SDR for the rapidly evolving demands of test and measurementStory
September 15, 2020
By Reza Mohammadi, Neelam Mughees, and Ghozali Suhariyanto Hadi
As communications technologies evolve rapidly, performing test and measurement on communications equipment more easily and flexibly has become increasingly crucial, particularly in military applications. Software-defined radio (SDR) technology-based testing equipment provides the cost efficiency, flexibility, and power to move forward these communications. Test-and-measurement equipment manufacturers must ensure that their product can help their customers accelerate their testing process and expand their testing capabilities, in order to shorten their time to market, reduce costs (as fewer pieces of testing equipment would be needed), and gain a better return on investment (ROI) on their existing testing equipment.
Software-defined radio (SDR) is capable of testing multiple current standards – such as Bluetooth, WiFi, GNSS, 4G, and 5G – and has the potential to work with future standards. This versatility means that even military users can accelerate the testing process, reduce inventory, and decrease human-resource costs with a single piece of equipment.
The core principle of the SDR technology is that the radio can be programmed, controlled, or specified completely using software. In contrast to conventional radios that are developed for a unique application and frequency, SDR can be programmed to test a wide range of frequencies and can be tailored to work in any application. For example, testing of a cellphone requires testing of its GPS, Bluetooth, cellular bands, and Wi-Fi. SDR enables and supports the testing of each of these components’ previous and latest versions with no need to replace or modify the testing hardware. SDR achieves this functionality due to its design (Figure 1).
[Figure 1 | Block diagram shows a general SDR architecture, with transmit and receive sides.]
In a recent market statement issued by Acumen Research and Consulting titled “Global Software-Defined Radio Market – Analysis and Forecast, 2020-2027,” the SDR industry was worth $21.85 billion in 2019 and is likely to hit $31.69 billion in 2027. The study anticipates that the industry will grow at compound annual growth rate of 7.19% over the 2020-2027 forecast period.
While SDR technology has been around since 1993, it is more directly the advances in semiconductor and software technology that have pushed higher development productivity in SDRs and made them valuable. With its widespread benefits, SDR is becoming the industry standard in markets such as test and measurement, electronic warfare (EW), spectrum monitoring, public-safety communications, signals intelligence, and military communications.
Problems and how SDR addresses them
Many criteria are taken into account when choosing a test and measurement system, the most important of which are the complexity of design being tested, volume of production, and test time. SDR is desirable in test-and-measurement applications that feature moderate to high complexity, low-to-moderate volumes, and moderate-to-high flexibility needs.
In these test-and-measurement scenarios, many complex systems with various independent devices operating at different frequencies must be tested before their release into the market. Figure 2 shows a radio spectrum, outlining the range in which different devices fall. Every device can have different protocol and testing requirements that may need to be adapted with time. Moreover, many communication protocols and products are still maturing, and system models are being replaced or tailored to handle the never-ending flood of data. Customers need a single device to work for several applications.
Additionally, as they deal with the emergence of new communication standards, many customers prefer to update the existing equipment as opposed to replacing it. Those who use SDRs have more flexibility: Unlike replacing the hardware, SDR testing can be patched, updated, or completely changed to address the latest protocols. Moreover, the commercially available high-performance programmable signal-processing devices used in SDR help in meeting testing’s throughput, flexibility, and development cost.
[Figure 2 | Spectrum graph shows frequency designation.]
For example, in the case of 5G, the new high frequencies permit more data movement and signal processing, but 5G also needs more testing for optimizing the traffic. Earlier, 100 MHz was considered a “wideband” instrument, but now the market demands bandwidths more than 1 GHz. Currently, various technology gears are expected in 5G, beginning with 4.5G and eventually going towards millimeter-wave technology. If testing is to be performed using traditional hardware, it may be too slow and expensive.
It is likely that when the hardware required for testing a particular protocol of 5G becomes available, that particular protocol may have changed. Therefore, the testing hardware becomes outdated shortly after that 5G technology hits the market. SDR’s wideband performance can be configured for use with many different devices as users address the need to use the 71 to 76 GHz band for 5G; moreover, SDR is very compatible with the upcoming millimeter-wave bands. SDR’s support of high bandwidth also means there are no restrictions on testing a variety of equipment (that is, it can be either narrow band or wideband).
For products that are tested in low to moderate volumes in comparison to devices such as base stations or mobile phones, setting up a new hardware test bench for every new design will cause major inefficiencies. Software-defined radios enable connection with a host where application development can be done through software. Especially with low-volume projects, an SDR will be a more effective tool than a traditional testing suite.
Reducing testing time
Another “must-have” for test and measurement is reducing the test time. For example, in a standard RF or mixed-signal test, the testing time is made up of data-processing and data-acquisition time, the setup time of the testing device, and the response time of the device under test (DUT). All of these, except DUT response, are largely a function of the test device. The test equipment should have minimal effect on the overall testing period. SDR can do inline testing through the onboard FPGA [field-programmable gate array] for a broad variety of complex consumer, industrial, and electronic products without the need for a host system when deployed, thereby speeding up the testing process.
Many manufacturers are offering a variety of SDR products to meet varying needs in markets such as satellites, military communications, LTE, and wireless connectivity. The accelerated development of the latest wireless technologies such as 5G and 802.11ax are spurring engineers to utilize flexible testing and measurement devices.
Reza Mohammadi is an engineering student at the University of Toronto; his work at Per Vices focuses on network infrastructure. Neelam Mughees is a registered engineer and a Ph.D. candidate in electrical engineering. Ghozali Suhariyanto Hadi is a Ph.D. candidate in computer science. His focus is on wireless (RF-based) sensing to combine robust hardware design and post-processing using machine learning.
Per Vices Corporation www.pervices.com