of access point:Two types of access point:– dedicated hardwarededicated hardware– integratedintegrated

The access point acts like a hub, providing The access point acts like a hub, providing connectivity for the wireless computers.connectivity for the wireless computers.Can connect the wireless LAN to a wired LAN, Can connect the wireless LAN to a wired LAN, allowing wireless computer access to LAN allowing wireless computer access to LAN resources, such as file servers or existing resources, such as file servers or existing internet connectivity.internet connectivity.

Dedicated Hardware Access Dedicated Hardware Access Point (HAP)Point (HAP)

Usually used as an Usually used as an extension of a wired extension of a wired networknetwork, providing additional access in , providing additional access in remote areas or for a mobile workforce.remote areas or for a mobile workforce.

Figure 2: Figure 2: 2:Dedicated hardware access point

Integrated Access Points Integrated Access Points

Multi functional devices which include features Multi functional devices which include features not commonly found in access points, such as not commonly found in access points, such as integrated PPPoE support and extensive integrated PPPoE support and extensive configuration flexibility.configuration flexibility.Provide both Provide both wired and wirelesswired and wireless access in one access in one unit.unit.With appropriate networking support, users on With appropriate networking support, users on the wireless LAN can share files and printers the wireless LAN can share files and printers located on the wired LAN and vice versa.located on the wired LAN and vice versa.All current configurations provide total support of All current configurations provide total support of the TCP/IPthe TCP/IP

Figure 3: Figure 3: Integrated access point

Infrastructure networkingInfrastructure networking

There could be many networked There could be many networked computers using a single access point.computers using a single access point.

Some hardware access points limit to 10.Some hardware access points limit to 10.

Newer models will support up to 225 Newer models will support up to 225 wireless connections.wireless connections.

It is a shared media, using more It is a shared media, using more computers than recommended will cause computers than recommended will cause performance and reliability to suffer.performance and reliability to suffer.

Infrastructure networkingInfrastructure networking

For large networks, designers could have / use For large networks, designers could have / use more than one access points to connect to a more than one access points to connect to a wired LAN, or even to a second wireless LAN if wired LAN, or even to a second wireless LAN if the access point supports this.the access point supports this.

In most cases, separate access points are In most cases, separate access points are interconnected via a wired LAN, providing interconnected via a wired LAN, providing wireless connectivity in specific areas such as wireless connectivity in specific areas such as offices or classrooms, but connected to a main offices or classrooms, but connected to a main wired LAN for access to network resources, wired LAN for access to network resources, such as file servers (figure 4).such as file servers (figure 4).

Figure 4: Figure 4: Large network with multiple access points

Infrastructure networkingInfrastructure networking

When using multiple access points, each When using multiple access points, each access point wireless area should overlap access point wireless area should overlap its neighbors. This provides a seamless its neighbors. This provides a seamless area for users to move around in using a area for users to move around in using a feature called feature called roaming.roaming.

Roaming:Roaming:– the extending of connectivity service in a the extending of connectivity service in a

network that is different than the network with network that is different than the network with which a station is registered. which a station is registered.

Infrastructure networkingInfrastructure networking

A wireless computer can “roam” from one A wireless computer can “roam” from one access point to another, with the software access point to another, with the software and hardware maintaining a steady and hardware maintaining a steady network connection by monitoring the network connection by monitoring the signal strength from in-range access signal strength from in-range access points and locking on to the one with the points and locking on to the one with the best quality (figure 5).best quality (figure 5).

Figure 5: RoamingFigure 5: Roaming

Wireless network Wireless network interconnects two or more interconnects two or more

LANsLANs

Ohhs…. It is too difficult to install fiber Ohhs…. It is too difficult to install fiber for networking the schools, for networking the schools,

campuses…campuses…

““ahh.. Wireless networking…”ahh.. Wireless networking…”

Wireless LANWireless LAN

Need to bridge to create WLAN.Need to bridge to create WLAN.There are two types of bridging:There are two types of bridging:– point-to-pointpoint-to-point– point-to-multipointpoint-to-multipoint

WLAN bridging connections can be WLAN bridging connections can be significantly less costly and a much faster significantly less costly and a much faster installation compared to time consuming installation compared to time consuming permit process and trenching needed for permit process and trenching needed for installing fiber.installing fiber.

Wireless LANWireless LAN

IEEE 802.11 (Wireless LAN) standard has IEEE 802.11 (Wireless LAN) standard has various versions.various versions.IEEE 802.11:IEEE 802.11:– a standard produced by the Institute of a standard produced by the Institute of

Electrical and Electronic Engineers (IEEE).Electrical and Electronic Engineers (IEEE).– define all aspects of Radio Frequency define all aspects of Radio Frequency

Wireless.Wireless.– Series Series 802.11b, 802.11a, 802.11g, 802.11b, 802.11a, 802.11g,

802.11n.802.11n.– Not all 802.11 networks are compatibleNot all 802.11 networks are compatible– Wi-Fi Certified (Wi-Fi.org).Wi-Fi Certified (Wi-Fi.org).

Wireless LANWireless LAN

Antennas are often used to increase the Antennas are often used to increase the range of WLAN systems, but proper range of WLAN systems, but proper antenna selection can also enhance the antenna selection can also enhance the security of WLAN.security of WLAN.

Using a directional antenna will decrease Using a directional antenna will decrease the chances of signal interception.the chances of signal interception.

Some bridges support repeater mode.Some bridges support repeater mode.

Figure 6: Point to Point

Figure 7: Point to Multipoint

Figure 8: Repeater Mode

Wireless TechnologyWireless Technology

BluetoothBluetooth

Bluetooth TechnologyBluetooth Technology

Is an open specification for short-range Is an open specification for short-range wireless communication between wireless communication between electronic devices.electronic devices.Has become a standard for Has become a standard for interconnecting small mobile devices in interconnecting small mobile devices in wireless world.wireless world.Its specification is developed, published Its specification is developed, published and promoted by Bluetooth Special and promoted by Bluetooth Special Interest Group (SIG).Interest Group (SIG).

Bluetooth TechnologyBluetooth Technology

Used for Wireless Personal Area Networks Used for Wireless Personal Area Networks (WPANs) with range around 10 m.(WPANs) with range around 10 m.– it is a low-power short-range radio communication it is a low-power short-range radio communication

technology.technology.The characteristic of the technology offers lot of The characteristic of the technology offers lot of advantages:advantages:– Low power requirementLow power requirement– Low CostLow Cost– Short Range of 10 m Short Range of 10 m – Bluetooth SecurityBluetooth Security– Transmission speed of 800 Kbps Transmission speed of 800 Kbps – 2.4 GHz ISM2.4 GHz ISM

Bluetooth vs. WLANBluetooth vs. WLAN

Bluetooth products work over shorter distances Bluetooth products work over shorter distances and are designed to solve different problems.and are designed to solve different problems.

Functionality WLAN stand alone as a network Functionality WLAN stand alone as a network component, the functionality of a Bluetooth component, the functionality of a Bluetooth component requires a host.component requires a host.

The host can be any number of Bluetooth The host can be any number of Bluetooth enabled devices:enabled devices:– cell phones, headsets, keyboards, PDAs, vending cell phones, headsets, keyboards, PDAs, vending

machines, cameras and bar code readersmachines, cameras and bar code readers

Bluetooth WLAN (802.11, 802.11b)

Data rate 4-700 kbps 4-6 Mbps

Range 10 m, up to 100 m 100 meter

# simultaneous users

7 10 – 50 depending on application

Frequency band 2,4 GHz 2,4 GHz

Transmitt power 1 mW, 2.5 or 100 mW  100 mW

Interfaces ADSL, Ethernet, ISDN, PSTN, USB, RS232

Primary Ehernet

Support for voice Yes Only VoIP

Type of clients Inbuilt in PC, PDA, Mobile Phone, PC-card, CF-card, Memory Stick (Sony), SSD-card, USB dongle, RS-232 Dongle

Inbuilt in PC, PC-card, CF-card, RS-232 dongle and Ethernet dongle

Power management

Yes Proprieatairy solutions

# of parallel systems

15 – 50 depending on application 3

Interoperability Yes Through WECA, not through standard