Open topic with navigation

One Signal Generator Solution for MxN MIMO

This example shows you how to set up the equipment and configure the N7617C Signal Studio for WLAN 2024 Update 1.0 software to create 802.11n waveform packets for a 2xN MIMO transmitter test application using one signal generator. Although this example demonstrates 2xN MIMO transmitter test, it is easy to expand it to 3xN and 4xN MIMO by configuring the Signal Studio software.

In this example, only one signal generator (E4438C, N5182A, N5182B, N5172B) is used. The N7617C software pre-calculates the waveform packets and applies effects of specific channels, then loads the waveform packets into the signal generator one by one and applies the signal directly to the DUT's receiver inputs.

In parameter configuration windows, you can check in the upper right, and then click the desired parameter for a brief description.

  1. Connect the PC and the signal generator as shown above.

  2. Click the Quick Setup button in the tree view and double click IEEE 802.11n MxN (1 SG) in the right pane to open the parameter view main window.

  3. Click Waveform Setup in the tree view to configure waveform parameters. The Waveform Basic section contains the key system parameters.

    1. Format: Select HT for this example.

    2. Generation Mode: Select Framed for this example.

    3. Idle Interval: Use the default setting, 20 us. This parameter determines the length of the idle time between frames.

    4. Bandwidth: Use the default 20 MHz.

    5. Leave the default settings for the other parameters.

  4. Click Signal Configuration in the tree view to configure the parameters for the 802.11n PHY and MAC layers.

  5. Configure Coding and Modulation parameters.

    1. The MCS Index can be changed if desired. It determines the number of spatial streams, and the modulation type, coding rate, and data rate as shown in the MCS table. Since we have chosen the IEEE 802.11n Mx2 setup, the range of possible choices for the MCS index is 0 to 15. Use any of these values.

    2. Number of Transmit Chains: Set it to 2. This parameter determines the M value in a MxNMIMO system.

    3. Number of Space Time Streams: Use the default of 2.

    4. Number of Extension Spatial Streams: Use the default value of 0.

    5. Short Guard Interval: Set it to OFF. This sets the guard interval to 800ns.

    6. Operating Mode: Select GreenField. In GreenField mode, HT packets are transmitted without a legacy compatible part.

    7. Spatial Mapping Scheme: Use the Spatial Expansion scheme.

    8. Scrambler, Convolutional Coder, and Interleaver: Enable scrambler, convolutional coder, and interleaver so that the channel is fully coded.

  6. Configure payload data.

    1. Aggregation MPDU, You can turn A-MPDU ON or OFF. For this example, turn it off to disable multiple MPDUs in one PSDU (PHY service data unit).

    2. Data Source Type: Select PN9 sequence.

    3. Data Length (Bytes): Use the default setting, 1024 Bytes in this example.

    4. MAC Header: Disable MAC Header in this example

    5. MAC FCS: Disable MAC FCS in this example.

    6. Number of Frames: Set it to 1.

  7. Configure Impairments in Waveform by clicking Signal Configuration in the tree view. Set Channel State to OFF in this example for a 2xN MIMO transmitter test. Leave the default settings for the other parameters.

  8. Keep the default signal generator settings.

  9. Click Graph to view the CCDF curves, if desired.

  10. Click Generate to generate waveform packets.

  11. Click Download to download waveforms to the signal generator after you have configured the instrument connection.

Because this example demonstrates a 2xN MIMO transmitter test, the Signal Studio software generates and downloads two waveforms to the signal generator. If you configure the software for 3xN or 4xN MIMO transmitter test, it will generate and download 3 or 4 waveforms correspondingly.

The software will automatically add a number at the end of the waveform name. For example, if it is 4xN MIMO and you name the waveform (In Waveform Setup -> Waveform Basic -> Waveform Name) as "WLAN", the names of the four downloaded waveform in the signal generators will be "WLAN0", "WLAN1", "WLAN2" and "WLAN3".

The signal generator will automatically play the first waveform. If you want the signal generator to play the second, third, or fourth waveform, operate the signal generator from the front panel or send SCPI commands to select the waveform as follows: