W1716 SystemVue Digital Pre-Distortion Builder

• Advanced 4G-ready algorithms for both PA modeling and pre-distortion
• Quickly assess 3G components for reuse in 4G systems with real 4G test vectors, without committing to a vendor-specific hardware implementation
• Step-by-step GUI wizard for easy set-up, extraction, and validation 
• Links to the latest wideband test equipment (up to 250MHz), as well as simulators, such as Agilent ADS
• Accommodates proprietary DPD models, extraction IP, test vectors, and allows creation of a custom GUI

The W1716 Digital Pre-Distortion (DPD) Builder quickly models and corrects common sources of 4G memory effects in both low and high-power PA’s, as well as transceiver IC’s. It contains several sophisticated capabilities rolled into a single, easy, wizard-based UI. System architects and RF component designers can use the W1716 to quickly assess and improve link-level performance, partitioning, and component selection. Baseband. RF architects and RF component designers can also use the W1716 to accelerate the actual implementation of linearization networks.

The W1716 DPD Builder is an add-on personality to the base W1461 SystemVue core environment.

Read: Practical Digital Pre-Distortion Techniques for PA Linearization in 3GPP LTE

Watch: Wideband DPD Using Agilent SystemVue and Agilent PXI Modular Hardware 

Webcast: Watch our September 1, 2011 webinar

The W1716 DPD Builder is highlighted in these Agilent app notes: 5990-6534EN, 5990-6742EN, 5990-7818EN, and 5990-8883EN.

How it works – Years of research, now minutes on the bench

The DPD process is simple, and only takes minutes. First, the W1716 DPD wizard downloads 4G waveform or user defined waveforms to an Agilent signal generator to stimulate a real device. The distorted output carrier response is captured into SystemVue using an Agilent VSA. The W1716 DPD Builder then compares the output waveform to an undistorted passthrough waveform, and extracts a nonlinear memory polynomial model. From the extracted model, the W1716 automatically creates a digital pre-distortion network.

The DPD network minimizes adjacent-channel spectral regrowth for that device by over 20dB (observed to date, varies by amplifier), extending the cellular range of the device, allowing it to run at full efficiency, prolonging battery life, and increasing system throughput. The W1716 commercializes and streamlines a linearization solution for a topic that has been the subject of many research, application notes, and homemade solutions. The resulting DPD network can be further used in link-level simulations, implemented using SystemVue’s paths to hardware, or exported to a corporate design flow for implementation.

Fast and Practical DPD for 4G

Unlike proprietary DPD solutions, the Agilent W1716 DPD utility is vendor-neutral, technology-independent, and also provides realistic LTE coded source generation, ready for download to a signal generator. It goes beyond 3G linearization algorithms in its ability to correct for wider bandwidths, higher dynamic range, and a variety of amplifier topologies. Part of this is made possible with a configurable Crest-Factor Reduction (CFR) algorithm, which intelligently shapes the signal itself to be more correctible, with minimized impact on final EVM. SystemVue capabilities for simulating modulated carriers with RF effects, built-in links to instruments for verification, and easily-scriptable environment help make this DPD personality an essential addition to the LTE architect’s toolset.

Memory Effect Model Supplements Analog X-parameters*

After extraction, both the corrected and uncorrected, nonlinear amplifier models remain available as simulation blocks to include in link-level studies using SystemVue. This complements other system-level component representations, such as analog X-parameters.

X-parameters provide RF power amplifier designers with a general-purpose, transportable analog model that predicts voltages, currents, harmonics, and frequency- and load-dependence. To contrast, the W1716 DPD Builder produces a native dataflow model that runs directly at the system-level for link-level coded PHY simulations with no additional modeling steps. The DPD dataflow model demonstrates memory effects, power dependence, and runs typically 1000x faster than an analog co-simulation without requiring access to RF circuit tools. In return for this speed advantage at the system-level, the DPD dataflow model discards lower-level analog details, and is valid over a narrower range of signal conditions and applications.

Since both of these new nonlinear component representations meet different design flow and application needs, Agilent SystemVue supports them both. For X-parameter support in SystemVue, refer to the W1719 RF System Design Kit.

Who should use Agilent’s DPD module?

• System architects use the W1716 DPD Builder to quickly assess the suitability of an uncorrected Analog/RF part for use in a particular 4G application, possibly extending the life an existing 3G design at lower cost.
• RF component designers and baseband architects can use the W1716 DPD Builder to correct common sources of memory effects in both low and high-power PA’s, as well as transceiver ICs.
• Both Wireless and Aerospace/Defense applications will benefit from the W1716 DPD Builder. Although the W1716 is targeted primarily at 3G vendors transitioning to 4G, its flexibility to use custom test vectors permits a broader appeal to other applications, such as military communications and radar.

Configuration

SystemVue Environment. W1716 DPD builder can be added to any SystemVue 2010 environment

• W1461 SystemVue Comms Architect
• W1462 SystemVue FPGA Architect
• W1464 SystemVue RF Architect
• W1465 SystemVue System Architect

Standards Libraries. The W1716 DPD builder allows users to define their own test vectors, and does not require additional libraries. However, the W1716 is most often used with the appropriate standards-based library, because of the convenient level of integration, as well as control of Crest Factor Reduction, Resource Block allocations, and oversampling. Of all the SystemVue libraries quoted with the W1716 DPD builder, these 3 are the most popular.

• W1910 LTE Baseband Verification Library
• W1917 WLAN Baseband Verification Library (includes 802.11ac)
• W1918 LTE-Advanced Baseband Verification Library

Test Equipment. The following hardware configurations are recommended most often with the W1716 DPD builder. (Refer to the configuration table in application note 5990-8883EN for more details):

• Up to 100 MHz bandwidth:
  - N5182A MXG signal generator, with internal baseband generator
  - N9030A PXA signal analyzer
  - 89601B VSA software, with Options 105, 300
• Up to 250 MHz bandwidth:
  - M9330A PXI arbitrary waveform generator
  - N5182A MXG or E8267D PSG signal generator
  - M9392A PXI Microwave vector signal analyzer
  - 89601B VSA software, with Options 105, 300

Follow the link below to view all SystemVue configurations:

• SystemVue Product Structure & Options Summary

* "X-parameters" is a trademark of Agilent Technologies, Inc. The X-parameter format and underlying equations are open and documented. For more information click here.