50 Why is MIMO different from standard OFDM 40MHz 40MHz 40MHz 40MHz 4 x

50 why is mimo different from standard ofdm 40mhz

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50 Why is MIMO different from standard OFDM 40MHz 40MHz 40MHz 40MHz ~ 4 x Information, but with 4 x the BW 40MHz ~ 3.5 x Information, but with 1 x the BW
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A G R E A T E R M E A S U R E O F C O N F I D E N C E © Copyright 2007-2008 Keithley Instruments, Inc. 51 MIMO Radio Configuration TX1 TX2 RX1 RX2 2x2 TX1 TX2 TX3 RX1 RX2 3x2 TX1 TX2 TX3 TX4 RX1 RX2 RX3 RX4 4x4
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A G R E A T E R M E A S U R E O F C O N F I D E N C E © Copyright 2007-2008 Keithley Instruments, Inc. 52 MIMO requires lots of paths! If you have two unknown transmitted signals and two measurements at the receivers. If the two measurements are sufficiently independent, you can solve for the transmitted symbols!
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A G R E A T E R M E A S U R E O F C O N F I D E N C E © Copyright 2007-2008 Keithley Instruments, Inc. 53 Mathematically Model the Channel y = Hx + n y = Receive Vector x = Transmit Vector H = Channel Matrix n = Noise Vector TX1 TX2 h 21 h 12 h 11 = a+jb RX1 RX2 h 22 Channel h 11 h 12 h 21 h 22 H = Header
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A G R E A T E R M E A S U R E O F C O N F I D E N C E © Copyright 2007-2008 Keithley Instruments, Inc. 54 Correct for channel effects RX = H * TX + n TX 1 TX 2 h 21 h 12 h 11 = a+jb RX 1 RX 2 RX 1 RX 2 TX 1 TX 2 = - n h 22 Channel h 11 h 12 h 21 h 22 Data Data Header
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A G R E A T E R M E A S U R E O F C O N F I D E N C E © Copyright 2007-2008 Keithley Instruments, Inc. 55 demo 2x2 Measurement Example
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A G R E A T E R M E A S U R E O F C O N F I D E N C E © Copyright 2007-2008 Keithley Instruments, Inc. 56 802.16e Matrix A and B Robust Symbols vs. More Symbols 11010101001010101 110001100110 TX1 TX2 RX1 RX2 TX1 TX2 RX1 RX2 11 01 Matrix A – Transmit Inverse Symbols Coverage Matrix B – Transmit Parallel Symbols Throughput
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A G R E A T E R M E A S U R E O F C O N F I D E N C E © Copyright 2007-2008 Keithley Instruments, Inc. 57 Beam Forming TX1 TX2 TX3 TX4 • Control the directionality and shape of the radiated pattern Increase range, capacity and throughput
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A G R E A T E R M E A S U R E O F C O N F I D E N C E © Copyright 2007-2008 Keithley Instruments, Inc. 58 The Beam Forming Process WiMAX Example - Closed Loop Sound Channel Feedback Channel Characteristics Direct Beam TX1 TX2 TX3 TX4
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A G R E A T E R M E A S U R E O F C O N F I D E N C E © Copyright 2007-2008 Keithley Instruments, Inc. 59 Typical Types of Beam Forming Statistical Eigen Beam Forming (EBF) Advantage – Quickly builds a channel model to form a beam, making it ideal for mobile applications. Disadvantage – Not as efficient as Maximum Ratio Transmission. Maximum Ratio Transmission (MRT) Advantage – builds a very accurate channel model, thus improving throughput and coverage. Disadvantage – Slow processing times limit to static transmissions
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A G R E A T E R M E A S U R E O F C O N F I D E N C E © Copyright 2007-2008 Keithley Instruments, Inc. 60 MIMO Instrument Requirements 2820 VSA 2820 VSA (Master) MIMO Synchronization Unit 2920 VSG 2920 VSG (Master) MIMO Synchronization Unit Hardware All 28/2920 VSAs are identical standard units Flexibility to use 2820 VSAs as stand-alone generators User-definable instrument configuration setting Stand-alone MIMO Master MIMO Slave System Common LO and clock signals for all analyzers
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  • Spring '16
  • WiMAX, Keithley Instruments

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