Research and Development

Aperio signals has a few different models semi-automatic SCSAS that can collect and analyse 2G, 4G and 5G OTA signals shown on system block diagram.
Our R&D is focusing on analysis automation. We will add the new functionality continously to meet the demands of wireless industry.

Below is some examples of the current SCSAS capability, and on request we would rent out IQ recorder to our clients and provide specalist services to streamline their engineering efforts and realise their innovative and advanced products smoothly and always be competetive in the world telecomm market.

RF signal visualisation

SCSAS provides the real-time visualisation capability of wireless RF signal, over the air or through RF cable in time domain and frequency domain, in order to reveal the fine details of the signal under concern. Here are the examples of the brief forms with basic identification and nature of the signals in front of us. Knowing the big picture user can further find many level of details with the help of the tool. This involves full details of 3GPP specs, and our R&D effort has made invisble RF signals visible and meanful by 3GPP spec. We enhance the visualisation capbility by signal analysis just like making good lenses and setting the right aperture and exposure time for capturing quality photos. It is just more sophisticated, as it needs to be a watertight system to identify PHY error to microsecond-Hz level.
.

One can use both time and frequency domain views of the signal to identify a symbol, its CP, as well as the frame structure with various features. The one below marks out the FDD LTE secondary synchornisation signal (SSS) details in time domain (top part: IQ amplitude vs time) and frequency domain (bottom part: spectrogram). To its right is the start of PSS symbol and left the ending part of CRS symbol.

SCSAS makes it simple for our client to have initial view, from which deeper analysis can be made according to 3GPP spec, including

more lower level down to channel response, and RF charateristics;
upper level to each and every logical channel.
message level, etc.

From gapless OTA IQ trace to the LTE & GSM system basics

Identify LTE symbols, logical channels and resource elements

From the OTA gaples IQ data SCSAS goes through its signal processing details to find the LTE signal details, such as PBCH with PSS, SSS, CID, MIB, SIBs and control channels PCFICH, PHICH PDCCH, then PDSCH, the DL data channel for different users. Each logical channel is identified and color coded and displayed in the resource grids as shwn here for the case of TDD. It can reveal to a bit modulated in QPSK, 16QAM and 64QAM.

Corresponding UL IQ data in the form of SC-OFDMA for multiple users can be visualsed in the similar way. Multiple UEs UL IQ can be further analyzed, leaving nothing to uncertainty, and provide definitive answers. Our results enabled multiple teams working with their strengths and changed the situation of having great capability from many functional engineering teams, but in dealing with challenging issue in the live network no one knows where to start or what to do to resolve the critical issues. Hundreds of engineers need solid evidence to make effective and efficent actions. Technical details are the very key output from our analysis and services that meet their needs.

We cover both DL and UL for both FDD and TDD LTE signal analysis. SCSAS will be designed to give highly interactive GUI for user to drill down the issues to the root causes. In many cases user are alerted with some hard to find PHY issues. Saving experts finding needle in hay stacts.

Identify PHY aspects and issues

SCSAS collects gapless IQ for the DL and UL, then pass them in the signal process SW which goes through varieties of PHY aspects and identifies the key properties, such as Carrier Frequency Offset and timing, etc. Corrections and equalisations are applied and put signal at right condition (and identify the PHY issues if there is any). SCSAS identifies issue to the symbol level and provide the report for with detail plots, on top of which pinpoint the instances of the issues, for example, the frequency drift, as shown below: One would find all real devices would have some frequency drift like this, the important thing is thedrift is under control and with certain range as 3GPP spec defines. The plot is showing the CFO and timing on the symbol basis, and it is clear some symbols were jump out of their expected phase positions, and it is accurate to micro-seconds and sub Hz level.

The interactive view showing one of many options in dispalying the symbol-subcarrier power profiles as well on LTE resource grids. Resource element vector view based on the coresponding modulation can be shown as well.
All logical channels' details are presented.

With detailed scrutiny capability, we are not only see the details of the issues, but also distingusih best quality from good ones. This is a plateform technology excellence can be fully apperciated. We will build banchmark database to show the top five of various PHY aspects in wireless industry. We can help our client to improve and enhance their products by true full view of their products in RF domain like no others. Above is only very limited selections of views examples. Stay tuned, you will see endless details that will make a great deal of differences in future wireless industry. We are passionately working on it, and bring changes to future wireless device quality with our innovative tools.

From IQ waveforms trace to message encoding issue

In some cases the modulation waveforms of the digital radio (part of PHY layer) were fine, but there were just obvious break down somewhere on the Tx chain. Here is an example of what SCSAS could do for the situation: Two or more UEs activity were recorded from which two UEs, one DUT and one reference UE IQ data for both DL and UL can be extracted and marked for their positions in the frame structur. Detailed waveforms have shown where the start and end of the issues be comparing between them, with SCSAS accuract marks for the sophsticated lay out defined in 3GPP specs. In the report below we have further incoperated the WPA messages in lab test, showing the breakdown point in order to double check with the third party tools. It traces from IQ waveforms to the encoded messages, and uncoded messages to reveal at which stage on which message things went wrong.

This particular case involved bugs on both side of UE and BTS, and we have identified both to the very bits on each side. The issue took a few months without conclusion. With SCSAS detailed report, full picture is shown, and within a few hours the fix in software is achieved.

Unique views to baseband signals that help everyone to understand issue

Seeing is believing, and in RF area, it is more than that. We traditionally work blindly with them. There are just a few experts who are able to guess what the RF signal might be and work indirectly from the math equations and steping stones of test results. SCSAS can make whole lot of differences by actually showing the engineers the live RF signals move and traces. The appraoch is not only revealing of the black art, but also the beauty of the technology we have. Here is an example of GSM phone at its call starting point, ad justing its power as spec defined in the steps of 2dB each time.

Aperio Signals

Contact us on