wireless technology and network convergence
TRANSCRIPT
Wireless Technology and Wireless Technology and Network ConvergenceNetwork Convergence
A Brief HistoryA Brief History Wireless communications originated with Wireless communications originated with
the demonstration by Tesla in 1893, the demonstration by Tesla in 1893, followed by the invention of wireless followed by the invention of wireless telegraph by Marconi in 1896telegraph by Marconi in 1896
Advances in wireless communications Advances in wireless communications have led to radio, television, mobile have led to radio, television, mobile telephones, and communication satellitestelephones, and communication satellites
Development of wireless networks: LAN, Development of wireless networks: LAN, MAN, and WANMAN, and WAN
Trend continues: Voice – Data – BroadbandTrend continues: Voice – Data – Broadband Need to support mobility Need to support mobility
TrendsTrends
Revenue for wireless communication Revenue for wireless communication industry has surpassed that of wired industry has surpassed that of wired telephony industrytelephony industry
Wireless applications span both local area Wireless applications span both local area and wide area for: and wide area for: • voice-oriented services, and voice-oriented services, and • data-oriented servicesdata-oriented services
Global cellular networks are providing very Global cellular networks are providing very convenient communication infrastructureconvenient communication infrastructure
Broadband wireless networks are evolving: Broadband wireless networks are evolving: Wireless LANs are very popularWireless LANs are very popular
Licensed and Unlicensed BandsLicensed and Unlicensed Bands Licensed: Licensed:
• Cellular/PCSCellular/PCS• Expensive (PCS bands in US were sold for around $20B)Expensive (PCS bands in US were sold for around $20B)• Time consuming to deploy new applications rapidly at Time consuming to deploy new applications rapidly at
low costslow costs Unlicensed:Unlicensed:
• Industrial, Medical, and Scientific (ISM) BandsIndustrial, Medical, and Scientific (ISM) Bands• Free, component costs are also lowFree, component costs are also low• New applications such as WLAN, Bluetooth are easily New applications such as WLAN, Bluetooth are easily
developeddeveloped With the increase in frequency and data rate, the With the increase in frequency and data rate, the
hardware cost increases, and the ability to hardware cost increases, and the ability to penetrate walls also decreasespenetrate walls also decreases
DuplexingDuplexing
Duplexing facilitates communications in Duplexing facilitates communications in both directions simultaneously: base both directions simultaneously: base station to mobile and mobile to base station to mobile and mobile to base stationstation
Duplexing is done either using frequency Duplexing is done either using frequency or time domain techniques:or time domain techniques:• Frequency division duplexing (FDD)Frequency division duplexing (FDD)• Time division duplexing (TDD)Time division duplexing (TDD)
FDD is suitable for radio communication FDD is suitable for radio communication systems, whereas TDD is more suitable for systems, whereas TDD is more suitable for fixed wireless systems fixed wireless systems
Multiple Access TechniquesMultiple Access Techniques
Frequency Division Multiple AccessFrequency Division Multiple Access Time Division Multiple AccessTime Division Multiple Access Spread Spectrum Multiple AccessSpread Spectrum Multiple Access Space Division Multiple AccessSpace Division Multiple Access Packet RadioPacket Radio
Frequency Division Multiple Access Frequency Division Multiple Access (FDMA)(FDMA)
The frequency spectrum is divided into The frequency spectrum is divided into unique frequency bands or channelsunique frequency bands or channels
These channels are assigned to users on These channels are assigned to users on demanddemand
Multiple users cannot share a channelMultiple users cannot share a channel Users are assigned a channel as a pair of Users are assigned a channel as a pair of
frequencies (forward and reverse frequencies (forward and reverse channels)channels)
FDMA requires tight RF filtering to reduce FDMA requires tight RF filtering to reduce adjacent channel interferenceadjacent channel interference
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Time Division Multiple Access-TDMATime Division Multiple Access-TDMA TDMA systems divides the radio spectrum TDMA systems divides the radio spectrum
into time slots, and in each time slot only one into time slots, and in each time slot only one use is allowed to either transmit or receiveuse is allowed to either transmit or receive
Transmission for any user is non-continuousTransmission for any user is non-continuous In each TDMA frame, the preamble contains In each TDMA frame, the preamble contains
the address and synchronization informationthe address and synchronization information TDMA shares a single carrier frequency with TDMA shares a single carrier frequency with
several usersseveral users TDMA could allocate varied number of time TDMA could allocate varied number of time
slots per frame to different users slots per frame to different users
TDMATDMA
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Spread Spectrum Multiple Access Spread Spectrum Multiple Access (SSMA)(SSMA)
SSMA uses signals that have a transmission SSMA uses signals that have a transmission bandwidth several orders of magnitude bandwidth several orders of magnitude greater than the minimum required RF greater than the minimum required RF bandwidthbandwidth
SSMA provides immunity to multipath SSMA provides immunity to multipath interference and robust multiple access interference and robust multiple access capabilitycapability
SSMA is bandwidth efficient in multi-user SSMA is bandwidth efficient in multi-user environmentenvironment
SSMA techniques:SSMA techniques:• Frequency hopped (FH) multiple accessFrequency hopped (FH) multiple access• Direct sequence (DS) multiple accessDirect sequence (DS) multiple access
Also known as code division multiple access (CDMA) Also known as code division multiple access (CDMA)
FHMAFHMA Carrier frequencies of individual users are varied in Carrier frequencies of individual users are varied in
a pseudorandom fashion within a wideband channela pseudorandom fashion within a wideband channel Data of each user is broken into uniform size bursts Data of each user is broken into uniform size bursts
that are transmitted on different channels at that are transmitted on different channels at different time instants based on their pseudo-noise different time instants based on their pseudo-noise (PN) code sequence(PN) code sequence
In the FH receiver, a locally generated PN code is In the FH receiver, a locally generated PN code is used to synchronize the receiver’s instantaneous used to synchronize the receiver’s instantaneous frequency with that of the transmitterfrequency with that of the transmitter
FHMA provides inherent security, and guard against FHMA provides inherent security, and guard against erasures through error control coding and erasures through error control coding and interleavinginterleaving
Use: Bluetooth and HomeRF Use: Bluetooth and HomeRF
CDMACDMA The narrowband message signal is multiplied by a very The narrowband message signal is multiplied by a very
large bandwidth signal called spreading signallarge bandwidth signal called spreading signal The spreading signal has a pseudo-noise code sequence The spreading signal has a pseudo-noise code sequence
that has a chip rate which is orders of magnitudes greater that has a chip rate which is orders of magnitudes greater than the data rates of the messagethan the data rates of the message
All users use the same carrier frequency and can transmit All users use the same carrier frequency and can transmit simultaneouslysimultaneously
Each use has its own pseudorandom codeword that is Each use has its own pseudorandom codeword that is orthogonal to the othersorthogonal to the others
The receivers need to know the codeword of the The receivers need to know the codeword of the corresponding sendercorresponding sender
Power control is used to combat the near-far problemPower control is used to combat the near-far problem Near-far problem:Near-far problem:
• When many mobile users share the same channel, the When many mobile users share the same channel, the strongest received mobile signal will capture the strongest received mobile signal will capture the demodulator at a base station. Thus a nearby subscriber demodulator at a base station. Thus a nearby subscriber could overpower the base-station receiver by drowning could overpower the base-station receiver by drowning out the signals of far away subscribers.out the signals of far away subscribers.
CDMA FeaturesCDMA Features Many users of CDMA share the same frequency – Many users of CDMA share the same frequency –
either TDD or FDD may be usedeither TDD or FDD may be used CDMA has soft capacity limit – system performance CDMA has soft capacity limit – system performance
is inversely proportional to the number of usersis inversely proportional to the number of users Multipath fading is reduced because of the signal Multipath fading is reduced because of the signal
spreadspread Channel data rates are very highChannel data rates are very high Prone to self-jamming and near-far problemProne to self-jamming and near-far problem
• Self-jamming: when the spreading sequences of different Self-jamming: when the spreading sequences of different users are not exactly orthogonalusers are not exactly orthogonal
Near-far problem occurs at a CDMA receiver if an Near-far problem occurs at a CDMA receiver if an undesired user has a high detected power undesired user has a high detected power compared to the desired usercompared to the desired user
Space Division Multiple Access Space Division Multiple Access (SDMA)(SDMA)
SDMA controls the radiated energy for each SDMA controls the radiated energy for each user and serves different users by using user and serves different users by using spot beam antennasspot beam antennas
Different areas covered by antenna beam Different areas covered by antenna beam may be served by same or different may be served by same or different frequenciesfrequencies
Reverse links present difficulty:Reverse links present difficulty:• Transmitted power from each subscriber must Transmitted power from each subscriber must
be controlled to prevent any single user from be controlled to prevent any single user from driving up the interference leveldriving up the interference level
• Transmit power is limited by battery Transmit power is limited by battery consumption at the subscriber unitconsumption at the subscriber unit
Packet RadioPacket Radio
In Packet Radio (PR) access techniques, In Packet Radio (PR) access techniques, many subscribers attempt to access a many subscribers attempt to access a single channel in an uncoordinated single channel in an uncoordinated mannermanner
Collisions from simultaneous transmissions Collisions from simultaneous transmissions from multiple transmitters are detected at from multiple transmitters are detected at the base station receiver, in which case an the base station receiver, in which case an ACK or NACK signal is broadcasted by the ACK or NACK signal is broadcasted by the base station to alert the userbase station to alert the user
PR subscribers use a contention technique PR subscribers use a contention technique to transmit on a common channel to transmit on a common channel
Carrier Sense Multiple Access Carrier Sense Multiple Access Protocols (CSMA)Protocols (CSMA)
In CSMA protocols, each terminal on In CSMA protocols, each terminal on the network is able to monitor the the network is able to monitor the status of the channel before status of the channel before transmitting informationtransmitting information
Variations:Variations:• 1-persistent CSMA1-persistent CSMA• non-persistent CSMAnon-persistent CSMA• p-persistent CSMAp-persistent CSMA• CSMA/CDCSMA/CD
Convergence of Public NetworkConvergence of Public Network
Carriers now use converged technology Carriers now use converged technology primarily in core, backbone portion of their primarily in core, backbone portion of their networks to carry customer traffic more networks to carry customer traffic more efficientlyefficiently
Although carriers increasingly add IP Although carriers increasingly add IP equipment when they replace their voice equipment when they replace their voice switches, the majority of voice traffic is switches, the majority of voice traffic is still carried in circuit switched networksstill carried in circuit switched networks
A A circuitcircuit is a physical path for the is a physical path for the transmission of voice, image or data.transmission of voice, image or data.
ITU defines circuit switching as :ITU defines circuit switching as :““The switching of circuits for the exclusive The switching of circuits for the exclusive
use of the connection for the duration of a use of the connection for the duration of a call”call”
When a person or modem dials a call, the When a person or modem dials a call, the network sets up a path between the caller network sets up a path between the caller and the dialed partyand the dialed party
Circuit switching is an example of a Circuit switching is an example of a connection-oriented system connection-oriented system
The path is maintained exclusively for the The path is maintained exclusively for the duration of the call and not sharedduration of the call and not shared
This causes wasteful utilization of network This causes wasteful utilization of network capacitycapacity
Circuit-SwitchingCircuit-Switching
Other Switching Technique-Other Switching Technique-Message SwitchingMessage Switching
Message switching transfers arbitrary Message switching transfers arbitrary sized messages from a source to a sized messages from a source to a destination using one or more destination using one or more message switchesmessage switches
Each switch stores the complete Each switch stores the complete message before forwarding itmessage before forwarding it
Normally messages are stored for Normally messages are stored for only a short time, but they may be only a short time, but they may be stored for days in some cases stored for days in some cases
A message being sent using one A message being sent using one intermediate message switch.intermediate message switch.
The telex network is an example of a The telex network is an example of a message switched networkmessage switched network
Since the messages are stored in each Since the messages are stored in each message switch, message switching is message switch, message switching is suitable for the transfer of electronic mail suitable for the transfer of electronic mail and is used to send email to isolated parts and is used to send email to isolated parts of the world using connections provided by of the world using connections provided by modems over the telephone networkmodems over the telephone network
Since there is no direct connection Since there is no direct connection between the sender and the recipient, it is between the sender and the recipient, it is not possible to use message switching to not possible to use message switching to login to a remote computerlogin to a remote computer
Rationale for ConvergenceRationale for Convergence The Internet Protocol (IP) does not have this The Internet Protocol (IP) does not have this
limitationlimitation The Internet is a connection-less packet-switched The Internet is a connection-less packet-switched
network.network. Packets from other sources fill pauses in one Packets from other sources fill pauses in one
conversationconversation Eg. when a call is on hold, network capacity is Eg. when a call is on hold, network capacity is
used for other trafficused for other traffic Moreover, technical advances have improved the Moreover, technical advances have improved the
quality of voice and video carried on packet quality of voice and video carried on packet networksnetworks
In addition, costs for routers, hard drives and fiber In addition, costs for routers, hard drives and fiber optics have decreasedoptics have decreased
The capability to deploy and maintain a single The capability to deploy and maintain a single network for voice, data and videonetwork for voice, data and video
As VoIP protocols become As VoIP protocols become increasingly standardised, custom increasingly standardised, custom interfaces between switches and interfaces between switches and applications will increasingly become applications will increasingly become unnecessaryunnecessary
VoIP NetworksVoIP Networks
Cable TV, wireless mobile and traditional Cable TV, wireless mobile and traditional local exchange carriers use common IP local exchange carriers use common IP core and edge IP network components core and edge IP network components when they upgrade their networks to IPwhen they upgrade their networks to IP
Components include:Components include:• SoftswitchesSoftswitches• Media gatewaysMedia gateways• Media serversMedia servers• Application serversApplication servers
SoftswitchesSoftswitches
Process calls (issue commands on Process calls (issue commands on setting up and ending calls)setting up and ending calls)
Communicate with billing systemsCommunicate with billing systems Acts as an overall network control Acts as an overall network control
pointpoint
Media GatewaysMedia Gateways
Switch calls and translate protocols Switch calls and translate protocols between different networks and between different networks and between public network trunks such between public network trunks such as T-1 and T-3 trunks and IP as T-1 and T-3 trunks and IP networksnetworks
Media ServersMedia Servers
Generate touch-toneGenerate touch-tone Play announcementsPlay announcements Generate voice over IP packets from Generate voice over IP packets from
voice mail applicationvoice mail application Convert voice mail messages to Convert voice mail messages to
digital IP packet and vice versadigital IP packet and vice versa Record voice mail messagesRecord voice mail messages Generate ring tones, busy signals, Generate ring tones, busy signals,
dial tonedial tone
Application ServersApplication Servers
Contain complex applications Contain complex applications Eg. Eg.
• unified messaging (capability to receive unified messaging (capability to receive voice mail, e-mail, and fax messages on voice mail, e-mail, and fax messages on personal computers)personal computers)
• Large audio conferencing systemsLarge audio conferencing systems
Peer-to-Peer ServicesPeer-to-Peer Services
P2P services operate in a P2P services operate in a decentralised mode without decentralised mode without softswitches to control signaling and softswitches to control signaling and communicationcommunication
Napster, Gnutella, KaZaA – enable Napster, Gnutella, KaZaA – enable sharing of free music over the sharing of free music over the InternetInternet
Skype introduced P2P architecture Skype introduced P2P architecture for VoIP without central serversfor VoIP without central servers
Calling 911-Calling 911-VoIP vs Circuit switchedVoIP vs Circuit switched
The Wireless Communication and Public Safety The Wireless Communication and Public Safety Act (1999) establishes 911 as the emergency Act (1999) establishes 911 as the emergency number throughout the US.number throughout the US.
The first emergency number was 999 used in The first emergency number was 999 used in London London
The act mandated all carriers to connect 911 call The act mandated all carriers to connect 911 call to appropriate local emergency dispatch centreto appropriate local emergency dispatch centre
It also mandated FCC to develop a plan for It also mandated FCC to develop a plan for wireless providers to transition to enhanced 911 wireless providers to transition to enhanced 911 (E911)(E911)
Under E911, the agent who answer 911 calls is Under E911, the agent who answer 911 calls is able to receive the callers’ phone number and able to receive the callers’ phone number and locationlocation
Mobile ServicesMobile Services
Competition between mobile network Competition between mobile network operators, and the desire for more operators, and the desire for more robust networks have led to the robust networks have led to the implementation of third generation implementation of third generation digital networks by major mobile digital networks by major mobile operatorsoperators
Evolution from 1G, 2G, 2.5G to 3GEvolution from 1G, 2G, 2.5G to 3G
The 1The 1stst G of cellular service used G of cellular service used analog equipment in the early 1980sanalog equipment in the early 1980s
The 1The 1stst service in US is AMPS service in US is AMPS The 2The 2ndnd G started in 1990s when G started in 1990s when
carriers upgrade their analog to carriers upgrade their analog to digital networks to gain more digital networks to gain more capacitycapacity
These include GSM, CDMA, TDMA and These include GSM, CDMA, TDMA and iDEN (Motorola)iDEN (Motorola)
2.5 G2.5 G Provides transition to WCDMAProvides transition to WCDMA Most GSM operators implemented GPRS Most GSM operators implemented GPRS
and EDGE before WCDMA for the following and EDGE before WCDMA for the following reasons:reasons:• WCDMA equipment was not stable until 2004WCDMA equipment was not stable until 2004• Small, lightweight 3G handset were not widely Small, lightweight 3G handset were not widely
available prior to 2004available prior to 2004• Installing GPRS and EDGE delayed the large Installing GPRS and EDGE delayed the large
expenses to upgrade to WCDMAexpenses to upgrade to WCDMA• Handset for GPRS and EDGE were readily Handset for GPRS and EDGE were readily
availableavailable• GPRS and EDGE operate on the same GPRS and EDGE operate on the same
frequencies as GSMfrequencies as GSM
3G3G
Transition from 2G CDMA TO 3G Transition from 2G CDMA TO 3G CDMA2000 is less costly and complex than CDMA2000 is less costly and complex than transition from GSM networks to WCDMAtransition from GSM networks to WCDMA
The major incentive for upgarding is the The major incentive for upgarding is the increased voice capacity as well as the increased voice capacity as well as the desire for a network capable of handling desire for a network capable of handling advanced applicationadvanced application
Because it is easier to implement, Because it is easier to implement, CDMA2000 has more subscribers CDMA2000 has more subscribers compared to WCDMAcompared to WCDMA
CDMA2000 1X (voice and data)CDMA2000 1X (voice and data) Provides “always on” data rates Provides “always on” data rates Doubles the voice capacity Doubles the voice capacity SK Telecom, the largest carrier in South SK Telecom, the largest carrier in South
Korea implements the 1Korea implements the 1stst release of release of CDMA2000 in October 2000CDMA2000 in October 2000
Only requires new cards in the base Only requires new cards in the base transceiver system and software in the transceiver system and software in the mobile switching centremobile switching centre
Routers, billing, authentication and Routers, billing, authentication and authorisation systems, and connection to authorisation systems, and connection to IP networks are necessary for data IP networks are necessary for data servicesservices
CDMA2000 1xEV-DO (data CDMA2000 1xEV-DO (data optimised- high data rate)optimised- high data rate)
Network providers already have the Network providers already have the 11stst stage CDMA2000 can upgrade to stage CDMA2000 can upgrade to higher data speeds by adding higher data speeds by adding software and channel cards to their software and channel cards to their base stations for high data ratebase stations for high data rate
HDR service is a data-only HDR service is a data-only enhancement with higher downlink enhancement with higher downlink speedsspeeds
No capacity is gained for voice trafficNo capacity is gained for voice traffic
WCDMAWCDMAReleaseRelease FeaturesFeatures
WCDMA WCDMA (Release 4)(Release 4)
Enables operators to prioritise Enables operators to prioritise data services per customer data services per customer subscriptionsubscription
WCDMA WCDMA (Release 5)(Release 5)
HSDPA (high speed downlink HSDPA (high speed downlink packet access)packet access)
IP voice and dataIP voice and data
WCDMA WCDMA (Release 6)(Release 6)
HASUPA (high speed uplink HASUPA (high speed uplink packet access)packet access)
Doubles the uplink speedDoubles the uplink speed
MobileFiMobileFi 802.20: IP Mobile Broadband Wireless Access802.20: IP Mobile Broadband Wireless Access In 2002, the IEEE stated its intention to provide In 2002, the IEEE stated its intention to provide
mobility in vehicles such as trains traveling up to mobility in vehicles such as trains traveling up to 150mph or 250kmph, and to support higher data 150mph or 250kmph, and to support higher data rates and more users than currently availablerates and more users than currently available
Flarion uses a form of orthogonal FDM (OFDM) in Flarion uses a form of orthogonal FDM (OFDM) in equipment called FLASH-OFDM.equipment called FLASH-OFDM.
Flash is short for Fast, Low-latency Access with Flash is short for Fast, Low-latency Access with Seamless HandoffSeamless Handoff
FLASH-OFDM spreads signals over a wider FLASH-OFDM spreads signals over a wider frequencies and at faster rate than OFDMfrequencies and at faster rate than OFDM
Flarion service includes handoffs between Flarion service includes handoffs between Wi-Fi and FLASH-OFDM networks so that Wi-Fi and FLASH-OFDM networks so that users use Wi-Fi when it is availabale and users use Wi-Fi when it is availabale and Flarion when it is notFlarion when it is not
Flarion supports VoIP and able to prioritise Flarion supports VoIP and able to prioritise traffictraffic
It is not expected to be available until It is not expected to be available until 20082008
T-Mobile, Vodafone and TIME dotCOM (in T-Mobile, Vodafone and TIME dotCOM (in Malaysia) are conducting trials of Flarion Malaysia) are conducting trials of Flarion equipmentequipment
Wi-Fi, Wireless broadband, Sensor Wi-Fi, Wireless broadband, Sensor Networks and PANsNetworks and PANs
Wi-Fi IEEE 802.11Wi-Fi IEEE 802.11 Wireless broadband - WiMaxWireless broadband - WiMax Zigbee and IEEE 802.15Zigbee and IEEE 802.15 PANsPANs
Evolution of Wireless LANEvolution of Wireless LAN Early experiences (1970-72): IBM, HP, MotorolaEarly experiences (1970-72): IBM, HP, Motorola
• Abandoned due to limited performance and Abandoned due to limited performance and unavailability of frequency bandsunavailability of frequency bands
Early challenges:Early challenges:• Complexity and costComplexity and cost• BandwidthBandwidth• CoverageCoverage• InterferenceInterference• Frequency administrationFrequency administration
Emergence of unlicensed bandsEmergence of unlicensed bands• Release of Industrial, Scientific and Medical (ISM) bands Release of Industrial, Scientific and Medical (ISM) bands
in 1985in 1985 Applications: military, home and enterprise Applications: military, home and enterprise
networks, mobile networks, teetherless accessnetworks, mobile networks, teetherless access
Wi-Fi is based on 802.11 technologyWi-Fi is based on 802.11 technology It is originally intended tio provide wireless It is originally intended tio provide wireless
computing for staffs within businesses and computing for staffs within businesses and commercial organisationscommercial organisations
However, residential customers adopted Wi-Fi However, residential customers adopted Wi-Fi faster than enterprises because of its simplicity, faster than enterprises because of its simplicity, fewer concerns about security and the benefit of fewer concerns about security and the benefit of avoiding the expenses for cablingavoiding the expenses for cabling
Its advantage is low equipment cost and easier Its advantage is low equipment cost and easier installationinstallation
Benefits were also immediately noticed for Benefits were also immediately noticed for healthcare, education, retailing and warehousinghealthcare, education, retailing and warehousing
IEEE 802.11IEEE 802.11 Standardization group formed in 1990, Standardization group formed in 1990,
first standards completed in 1997first standards completed in 1997 IEEE 802.11 is the first WLAN standard; IEEE 802.11 is the first WLAN standard;
only one to secure a marketonly one to secure a market 802.11a: PHY layer supports 11Mbps using 802.11a: PHY layer supports 11Mbps using
CKK (complementary code keying) CKK (complementary code keying) technologytechnology
802.11b: PHY layer supports 54 Mbps 802.11b: PHY layer supports 54 Mbps using OFDMusing OFDM
Uses CSMA/CA for contention dataUses CSMA/CA for contention data Supports both infrastructure as well as ad Supports both infrastructure as well as ad
hoc modeshoc modes
Logical link control
Point coordination function (PCF)
Distributed coordination function (DCF)
2.4-Ghz frequency-
hopping spread
spectrum 1Mbps 2Mbps
2.4-Ghz direct
sequence spread
spectrum 1Mbps 2Mbps
Infrared 1Mbps 2Mbps
5-Ghz orthogonal FDM 6, 9. 12. 18, 24, 36, 48, 54
Mbps
2.4-Ghz direct
sequence spread
spectrum 5.5 Mbps 11 Mbps
Contention-free service Contention
service
MAC layer
IEEE 802.11 Protocol ArchitectureIEEE 802.11 Protocol Architecture
IEEE 802.11 IEEE 802.11a IEEE 802.11b
802.11a – higher speeds, smaller 802.11a – higher speeds, smaller coverage, more channelscoverage, more channels
Wi-Fi is also sold to hotspot operators particularly Wi-Fi is also sold to hotspot operators particularly hotel, convention centres, cafes, airportshotel, convention centres, cafes, airports
Hotspots offer higher-speed Internet access than Hotspots offer higher-speed Internet access than most cellular network’s data offering and cost most cellular network’s data offering and cost less to build than cellular base stationless to build than cellular base station
802.11 wireless standards are based on Ethernet 802.11 wireless standards are based on Ethernet protocols protocols
802.11a is the only 802.11 standard that 802.11a is the only 802.11 standard that operates at 5 GHzoperates at 5 GHz
The use of 5 GHz band avoids interference from The use of 5 GHz band avoids interference from microwave ovens, Bluetooth equipments and microwave ovens, Bluetooth equipments and cordless phones that operate at 2.4 GHzcordless phones that operate at 2.4 GHz
Disadvantage is the signal fade fasterDisadvantage is the signal fade faster
802.11b 802.11b
When they were first available, When they were first available, 802.11 equipments were equipped 802.11 equipments were equipped with only 802.11b chipswith only 802.11b chips
Now most use b and g which are Now most use b and g which are designed to interoperatedesigned to interoperate
Because home broadband Because home broadband connections are slower than 802.11 connections are slower than 802.11 networks, no advantage is gained networks, no advantage is gained
802.11g802.11g
Support higher data rates than Support higher data rates than 802.11b802.11b
Use 2.4 gHz bandsUse 2.4 gHz bands The higher speeds and capacity of g The higher speeds and capacity of g
and a are required to support voice and a are required to support voice over IP on WLANsover IP on WLANs
802.11n802.11n
Backward compatibility with a, b and Backward compatibility with a, b and gg
Improve coverage by overcoming a Improve coverage by overcoming a certain amount of interferencecertain amount of interference
Increase speeds and supports more Increase speeds and supports more users per access pointusers per access point
Broadband wireless accessBroadband wireless access Wimax and universal mobile telecommunication Wimax and universal mobile telecommunication
system time division duplex (UMTS TDD) may in system time division duplex (UMTS TDD) may in the future provide mobile wireless broadband the future provide mobile wireless broadband service for pedestrian, people in moving vehicles service for pedestrian, people in moving vehicles and within buildingsand within buildings
However, most current implementations are for However, most current implementations are for less complex wireless service between fixed less complex wireless service between fixed locations or for wireless service with Internet locations or for wireless service with Internet access and portability within a service provider’s access and portability within a service provider’s coverage areacoverage area
Currently no portability is provided within Currently no portability is provided within buildings (therefore, Wi-Fi is still needed)buildings (therefore, Wi-Fi is still needed)
Wimax is based on 802.16Wimax is based on 802.16
WCDMA Modified for Wireless WCDMA Modified for Wireless Local LoopLocal Loop
SOMA Networks provide a packetized wireless SOMA Networks provide a packetized wireless local loop service to replace broadband cable and local loop service to replace broadband cable and DSL serviceDSL service
The service is designed for circuit-switched voice, The service is designed for circuit-switched voice, fax and high-speed datafax and high-speed data
The equipments operate in the 1.9, 2.3 and 2.6 The equipments operate in the 1.9, 2.3 and 2.6 GHz licensed frequency bandsGHz licensed frequency bands
SOMA is used in developing countries where SOMA is used in developing countries where cabling to residential or rural areas is rarecabling to residential or rural areas is rare
SOMA modified 3G WCDMA to provide end-to-end SOMA modified 3G WCDMA to provide end-to-end QOS and multimegabit data speedQOS and multimegabit data speed
SOMA is not portable or mobileSOMA is not portable or mobile However, it is rolling out integrated Wi-Fi handset However, it is rolling out integrated Wi-Fi handset
for portable voice within homefor portable voice within home Jaring uses SOMA equipmentsJaring uses SOMA equipments
Sensor NetworksSensor Networks An emerging technology to monitor condition in An emerging technology to monitor condition in
buildings, control manufacturing systems, etcbuildings, control manufacturing systems, etc Until recently, large-scale sensor networks are Until recently, large-scale sensor networks are
expensive because sensors require wired expensive because sensors require wired connection to each other and the LANconnection to each other and the LAN
The new sensor network is able to send info The new sensor network is able to send info wirelesslywirelessly
2 topology can be deployed2 topology can be deployed Full-mesh: each sensor is connected to every Full-mesh: each sensor is connected to every
other deviceother device Partial-mesh: some nodes are connected to each Partial-mesh: some nodes are connected to each
other, others only to the nodes they exchange other, others only to the nodes they exchange the info mostthe info most
Based on 802.15.4 which is slow speed (20-Based on 802.15.4 which is slow speed (20-250kbps), non line-of-sight (LOS)250kbps), non line-of-sight (LOS)
IEEE 802.15.4 and ZigBeeIEEE 802.15.4 and ZigBee
Home ApplicationsHome Applications• Internet connectivity, multi-PC connectivity, Internet connectivity, multi-PC connectivity,
audio/video networking audio/video networking
[broadband, always-on, relatively expensive][broadband, always-on, relatively expensive]• Home automation, security, device management Home automation, security, device management
[low-throughput, power-constraint, low-cost][low-throughput, power-constraint, low-cost] IEEE 802.11 and Bluetooth do not satisfy IEEE 802.11 and Bluetooth do not satisfy
the requirements of the second setthe requirements of the second set Evolution of IEEE 802.15.4 and ZigBee in Evolution of IEEE 802.15.4 and ZigBee in
20002000
ZigBeeZigBee Based on 802.15.4 standard, developed by Based on 802.15.4 standard, developed by
ZigBee Alliance ZigBee Alliance Defined higher-level protocols that will operate Defined higher-level protocols that will operate
over network using 802.15.4over network using 802.15.4 ZigBee 1.0 was announced in Dec 2004ZigBee 1.0 was announced in Dec 2004 It is a lightweight routing protocol for mesh It is a lightweight routing protocol for mesh
network that adds security and additional mesh network that adds security and additional mesh networking function to 802.15.4networking function to 802.15.4
It has potential to control alarms, monitor It has potential to control alarms, monitor electricity, provide status from smoke detectors, electricity, provide status from smoke detectors, thermostat, and hot water tanks in commercial or thermostat, and hot water tanks in commercial or residential buildingsresidential buildings
Protocol StackProtocol Stack
APPLICATIONS
APPLICATION FRAMEWORK
NETWORK/SECURITY LAYERS
MAC LAYER
PHY LAYER
User Defined
ZigBee Alliance
IEEE 802.15.4
It can monitor windows to determine It can monitor windows to determine if they are closed or notif they are closed or not
Its target application include remote Its target application include remote controls (now using infrared that controls (now using infrared that requires LOS)requires LOS)
However, it receives competition However, it receives competition from companies providing alarm from companies providing alarm services like ADT services like ADT
Has potential for future useHas potential for future use
PANsPANs Bluetooth- widely used (not discussed here)Bluetooth- widely used (not discussed here) Ultra-Wideband (802.15.3a)Ultra-Wideband (802.15.3a) Is high-speed, short range wireless tech that Is high-speed, short range wireless tech that
works by transmitting low-power signals over a works by transmitting low-power signals over a wide range of frequencieswide range of frequencies
Does not require spectrum licenseDoes not require spectrum license It is designed not to interfere with conventional It is designed not to interfere with conventional
radioradio It can penetrate walls and do not drain batteries It can penetrate walls and do not drain batteries
quickly quickly It is faster than Bluetooth and Wi-FiIt is faster than Bluetooth and Wi-Fi Can be used to link electronics for home Can be used to link electronics for home
entertainment network and asset tracking entertainment network and asset tracking However, lack of uniform standard is holding its However, lack of uniform standard is holding its
salessales
RFIDRFID A non-LOS wireless tech used to control, A non-LOS wireless tech used to control,
detect and tract objectsdetect and tract objects RFID system is made up ofRFID system is made up of
• Interrogator – readersInterrogator – readers• Transponder with integrated antenna on chipsTransponder with integrated antenna on chips
Active transponder has battery, larger in Active transponder has battery, larger in size, more costly than passive one. size, more costly than passive one. However can be read at further distance However can be read at further distance from readerfrom reader
Passive one has no battery, size of a 5 Passive one has no battery, size of a 5 cent coin, are woken up by magnetic cent coin, are woken up by magnetic induction from reader, also known as taginduction from reader, also known as tag
A middleware is required to reformat A middleware is required to reformat information gathered by readers to make information gathered by readers to make it compatible with databaseit compatible with database
RFID tags have electronic product codes RFID tags have electronic product codes (EPC)(EPC)
Super RFID can be used for sensor network Super RFID can be used for sensor network –requires intelligent tags and readers that –requires intelligent tags and readers that record conditions being monitored and set record conditions being monitored and set off alarms if the thresholds are exceededoff alarms if the thresholds are exceeded
Operates in Operates in • low frequency (30-500KHz)- shorter rangelow frequency (30-500KHz)- shorter range• High frequency (850-950KHz/2.4-2.5GHz) High frequency (850-950KHz/2.4-2.5GHz)
– – range up to 90 feetrange up to 90 feet- may interfere with Bluetooth and Wi-Fi gear- may interfere with Bluetooth and Wi-Fi gear