NEW TRENDS IN WIRELESS NEW TRENDS IN WIRELESS COMMUNICATION COMMUNICATION
TECHNOLOGYTECHNOLOGY
(WITH SUITABLE MULTIPLE (WITH SUITABLE MULTIPLE ACCESS)ACCESS)
Manoj Kr. Shukla
Assistant Professor
Dept. of Electronics Engineering
Harcourt Butler Technological Institute
Kanpur 208002
Email: [email protected], [email protected]
QuestionQuestion
• The EM spectrum is a limited resourceThe EM spectrum is a limited resource
• How can we “share” it?How can we “share” it?– TimeTime– SpaceSpace– FrequencyFrequency– PolarizationPolarization– Spread Spectrum - use a wider bandwidth?Spread Spectrum - use a wider bandwidth?
Multiple Access techniquesMultiple Access techniques
• GoalGoal
• Time Division Multiple Access (TDMA)Time Division Multiple Access (TDMA)• Space Division Multiple Access (SDMA)Space Division Multiple Access (SDMA)• Frequency Division Multiple Access (FDMA)Frequency Division Multiple Access (FDMA)• Polarization Division Multiple Access (PDMA)Polarization Division Multiple Access (PDMA)• Code Division Multiple Access (CDMA)Code Division Multiple Access (CDMA)• Interleave Division Multiple Access (IDMA)Interleave Division Multiple Access (IDMA)• Orthogonal Frequency Division Multiple Access Orthogonal Frequency Division Multiple Access
(OFMA) (OFMA)
allow many users to allow many users to simultaneously share a simultaneously share a communications resourcecommunications resource
Key IssueKey Issue• separate the signals at the receiver separate the signals at the receiver
to extract to extract your your informationinformation
Two methodsTwo methods• Do not mix the signals in the first place Do not mix the signals in the first place
– can use space or time (SDMA or TDMA)can use space or time (SDMA or TDMA)
• Use distinctive properties of each signal as Use distinctive properties of each signal as a means to identify a means to identify – Frequency spectrum (FDMA)Frequency spectrum (FDMA)– Polarization of waves (PDMA)Polarization of waves (PDMA)– code sequence attached to each message code sequence attached to each message
(CDMA)(CDMA)
International Cocktail PartyInternational Cocktail Party
• FDMA – Large room divided up into small rooms FDMA – Large room divided up into small rooms with limited microphones. Each pair of people with limited microphones. Each pair of people takes turns speaking.takes turns speaking.
• TDMA – Large room divided up into small rooms TDMA – Large room divided up into small rooms with limited microphones. Certain pairs of people with limited microphones. Certain pairs of people per room, however, each pair gets limited seconds per room, however, each pair gets limited seconds to speak.to speak.
• CDMA – No small rooms. Everyone is speaking in CDMA – No small rooms. Everyone is speaking in different languages with own microphones. If voice different languages with own microphones. If voice volume is minimized, the number of people is volume is minimized, the number of people is maximized.maximized.
DefinitionsDefinitions• TDMA – Time Division Multiple AccessTDMA – Time Division Multiple Access
• FDMA – Frequency Division Multiple AccessFDMA – Frequency Division Multiple Access
• CDMA – Code Division Multiple AccessCDMA – Code Division Multiple Access
• IDMA- Interleave Division Multiple AccessIDMA- Interleave Division Multiple Access
General Specification of General Specification of TDMATDMA• Rx: 869-894MHz Tx: 824-849MHzRx: 869-894MHz Tx: 824-849MHz
• 832 Channels spaced 30kHz apart832 Channels spaced 30kHz apart(3 users/channel)(3 users/channel)
• DQPSK modulation schemeDQPSK modulation scheme
• 48.6kbps bit rate48.6kbps bit rate
• Interim Standard (IS) – 54Interim Standard (IS) – 54
• Digital AMPS (Advanced Mobile Phone Digital AMPS (Advanced Mobile Phone System)System)
• Uses Time Division Duplexing (TDD) usuallyUses Time Division Duplexing (TDD) usually
• The incoming data from each source are The incoming data from each source are briefly buffered and scanned to to form a briefly buffered and scanned to to form a composite digital data stream composite digital data stream mmc c ( ( t t ) .) .
TDMA DetailsTDMA Details
Buffer
Buffer
Buffer
1 2 N
U1U1
U2U2
UNUN
m1 ( t )
m2 ( t )
mN ( t )
mc ( t )
Scan operation
pre
am
ble
1 2 N
pre
am
ble
...
information
Each slot may be empty or occupied.+ has preamble & guard bits
Frame Frame
Time slot
TDMA SystemTDMA System
• Each user receives half Each user receives half of the frame and the full of the frame and the full bandwidth.bandwidth.– Users can resolve both Users can resolve both
multipathmultipath
• Time allocation is Time allocation is independent of power independent of power allocation.allocation.
• Nonlinear ISI Nonlinear ISI cancellation.cancellation.– Cancel edge effects as Cancel edge effects as
well.well.
s0 h1 s0 h2
s1 h1 s1 h2
s2 h1 s2 h2
Interval of Interest
TDMA Block DiagramTDMA Block Diagram
Estimate Channel
Equalize
User 1 Data
User 2 Data
ChannelISI
CancellationDetect and
Decode
Output
Advantages of TDMAAdvantages of TDMA
• Flexible bit rateFlexible bit rate• No frequency guard band requiredNo frequency guard band required• No need for precise narrowband filtersNo need for precise narrowband filters• Easy for mobile or base stations to initiate Easy for mobile or base stations to initiate
and execute hands offand execute hands off• Extended battery lifeExtended battery life• TDMA installations offer savings in base TDMA installations offer savings in base
station equipment, space and maintenancestation equipment, space and maintenance• The most cost-effective technology for The most cost-effective technology for
upgrading a current analog system to upgrading a current analog system to digitaldigital
Disadvantages to using Disadvantages to using TDMATDMA• Requires network-wide timing Requires network-wide timing
synchronizationsynchronization
• Requires signal processing fro Requires signal processing fro matched filtering and correlation matched filtering and correlation detectiondetection
• Demands high peak power on uplink Demands high peak power on uplink in transient modein transient mode
• Multipath distortionMultipath distortion
General Specification of General Specification of FDMAFDMA• Rx: 869-894MHz Tx: 824-849MHzRx: 869-894MHz Tx: 824-849MHz• 832 Channels spaced 30kHz apart832 Channels spaced 30kHz apart
(3 users/channel)(3 users/channel)• DQPSK modulation schemeDQPSK modulation scheme• 48.6kbps bit rate48.6kbps bit rate• Used in analog cellular phone systems (i.e. Used in analog cellular phone systems (i.e.
AMPS)AMPS)• Uses Frequency Division Duplexing (FDD)Uses Frequency Division Duplexing (FDD)• ISI (Intersymbol Interference) is lowISI (Intersymbol Interference) is low
Advantages of FDMAAdvantages of FDMA
• Channel bandwidth is relatively narrow (30kHz)Channel bandwidth is relatively narrow (30kHz)
• Simple algorithmically, and from a hardware Simple algorithmically, and from a hardware standpointstandpoint
• Fairly efficient when the number of stations is Fairly efficient when the number of stations is small and the traffic is uniformly constantsmall and the traffic is uniformly constant
• Capacity increase can be obtained by reducing the Capacity increase can be obtained by reducing the information bit rate and using efficient digital codeinformation bit rate and using efficient digital code
• No need for network timingNo need for network timing
• No restriction regarding the type of baseband or No restriction regarding the type of baseband or type of modulationtype of modulation
Disadvantages to using Disadvantages to using FDMAFDMA• The presence of guard bandsThe presence of guard bands
• Requires right RF filtering to minimize Requires right RF filtering to minimize adjacent channel interferenceadjacent channel interference
• Maximum bit rate per channel is fixed Maximum bit rate per channel is fixed
• Small inhibiting flexibility in bit rate Small inhibiting flexibility in bit rate capabilitycapability
• Does not differ significantly from analog Does not differ significantly from analog systemsystem
• If channel is not in use, it sits idleIf channel is not in use, it sits idle
SDMA SDMA Space Division Multiple AccessSpace Division Multiple Access • Use highly directionalUse highly directional
– The receiver selects the beam that provides The receiver selects the beam that provides the greatest signal enhancement and the greatest signal enhancement and interference reductioninterference reduction
– Smart antenna Smart antenna systems can adjust systems can adjust their antenna their antenna pattern to enhance pattern to enhance the desired signal, the desired signal, null or reduce null or reduce interference.interference.
Desired Signal
Direction
SDMA Pros and ConsSDMA Pros and Cons
AdvantagesAdvantages
• BW increases with BW increases with kmkm22
• Simple systemSimple system
DisadvantagesDisadvantages
• Restricted GeometryRestricted Geometry– terminals in same terminals in same
direction cannot sharedirection cannot share
• May have unused BWMay have unused BW– if no terminals in if no terminals in
given zone, bw not given zone, bw not usedused
PDMA PDMA Polarization Division Multiple AccessPolarization Division Multiple Access
• Two methodsTwo methods– Two antennas with orthogonal Two antennas with orthogonal
polarizations polarizations – an antenna with dual-polarization an antenna with dual-polarization
(SATCOM)(SATCOM)
• Each polarization provides one Each polarization provides one separate channelseparate channel
PDMA Pros and ConsPDMA Pros and Cons
AdvantagesAdvantages
• doubles BWdoubles BW
DisadvantagesDisadvantages
• Large specialized AeLarge specialized Ae
Spread SpectrumSpread Spectrum
CDMA - FHMA - DSMA - SSMACDMA - FHMA - DSMA - SSMA
Definition - Spread Definition - Spread SpectrumSpectrum
• The transmission bandwidth must be The transmission bandwidth must be much larger than the information much larger than the information bandwidthbandwidth
• The resulting RF bandwidth is The resulting RF bandwidth is determined by a function other than determined by a function other than the information being sentthe information being sent
ff
Power Power DensityDensity
PDPDii
PDPDSSSS
Conventional Conventional TransmissionTransmission
Spread Spectrum Spread Spectrum TransmissionTransmission
BBSSSS
BBii
same total powersame total power
Spread Spectrum - Spread Spectrum - illustratedillustrated
HowHow
• Two main methodsTwo main methods– Frequency Hopped Multiple Access Frequency Hopped Multiple Access
(FHMA)(FHMA)– Direct Sequence Multiple Access (DSMA)Direct Sequence Multiple Access (DSMA)– THMA does exist, but not commonTHMA does exist, but not common
• Both depend on pseudo random Both depend on pseudo random orthogonal codesorthogonal codes
• often called pseudo noiseoften called pseudo noise
FHSS FHSS Frequency Hopping Multiple AccessFrequency Hopping Multiple Access
• message is "cut" into small "chunks"message is "cut" into small "chunks"
• Each chunk is modulated by a different fEach chunk is modulated by a different fcc (determined by pseudo-random code)(determined by pseudo-random code)
• A band pass filter accepts the signals A band pass filter accepts the signals that follow the hopping sequence and that follow the hopping sequence and rejects all other rejects all other requires synchronizationrequires synchronization
• note - some early systems used short note - some early systems used short predictable patternspredictable patterns
FHSS - illustratedFHSS - illustratedFrequencyFrequency
TimeTime
TuneTime
FrequencyFrequencyHopHop
DwellDwellTimeTime
DSMA DSMA Direct Sequence Multiple AccessDirect Sequence Multiple Access
• Each bit is “chipped”Each bit is “chipped”
• Example - time domainExample - time domain
DataData
ChipsChips
0.1 ms0.1 ms
1 bit1 bit
0.1 0.1 ss
1000 chips1000 chips
Requires much wider bandwidth
Cross CorrelationCross Correlation
to determine start of codeto determine start of code
to lock onto correct codeto lock onto correct code
• Mathematical process used to determine Mathematical process used to determine the similarity between two signalsthe similarity between two signals
111101011001000011110101100100
100011110101100Modulo-2 sum-2 sum
15-bit Code
Received SignalReceived Signal
Correlation = -1/15 (very poor)
Used for despreading
Pseudo Random Pseudo Random Orthogonal...Orthogonal...• Different sequences are said to be Different sequences are said to be
orthogonal if they do not interfere orthogonal if they do not interfere with one another with one another (ie have low cross correlation)(ie have low cross correlation)
• A sequence is pseudo random if it is A sequence is pseudo random if it is orthogonal with a time shifted orthogonal with a time shifted version of itselfversion of itself
• note - this significantly reduces the note - this significantly reduces the number of codes available << 2number of codes available << 2 n n -1-1
Transmitted Transmitted (Coded) Signal(Coded) Signal
Baseband Baseband Signal Signal
NoiseNoiseInfo SignalInfo Signal
Before spreadingBefore spreading After spreadingAfter spreading
Info
Spreading ProcessSpreading Process
How can you recover signal < noise
SNRout BWRF
SNRin Rinfo
SNR gain of spread SNR gain of spread spectrumspectrum
• The ratio of the ‘SNR out’ to the ‘SNR into’ The ratio of the ‘SNR out’ to the ‘SNR into’ the demodulator (the demodulator ( spreading factor). spreading factor).
GP = =
Given: 1 Mcps PN codeGiven: 1 Mcps PN code
1 kbps information data signal 1 kbps information data signal
BWBW RFRF = 2 MHz= 2 MHz
G = 2 x 10 = 2000 = 33 dBG = 2 x 10 = 2000 = 33 dBpp
66
101033
This means that after de-spreading, signal This means that after de-spreading, signal is 33 dB (2000 times) bigger than the noise. is 33 dB (2000 times) bigger than the noise.
ExampleExample
General Specification of General Specification of CDMACDMA• Rx: 869-894MHz Tx: 824-849MHzRx: 869-894MHz Tx: 824-849MHz
• 20 Channels spaced 1250kHz apart20 Channels spaced 1250kHz apart(798 users/channel)(798 users/channel)
• QPSK/(Offset) OQPSK modulation schemeQPSK/(Offset) OQPSK modulation scheme
• 1.2288Mbps bit rate1.2288Mbps bit rate
• IS-95 standardIS-95 standard
• Operates at both 800 and 1900 MHz Operates at both 800 and 1900 MHz frequency bandsfrequency bands
CDMA OperationCDMA Operation• Spread Spectrum Spread Spectrum
Multiple Access Multiple Access TechnologiesTechnologies
CDMA in theoryCDMA in theory• Sender A Sender A
– sends Asends Add = 1, key A = 1, key Akk = 010011 („0“= -1, „1“= = 010011 („0“= -1, „1“= +1)+1)
– sending signal Asending signal Ass = A = Add * A * Akk = (-1, +1, -1, -1, = (-1, +1, -1, -1, +1, +1)+1, +1)
• Sender BSender B– sends Bsends Bdd = 0, key B = 0, key Bkk = 110101 („0“= -1, „1“= = 110101 („0“= -1, „1“=
+1)+1)
– sending signal Bsending signal Bss = B = Bdd * B * Bkk = (-1, -1, +1, -1, = (-1, -1, +1, -1, +1, -1)+1, -1)
• Both signals superimpose in space Both signals superimpose in space – interference neglected (noise etc.)interference neglected (noise etc.)
– AAss + B + Bss = (-2, 0, 0, -2, +2, 0) = (-2, 0, 0, -2, +2, 0)
Decoding CDMADecoding CDMA
• Receiver wants to receive signal from Receiver wants to receive signal from sender Asender A– apply key Aapply key Akk bitwise (inner product) bitwise (inner product)
•AAee = (-2, 0, 0, -2, +2, 0) = (-2, 0, 0, -2, +2, 0) A Ak k = 2 + 0 + 0 + 2 + 2 + = 2 + 0 + 0 + 2 + 2 + 0 = 60 = 6
•result greater than 0, therefore, original bit was „1“ result greater than 0, therefore, original bit was „1“
– receiving Breceiving B•BBee = (-2, 0, 0, -2, +2, 0) = (-2, 0, 0, -2, +2, 0) B Bkk = -2 + 0 + 0 - 2 - 2 + = -2 + 0 + 0 - 2 - 2 +
0 = -6, i.e. „0“0 = -6, i.e. „0“
CDMA Encode/Decode
slot 1 slot 0
d1 = -1
1 1 1 1
1- 1- 1- 1-
Zi,m= di.cmd0 = 1
1 1 1 1
1- 1- 1- 1-
1 1 1 1
1- 1- 1- 1-
1 1 11
1-1- 1- 1-
slot 0channeloutput
slot 1channeloutput
channel output Zi,m
sendercode
databits
slot 1 slot 0
d1 = -1d0 = 1
1 1 1 1
1- 1- 1- 1-
1 1 1 1
1- 1- 1- 1-
1 1 1 1
1- 1- 1- 1-
1 1 11
1-1- 1- 1-
slot 0channeloutput
slot 1channeloutputreceiver
code
receivedinput
Di = Zi,m.cmm=1
M
M
CDMA: two-sender interference
MC-CDMA SystemMC-CDMA System
• Complex orthogonal Complex orthogonal spreading codes.spreading codes.– Length 2Length 2– Spread over two Spread over two
subcarriers.subcarriers.• Both users use full Both users use full
bandwidth and full frame.bandwidth and full frame.• Each subcarrier is flat Each subcarrier is flat
fadingfading• Code allocation and Code allocation and
spreading length is spreading length is independent of power independent of power allocation.allocation.
s1c11f1 s1c12f2
s2c21f1 s2c22f2
Full Bandwidth
Half Bandwidth
User 1
User 2
First Subcarrier
Second Subcarrier
Multicarrier CDMAMulticarrier CDMA
• The data is serial-to-parallel converted.The data is serial-to-parallel converted.
• Symbols on each branch spread in time.Symbols on each branch spread in time.
• Spread signals transmitted via OFDMSpread signals transmitted via OFDM
• Get spreading in both time and frequencyGet spreading in both time and frequency
c(t)
IFFT
P/S convert
.. .S/P convert
s(t)c(t)
MC-CDMA Block DiagramMC-CDMA Block Diagram
Estimate Channel
FFT
Despread
Spread
Spread IFFT
IFFT
ChannelInterference Cancellation
Equalize
Detect and Decode
User 1 Data
User 2 Data
Output
DS-CDMA SystemDS-CDMA System
• Complex, orthogonal Complex, orthogonal spreading codes.spreading codes.– Length 2Length 2
• Synchronous transmissionSynchronous transmission• Users can resolve both Users can resolve both
multipath components.multipath components.• Nonlinear interference Nonlinear interference
cancellationcancellation– ISIISI– Other userOther user
• Code assignment and Code assignment and spreading length are spreading length are independent of power independent of power allocation.allocation.
s1c11h s1c12h
s2c21h s2c22h
Symbol Interval
Chip Interval
User 1
User 2
DS-CDMA Block DiagramDS-CDMA Block Diagram
Estimate Channel
Despread
Detect and Decode
User 1 Data
User 2 Data
Spread
Spread
ChannelInterference Cancellation
Equalize
Output
CapacityCapacity
• CDMA has the ability to deliver 10 CDMA has the ability to deliver 10 to 20 times the capacity as FDMA to 20 times the capacity as FDMA for the same bandwidth. for the same bandwidth.
• CDMA also has a capacity CDMA also has a capacity advantage over TDMA by 5 to 7 advantage over TDMA by 5 to 7 times.times.
TD-SCDMA developmentTD-SCDMA development• Datang Telecommunication Datang Telecommunication
technology (former China technology (former China Academy of Academy of Telecommunication Telecommunication Technology) is the most active Technology) is the most active TD-SCDMA developerTD-SCDMA developer
• The biggest manufacturers The biggest manufacturers have formed number of Joint have formed number of Joint Ventures for TD-SCDMA R&DVentures for TD-SCDMA R&D
• The Chinese Government has The Chinese Government has already invested more than 1 already invested more than 1 billion (US$123.3 million) in the billion (US$123.3 million) in the research and development research and development (R&D) of TD-SCDMA(R&D) of TD-SCDMA
• Domestic companies have got Domestic companies have got heavy public subsidies for TD-heavy public subsidies for TD-SCDMA developmentSCDMA development
TD-SCDMA developer pool
TD-SCDMATD-SCDMA• ITU standard, belongs to 3GPPITU standard, belongs to 3GPP
• TDD technology, fully TDD technology, fully compatible with GSM and compatible with GSM and GPRSGPRS
• Easy to upgrade from existing Easy to upgrade from existing infrastructureinfrastructure
• Efficient use of spectrumEfficient use of spectrum
• Effective data transmission. Effective data transmission. Asynchronous uplink – Asynchronous uplink – downlink, suitable for Internet downlink, suitable for Internet traffictraffic
• Use of Smart Antenna Use of Smart Antenna technologytechnology
• Good mobility: > 120 km/hGood mobility: > 120 km/h
• Large cells, with diameter up Large cells, with diameter up to 40 kmto 40 km
• Standard development far Standard development far behind rivals. Standard is behind rivals. Standard is very immature, no very immature, no commercial use so farcommercial use so far
• No large scale support from No large scale support from industry. Only few TD-SCDMA industry. Only few TD-SCDMA chips availablechips available
• Lack of equipments and Lack of equipments and handsets. No mass handsets. No mass production.production.
• No uniform platform for No uniform platform for applications -> No application applications -> No application developer “pool”developer “pool”
• Some unsolved technical Some unsolved technical problems:problems:– Cell interferenceCell interference– large cell area functionslarge cell area functions– high speed mobility high speed mobility – poor stability of existing ICpoor stability of existing IC’’ss– Power consumption of Power consumption of
handsetshandsets
Pros: Cons:
TD-SCDMA forumTD-SCDMA forum
• Industry consortium devoted to develop Industry consortium devoted to develop and support TD-SCDMA technologyand support TD-SCDMA technology
• Established in Dec/2000 by China Mobile, Established in Dec/2000 by China Mobile, China Telecom, China Unicom, Datang, China Telecom, China Unicom, Datang, Huawei, Motorola, Nortel and SiemensHuawei, Motorola, Nortel and Siemens
• More than 420 membersMore than 420 members– 16 Board Members16 Board Members– 18 Senior Members18 Senior Members– 390 ordinary members390 ordinary members
5. Third Generation Mobile
5.3 TD-SCDMA
Advantages of CDMAAdvantages of CDMA
• Many users of CDMA use the same frequency, Many users of CDMA use the same frequency, TDD or FDD may be usedTDD or FDD may be used
• Multipath fading may be substantially Multipath fading may be substantially reduced because of large signal bandwidthreduced because of large signal bandwidth
• No absolute limit on the number of usersNo absolute limit on the number of users• Easy addition of more usersEasy addition of more users• Impossible for hackers to decipher the code Impossible for hackers to decipher the code
sentsent• Better signal qualityBetter signal quality• No sense of handoff when changing cellsNo sense of handoff when changing cells
Disadvantages to using Disadvantages to using CDMACDMA• As the number of users increases, the As the number of users increases, the
overall quality of service decreasesoverall quality of service decreases
• Self-jammingSelf-jamming
• Near- Far- problem ariseNear- Far- problem arise
• higher complexity of a receiverhigher complexity of a receiver
• all signals should have the same all signals should have the same strength at a receiverstrength at a receiver
• Terminals A sends and B receivesTerminals A sends and B receives– signal strength decreases proportional signal strength decreases proportional
to the square of the distanceto the square of the distance– the signal of terminal B therefore the signal of terminal B therefore
drowns out A’s signaldrowns out A’s signal
near and far terminalsnear and far terminals
A B
Comparison SDMA/TDMA/FDMA/CDMAComparison SDMA/TDMA/FDMA/CDMA
Approach SDMA TDMA FDMA CDMAIdea segment space into
cells/sectorssegment sendingtime into disjointtime-slots, demanddriven or fixedpatterns
segment thefrequency band intodisjoint sub-bands
spread the spectrumusing orthogonal codes
Terminals only one terminal canbe active in onecell/one sector
all terminals areactive for shortperiods of time onthe same frequency
every terminal has itsown frequency,uninterrupted
all terminals can be activeat the same place at thesame moment,uninterrupted
Signalseparation
cell structure, directedantennas
synchronization inthe time domain
filtering in thefrequency domain
code plus specialreceivers
Advantages very simple, increasescapacity per km²
established, fullydigital, flexible
simple, established,robust
flexible, less frequencyplanning needed, softhandover
Dis-advantages
inflexible, antennastypically fixed
guard spaceneeded (multipathpropagation),synchronizationdifficult
inflexible,frequencies are ascarce resource
complex receivers, needsmore complicated powercontrol for senders
Comment only in combinationwith TDMA, FDMA orCDMA useful
standard in fixednetworks, togetherwith FDMA/SDMAused in manymobile networks
typically combinedwith TDMA(frequency hoppingpatterns) and SDMA(frequency reuse)
still faces some problems,higher complexity,lowered expectations; willbe integrated withTDMA/FDMA
CDMA Design ConsiderationsCDMA Design Considerations
• Bandwidth – limit channel usage to 5 MHzBandwidth – limit channel usage to 5 MHz
• Chip rate – depends on desired data rate, need for Chip rate – depends on desired data rate, need for error control, and bandwidth limitations; 3 Mcps or error control, and bandwidth limitations; 3 Mcps or more is reasonablemore is reasonable
• Multirate – advantage is that the system can flexibly Multirate – advantage is that the system can flexibly support multiple simultaneous applications from a support multiple simultaneous applications from a given user and can efficiently use available capacity given user and can efficiently use available capacity by only providing the capacity required for each by only providing the capacity required for each serviceservice
CDMA2000 Pros and ConsCDMA2000 Pros and Cons• Evolution from original Qualcomm CDMAEvolution from original Qualcomm CDMA
– Now known as cdmaOne or IS-95Now known as cdmaOne or IS-95
• Better migration story from 2G to 3GBetter migration story from 2G to 3G– cdmaOne operators don’t need additional spectrumcdmaOne operators don’t need additional spectrum– 1xEVD0 promises higher data rates than UMTS, i.e. W-1xEVD0 promises higher data rates than UMTS, i.e. W-
CDMACDMA
• Better spectral efficiency than W-CDMA(?)Better spectral efficiency than W-CDMA(?)– Arguable (and argued!)Arguable (and argued!)
• CDMA2000 core network less mature CDMA2000 core network less mature – cmdaOne interfaces were vendor-specificcmdaOne interfaces were vendor-specific– Hopefully CDMA2000 vendors will comply w/ 3GPP2Hopefully CDMA2000 vendors will comply w/ 3GPP2
W-CDMA (UMTS) Pros and W-CDMA (UMTS) Pros and ConsCons•Wideband CDMAWideband CDMA
– Standard for Universal Mobile Telephone Service Standard for Universal Mobile Telephone Service (UMTS)(UMTS)
•Committed standard for Europe and likely migration Committed standard for Europe and likely migration path for other GSM operatorspath for other GSM operators– Leverages GSM’s dominant positionLeverages GSM’s dominant position
•Requires substantial new spectrumRequires substantial new spectrum– 5 MHz each way (symmetric)5 MHz each way (symmetric)
•Legally mandated in Europe and elsewhereLegally mandated in Europe and elsewhere
•Sales of new spectrum completed in EuropeSales of new spectrum completed in Europe– At prices that now seem exorbitant At prices that now seem exorbitant
TD-SCDMATD-SCDMA•Time division duplex (TDD)Time division duplex (TDD)
•Chinese developmentChinese development– Will be deployed in ChinaWill be deployed in China
•Good match for asymmetrical traffic!Good match for asymmetrical traffic!
•Single spectral band (1.6 MHz) possibleSingle spectral band (1.6 MHz) possible
•Costs relatively lowCosts relatively low– Handset smaller and may cost lessHandset smaller and may cost less– Power consumption lowerPower consumption lower– TDD has the highest spectrum efficiencyTDD has the highest spectrum efficiency
•Power amplifiers must be very linearPower amplifiers must be very linear– Relatively hard to meet specificationsRelatively hard to meet specifications
IMT-2000 Radio StandardsIMT-2000 Radio Standards• IMT-SC*IMT-SC* Single Carrier (UWC-136) Single Carrier (UWC-136): EDGE: EDGE
– GSM evolution (TDMA); 200 KHz channels; GSM evolution (TDMA); 200 KHz channels; sometimes called “2.75G”sometimes called “2.75G”
• IMT-MC*IMT-MC* Multi Carrier CDMA: Multi Carrier CDMA: CDMA2000CDMA2000– Evolution of IS-95 CDMA, i.e. cdmaOneEvolution of IS-95 CDMA, i.e. cdmaOne
• IMT-DS*IMT-DS* Direct Spread CDMA: Direct Spread CDMA: W-CDMAW-CDMA– New from 3GPP; UTRAN FDDNew from 3GPP; UTRAN FDD
• IMT-TC**IMT-TC** Time Code CDMA Time Code CDMA– New from 3GPP; UTRAN TDDNew from 3GPP; UTRAN TDD
– New from China; New from China; TD-SCDMATD-SCDMA
• IMT-FT**IMT-FT** FDMA/TDMA (DECT legacy) FDMA/TDMA (DECT legacy)* Paired spectrum; ** Unpaired spectrum
Dept. of Electronics & Dept. of Electronics & Communication EngineeringCommunication Engineering 5757
Some Requirements for Future Some Requirements for Future Wireless SystemsWireless Systems• low receiver costlow receiver cost• de-centralized (i.e., asynchronous) control,de-centralized (i.e., asynchronous) control,• simple treatment of ISI,simple treatment of ISI,• cross-cell interference mitigation,cross-cell interference mitigation,• diversity against fading,diversity against fading,• power efficiency (long battery life),power efficiency (long battery life),• multi-media services (e.g., mixed voice and IP),multi-media services (e.g., mixed voice and IP),• high user number,high user number,• high throughput and high spectral efficiency,high throughput and high spectral efficiency,
FDMA ×TDMA ×CDMA ×
Dept. of Electronics & Dept. of Electronics & Communication EngineeringCommunication Engineering 5858
Evolution of IDMAEvolution of IDMA• A conventional CDMA system requires separate A conventional CDMA system requires separate
coding and spreading operations.coding and spreading operations.
• Verdu and Viterbi [2]* has shown that the Verdu and Viterbi [2]* has shown that the optimum multiple channel capacity (MAC) is optimum multiple channel capacity (MAC) is achievable only when entire bandwidth is achievable only when entire bandwidth is devoted to coding. devoted to coding.
This suggests combining the coding and This suggests combining the coding and spreading operations using low-rate codes to spreading operations using low-rate codes to maximize coding gain. maximize coding gain. *S. Verdú and S. Shamai, “Spectral efficiency of CDMA with random
spreading,” IEEE Trans. Inform. Theory, vol. 45, pp. 622–640, Mar. 1999
Dept. of Electronics & Dept. of Electronics & Communication EngineeringCommunication Engineering 5959
Possible Solution for User SeparationPossible Solution for User Separation
• Narrow band coded-modulation scheme using Narrow band coded-modulation scheme using trellis code structures [4]trellis code structures [4]
• To employ chip-level interleavers [3][4][5][6]To employ chip-level interleavers [3][4][5][6]
Improvement in CDMA scheme by assigning Improvement in CDMA scheme by assigning different interleavers to different users different interleavers to different users [5]*[6]**[5]*[6]**
Evolution of IDMA…..
*A. Tarable,et al, “Analysis and design of interleavers for CDMA systems,” IEEE Commun. Lett., vol. 5,, Oct. 2001.
**S. Brück, U. Sorger, S. Gligorevic, and N. Stolte, “Interleaving for outer convolutional codes in DSCDMA Systems,” IEEE Trans. Commun.,July 2000.
Dept. of Electronics & Dept. of Electronics & Communication Communication EngineeringEngineering 6060
Encoder (C)
Encoder (C)User K
User 1Interleaver
Interleaver
Spreader 1
Spreader K
Multiple AccessMultipath Channel
Multiple AccessMultipath Channel
Correlator Bank
ElementaryMulti-User Detector(EMUD)
Interleaver
Deinterleaver
Interleaver
Deinterleaver
Decoder
Decoder
User1
User K
Turbo Processor
Conventional CDMA Transmitter and an Iterative MUD Receiver
Dept. of Electronics & Dept. of Electronics & Communication Communication EngineeringEngineering 6161
Encoder (C)
Encoder (C)User K
User 1Spreader
Spreader
Interleaver 1
Interleaver K
Multiple AccessMultipath Channel
Multiple AccessMultipath Channel
ElementarySignal
Estimator(ESE)
Interleaver 1
Deinterleaver 1
Interleaver K
Deinterleaver K
Decoder(DEC)
Decoder(DEC)
User 1
User K
Turbo Processor
IDMA Transmitter and Receiver structures
CODER
eESE (x1 (j))
eESE (xK (j))
eDEC (xK (j))
eDEC (x1 (j))
r(j)
Categories of Wireless Categories of Wireless NetworksNetworks
<source : Wireless communication technology landscape, DELL >
WPAN :Personal Area Connectivity10 meters
WLAN :Local Area Connectivity100 meters
WMAN :Metro Area Connectivity(City or suburb)
WWAN :Wide Area Connectivity(Broad geographiccoverage)
Beyond 100 meters
Bluetooth, UWB WiFi, HiperLan WiMaxAMPS, GSM, IS-95cdma2000, W-CDMA
Digital TechnologyDigital Technology• Frequency-shift keying (FSK)Frequency-shift keying (FSK)
- uses two frequencies (one for 1s & the other for - uses two frequencies (one for 1s & the other for 0s)0s)
- alternates between the two frequencies- alternates between the two frequencies
• modulation and encoding schemesmodulation and encoding schemes
- convert the analog ->digital, compress it-- convert the analog ->digital, compress it->analog>analog
- acceptable level of voice quality maintained- acceptable level of voice quality maintained
• Cell phones need a lot of processing powerCell phones need a lot of processing power
Cellular vs. PCSCellular vs. PCS
• ““digital cellular”, digital cellular”, paging, caller ID paging, caller ID and emailand email
• PCS has smaller PCS has smaller cells and larger cells and larger number of number of antennas.antennas.
CellularCellular PCSPCS
FrequencyFrequency 824824MHz-MHz-
894 894 MHzMHz
1850 1850 MHz-MHz-1990 1990 MHzMHz
Channel Channel spacingspacing 3030 KHz KHz 200200 KHz KHz
Time slotsTime slots 33 88
Dual band, Dual modeDual band, Dual modeTriband, TrimodeTriband, Trimode• What is Dual band?What is Dual band?
– CDMA digital cellular (800 MHz) or CDMA CDMA digital cellular (800 MHz) or CDMA digital PCS (1900 MHz). digital PCS (1900 MHz).
• What is Triband?What is Triband?– GSM 900, 1800 and 1900 (MHz)GSM 900, 1800 and 1900 (MHz)
• Dual ModeDual Mode– AMPS and TDMAAMPS and TDMA– Analog and digitalAnalog and digital
• TrimodeTrimode– Two digital (CDMA and TDMA) and analogTwo digital (CDMA and TDMA) and analog– Two bands in digital and analogTwo bands in digital and analog
WWAN (Wireless Wide Area WWAN (Wireless Wide Area Network)Network)
AMPS
FDMA
IS-95
GSM
IS-136/PDC
IS-95B
CDMA CDMA
cdma2000
CDMA
GPRS
EDGE
W-CDMA
TDMA
CDMA
TDMA
W-CDMA/HSDPA
cdma2000EV,DO,DV
TDMA TDMA
?
CDMA
CDMA
OFDM
1G 2G 2.5G 3G 3.5G 4G
Analog Digital
FDMA
CDMA
TDMAOFDM
Voice 64~384K Packet ~2M Multimedia ~10M Multimedia ~100M Multimedia
Can be Implemented by Programmable DSP No fully programmable H/W solutions
NMTTACT
FDMA IDMA
The The FUNDAMENTALFUNDAMENTAL Issue: Issue: Network CongestionNetwork Congestion
AT&T MCI
SPRINT
Local ExchangeNetworks
Mobile Switch
Wireless Priority Service addresses wireless congestion at
Government Emergency Telecommunications Service
addresses wireline congestion
Local ExchangeNetworks
MobileSwitchMobileSwitch
call origination and call termination
Congestion,Congestion,at at oneone of of manymany points, can block a call ! points, can block a call !
Key ResourceKey Resource
• Spectrum:Spectrum:– 802.11 operates in the unlicensed band 802.11 operates in the unlicensed band
(ISM – Industrial Scientific and Medical (ISM – Industrial Scientific and Medical band) ~ 3 such bandsband) ~ 3 such bands•Cordless Telephony:Cordless Telephony: 902 to 928 MHz 902 to 928 MHz
•802.11b:802.11b: 2.4 to 2.483 GHz 2.4 to 2.483 GHz
•33rdrd ISM Band: ISM Band: 5.725 to 5.875 GHz 5.725 to 5.875 GHz
•802.11a: 5.15 to 5.825 GHz802.11a: 5.15 to 5.825 GHz
Data Rates and RangeData Rates and Range• 802.11:802.11: 2Mbps (Proposed in 1997) 2Mbps (Proposed in 1997)
• 802.11b:802.11b: 1, 2, 5.5 and 11 Mbps, 100mts. 1, 2, 5.5 and 11 Mbps, 100mts. range (product released in 1999, no product range (product released in 1999, no product for 1 or 2 Mbps)for 1 or 2 Mbps)
• 802.11g:802.11g: 54Mbps, 100mts. range (uses OFDM; 54Mbps, 100mts. range (uses OFDM; product expected in 2003)product expected in 2003)
• 802.11a:802.11a: 6 to 54 Mbps, 50mts. range (uses 6 to 54 Mbps, 50mts. range (uses OFDM)OFDM)
2G+ networks (contd.)2G+ networks (contd.)HSCSD one step towards 3G wideband mobile data networks.This circuit switched technology improves data rates up to 57.6 kbps.GPRS packet based and designed to work in parallel with 2G GSM, PDC and TDMA technologies.
EDGE enhances the throughput per timeslot for both HSCSD and GPRS. ECSD (max data rate 64 kbps and EGPRS data rate per time slot triples to a staggering 384 kbps.
1 MB FileModem Technology Throughput Download Speed
GSM/TDMA 2G Wireless <9.6 Kbps ~20 minAnalog Modem Fixed Line Dial-up 9.6 Kbps 16 min
GPRS 2.5G Wireless 30-40 Kbps 4.5 minISDN Fixed Line Digital 128 Kbps 1.1 min
CDMA 1x 2.75G Wireless 144 Kbps 50 secEDGE 2.75G Wireless 150 - 200 Kbps 36 to 47 secDSL Fixed Line DSL 0.7 - 1.5 Mbps 1 to 3 sec
W-CDMA 3G Wireless 1.0 Mbps 1.5 secCable Fixed Line Cable 1.0 - 2.0 Mbps 0.8 to 1.5 sec
EDGE Cheaper and GivesEDGE Cheaper and GivesNear-3G PerformanceNear-3G Performance
• EDGE is 2.75G, with significantly higher data rates than GPRSEDGE is 2.75G, with significantly higher data rates than GPRS
• Deploying EDGE significantly cheaper than deploying W-CDMADeploying EDGE significantly cheaper than deploying W-CDMA
• Takeaway: Look for EDGE to gain traction in 2002/2003+Takeaway: Look for EDGE to gain traction in 2002/2003+
2G GSM CDMA TDMA
2.5G / 2.75G GPRS CDMA 1x GSM/GPRS/EDGE
Software/Hardware Software-based Hardware-based Hardware and software
Cost Incremental Substantial Middle of the road
3G W-CDMA cdma2000 W-CDMA
Software/Hardware Hardware-based Software-based Hardware-based
Cost Substantial Incremental Middle of the road
Upgrade Cost, By Upgrade Cost, By TechnologyTechnology
• CDMA upgrade to 2.75G is expensive; to 3G is cheapCDMA upgrade to 2.75G is expensive; to 3G is cheap
• GSM upgrade to 2.5G is cheap; to 3G is expensiveGSM upgrade to 2.5G is cheap; to 3G is expensive
• TDMA upgrade to 2.5G/3G is complexTDMA upgrade to 2.5G/3G is complex
• Takeaway: AT&T and Cingular have a difficult road to 3GTakeaway: AT&T and Cingular have a difficult road to 3G
3G CDMA Reported* Subscribers3G CDMA Reported* Subscribers(As of March 30, 2007)(As of March 30, 2007)
05
10152025303540455055606570758085
Mar Apr May June July Aug Sep Oct Nov Dec Jan Feb Mar
Su
bscri
bers
(M
)
88.2 million
6.46 million
4.31 million
Source: www.3Gtoday.com
Worldwide CDMA Subscriber Evolution ForecastWorldwide CDMA Subscriber Evolution Forecast
0
100
200
300
400
500
600
700
800
2000 2001 2002 2003 2004 2005 2006 2007 2008
2G CDMA 3G CDMA 3G WCDMA
Future(Millions)
Source: Strategy Analytics, April 2003 and www.3gtoday as of December 2003, CDG September 2003
3G CDMA is Well Established & Growing3G CDMA is Well Established & GrowingNow in Use in Two Flavors: CDMA2000Now in Use in Two Flavors: CDMA2000®® and and WCDMAWCDMA
Over 800M Subscribers, 205 Operators, 74 Countries, 530 Handsets, 63 Vendors
September >174M subs
Latest Trends and Driving Latest Trends and Driving FactorsFactors• High Intensity Multi-Media High Intensity Multi-Media
CapabilitiesCapabilities– More efficiency in multi-More efficiency in multi-
media content deliverymedia content delivery
• Enhancements to support Enhancements to support Quality of ServiceQuality of Service
• Efficient and flexible Packet Efficient and flexible Packet based Video Telephonybased Video Telephony
65005500
“Push to See”
Samsung SCH V310
• Support for VoIP and Low-latency Support for VoIP and Low-latency applications, e.g., Gaming applicationsapplications, e.g., Gaming applications
• Instant Multi Media (IMM)Instant Multi Media (IMM)
• Broadcast and Multicast servicesBroadcast and Multicast services
• High Speed Data on both Up and Down LinksHigh Speed Data on both Up and Down Links
200620052004200320022001200019991995 200620052004200320022001200019991995
In -Band Migration and
Designed for In-Band Migration and New Spectrum
3G CDMA
2G CDMA
3G CDMA Evolution
1.25 MHz
Voice & Data
2.5G CDMA
Rel. 4
HSDPA
Additional voice capacity doubling
- Terminal antenna diversity
Rel. 5
CDMA2000 1X
14.4 kbps dataSoft HandoffSynchronous Timing
64 kbps packet data
− Channel Concatenation
Double voice capacity− Fast Fwd Power
Control− Coherent Uplink 153.6 kbps packet data− Turbo Codes
307 kbps packet data
Simultaneous voice and data
Dedicated & OptimizedFor Packet Data2.4 Mbps Peak Rates All IP Architecture
Improvementsto data services.
More flexible data packet scheduling.
64/384 kbps cs/packet dataSoft handoffAsynchronous timing
Improvements to data services
More flexible datapacket scheduling
cdmaOne
QoS, Broadcast, Personal Media, IMM ,2x
1xEV-DV
Forward Link: Peak Rate: 3.1 mbps
Reverse Link: Peak Rate:1.8 mbps
Fwd & Rev. Capacity Gains
Forward Link: Peak Rate 3.1 mbps
Reverse Link: Peak Rate 1.8 mbps
EUL
Rel. 6
EnhancedUp-Link
IS - 95A IS-95B
1.25 MHzOptimized for Data
IS-2000 Rel. 0 Rel. A Rel. B Rel. C Rel. D
Designed for New Spectrum
5 MHzVoice & Data
3GPP Rel. 99
CDMA2000 1xEV-DO
UMTS(WCDMA)
IS-856, Rel. 0 Enhancements Rel. A
CDMA
GSM
TDMA
PHS (IP-Based)
64 Kbps
GPRS
115 Kbps
CDMA 1xRTT
144 Kbps
EDGE
384 Kbps
cdma20001X-EV-DV
Over 2.4 Mbps
W-CDMA (UMTS)
Up to 2 Mbps
2G2.5G
2.75G 3G
1992 - 2000+2001+
2003+
1G
1984 - 1996+
2003 - 2004+
TACS
NMT
AMPS
GSM/GPRS
(Overlay) 115 Kbps
9.6 Kbps
9.6 Kbps
14.4 Kbps/ 64 Kbps
9.6 Kbps
PDC
Analog Voice
Digital Voice
Packet Data
IntermediateMultimedia
Multimedia
PHS
TD-SCDMA
2 Mbps?
9.6 Kbps
iDEN
(Overlay)
iDEN
Source: U.S. Bancorp Piper Jaffray
Migration To 3GMigration To 3G
CDMA2000 Standards CDMA2000 Standards StatusStatus
IS-95A/B
1xRelease 0
1x/3xRelease A
1x/3x Release B
1xEV-DO Revision 0
1xRevision C(1xEV-DV FL)
Arrow denotes evolution of standard, maintaining backward compatibility
cdma2000 family
Done
Done Done Done Done
1xRevision D(1xEV-DV RL)
Done
1xEV-DO Revision A
Publish Date: March 2006
Publish Date: March 2006
CDMA2000 CompatibilityCDMA2000 Compatibility• CDMA2000 Revision C is fully backward compatible:CDMA2000 Revision C is fully backward compatible:
– IS-95A or newer mobile stations can operate in a IS-95A or newer mobile stations can operate in a Revision C cellRevision C cell
– 1xEV-DV capable mobiles can do data on older systems1xEV-DV capable mobiles can do data on older systems
Mobile Station supporting Revision C
Base Base Station Station
supporting supporting Revision CRevision C
F-PDCH
Base Base Station Station
supporting supporting Revision 0Revision 0
F-SCH
Mobile Station supporting Revision C
Mobile Station supporting Revision C
F-PDCH
E
Key Factors to Better Key Factors to Better PerformancePerformance
• Capacity ImprovementCapacity Improvement
– Higher Data Rates and Finer QuantizationHigher Data Rates and Finer Quantization
• Data rates ranging from 4.8 kbps to 1.8 MbpsData rates ranging from 4.8 kbps to 1.8 Mbps
• Smoother rate transitions and interference variationSmoother rate transitions and interference variation
– Improved code rates and higher order modulation for Improved code rates and higher order modulation for large packets large packets
• QPSK modulation introducedQPSK modulation introduced
• Data channel spreading uses either or both of 2-ary Data channel spreading uses either or both of 2-ary and 4-ary Walsh code channeland 4-ary Walsh code channel
• Code rate 1/5 for all 16-slot packetsCode rate 1/5 for all 16-slot packets
– Hybrid ARQ with IR Hybrid ARQ with IR
• Enables packet to early terminate in the presence of Enables packet to early terminate in the presence of channel variation and imperfect power controlchannel variation and imperfect power control
Biggest Threat to Today’s Biggest Threat to Today’s 3G —3G —Wireless LANsWireless LANs•Faster than 3GFaster than 3G
– 11 or 56 Mbps vs. <2 Mbps for 3G when stationary11 or 56 Mbps vs. <2 Mbps for 3G when stationary
•Data experience matches the InternetData experience matches the Internet– With the added convenience of mobileWith the added convenience of mobile– Same user interface (doesn’t rely on small screens)Same user interface (doesn’t rely on small screens)– Same programs, files, applications, Websites.Same programs, files, applications, Websites.
•Low cost, low barriers to entryLow cost, low barriers to entry
•Organizations can build own networksOrganizations can build own networks– Like the Internet, will grow virallyLike the Internet, will grow virally
•Opportunity for entrepreneurs!Opportunity for entrepreneurs!
•Opportunity for wireless operators?Opportunity for wireless operators?
Critical For 3G — Critical For 3G — Continued Growth In ChinaContinued Growth In China
• CDMA IS-95 (2G) has been slow to launch in ChinaCDMA IS-95 (2G) has been slow to launch in China– Why would the launch of 3G be any different?Why would the launch of 3G be any different?
• PHS (2G) with China Telecom/Netcom is gaining momentumPHS (2G) with China Telecom/Netcom is gaining momentum
Likely 3G licensing Likely 3G licensing outcomes:outcomes:
• China Unicom — China Unicom — cdma2000cdma2000
• China Mobile — W-China Mobile — W-CDMACDMA
• China Telecom — W-China Telecom — W-CDMA/ TD-SCDMA?CDMA/ TD-SCDMA?
• China Netcom — W-China Netcom — W-CDMA/ TD-SCDMA?CDMA/ TD-SCDMA?
Risk:
Mobile Standard Mobile Standard Organizations Organizations
ARIB(Japan)
T1(USA)
ETSI(Europe)
TTA(Korea)
CWTS(China)
TTC(Japan)
TIA(USA)
Third GenerationPatnership Project
(3GPP)
Third GenerationPartnership Project II
(3GPP2)
ITU
MobileOperators
ITU Members
IS-95), IS-41, IS-2000, IS-835
GSM, W-CDMA,UMTS
UWB Technology & Advantages
•Doesn’t need licensed dedicated spectrum
•Low power consumption
•Small semiconductor size
•Ranging/location as a byproduct of communications
Questions ?
Manoj Kr. Shukla
Assistant Professor
Dept. of Electronics Engineering
Harcourt Butler Technological Institute
Kanpur 208002
Email: [email protected], [email protected]
Thanks for Listening and Have a
Great Workshop
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