Download - MIMO Antenna
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08BEC024 Jaydip Fadadu08BEC030 Kuldip Gor
Nirma University
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` Introduction
` Motivation for design
` Basics
` Diversity and Spatial Multiplexing` Applications
` Conclusion
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` MIMO Multiple Input Multiple Output
Array of antennas at transmitter and receiver at input
Diversity Gain improves BER Spatial Multiplexing improves data rates
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` To achieve high data rate that still offer good Quality of
Service (QoS) ( i.e. improves BER)
` But using Less complex system
Minimum power transmission
Minimum bandwidth
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` In SISO system to achieve high data rate more signal
power and more bandwidth is required.
` A combination a smart modulation, coding and
multiplexing techniques have yielded good results but
not sufficient for 1GBPS!!!
channel
User data stream
User data stream
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` se multiple antenna at Tx and Rx
` Now that supports higher data rates but
How!!!??? Lets see
User data streamUser data stream
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1
2
MT
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1
2
MR
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channel
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` Transmitter uses a weighting vector
u = [u1, u2] while receiver uses a weighting vector
v = [v1, v2]
` Channel coefficient matrix H (??)` s(t) = transmitting signal, r(t) = received signal
` r1(t) = (u1H v1) * s1(t) + (u2H v1) * s2(t)
` r2(t) = (u1H v2) * s1(t) + (u2H v2) * s2(t)
` We can decide value of u and v according to our
need.
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` Diversity Gain Minimize BER
Reliable QoS
`
Spatial Multiplexing Gain` Maximize transmission rate
` Uses rich scattering/fading to your advantage
` System designs are based on trying to achieve
either goal or a little of both
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` Each pair of transmit-receive antennas provides a signalpath from transmitter to receiver. By sending the SAME
information through different paths, multiple independently-
faded replicas of the data symbol can be obtained at the
receiver end. Hence, more reliable reception is achieved
` The maximal diversity gain dmax is the total number ofindependent signal paths that exist between the transmitter
and receiver
` For an (MR,MT) system, the total number of signal paths is
MRM
T1 d dmax= MRMT
` The higher my diversity gain, the lower my Pe
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1
2
MT
Channel coding Symbol
mapping
Space-Time
Coding.
.
R bits/symbol
Spectral efficiency = (R*Rc info bits/symbol)(rs)(Rs symbols/sec)/w
= R*Rc*rs bits/s/Hz assuming Rs = w
rs is the parameter that we are concerned about: 0 rs MT
If rs = MT, we are in spatial multiplexing mode (max transmission rate)
If rs 1, we are in diversity mode
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Scheme Spectral
Efficiency
Pe Implementation
Complexity
V-BLAST HIGH HIGH LOW
D-BLAST MODERATE MODERATE HIGH
ALAMOUTI LOW LOW LOW
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the data is divided among large number of closely spaced carriers
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` WLAN WiFi 802.11n
` Mesh Networks (e.g., MuniWireless)
` WMAN WiMAX 802.16e
` 4G` Digital Home
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` Target applications include: large files backup, HD
streams,online interactive gaming, home
entertainment, etc.
` Channel bandwidth of 20 MHz and 40 MHz` Current product offerings (pre-N) use only 2
spatial streams with 3Tx/3Rx in the AP and
2Tx/3Rx in the mobile supporting up to 300 Mbps
` Spatial diversity, spatial multiplexing
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High capacity (MIMO) cross-links
WiFi access
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` Non line of site, up to 4-6 mbps per user for a fewkm
` 2.5 GHz (US) and 3.5 GHz licensed bands
` Channel bandwidth from 1.25 to 20 MHz
` QPSK, 16 QAM and 64 QAM modulation
` OFDMA access (orthogonal uplink)
` TDD for asymmetric traffic and flexible BWallocation
` Advanced Antenna Systems (AAS):spatialdiversity, spatial multiplexing using MIMO (2x2)
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` MIMO delivers whole home coverage with thespeed and reliability to stream multimediaapplications
` MIMO can reliably connect cabled video devices,
computer networking devices, broadbandconnections, phone lines, music, storage devices,etc.
` MIMO is interoperable and can leverage the
installed based of 802.11 wireless that is alreadydeployed: computers, handheld gaming devices,cameras, VoIP Phones, etc.