MSR: Generating a Library Waveform

A Library Waveform is an enhanced carrier type specifically designed for multi-standard radio (MSR). The Waveform Library allows you to manage imported waveforms with resampling and filtering already applied. This enables faster summing of carriers when you change offset frequency or power by eliminating redundant resampling and filtering processes.

The initial process for library waveforms is the same as described in the MSR: Generating a Waveform topic and is repeated here for your convenience. This process enables you to generate library waveforms using exported waveforms. Refer to the MSR: Using the Waveform Library Manager.

If desired, you can use Imported Waveforms in combination with your Library Waveforms in the Waveform Setup node, but there will be an increase in the time required to generate the waveform. To avoid longer waveform generation times, add any additional Imported Waveforms to the Waveform Library folder using the

Tools dropdown before generating your waveforms in the Waveform Setup node.

Below is a list of the Signal Studio waveforms that can be imported into the MSR feature for LTE/LTE-Advanced TDD signals.

N7600C Signal Studio for W-CDMA/HSPA+
N7601C Signal Studio for cdma2000/1xEV-DO
N7602C Signal Studio for GSM/EDGE/Evo
N7612C Signal Studio for TD-SCDMA/HSDPA
N7617C Signal Studio for WLAN^a
N7624C Signal Studio for LTE/LTE-Advanced FDD (non-MSR waveforms)^b
N7625C Signal Studio for LTE/LTE-Advanced TDD (non-MSR waveforms)^b
N7626C Signal Studio for V2X (non-MSR waveforms)^b
N7631C Signal Studio for 5G NR

Supports high-resolution waveform export, providing better signal quality in the resulting MSR waveform.
Supports high-resolution waveform import and export, providing better signal quality in the resulting MSR waveform.

You cannot recursively import waveforms. That is, an MSR waveform cannot be used as a component waveform in a new MSR waveform. In this case, an error message appears in the status area.

Using the Waveform Library and Library Waveforms:

Before using library waveforms you must first import a waveform into the Waveform Library Folder from your exported waveforms folder. Refer to the procedure below.

To minimize the waveform generation time, all the Library Waveforms selected to be generated simultaneously should have common sampling ratios. Typically, 30.72 MHz or 61.44 MHz works well. An oversampling rate of 61.44 MHz works best when Frequency Offset values other than 0 are used. To do this, use the Waveform Manager to import your waveforms and select a common sampling rate that corresponds to the different waveforms that are to be generated together in the Waveform Setup node.

Requirements

Licensing

Library waveforms that are used for the multi-standard radio (MSR) capability must have proper Signal Studio licensing. The MSR waveform comprises all the license requirements for each of the component waveform-types used.

The maximum number of component waveforms that can be imported into an MSR composite waveform are limited by the number of unique licenses required to generate the MSR waveform. For example:

LTE FDD waveform + V2X waveform + 5GNR waveform = 3 waveform licenses

Typically, up to approximately 11 waveforms can be used in a MSR waveform. If the number of waveforms exceeds the MSR feature's limits, an error message will be displayed.

Connectivity

To use the MSR feature, you must have the correct waveform options and the correct instrument connectivity.

For additional hardware requirements, refer to the "Hardware and System Requirements for Multi-Standard Radio (MSR)" in the System Requirements.

Memory

Each waveform sample point requires about 25 bytes of hard drive space, so a 1 GSa waveform requires 25 GB of available drive space.

MSR and Library Waveform Generation Procedure

If you want to use high-resolution component waveforms to generate an MSR waveform, refer to MSR: Using High-Resolution Waveforms first.

Using the N7600C, N7601C, N7602C, N7612C, N7617C, N7624C, N7625C, N7626C, or N7631C software, export each of the required component waveforms using the exported waveform settings below. Refer to your component waveform's help for more information.

Waveform Type	Waveform Length (Recommended) ^{a, c} (N = integer)	Oversampling Rate (OSR) – (Recommended) ^{b, d}	Notes ^h
N7600C W-CDMA/ HSPA+	10 msec * N repetitions (Basic) Number of msec or Number of frames * N repetitions (Advanced)	8x or AUTO (Basic) AUTO (Advanced Single Carrier)	Avoid exporting the PRACH and CELL_FACH carriers. Avoid exporting multicarrier waveforms. Instead, export the Advanced carriers individually and then import the single carriers using the N7625C, to create a multicarrier waveform.
N7601C cdma2000/ 1xEV-DO	26.6666 msec * N repetitions (Basic C2K and 1xEV-DO)	25x or AUTO (Basic)	Advanced 1xEV-DO is not recommended (240 msec x N repetitions). Avoid using 26.6666 msec * 4 repetitions. Avoid exporting multicarrier waveforms. Instead, export the Advanced carriers individually and then import the single carriers using the N7625C, to create a multicarrier waveform.
N7602C GSM/EDGE/ Evo	60 msec * N repetitions (Basic and Advanced)	128x or AUTO (Basic) AUTO (Advanced Single Carrier)	Default or integer multiple of 13 frames (60 msec) is required to import basic carrier waveform file. Avoid exporting the Control channel carrier. Avoid exporting older default GSM/EDGE 4 frame waveforms (≤ v2.x). Avoid exporting multicarrier waveforms. Instead, export the Advanced carriers individually and then import the single carriers using the N7625C, to create a multicarrier waveform.
N7612C TD-SCDMA/ HSDPA	5 msec * N repetitions	24 is recommended (1.28 * 24 = 30.72)	Default or integer multiple of 5 ms is required to import basic carrier waveform file.
N7617C WLAN	10 msec * N repetitions	Set the Oversampling Ratio (located under Waveform Setup) to adjust the ARB Sample Clock value so it is close to an integer multiple of 30.72 Msps (LTE/LTE-Advanced TDD software's base sample rate). This improves waveform quality.	Waveform signal length needs to be integer multiple of 10 msec by adjusting parameters “Idle Interval” and “# of frames" when generating from N7617B. (RF burst + idle interval) x (# of frame) = waveform signal length. Note: “waveform signal length” needs to be integer multiple of 10 msec (in actual time length). “RF burst” length changes by various WLAN parameters including bandwidth. Waveform signal length (in “actual time length”) = (total sample points) / (ARB sample clock) Note: ARB sample clock is affected by bandwidth.
N7624C LTE/LTE-Advanced FDD	For N7624C waveforms: non-MSR (external) waveform files can be imported.	Set the Oversampling Ratio (located under Waveform Setup > Carrier n) to adjust the Waveform Sampling Ratio so it is an integer multiple of 30.72 Msps (LTE/LTE-Advanced TDD software's base sample rate). This is required for the waveform data to be imported into MSR and improves waveform quality. The Waveform Sampling Ratio updates after each waveform generation to show the actual value, so you can use that to fine tune.	To prevent recursive imports, no external MSR files of any type, can be imported.
N7625C LTE/LTE-Advanced TDD	For N7625C waveforms: non-MSR (external) waveform files can be imported.	Set the Oversampling Ratio (located under Waveform Setup > Carrier n) to adjust the Waveform Sampling Ratio so it is an integer multiple of 30.72 Msps (LTE/LTE-Advanced TDD software's base sample rate). This is required for the waveform data to be imported into MSR and improves waveform quality. The Waveform Sampling Ratio updates after each waveform generation to show the actual value, so you can use that to fine tune.	To prevent recursive imports, no external MSR files of any type, can be imported.
N7626C V2X	For N7626C waveforms: non-MSR (external) waveform files can be imported.	Set the Oversampling Ratio (located under Waveform Setup > Carrier n) to adjust the Waveform Sampling Ratio so it is an integer multiple of 30.72 Msps (LTE/LTE-Advanced TDD software's base sample rate). This is required for the waveform data to be imported into MSR and improves waveform quality. The Waveform Sampling Ratio updates after each waveform generation to show the actual value, so you can use that to fine tune.	To prevent recursive imports, no external MSR files of any type, can be imported.
N7631C 5G NR	No recommended setting.	No recommended setting.

ARB Sample Clock ≥ 100 MHz can be used, but performance may be degraded. The ARB Sample Clock parameter is displayed under the Instrument node. It is automatically calculated by the software based on the signal generator's ARB Sample Clock settings. The ARB Sample Clock should be < 100 MHz. If a Frequency Offset is applied to a waveform, the settings should be compatible with the ARB Sample Clock settings on the signal generator.
Higher OSR values will degrade performance once the waveforms are imported into the N7625C's MSR waveform. For Advanced N7600C or N7601C carriers, OSR's = 1 are not recommended while Signal Studio is in Simulation Mode (e.g. use AUTO).
The waveform length is dependent on the resampling ratio:
- The source waveform clock > baseband sampling clock; source waveform will be decimated. This is typically not desirable, but will decrease waveform size.
- The source waveform clock < baseband sampling clock; source waveform will be oversampled. This is typically acceptable, but will increase waveform size.
- Waveform quality will always degrade on resampling.
The MSR waveform requirements (source wavelength * baseband sampling clock) should be ≥ 1024 sample points and ≤ 1024e6 sample points.
For all of the component waveforms, set the Frequency Offset to 0. Frequency Offset can be set in the N7625C software, after importing all of the waveforms.
For the N7600C, N7601C, N7602C, N7612C, N7624C and N7625C software, to better understand the carrier power level calculations for an exported waveform, refer to Output Power Calculation (Downlink) and Output Power Calculation (Uplink).
Size of exported file must be ≤ 1024 Msa. If the waveforms exceed the maximum allowable, the System Message window is displayed.
There are three different descriptions for the various waveform setups:
- The recommended waveform settings yield the best overall performance with the MSR feature (i.e. faster waveform loading times, minimal intermodulation products, and minimal EVM).
- The waveform settings that are not recommended will work, but with reduced waveform performance (i.e. increased waveform loading times, increased intermodulation products, and degraded EVM).
- The waveform settings that are to be avoided may not work as desired or have some other unpredictable behavior.
The maximum number of component waveforms that can be imported into an MSR composite waveform are limited by the number of unique licenses required to generate the MSR waveform. For example:

LTE FDD waveform + V2X waveform + 5GNR waveform = 3 waveform licenses

Typically, up to approximately 11 waveforms can be used in a MSR waveform. If the number of waveforms exceeds the MSR feature's limits, an error message will be displayed.

Library Manager: After your waveforms have been exported to your waveforms folder using the settings in step 1 above, use the Library Manager to import and save your exported waveforms as Library Waveforms. Importing and saving your waveforms to the Waveform Library folder as Library Waveforms enables faster waveform generation. Waveforms that are imported into the Waveform Library Manager should meet the criteria in the table below.

For information on how to import a waveform and save it to the Library Folder as a Library Waveform, refer to the MSR: Using the Waveform Library Manager topic.

MSR Waveform Setting Levels	Baseband Sampling Rate ^{a, b}	Frequency Offset ^a	Power (Offset)	Notes
Recommended	AUTO, 61.44 MHz	as required	as required	Where the Frequency Offset = 0, a Baseband Sampling Rate of 30.72 MHz can be used to decrease waveform build time.
Allowable	184.32 MHz	as required	as required	Possible degradation in waveform generation time and in waveform performance quality.

After importing the waveforms into the MSR waveform, the default Baseband Sampling Rate is set to 61.44 MHz. This value is required for non-zero Frequency Offsets and optional for 0 Hz Frequency Offsets. If the Frequency Offset is set to 0 Hz in the N7625C, the Baseband Sampling Rate can be set to 30.72 MHz and the waveform build-time will be faster. The Baseband Sampling Rate of 184.32 MHz can be used, but the waveform's performance may be degraded. The Baseband Sampling Rate = (chip rate * oversampling ratio). For best results, the Baseband Sampling Rate should be < 100 MHz.
To avoid degradation of the signal, in the N7625C software, do not use the default oversampling rate of 1 with MSR waveforms. For best results, use AUTO for the OSR value.
The MSR waveform requirements (source wavelength * baseband sampling clock) should be ≥ 1024 sample points and ≤ 1024e6 sample points.

Library Waveforms: After your Library Waveform files have been imported to the Waveform Library Folder, click the Add to Signal Studio as a new carrier button to select Library Waveform:

Steps a through d (below) only work if you have previously stored Library Waveforms to your Waveform Library folder. Refer to the MSR: Using the Waveform Library Manager topic.
1. Click Add Carrier to open a Library Waveform.
2. Click Waveform Setup > Carrier n > Source Waveform Name.
3. When the Selects Source Waveform window opens, open the Waveform Library folder where your waveforms are located and click on the desired Library waveform.
4. Click OK to add the waveform to your Waveform Setup node.
5. To add additional Library Waveforms with different resample targets (sampling ratios) and Filter Ratios, repeat steps a through d.
6. Signal Studio: If necessary, in the Carrier n node, click to change the following:
7. Repeat step f for all of your Carriers. Otherwise, continue to next step.
8. Click Generate Waveform.
9. If you are satisfied with your Library Waveform's configuration and the resulting MSR waveform, proceed to step 4. Otherwise, continue to next step.
10. For best results, if you need to make changes to the Filter Ratio or the Resample Target for the Library values, use the Library Manager and the Resample... button.
  
  When you open a Library Waveform and click the Resample... button to modify the Filter Ratio or Resample Target values, any resample values that were previously selected for the Library Waveform are grayed out (inactive), as shown here in the Resample Waveform window. These previously selected values have already been resampled and are saved to your Waveform Library folder or subfolders. They do not need to be resampled. The Import Waveform window displays this same information.
  
  Changing your waveform's Baseband Sampling Rate, Timing Offset, Power, Initial Phase, and Filter Ratio parameters outside of the Library Manager may potentially increase your waveform generation times.
  1. Optionally, in the Signal Studio's Carrier n node, click Baseband Sampling Rate, Frequency Offset, Power, Timing Offset, Initial Phase, or Filter Ratio to change these parameters.
  2. Click Generate Waveform to update your system to the new settings. Refer to step 4 for waveform output examples.
11. To make additional changes to your waveforms, repeat step j as necessary.
Signal Studio: After all of the component waveform files have been imported, generate and download the waveform by choosing the correct file path for the MSR waveform file. The new multicarrier waveform comprises all the license requirements for each of the component waveform types used. Here is an example of an MSR waveform with five component carriers.
In the MSR composite waveform, the waveforms that have narrower bands — like CW and EDGE waveforms — are displayed with higher power levels. This is because the waveforms' power is defined by its integrated power and not by its power spectral density (PSD).
To minimize spurious images, optimize the channel waveform filtering and frequency offsets for the imported component waveforms. Refer to MSR: Applying a Waveform Channel Filter.