Protecting Government Wireless Systems with Interference Analysis

Protecting Government Wireless Systems with Detailed Signal Emulation and Interference Analysis

Around the world, every national government has at least one agency tasked with managing an increasingly scarce resource: the radio frequency (RF) spectrum. These agencies carry a portfolio of responsibilities that includes advising on telecommunication policy, maximizing spectrum utilization, researching new technologies, and managing government wireless systems. One such agency is focused on telecom research and engineering aimed at advancing new technologies and ensuring efficient use of the available spectrum. The breadth of its work requires interaction with other agencies, local governments, commercial entities, and international organizations. Within this mandate the agency also serves as a national resource for the investigation and analysis of potential interference issues. In 2018, agency researchers were asked to investigate signal interference and spectral coexistence related to the performance of government systems in the presence of commercial wireless signals. Much of the work was to be completed in a laboratory setting, and this suggested the use of an advanced solution for signal creation, emulation, measurement and analysis.

Company:

• Government Telecommunication Agency

Key Issues:

• Managing and protecting scarce radio frequency spectrum

• Investigating interference and coexistence related to mission critical wireless receivers

• Completing a broad research program as quickly as possible

Solutions:

• Keysight Signal Studio with real-time fading waveforms

• Keysight N5182B MXG vector signal generator

• Keysight N9030B PXA X Series signal analyzer, multi-touch

Results:

• Quickly and easily completed advanced testing and analysis of wireless receivers

• Characterized the effects of satellite transmissions on radar receivers

• Deployed multiple systems across a variety of government agencies 

The Challenge:

Protecting Mission-critical Systems The central purpose of the research project was to investigate interference that could disrupt the operation of the government’s mission-critical wireless systems. One crucial goal was to understand how these systems behave in the presence of innumerable sources of interference, ranging from commercial wireless signals to accidental spurious signals to intentional suppression signals. Given the investigative nature of the research, the team needed the ability to model a variety of highly complex signals, add common impairments, generate accurate simulations, and analyze the effects on wireless receivers. The team also had a strong sense of urgency because it had been asked to complete this broad-scale research in a timely manner. Planning ahead, they also wanted the ability to respond rapidly to any future requests to investigate new sources of interference. 

The Solution: Emulating Interferers and Analyzing the Effects

Working with the local Keysight team, the agency selected a fading-emulation solution that included simulation software, a signal generator, and a signal analyzer. The foundation for emulation was Keysight Signal Studio signal-creation software and its add-on for real-time fading waveforms.

To simulate different propagation environments, the software includes a variety of fading types: Rayleigh, Rician, Suzuki, log normal, pure Doppler, and constant phase (Figure 1). It also provides preconfigured setups for all of the major digital communications technologies, ranging from legacy protocols to the latest cellular and WLAN standards.

Emulation is accomplished using the Keysight N5182B MXG vector signal generator. With frequency coverage spanning 9 kHz to 6 GHz, the MXG is capable of producing a wide variety of signals, from simple to complex, and from clean to impaired. It is also compatible with Signal Studio, supporting direct downloads of signals created using the software.

For detailed analysis, the agency chose the Keysight N9030B PXA X-Series signal analyzer (Figure 2). The PXA is Keysight’s benchmark for readily accessible performance that accelerates progress in detailed interference analysis and other demanding applications. The streamlined multi-touch user interface makes it possible to perform most operations in two steps or less.

The Results: Predicting and Mitigating Wireless Interference

This solution is enabling agency researchers to quickly and easily perform advanced testing and analysis of wireless receivers. As one example, they were able to simulate the interaction between satellite transmitters and ground-based radar receivers. The PXA signal analyzer was able to capture the interfering signal and then help researchers characterize and understand its effects on the receiver.

Signal Studio and the MXG are enabling the team to simulate numerous standards based wireless signals—with impairments—and then apply them to a variety of receiver systems. This has enhanced the agency’s ability to not only predict but also take steps to mitigate the effects of commercial wireless signals on essential government systems.

Going Forward

The initial success of this solution for interference research has led to the deployment of multiple systems throughout a variety of government agencies. With ongoing updates that support new and emerging wireless standards, Signal Studio, the MXG, and the PXA will continue to contribute to general research and specific investigations.