White Paper

Testing is, of course, an essential step in wireless product development, but the correct balance between field and lab testing can be difficult to discern. Field test plans cannot practically capture the wide range conditions that a product will operate in, yet creating realistic radio channel environments in the lab has typically required a high degree of time and skill. Both of these approaches have only gotten more complex with the introduction of 5G radio technologies. Today’s engineers from a wide range of industries are developing wirelessly-connected products. They need user-friendly tools that reduce testing complexities and help them get to market quickly with innovative products and services.

The Simplification of Radio Channel ModelingGraphical Software Makes 5G RF Testing Practical for Developers

“It’s a kind of perfect storm. With 5G, radio channel modeling is much more complicated, and system performance gains depend on designers getting it right,” says Phil Marshall, chief research officer at Tolaga Research. “As 5G targets vertical markets, some designers coming from other disciplines may have limited levels of wireless experience. Simplified and reliable channel modeling is crucial for 5G to live up to expectations.

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The Simplification of Radio Channel ModelingGraphical Software Makes 5G RF Testing Practical for Developers

To make 5G testing practical for mass-market developers, Spirent offers Advanced Channel Modeling (ACM) Software, a PC-based application that provides a simple graphical user interface (GUI) developers can use to test 5G scenarios without knowing the science of radio communications or channel modeling methodologies. Developers can test how their solutions will behave in a variety of realistic RF environments. How well do protocol, application and cloud layers react to varying radio link performance caused by handovers, reflections, motion, interference, congestion and other RF propagation issues? A repeatable and powerful lab test solution promotes earlier issue discovery, faster issue resolution, and more robust regression and QA stages. The ACM software is used in conjunction with Spirent’s Vertex channel emulator.

This whitepaper discusses 5G technology complexities and markets and the implications for testing. It explains the need for channel modeling and the barrier traditional modeling methods present to market expansion. The paper summarizes the conveniences Spirent’s ACM brings to the modeling process so

anyone—experts and non-experts alike—can evaluate and refine their 5G products.

5G Complexities, Markets and the Implications for Product Testing

Cellular technologies have evolved steadily over the years to improve performance and versatility, but with every advancement the technology has become more complex and testing requirements have increased accordingly.

A 2G mobile phone in 1995, for example, could communicate with just one radio technology (such as GSM), and one frequency band (such as 900 MHz), and applications were very basic: voice calls and texting. Laboratory testing was similarly straightforward: An engineer could connect a transmitter and a receiver to equipment that emulates the expected RF propagation environment and test performance under relatively simple operating conditions.

Fast forward from 2G to 3G to today’s 4G smartphones, which use multiple radios and dozens of simultaneous frequency bands to support not only calling and texting, but also high-speed web browsing, high-definition video, and other applications. The technology is advancing again with 5G, which bolsters performance substantially to support pervasive use of the network for all types of consumer and vertical industry use cases.

5G New Radio: 5G will use an entirely new radio, aptly named 5G NR, to revolutionize performance, capacity and services. 5G NR operates in many more frequency bands than 4G, including sub-1GHz low band, sub-6GHz mid-band, and even 24 GHz+ high-band millimeter wave frequencies that have not been used for cellular communications before. 5G also uses more antennas and new antenna schemes, such as Massive MIMO, beamforming and beam tracking, to support dramatically more customers with higher data speeds than was previously possible.

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Expanded Markets: Thanks to its performance and versatility, cellular technology will also evolve from a personal communications technology to a general purpose technology applicable in any market.

• Enhanced mobile broadband (eMBB) services for example, will deliver gigabit data speeds for immersive video, gaming, augmented reality (AR), virtual reality (VR), and other high-bandwidth applications for consumers, enterprises, governments and industries.

• Ultra-reliable, low-latency communications (URLLC) will facilitate mission-critical connections for self-driving cars, smart grids, smart trains, military drones and public safety communications as well as remote surgeries, industrial automation, and video surveillance.

• 5G networks will support connectivity for massive numbers of IoT devices (mIoT) to facilitate smart appliances, smart buildings, smart cities, precision agriculture, mobile health, environmental monitoring, and other applications.

Operators will also be able to offer fixed-wireless services with fiber-like performance for homes and businesses.

Service providers are tailoring initial deployments to increase capacity and deliver eMBB to consumers, but vertical industries are eager to use the technology. Industrial companies, such as manufacturers, are a case in point: A 2019 multi-national study by Capgemini found that the vast majority (75%) of industrial companies say 5G is essential to their digital transformation strategies. Nearly half (47%) of the largest industrial firms want to operate their own private 5G networks. “This research makes it clear that industrial companies are confident about the benefits of 5G before it has even come to market,” noted Pierre Fortier, principal consultant in telecom, media and technology at Capgemini Invent.

Implications for Test: 5G has immediate implications for the test and verification process because the new radio is more challenging to evaluate than previous cellular technologies and a device must be tested under all potential usage conditions. In particular, the complex antenna schemes are difficult to model in a lab setting, and even more difficult to control in field tests. The advanced antenna technologies alone can require testing dozens and even hundreds of radio links simultaneously to verify the reliability and quality of services for networks and devices. Devices that use mmWave frequencies also require extensive testing because these frequencies are extremely sensitive to the propagation environment.

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The Simplification of Radio Channel ModelingGraphical Software Makes 5G RF Testing Practical for Developers

Market Applications for 5G

Automotive: Car manufacturers are planning private 5G networks to improve factory productivity and the

manufacture of self-driving cars.

Consumer Sports: Sports equipment vendors are embedding 5G in home

exercise equipment so consumers can work out remotely with trainers and

participate in virtual classes

Healthcare: Hospitals are demonstrating connected

ambulance services, including remote ultrasound scans over 5G.

Financial Services: Banks are using 5G to improve connectivity

at branches, enable 4K video conferencing and VR-enabled

co-working.

Farming: Organizations can use 5G-connected sensors and AI to

remotely monitor weather patterns, livestock wellness, and soil nutrients

Defense: Military experts are identifying 5G use cases for

operating bases. Examples including communications between command

post vehicles; connecting sensors and cameras to improve base security;

using 5G’s multiple frequency bands to prevent network jamming.

Intelligent Transportation: Governments are installing 5G base stations on traffic signals for traffic monitoring and automated driving.

Energy: Power plant operators are using 5G to monitor plant equipment

in real time to optimize operations.

Retail: Large retail companies are developing innovative logistics

and distribution solutions that use 5G, as well as immersive shopping

applications that use AR/VR over 5G.

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Traditional Channel Modeling: An Esoteric Science Requiring Special Knowledge and Expertise

Channel modeling is a powerful method of bringing real-world operating conditions into the lab. It has been used for decades by chipset firms, cellular network equipment vendors, device manufacturers and service providers to test and verify the performance of wireless products, but it is an esoteric science and a complicated process, and it requires specific wireless engineering expertise.

Channel models are mathematical descriptions of radio signal propagation. They can describe effects such as the multiple signals received due to reflections and refraction, the phase and frequency shifts caused by motion, and the geometric considerations associated with antenna height and angles of departure and arrival.

Because deployment environments and operating scenarios are virtually limitless, the wireless industry has standardized cellular and wi-fi channel models for the most common use cases. The models are based on observations of radio propagation in nature and measurements taken in the field that characterize signal behavior in time, frequency and space. Typical channel models include:

Urban

Indoor

Suburban Rural

Flight-to-groundHigh-speed train

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The Simplification of Radio Channel ModelingGraphical Software Makes 5G RF Testing Practical for Developers

Engineers must customize each channel model, based on a variety of parameters for base stations and mobile devices, to define an intended operating scenario. Key parameters include:

Mobility and non-mobility | Pedestrian or high-speed motion

The height of base stations and distance between sites | Density of cells

Number of base stations Number of devices | Operating frequency | Location

Antenna characteristics and configuration | Power level

3D geometries such as angle of the signal’s departure or arrival

Line of sight between transmitter and receiver | Non line of sight

Reflections or refractions | Interference | Types and density of buildings

Presence of trees, hills, bodies of water or other landscape features

Once a channel model is created, it is executed in a channel emulator. The emulator is a hardware-in-the-loop system, meaning that it takes RF signals from the physical device or system under test, implements the mathematics of the channel model and applies the model to the input signal, then outputs the resulting signal. This allows the designer to replicate the wide variety of real-world radio issues in the lab so that they can understand how well their system performs. It enables evaluation of every level of the hardware and software design, and provides a repeatable platform for measuring KPIs of interest such as data rates and throughput, latency, and voice and video quality..

The challenge for developers is that creating and implementing realistic channel models has historically been in the domain of a handful of experts. Since 5G will be embedded in all types of products offered by numerous industries, new approaches are needed so the general ecosystem of design engineers can evaluate their designs.

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Spirent’s Advanced Channel Modeling: User-Friendly Software Enables Just About Anyone to Create Complex Models and Operating Scenarios

Spirent’s Advanced Channel Modeling software gives developers an easy-to-use GUI for creating realistic radio channel models. Offered in conjunction with Spirent’s Vertex Channel Emulator, ACM enables wireless and non-wireless engineers, as well as application and software development and test teams, to create test scenarios.

A factory floor, for example, can be modeled with many

stationary and moving endpoints.

Communications from shore to an off-shore oil platform can be modeled, including

aircraft-to-platform channels.

Autonomous vehicle teams can evaluate how multiple

endpoints with various speeds and paths interact.

Organizations within the cellular industry as well as companies in industries from consumer product manufacturers to appliance or automobile manufacturers to utility companies, government agencies, and military organizations can use ACM to create the scenarios that matter for them.

Drone

Fast movingvehicle

InterferingBase Station

Base Station

Mobile device

Figure 1. ACM can create realistic radio propagation environments for a wide variety of applications.

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The Simplification of Radio Channel ModelingGraphical Software Makes 5G RF Testing Practical for Developers

The Graphical User Interface: ACM’s GUI centers around a visual representation of the deployment environment. One or more base stations are placed on a map. Heights, distances and power levels are completely definable, making it easy to create macro and micro models (or combined, of course). Devices are placed on the map as well, along with an optional motion path.

The software will automatically create and download the desired model to the Vertex Channel Emulator. Vertex uses the model to simulate a real-world RF environment of the test case and modify the uplink and downlink signals to each of the elements.

Developers can quickly input parameters or change base station configurations, mobile device configurations or propagation scenarios to perform what-if analyses and refine their designs. Advanced base station parameters offer the ability to model sophisticated two-dimensional multi-element array antennas for Massive MIMO configurations.

ACM automatically creates and displays connection setups needed to connect RF cables to the Vertex Channel Emulator. Simply create the channel model and the Vertex software will define and diagram the required connections.

Figure 2. RF environments are described in a graphical interface.

Base station parameters

Device parameters

Geometry & motion

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Typical propagation scenarios: Developers can use the ACM GUI to test their product performance under dynamic or static conditions.

Dynamic testing is particularly important because these scenarios involve one or multiple connected devices moving within the deployment environment. Infrastructure vendors and connected car manufacturers, for example, need to test their designs under these types of conditions and their models must be able to adapt along with changes in device locations. The ACM GUI makes it easier to conceptualize and perform dynamic tests.

ACM’s dynamic motion scenarios can be circular, linear or follow an arbitrary path in 2D or 3D.

In a circular scenario, one or more devices are moving in a circle in or around a 5G (or other) base station. This scenario is useful for testing the performance of the base station’s beam tracking and beamforming algorithms. It can also be used in multi-user cases to simultaneously test multiple devices, which have different location coordinates, to reveal conflicts that might occur if the devices cross paths in a given time and space. A similar set of applications can also be tested along an arbitrary device path comprised of multiple line segments.

A linear scenario can be used to test beamforming, beam tracking, power control, handover, and other algorithms when, for example, a train or other vehicle is traveling at high speed along a linear route.

Static scenarios are used for performance testing of 5G base stations or non-mobile end-user devices. A key use case for this scenario is the evaluation of infrastructure and customer premises equipment used in fixed-wireless deployments.

Four types of lab environments: The propagation scenarios developed with ACM can be used in the lab with four types of test environments:

• Conductive testing: This uses a traditional setup at the lab bench. In this environment, antennas are removed from the devices, and transmitters and receivers are connected to the channel emulator via RF cables. ACM can support large antenna counts and several mesh network configurations (full, convoy, loop and star).

• Over-the-Air (OTA) testing in an RF chamber

— For base stations: OTA testing is essential with 5G because base stations and user devices will be built with massive MIMO antenna schemes and configurations that cannot be accurately represented or evaluated via conductive approaches. Developers can create channel models with ACM and use a tool, provided with the Vertex channel emulator, to convert their original channel models for use in OTA test environments.

— For devices: MIMO OTA at the device side allows the assessment of the performance of the mobile terminal. ACM can create spatial channel models that test the device’s receiver (antenna subsection and chipset) to its limits.

• Virtual OTA: This feature works by measuring the antenna patterns and the propagation paths inside the chamber; then ACM takes care of the rest by convolving the channel model with the antenna patterns and inverting the propagation paths.

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The Simplification of Radio Channel ModelingGraphical Software Makes 5G RF Testing Practical for Developers

• Phase Matrix: 5G’s massive MIMO and beamforming employ antennas with dozens or hundreds of elements (in contrast to just a few elements in 4G). The resulting number of distinct RF connections for lab testing is much higher as well. Spirent has pioneered the industry’s use of the phase matrix solution for conducted mode testing, which scales back the number of RF connections by handling some of the RF phase and amplitude modeling prior to channel emulation. It can be used to emulate signals from a massive MIMO base station transceiver to a MIMO mobile unit or vice versa, from the MIMO mobile unit to a massive MIMO base station. ACM can convert a developer’s original channel model for use with the phase matrix.

Groundbreaking Benefits: Fundamentally, ACM is convenient for developers because the GUI offers channel modeling at a higher level of abstraction, with less detail than traditional methods. Developers do not need any expertise in channel models or how to build the proper setup in the lab. They only need to know what they want to prove with a test case. Simply create a scenario and the tool does all the work, increasing productivity and reliability of the testing while reducing costs.

The Simplification of Radio Channel ModelingGraphical Software Makes 5G RF Testing Practical for Developers

About Spirent Communications

Spirent Communications (LSE: SPT) is a global leader with deep expertise and decades of experience in testing, assurance, analytics and security, serving developers, service providers, and enterprise networks.

We help bring clarity to increasingly complex technological and business challenges.

Spirent’s customers have made a promise to their customers to deliver superior performance. Spirent assures that those promises are fulfilled.

For more information, visit: www.spirent.com

Contact Us

For more information, call your Spirent sales representative or visit us on the web at www.spirent.com/ContactSpirent.

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© 2020 Spirent Communications, Inc. All of the company names and/or brand names and/or product names and/or logos referred to in this document, in particular the name “Spirent” and its logo device, are either registered trademarks or trademarks pending registration in accordance with relevant national laws. All rights reserved. Specifications subject to change without notice.

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Rev A | 02/20

Easy Testing Empowers Developers to Focus on Innovation and Product Development

5G is revolutionary as a cellular communications standard because it is designed to deliver dramatic performance improvements, provide connectivity to all types of products, and unleash new use cases for vertical industries and consumers. For so many potential 5G products and use cases to succeed, a broad ecosystem of engineers must have tools that encourage and facilitate their participation in the market.

Spirent’s ACM is groundbreaking because it serves this need, enabling mainstream developers to perform channel modeling and use the Vertex radio channel emulator for their test applications. A non-wireless test engineer, business manager or layperson can create meaningful test cases quickly while reducing risks. The solution empowers developers to focus on their core competencies—product innovation for their target markets—rather than learning an esoteric wireless testing discipline. ACM conveniences also benefit RF and wireless design engineers because they, too, can innovate better with tools that reduce the complexities and economics of testing and accelerate their time-to-market with 5G products and services.