Physical Mode: Basic Downlink Setup

This example shows how to configure and download a basic downlink waveform to the signal generator using Physical as the frame setup mode.

Step 1: Select a Quick Setup

Step 2: Configure the Project Property Parameters

Step 3: Configure the Signal Generator Settings

Step 4: Configure the Downlink Frame Structure

Step 5: Generate and Download the Waveform

Step 1: Select a Quick Setup

1. Click Quick Setup in the tree view. Click the 802.16-2004 (WiMAX) button in the right pane to access the main window.

   

2. Notice that Project is highlighted and the parameter view displays three panes: Project Property, Projected Waveform, and Signal Generator Settings.

Step 2: Configure the Project Property Parameters

1. In the Project Setup table:

2. Change the default Project Name (Untitled) to a unique name of eight characters or less. You may also enter a Project Comment to describe the waveform.

2. Use the WiMAX Basic Parameters table to edit waveform generation parameters. Set up a waveform with the following characteristics:

• Bandwidth: 5 MHz

• G: 1/4 (G is the ratio of the cyclic prefix or guard interval time to the useful signal time.)

• Frame Duration: 2.5 ms

• Optimize for: ACPR (adjacent channel power ratio)

3. Select Physical for the frame setup mode in the WiMAX Operation Set Up pane.

4. In the WiMAX Signal Configuration table:

• Leave the default settings for MARKER1-4: Frame Start, None, Burst Envelope, and ALC Hold, respectively.

5. Observe the waveform's length characteristics in the Projected Waveform pane. The Data Points cell is calculated as follows: [Data Points] = [Sampling Clock] * [Frame Duration] * [Built Frames].

Step 3: Configure the Signal Generator Settings

1. Configure the signal generator's frequency, amplitude, and arbitrary waveform playback parameters in the Signal Generator Settings pane. Set Frequency to 3.5 GHz and Amplitude to –10 dBm.

The signal generator's amplitude setting refers to the average power level of the FCH/Bursts, as indicated by Amplitude Reference. The preamble power level is defined in the standard to be 3 dB higher than the level of the rest of the burst, so it will always be 3 dB higher than the amplitude setting of the signal generator. If you create a waveform that only has a preamble, select Preamble as the Amplitude Reference.

2. The sampling clock frequency for the signal generator is automatically calculated as [Sampling Clock] = floor(n * Bandwidth / 8000) * 8000 *OSR. This is the same as the “sampling frequency” defined in the IEEE 802.16-2004 standard.

Step 4: Configure the Downlink Frame Structure

1. Click Physical in the tree view. This displays the frame structure in the right pane, with the downlink subframe on the top half and the uplink subframe on the bottom half.

2. Click the Add Preamble button.

3. Click the buttons, Add FCH, Add Burst (three times), and Add Gap in the right pane to add an FCH, three bursts and a gap with their respective default values. Notice that the new FCH and burst frame components are added to the table and the tree view. The gap (also referred to as the transmit/receive transition gap or TTG) allows the base station time to change from transmit to receive mode.

4. Click Frame in the tool bar to display a plot of the frame layout with the new FCH and bursts. Clicking Frame again will hide the plot.

5. Edit the burst parameters. Double-click in the first column in the table for the item, or click on the item in the tree view on the left. A window appears that shows parameters specific to the selected burst type. Change the parameters as follows:

   Deleting and Moving Components

   To delete a particular frame component, click anywhere in the row of that item and then click Delete.

   To change the order of the frame components, click anywhere in the row of that item and use the up or down arrow to move it higher or lower in the table.

• For DL Burst#2, change the OFDM Symbol Length to 10.

• For DL Burst#3, change the Modulation Type to 16QAM and the OFDM Symbol Length to 10.

• For DL Burst#4, change the Modulation Type to 64QAM and the OFDM Symbol Length to 10.

• Click Physical in the tree view to return to a view of the overall frame.

  

6. Click the Check Parameters button in the tool bar to verify that the configured bursts do not exceed the length of the defined frame. If the configuration is valid, a result message "Parameters are fine" will be shown in the status bar at the bottom of the window. If not, a message "Defined frame exceeds the maximum frame length" appears.

Step 5: Generate and Download the Waveform

1. From the tool bar, click Generate. The software generates an I/Q waveform file in accordance with the current physical channel configuration and waveform generation setup. Waveform generation time varies proportionally with the complexity and length of the waveform. Messages showing the waveform generation progress and status are displayed in the status bar.

2. From the tool bar, click CCDFs to toggle the graph view on and off. The graph view enables you to examine waveform characteristics, such as baseband spectrum, I and Q signals, and CCDF curves, prior to downloading the file to the signal generator.

3. From the tool bar, click Download to generate and download the waveform to the signal generator. The waveform file automatically begins to play. You can re-enable local control of the signal generator by pressing the Local hardkey, enabling you to modify signal generator settings from the front panel. The waveform file cannot be modified after downloading it to the signal generator. However, the carrier frequency and amplitude can be changed.

You can use the 89601A software (version 5.3) with Option B7S (802.16 Modulation Analysis) to view the waveform on a signal analyzer such as the E4406A (VSA) or others in the PSA family.

Related Topics

Using the MAC Editor

Frame Plot View

Graph View

DLFP Editor

Related Websites

IEEE 802-16-2004 standard
ESG product information
PSG product information
MXG product information
Agilent Signal Studio software