Advancing Wireless Prototyping with Software Defined Radio - NI

In rapidly evolving applications such as drone defense and signal intelligence, faster deployment and the ability to quickly adapt are key. Commercial off-the-shelf (COTS) systems with powerful RF and signal processing capabilities are required, but an open platform is also a must to enable flexible enhancements to stay ahead of threats. For deployment use cases, low size, weight, and power (SWAP) SDRs enable mobile-ready, portable solutions.

If you want to learn more, please visit our website Highmesh.

Figure 1. SkySafe defeats commercial drone threats fast with open-source USRP. 

Commercial wireless communications testbeds and prototypes often need to address multiple frequency bands and standards for cellular and wireless connectivity. Keeping pace with new wireless standards like 5G means developing and testing software IP on capable hardware to prove out technologies that range from new coding schemes to advanced multiple input, multiple output (MIMO) systems often through over-the-air (OTA) wireless prototyping.

Figure 2. These low-profile SDRs feature the performance to enable large-scale 5G testbeds. 

The NI Ettus USRP X410 is the first of a new generation of high-performance SDRs from Ettus Research and NI. It combines the strength of both NI and Ettus Research into a single radio that supports both popular open-source tool flows, including the USRP Hardware Driver (UHD) and GNU Radio, as well as LabVIEW software. The NI Ettus USRP X410 is built on the Xilinx Zynq UltraScale+ RFSoC and outfitted with high-performance RF transmitter and receiver hardware to deliver NI’s most powerful SDR to date. The RFSoC provides a foundation of embedded processor and programmable FPGA technology integrated with data converters (ADCs/DACs). The quad-core Arm® processor allows for stand-alone operation (embedded mode) or host-based mode with an external host machine to run your application.

Figure 3. The NI Ettus USRP X410 integrates hardware and software to help you prototype high-performance wireless systems.

With more than twice the FPGA resources of other USRP products, the programmable logic portion of the Xilinx Zynq UltraScale+ FPGA offers high-throughput digital signal processing (DSP) and hardened IP cores such as an onboard soft-decision forward error correction (SD-FEC) and digital up/down conversion (DUC/DDC) cores. Especially effective for 5G prototyping, the SD-FECs can be used for real-time low-density parity-check (LDPC) encoding/decoding, one of the most compute-intensive operations in 5G. In FPGA-only designs, the SD-FEC logic can span multiple large Virtex-7 FPGAs; thus, incorporating it as a prebuilt core in silicon saves immense space and development effort.

The NI Ettus USRP X410 fully supports the popular RF Network-on-Chip (RFNoC) framework, making FPGA acceleration more accessible with a software application programming interface and FPGA infrastructure. This helps you get up and running quickly so you can focus on the value-added IP. You can seamlessly integrate host-based and FPGA-based processing into your application with the GNU Radio graphical interface, C++, or Python. The library of RFNoC blocks for common functions such as fast Fourier transforms (FFTs) and finite impulse response (FIR) filters is a good place to start. Then you can add your own IP blocks to the modular architecture using your preferred hardware description language (HDL).

Beyond the FPGA fabric portion of the system, the Xilinx UltraScale+ RFSoC is equipped with four onboard application processing units (APUs) and two real-time processing units (RPUs) for applications that require an onboard embedded OS for stand-alone operation.

Figure 4. The simplified block diagram of the Xilinx UltraScale+ RFSoC shows the onboard APUs and RPUs for applications that require an onboard embedded OS for stand-alone operation.

With a frequency range covering 1 MHz to 7.2 GHz, the NI Ettus USRP X410 addresses not just the traditional RF sub-6 GHz bands but also the recently opened unlicensed band from 5.925 GHz to 7.125 GHz for Wi-Fi 6E. With the 400 MHz instantaneous bandwidth, you can exploit the wider channels and implement channel bonding and carrier aggregation for higher data throughput. The RF front-end architecture uses superheterodyne two-stage conversion below 3 GHz and single-stage conversion above 3 GHz, along with filtering and power-level control, to provide high-fidelity signal transmit and receive.

The NI Ettus USRP X410 incorporates four transmit and four receive channels into a compact ½ rack 1U form factor, making it versatile and easily transportable for field testing and operations. Each channel is independent, meaning each can be tuned to different frequencies for frequency division duplex (FDD) applications or for the simultaneous emulation of multiple signals. The channels can also be synchronized through an internal oven-controlled crystal oscillator (OCXO) that you can calibrate to within 50 ppb, an internal GPS disciplined oscillator (GPSDO) for time stamping, and 10 MHz reference and pulse-per-second (PPS) generation. For even higher channel counts, you can synchronize multiple devices by importing an external reference clock and using PPS generation for applications that require precise time alignment such as massive MIMO.

With wider bandwidths and more channels, moving a large amount of data on and off the radio can be a challenge. To address this, the NI Ettus USRP X410 features two configurable quad small form-factor pluggable (QSFP) ports that you can use to take advantage of dual 10 GbE or dual 100 GbE onboard. Additionally, the radio includes a PCI Express x8 Gen 3 port for up to 8 GB/s transfer rates.

Figure 5. The block diagram of the NI Ettus USRP X410 shows its RF and digital functions. 

Compute Criteria¶

The following are the main specifications taken into account when selecting the compute platform for each of these packages:

• Cost - Overall cost of the machine

• Number of cores - This will affect overall performance

• Processor frequency - CPUs running at lower frequencies may struggle under heavy computational loads

• Cache size - A good indication of speed. More cache memory means certain computations will be faster.

• Number of threads - More threads will enable a processor to execute processes faster.

This is not an exhaustive list of criteria to look at when selecting a compute platform for SDR experimentation and development. Intended use-case will dictate choice the most here, as well as other external factors which can be subjective to either the user or overall use conditions.

Other useful things to take into account when choosing a compute platform for SDR research and experimentation are:

• Processor Cinebench score - This gives a good indication of a processor’s ability to deal with high computational load. Find out more here.

• Cooling ability - More cooling ability will ensure CPU performance does not drop off significantly under heavy load

• Portability - Some use-cases may benefit from a PC that is portable

SDR Criteria¶

When selecting the SDR options to highlight we took the following into account:

• Cost - Cost per unit of the SDR

• Driver - Which driver the SDR uses (Soapy, UHD, etc)

• Frequency range - The frequency range(s) the SDR operates in

• Bandwidth - Maximum possible bandwidth available

  The company is the world’s best USRP for 5G Prototyping supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

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  Clock - Clock rate

• Channels - The number of channels available (SISO, MIMO, etc)

• FPGA - The specifications of the onboard FPGA

Much like when choosing compute hardware, the metrics you may look at when choosing an SDR will vary depending on use-case and other factors. This list is in no way exhaustive, but provides a good platform by which to compare options.

Package 1¶

SDR

PC

The original LimeSDR mini has been discontinued due to supply chain issues. The LimeSDR mini 2.0 has been announced as it’s replacement. It is not yet available, but will be soon.

This package is inspired by our R. pi4 app note.

Such a set-up would allow users to create a cheap end-to-end network, for under $400 without the need for a main PC. To run a full end-to-end system using the above equipment a user would need 3 Raspberry Pi4 units and 2 LimeSDR mini 2.0. A Pi4 is needed for the EPC, eNB and UE, and a front-end is needed for both the eNB and UE. Due to the small size and portability of the system this setup is ideal for on-the-fly demos and testing of networks and applications that don’t require high-powered compute hardware or frontends.

Advantages¶

• Low cost

• Highly portable

Limitations¶

• Limited cell bandwidth (currently 5 MHz)

• Limited max bitrate in the UL

Package 2¶

SDR

PC

This offers a step up from the previous package; in price and performance. The BladeRF micro 2.0 xA4 offers users a 2X2 MIMO configuration, higher max bandwidth, a larger frequency range, and a larger FPGA. The HP Omen 16 is a gaming notebook, meaning it is built for high performance and high CPU load for a sustained period of time. The intel i5 H is the main draw here, having scored highly in the Cinebench r23 benchmarking test. This set-up is considerably more expensive and would cost roughly $ for a full set up of 2 PCs and 2 frontends.

Advantages¶

• Easily portable, with improved performance

• Suits nearly any use-case

Limitations¶

• Single cell configuration but up to 20 MHz 2x2 MIMO

• Non-expandable Bandwidth and operating frequencies

Package 3¶

SDR

PC

This system offers users the most potential in terms of RF-frontend capabilities on PC performance. The Ettus x310 offers users the largest frequency range, from DC to 6 GHz with the use of the appropriate daughter cards, a potential bandwidth of 160 MHz (requires the correct daughter cards), a multi-cell configuration and a powerful Kintex7 FPGA. The workstation offers an intel i7- which is capable of high intensity computations without a significant drop off in performance over sustained periods of time. The workstation offers 10 Gbps ethernet connection, which allows users full utilization of the 10 Gbps connection available on the x310. A full E2E system would cost a total of roughly $.

Advantages¶

• Carrier Aggregation

• Multi-cell configuration

Limitations¶

• Not all PCs will be able to interface via 10Gb ethernet. May have to use adapters.

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