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Wireless communication and networking

Jul 15, 2015



Wireless Communication and Networking

Wireless Communication and Networking.Presentation OutlineWireless CommunicationsWireless Technology overviewThe IEEE 802.11 WLAN StandardsSecure Wireless LANsMigrating to Wireless LANs (Cutting the cord)

WIRELESSAny type of electrical or electronic operation without use of wiresWireless connections use air to connect sending and receiving devicesChannel is a division in transmission medium

COMMUNICATIONIt is transmission of signals i.e. sending of electromagnetic waves by electronic transmitters

WIRELESS COMMUNICATION Communication networks are generally implemented with some type of remote information transmission system that uses electromagnetic waves.

Wireless communication may be via:Radio frequency communicationMicrowave communicationInfrared short range communication

Types of Networks

LAN Local Area NetworkMAN Metropolitan Area NetworkWAN Wide Area NetworkGSM Global System for Mobile CommunicationsPCS Personal Communication ServicesWi-Fi Wireless FidelityGPRS General Packet Radio ServiceAMPS- Advanced Mobile Phone System

Wireless NetworkWhat is a wireless network?A technology that enables two or more entities to communicate without network cabling

Common TopologiesThe wireless LAN connects to a wired LANThere is a need of an access point that bridges wireless LAN traffic into the wired LAN.The access point (AP) can also act as a repeater for wireless nodes, effectively doubling the maximum possible distance between nodes.

Common TopologiesComplete Wireless NetworksThe physical size of the network is determined by the maximum reliable propagation range of the radio signals. Referred to as ad hoc networks Are self-organizing networks without any centralized control Suited for temporary situations such as meetings and conferences.

How do wireless LANs work?Wireless LANs operate in almost the same way aswired LANs, using the same networking protocolsand supporting the most of the sameapplications.

How are WLANs Different?They use specialized physical and data link protocolsThey integrate into existing networks through access points which provide a bridging functionThey let you stay connected as you roam from one coverage area to anotherThey have unique security considerations They require different hardware They offer performance that differs from wired LANs.

Physical and Data Link LayersPhysical Layer:The wireless NIC takes frames of data from the link layer, scrambles the data in a predetermined way, then uses the modified data stream to modulate a radio carrier signal. Data Link Layer:Uses Carriers-Sense-Multiple-Access with Collision Avoidance (CSMA/CA).

Integration With Existing NetworksWireless Access Points (APs) - a small device that bridges wireless traffic to your network. Most access points bridge wireless LANs into Ethernet networks.

Integration With Existing Networks

Roaming Users maintain a continuous connection as they roam from one physical area to another Mobile nodes automatically register with the new access point. Methods: DHCP, Mobile IPIEEE 802.11 standard does not address roaming, you may need to purchase equipment from one vendor if your users need to roam from one access point to another.

What is 802.11?A family of wireless LAN (WLAN) specifications developed by a working group at the Institute of Electrical and Electronic Engineers (IEEE)Defines standard for WLANs using the following four technologiesFrequency Hopping Spread Spectrum Direct Sequence Spread Spectrum Infrared Orthogonal Frequency Division Multiplexing Versions: 802.11a, 802.11b, 802.11g, 802.11n

WIFI Standard..802.11a offers speeds with a theoretically maximum rate of 54Mbps in the 5 GHz bandPros of 802.11a- fast maximum speed; regulated frequencies prevent signal interference from other devicesCons of 802.11a- highest cost; shorter range signal that is more easily obstructed

802.11b July 1999 offers speeds with a theoretically maximum rate of 11Mbps at in the 2.4 GHz spectrum bandPros of 802.11b- lowest cost; signal range is good and not easily obstructedCons of 802.11b- slowest maximum speed; home appliances may interfere on the unregulated frequency band

WIFI Standard..802.11g 2002 and 2003is a new standard for data rates of up to a theoretical maximum of 54 Mbps at 2.4 GHz.Pros of 802.11g- fast maximum speed; signal range is good and not easily obstructedCons of 802.11g- costs more than 802.11b; appliances may interfere on the unregulated signal frequency802.11n (Recently)Specifications providing for up to300 Mbpsof network bandwidth. 802.11n also offers somewhat better range over earlier Wi-Fi standards due to its increased signal intensityMIMOtechnology(Multiple Input Multiple output) MESH

WIFI StandardPros of 802.11n- fastest maximum speed and best signal range; more resistant to signal interference from outside sourcesCons of 802.11n- standard is not yet finalized; costs more than 802.11g.

Operating Frequency2.4 GHz Indoor AP(Access Point) operate 2.4GHz due good penetration power.5 GHz Outdoor AP(Access Point) operate on 5GHz for maximum coverage.

Problem. If we have to install more than One AP at a single location what about the Frequency interference?

Frequency ChannelDivision of FrequencyTo Avoid from interference we use non-overlapping frequency channel of same frequency band(Band 2.4GHz , 5.0 GHz)

Different Devices Support different number of frequency channel.

2.4GHZ ChannelCHANNEL NUMBERLOWER FREQUENCYMHZCENTER FREQUENCYMHZUPPER FREQUENCYMHZ1240124122423224042417242832411242224334241624272438524212432244362426243724487243124422453824362447245892441245224631024512457246811245124622473122456246724781324612472248314247324842495

Non-overlapping Frequency Channel

Non-overlapping Frequency Channel


AP (ACCESS POINT)Is a device that allows wireless devices to connect to a wired network using Wi-Fi, or related standards. The AP usually connects to a router (via a wired network) as a standalone device, but it can also be an integral component of the router itself. AP emit the signal called SSID(Service Set Identifier). AP ROLERAP (special scenario)MAP (Special scenario)ClientRepeater

RAP (Remote Access Point)Provide up link to its nearest APRAP is connected via Bridge to the NOC (network operation Center)RAP also provide the services to end client

MAP (Mesh Access Point)Get uplink from RAP.Provide services to end user

CLIENTSingle AP ,decently connected with network switch.BridgeA Bridge is used to provide uplink to a remote AP via WirelessRepeater/BoosterRepeater and Booster are used to amplify the Signal on the behalf of other AP

WLC (Wireless LAN Controller)Assign the role of RAP & MAPControl the traffic of Wireless DeviceAuto Shifting of RAP (Incase Parent RAP is down)Has ability to differentiate between Voice and DATATraditional roles of access points, such as association or authentication of wireless clients, are done by the WLCCAPWAP (Controlling and provisioning of wireless AP) IOS of WLC CAPWAP is used to communicate between the controller and other lightweight access points on the network

WLC (Wireless LAN Controller)All the client (802.11) packets are encapsulated in a LWAPP packet by the AP and sent to the WLC.

Security Measures SSID hidingA simple but ineffective method to attempt to secure a wireless network is to hide theSSID(Service Set Identifier).This provides very little protection against anything but the most casual intrusion efforts.MAC ID filteringOne of the simplest techniques is toonly allow accessfrom known, pre-approved MAC addresses. Most wireless access points contain some type ofMACID filtering. However, an attacker can simply sniff the MAC address of an authorized client andspoof this addresses.Static IP addressingTypical wireless access points provideIP addressesto clients viaDHCP. Requiring clients to set their own addresses makes it more difficult for a casual or unsophisticated intruder to log onto the network, but provides little protection against a sophisticated attacker

802.11 security

IEEE 802.1X is the IEEE Standard Authenticationmechanisms to devices wishing to attach to a Wireless LAN.WEP (Wired Equivalent Privacy) The 64-bit WEP data encryption method allows for a five-character (40-bit) input. Additionally, 24 factory-set bits are added to the forty-bit input to generate a 64-bit encryption key. data encryption method allows for a five-character (40-bit) input. Additionally, 24 factory-set bits are added to the forty-bit input to generate a 64-bit encryption key.WPAv1 (Wi-Fi Protected Access)TheWi-Fi Protected Access(WPA and WPA2) security protocols were later created to address the problems with WEP.WAP and WAP2 support up to 14 character.