MIMO Test
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• Conventional (fixed or switched beam) beam formers • Adaptive beam formers or phased array
MIMO Test
• Advanced digital Complexity of Multi radio Architectures
• V-BLAST(Vertical-BLAST)
• Each sub stream correspond to a transmit antenna, but the corresponding relationship will not be cyclically changed
Spatial multiplexing
• MIMO decoder must
• Estimate the individual channel transfer coefficient hij • Determine the channel transfer matrix[H] during the MIMO Preamble of the packet • Determine the inverse of transfer matrix [H]-1 from [H]
• T-BLAST(Threaded-BLAST)
• All transmit antenna are simultaneously sent data streams • Each sub stream not correspond to a transmit antenna, and the corresponding relationship will be cyclically changed
MIMO-What and Why
• Channel capacity is along with the number of antennas linear increases • Using multiple signal to improve channel capacity without increasing the bandwidth and antenna transmit power
MIMO Test
Yl Zhou
Agenda
• • • • MIMO-What and Why How MIMO System Works MIMO Technology MIMO Test
MIMO-What and Why
• Terminology
Single-Input Single -Output Single-Input Multiple-Output Multiple-Input Single -Output Multiple-Input Multiple-Output
• Test Multiple Transmit and Multiple Receive chains • Interference may degrade system performance • Imbalance among Tx and Rx in MIMO radios may degrade system performance
MIMO System Transfer Matrix
• Received signal at receiver can be described as:
Rx1 = h11Tx1 + h12Tx2 + … + h1nTxn Rx2 = h21Tx1 + h22Tx2 + … + h2nTxn : : Rxm = hm1Tx1 + hm2Tx2 + … + hmnTxn
Transmit EVM Measurement
• Error Vector Magnitude--The vector difference between measuring waveform and ideal modulating waveform • Modulation signal can be expressed as the same phase (I) component and a orthogonal (Q) component of the vector sum
How MIMO System Works
• MIMO System Link Model
How MIMO System Works
• MIMO Transmitter
• Through different transmit antennas • Sends independent data streams பைடு நூலகம்Tx1;Tx2;…Txn] • Transmits simultaneously and using the same radio channel
Spatial diversity
• A single(unlike multiple streams in spatial multiplexing) stream is transmitted • The signal is coded using techniques called space-time coding • Improve the reliability of the channel • Reduce channel error code rate
Beam forming
• Beam forming is a signal processing technique used in sensor arrays for directional signal transmission or reception. • Beam forming techniques can be broadly divided into two categories:
• MIMO Test Requirements
• MIMO system requires higher transmitter performance • MIMO system are more sensitive to Rx impairments
• Advanced Test Instruments
MIMO-What and Why
• Apply to high throughput standard IEEE802.11n • Dramatically improve wireless network performance
• • • • • Higher data throughput(480+Mbit/s) Better quality and more reliable RF link Extended coverage Better Spectral Efficiency(bits/bandwidth) Backward compatible with 802.11 a/b/g
Transmit Power
• The maximum allowable output power of the device is the same as in legacy 802.11a or 802.11g transmitter.
• If more than one transmit chain is used, the total power in all transmit chains shall be equal to the total power possible for a legacy 802.11a/g transmitter. • If a 40MHz channel is used, the total transmitted power in the 40MHz bandwidth shall be equal to the total trans mitted power allowed for a legacy 802.11a transmitter in a 20MHz channel.
• A high rate signal is split into multi lower rate streams • Each stream is transmitted from a different transmit antenna in the same frequency channel • Increase channel capacity at higher SNR • Spatial multiplexing systems can be divided into three kinds of models: D-BLAST, V-BLAST, T-BLAST.
• MIMO Receiver
• Through different receive antennas • Received signal represented by [Rx1;Rx2;…Rxm] • Each receives the composite signal from all transmitters
Spatial multiplexing
• D-BLAST(Diagonally-BLAST)
• Each sub stream independent encode • Each sub stream not correspond to a transmit antenna, and the corresponding relationship will be cyclically changed
• Advanced digital signal processing • Low instrument phase noise • Wide signal/modulation bandwidth
MIMO Test Item
• • • • • • • • • • • • Transmit Power Transmit EVM Tolerance Transmit Spectrum Mask Spectral Flatness Transmit Center Frequency Tolerance Transmit Symbol Clock Tolerance Transmit Carrier Frequency Transmit Carrier Leakage Transmit Channel Isolation Transmit IQ Imbalance Receive Channel Isolation Receiver Sensitivity
MIMO-What and Why
• Theoretical capacity and antenna number relations
• Transmit(receiving) antenna is fixed (=4), SNR is unchanged; the channel capacity will increase while the number of receiving(transmit) antennas increase, but the increasing more and more small • When the number of transmit antenna and receiving antenna is same(=4), SNR increases, channel capacity will increase • When the number of transmit antenna is more than 10 receiving antenna , channel capacity is basically not much change
• Transmitted data stream can be reconstructed as
[Tx] = [H]-1 [Rx]
MIMO Technology
• Spatial multiplexing • Spatial diversity • Beam forming
Spatial multiplexing
MIMO Test
• Advanced digital Complexity of Multi radio Architectures
• V-BLAST(Vertical-BLAST)
• Each sub stream correspond to a transmit antenna, but the corresponding relationship will not be cyclically changed
Spatial multiplexing
• MIMO decoder must
• Estimate the individual channel transfer coefficient hij • Determine the channel transfer matrix[H] during the MIMO Preamble of the packet • Determine the inverse of transfer matrix [H]-1 from [H]
• T-BLAST(Threaded-BLAST)
• All transmit antenna are simultaneously sent data streams • Each sub stream not correspond to a transmit antenna, and the corresponding relationship will be cyclically changed
MIMO-What and Why
• Channel capacity is along with the number of antennas linear increases • Using multiple signal to improve channel capacity without increasing the bandwidth and antenna transmit power
MIMO Test
Yl Zhou
Agenda
• • • • MIMO-What and Why How MIMO System Works MIMO Technology MIMO Test
MIMO-What and Why
• Terminology
Single-Input Single -Output Single-Input Multiple-Output Multiple-Input Single -Output Multiple-Input Multiple-Output
• Test Multiple Transmit and Multiple Receive chains • Interference may degrade system performance • Imbalance among Tx and Rx in MIMO radios may degrade system performance
MIMO System Transfer Matrix
• Received signal at receiver can be described as:
Rx1 = h11Tx1 + h12Tx2 + … + h1nTxn Rx2 = h21Tx1 + h22Tx2 + … + h2nTxn : : Rxm = hm1Tx1 + hm2Tx2 + … + hmnTxn
Transmit EVM Measurement
• Error Vector Magnitude--The vector difference between measuring waveform and ideal modulating waveform • Modulation signal can be expressed as the same phase (I) component and a orthogonal (Q) component of the vector sum
How MIMO System Works
• MIMO System Link Model
How MIMO System Works
• MIMO Transmitter
• Through different transmit antennas • Sends independent data streams பைடு நூலகம்Tx1;Tx2;…Txn] • Transmits simultaneously and using the same radio channel
Spatial diversity
• A single(unlike multiple streams in spatial multiplexing) stream is transmitted • The signal is coded using techniques called space-time coding • Improve the reliability of the channel • Reduce channel error code rate
Beam forming
• Beam forming is a signal processing technique used in sensor arrays for directional signal transmission or reception. • Beam forming techniques can be broadly divided into two categories:
• MIMO Test Requirements
• MIMO system requires higher transmitter performance • MIMO system are more sensitive to Rx impairments
• Advanced Test Instruments
MIMO-What and Why
• Apply to high throughput standard IEEE802.11n • Dramatically improve wireless network performance
• • • • • Higher data throughput(480+Mbit/s) Better quality and more reliable RF link Extended coverage Better Spectral Efficiency(bits/bandwidth) Backward compatible with 802.11 a/b/g
Transmit Power
• The maximum allowable output power of the device is the same as in legacy 802.11a or 802.11g transmitter.
• If more than one transmit chain is used, the total power in all transmit chains shall be equal to the total power possible for a legacy 802.11a/g transmitter. • If a 40MHz channel is used, the total transmitted power in the 40MHz bandwidth shall be equal to the total trans mitted power allowed for a legacy 802.11a transmitter in a 20MHz channel.
• A high rate signal is split into multi lower rate streams • Each stream is transmitted from a different transmit antenna in the same frequency channel • Increase channel capacity at higher SNR • Spatial multiplexing systems can be divided into three kinds of models: D-BLAST, V-BLAST, T-BLAST.
• MIMO Receiver
• Through different receive antennas • Received signal represented by [Rx1;Rx2;…Rxm] • Each receives the composite signal from all transmitters
Spatial multiplexing
• D-BLAST(Diagonally-BLAST)
• Each sub stream independent encode • Each sub stream not correspond to a transmit antenna, and the corresponding relationship will be cyclically changed
• Advanced digital signal processing • Low instrument phase noise • Wide signal/modulation bandwidth
MIMO Test Item
• • • • • • • • • • • • Transmit Power Transmit EVM Tolerance Transmit Spectrum Mask Spectral Flatness Transmit Center Frequency Tolerance Transmit Symbol Clock Tolerance Transmit Carrier Frequency Transmit Carrier Leakage Transmit Channel Isolation Transmit IQ Imbalance Receive Channel Isolation Receiver Sensitivity
MIMO-What and Why
• Theoretical capacity and antenna number relations
• Transmit(receiving) antenna is fixed (=4), SNR is unchanged; the channel capacity will increase while the number of receiving(transmit) antennas increase, but the increasing more and more small • When the number of transmit antenna and receiving antenna is same(=4), SNR increases, channel capacity will increase • When the number of transmit antenna is more than 10 receiving antenna , channel capacity is basically not much change
• Transmitted data stream can be reconstructed as
[Tx] = [H]-1 [Rx]
MIMO Technology
• Spatial multiplexing • Spatial diversity • Beam forming
Spatial multiplexing