Create a Waveform with 2x2 MIMO (Matrix B) for DL-PUSC

This example shows how to create waveforms for the 2x2 MIMO Matrix B system (as shown below) with two DL PUSC zones. It assumes that you know the frame structure, zones, and bursts that you want to set up, and is a "tops down” approach. Two bursts are created within the DL PUSC zone, each with a different modulation type for demonstration purposes. You might use this type of setup for receiver test.

1. Set up the PC and the instruments as shown in Multiple Antennae Solution without Baseband Timing Alignment and RF Phase Coherency.

2. From the Quick Setups, select Mx2 (Multiple Antennae Simulated Hardware).

3. Click the two instruments under Hardware in the tree view to set up the frequency and amplitude for the instruments. The setting should be the same for both of them. See Power Setting for more details.

4. Click Waveform Setup in the tree view. This section of the table contains the key system parameters. These parameters include the number of frames to build in the waveform, the output mode, and downlink ratio. The default settings are used for this exercise. 

5. Click Carrier 1 in tree view.

   1. Reference Specification: Use the default of 802.16e-2005 for this example. However, flexibility is provided to select either 802.16-2004/Cor1/D2 or 802.16-2004/Cor1/D3 depending on which standard specifications you want to use for subchannel randomization and subcarrier allocation.

   2. Bandwidth: Use the default 10 MHz.

   3. FFT Size: Use the default 1024.

   Hint: Click the frame tab in the lower portion of the window to display the frame plot view. A small yellow triangle at the bottom of the graph indicates the division between the downlink and uplink. The available subframe time determines how many symbols can be put into the subframe (see example.) Note that when the output mode is Downlink Only (TDD), the RF burst off time will include any unused frame time, shown as a gap (TTG), plus the uplink portion (grayed out) of the TDD frame.

   Refer to section 8.4.2.3 of the 802.16-2004 standard for parameter definitions.

   For a 10 MHz BW:

   • Sampling frequency: Fs = 11.424 MHz

   • Subcarrier spacing: 11.15625 kHz

   • Useful symbol time: 0.0896 ms

   • For G=1/8, CP time: 0.0112 ms

   • OFDMA symbol time: 0.1008 ms

   With a frame length of 5 ms and a 50% downlink ratio selected, there is 2.5 ms available or 24 symbols maximum.

6. Click Downlink in the tree view. The lower half of this window allows you to add, delete, or copy PUSC, FUSC or AMC zones. Note that there are two PUSC zones under the downlink node by default.

   Hint: You can delete an unwanted zone by clicking in the first column and then clicking Delete. However, Zone#1,PUSC is the default zone and cannot be deleted or re-ordered.

7. Click Zone#1, PUSC in the tree view. Note the additional zone view to the right of the frame plot. The Zone Setting window displayed in the parameter view lists parameters specific to this zone. Zone boosting is used to increase the power in the DL PUSC zone when not all subchannels are in use. The zone boosting factor is calculated by the software and cannot be changed. Use default values for this example.

   1. First PUSC Zone Setting: You can choose whether to automatically generate an FCH, DL-MAP, or UL-MAP which is always at the start of the first zone when present. Leave Auto FCH on and Auto UL-MAP off for this example. Turn on the Auto DL-MAP since a normal DL signal would contain a DL-MAP.

   2. The bottom half of the screen allows you to add bursts to this zone. One regular burst is present by default. Click to add second regular burst. The white fields in the table can be edited directly, while the gray fields cannot be changed here (true in general for similar tables in this software).

8. Click Zone#2, PUSC in the tree view. Set the STC Type to Matrix B.

   In keeping with the standard, the first DL-PUSC zone can not be set for STC.

9. Click Carrier 1 in tree view.

   1. Notice that the Number of BS Antennae is 2 and the Number of MS Antennae is 2, because you have chosen Matrix B as the STC type under the second PUSC zone.

   2. Channel State:  

      1. Turn channel fading on if you want to create waveform that would be received by the receiver antennae. Then you can specify the fading channel parameters, which represent the condition between the combination of the two base station antennas and the two subscriber station antennas in a 2x2 MIMO configuration.

      2. Turn channel fading off if you want to create waveforms that correspond to the transmitted signal from the two base station antennas.

10. Click Check Parameters to verify all parameters are okay. View the result in the Status window at the bottom of the main window.

11. Click on Waveform Setup in the tree view to view the CCDF, Waveform, or Power Envelope graphs at the bottom of the page if desired.

12. Click Generate to generate waveform.

13. Click Download to download waveforms to the instruments if you have configured the instrument connection.

    When channel fading is off, the waveform for the transmitter antenna 0 will be downloaded to the master instrument and the waveform for the transmitter antenna 1 will be downloaded to the slave instrument.

    When channel fading is on, the waveform for the receiver antenna 0 will be downloaded to the master instrument and the waveform for the receiver antenna 1 will be downloaded to the slave instrument.