Spatial Mapping Matrix (802.11n/ac/ax/be)
The property specifies the type of spatial mapping used in the signal. The spatial mapping matrix is sometimes referenced as "Q" in the IEEE Institute of Electrical and Electronics Engineers. A US-based membership organisation that includes engineers, scientists, and students in electronics and related fields. The IEEE developed the 802 series wired and wireless LAN standards. Visit the IEEE at http://www.ieee.org 802.11n/ac/ax/be standards. This group of parameters is visible when an 802.11ax/be standard (HE/EHT format) is selected, and enabled when SU Single user is set as the PPDU Format (802.11ax only).
Set the property to match the transmitter spatial mapping. The Spatial Mapping Matrix is used only for MIMO Multiple Input, Multiple Output: A physical layer (PHY) configuration in which both transmitter and receiver use multiple antennas. signals. In a single-channel measurement, the Spatial Mapping Matrix property is disabled and has no effect on the measurement.
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Select Direct Map when an Identity matrix is used by the transmitter. An Identity matrix means that 1) each space-time stream is sent to only one transmitter antenna and 2) there is no interference between the space-time streams. This is the simplest possible matrix, and is often used when testing a transmitter. |
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Select Fourier when a Fourier matrix is used by the transmitter. This matrix type mixes all space-time streams onto all select antennas, and is commonly used when deploying operational transmitters. |
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Select Automatic to cause the demodulator to detect the mapping used automatically. |
When is set incorrectly, the signal may still partially demodulate, but the sync correlation will be artificially low causing less accurate measurement results for some error data, like IQ Imbalance. In some cases, when is set incorrectly, the signal will not demodulate, indicated by the "SYNC NOT FOUND" trace indicator.
Multiple-channel Measurements
The Fourier matrix used to generate multiple-channel signals is represented by the following formula:
Fn,k = 1/sqrt(N) * exp( j * 2p * k * n )
where:
N = number of channels
Fn,k is the element of the Fourier matrix at the nth row, kth column
Examples
For a 2-channel transmitter, the Fourier matrix is:
[ k k ]
[ k -k ] where k = 1/sqrt(2)
For a 3-channel transmitter, the Fourier matrix is:
[ k k k ]
[ k -k/2+j0.5 -k/2-j0.5 ] where k = 1/sqrt(3) and j = sqrt(-1)
[ k -k/2-j0.5 k/2+j0.5 ]
For a 4-channel transmitter, the Fourier matrix is:
[ k k k k ]
[ k jk -k -jk ]
[ k -k k -k ] where k = 0.5 and j = sqrt(-1)
[ k -jk -k jk ]
See Also
