Agilent Technologies' New LTE Applications Target 4G System-Level Designers

While 4G networks promise dramatic improvements in data throughput and spectral efficiency, the complexity of the evolving 3GPP LTE standard has forced many system architects to reconsider their use of general-purpose toolsets. By cutting across a variety of domains (such as signal processing and mathematics, baseband hardware design, RF/analog design and measurements), Agilent's new 4G products are able to provide system architects with the focused application support for LTE v.8.9.0 that they demand. Agilent's 4G products streamline verification and bring measurement-level realism into the creative process. The result is higher-performance Layer 1 architectures and algorithms resulting in earlier design maturity and the need for less design margin.

The four new products introduced by Agilent at Mobile World Congress 2010 include:

W1715 MIMO Channel Builder:

The W1715 MIMO Channel Builder is a simulation blockset for LTE architecture and receiver designers, based on the WINNER and WINNER-II fading algorithms. By incorporating non-ideal MIMO antenna performance (e.g., crosstalk and directionality), the W1715 goes beyond these standard propagation models. It enables 2D far-field data to be imported from antenna measurements or 3D EM simulations, including Agilent EM PRO. Realistic antenna degradations allow accurate assessments of link-level LTE architectures and receiver algorithms to be made at a very early stage, before prototypes have been committed for the mechanical, RF/antenna, or baseband/DSP designs. Previously, interactions between these domains required a fully operational hardware radio and came much later in the design process, possibly during drive test. The W1715 brings some of this drive-test realism into the algorithm phase of the design, accelerating design maturity and performance.

The W1715 also follows the design into hardware test. The same Agilent SystemVue simulation modules are used to generate test vectors for download into multi-channel Agilent signal generators (e.g., the N5106A PXB) or interoperate with the 89601 VSA software. The W1715 offers an economical alternative to real-time hardware faders, since SystemVue can be shared on a computer network and used throughout the design process by distributed teams. Agilent's integration of design and test platforms across the LTE design cycle maximizes re-use of assets, minimizes engineering effort, and produces consistent results.

W1716 Digital Pre-Distortion (DPD) Software

The W1716 Digital Pre-Distortion builder helps LTE system integrators, RF component designers, and baseband architects quickly transition from 3G to 4G by creating baseband signal processing networks that improve the range of analog power amplifiers and transceiver ICs, improve efficiency, and extend battery life. The W1716 also quickly assesses the suitability of existing 3G designs for 4G applications. Such capabilities translate into savings for both design effort and component cost.

The W1716 consists of a wizard-based UI that automatically models and corrects common sources of memory effects, in-band EVM degradation and adjacent-channel power re-growth. The software controls signal generators and analyzers to characterize the component response to a configurable LTE signal. The W1716 produces two networks: an impaired dataflow simulation model to use at the link level, and a baseband pre-distortion network to correct for those impairments. After extraction, the W1716 completes a report documenting the actual DPD improvement it achieved, using authentic LTE v.8.9.0 waveforms, or any user-defined waveform that can be made with SystemVue.

We identified a gap between today's proprietary 3G DPD solutions and the market's need for an inexpensive, open, technology-neutral platform for 4G, said Jian Yang, ESL integrating manager at Agilent Technologies. The new W1716 software addresses this gap. It is producing 20-dB ACP improvements on the bench, on real LTE waveforms. What used to take months in a high-end lab now takes minutes, thanks to this new technology and guided UI.

W1910/2 LTE Baseband Verification Library Reference Blockset

Agilent's W1910 LTE Baseband Verification Library reference blockset has been updated to LTE v.8.9.0 and now includes expanded PRACH and HARQ support. The HARQ simulation support uses a unique dynamic dataflow simulation mode. This mode allows the symbol rate to change dynamically over the course of the simulation while retaining the timing and carrier information necessary for full RF effects, frequency-dependent phase noise, and channel fading. This capability reduces LTE simulations to minutes or hours for meaningful throughput, and BLER and EVM compliance measurements. Additionally, the updated W1910 keeps pace with changes to the Agilent Signal Studio and VSA software to maintain interoperability with Agilent measurement solutions.

We used Agilent's SystemVue LTE baseband verification library to validate Xilinx's LTE reference IP against the latest version of the LTE standard, said Bill Wilkie, wireless and signal processing director for Xilinx in Europe. When combined with Agilent's N5106A PXB, SystemVue not only saved us weeks of validation time, but also it gave us confidence that our LTE Layer 1 reference design was 'production ready' for our customers. SystemVue clearly added value to our traditional Layer 1 design and verification process. As a result, we will be using SystemVue more in the future.

The W1912 LTE Baseband Exploration Library is a C++ source code version of the W1910 and has also been updated. The W1912 allows deeper algorithmic insights, control, line-by-line software debugging, and precise test vector generation from inside the algorithms of a working LTE v.8.9.0 physical layer.