With 5G moving out of the lab and onto the street, we've received a flurry of recent announcements regarding collaborations the print 5G design and test products to market.

Field trial
Lower latency, on the order of 1 ms, is an expected feature of 5G. It will be needed for industrial control applications and even more so in V2X communications needed for connected cars. In an effort to reach that goal, Rohde & Schwarz has worked with Huawei in field trials to measure network latency. Tests performed in Munich and Shanghai showed latency measurement on the order of a few milliseconds with accuracy of ±2 µs, according to Rohde & Schwarz.

Tests were performed by using GPS to measure the latency of single internet protocol (IP) packets transmitted between a base station and a moving receiver. When asked how the measurement were taken, a representative of Rohde & Schwarz said "The communication was between the car and a 5G base station, the absolute time was derived from a GPS signal and a network card was synchronized to that time, both on the transmitter and receiver side. Each data packet, therefore, has an absolute timestamp at the transmitter and the receiver. The difference of these timestamps is the latency."



The two companies started the tests using proprietary 5G radios but have since moved to 5G NR transmitters and receivers. All carrier frequencies were in the FR1 (below 6 GHz) cellular band, including a 3.5 GHz carrier. Rohde & Schwarz would not disclose the data rates of the transmissions, but that wasn't the point of the tests.

Compliance validation
Keysight Technologies announced that its 5G Conformance Toolset is the first 5G NR test tool to receive PTCRG validation for 5G test certification. The result: 5G NR devices tested using the toolset can now be certified for use by PTCRB.

Keysight's 5G Conformance Toolset consists of the E7515B UXM 5G Wireless Test Platform combined with the 5G Protocol R&D Toolset and 5G RF DVT Toolset.

The 5G Protocol R&D Toolset lets you emulate and test communications between a simulated base station (the UXM 5G, right) and user equipment. Here, you enter configuration data that includes cellular band, frame structure, and cell power. The 5G Protocol R&D Toolset adds tests for Layer 2 (Data Link Layer) protocols needed to establish a connection between a base station and user equipment. Because the toolset lets you emulate Layer 2 protocols, you can test chipsets before implementation of Layer 3.

With the RF DVT Toolset, the UXM 5G lets you automate measurement parameters such as channel frequency, bandwidth, signal power in accordance with 3GPP Release 15. You can develop automated tests by dragging test functions into a table, from which the tool produces test scripts for both 5G NR and LTE radios and protocols.

You can use the UXM 5G for channels in the FR1 (sub-6 GHz) band and, with the addition of the M1740A mmWave Transceiver, can run tests in the FR2 mmWave band (24.25 GHz to 52.6 GHz).

According to Keysight's Muthu Kumaran, Senior Director Device Acceptance Segment, "The test case validates the user equipment meets minimum output power requirements from 3GPP specific to dual connectivity for band 5A (LTE band) and band n78 (5G NR band)."

The validation includes protocol testing, which Kumaran described as the messaging used to establish and maintain a radio connection between the mobile device and the base station. You can test a mobile device because the UXM 5G emulates the base station and network. "In this context," explained Kumaran, it is much more than the physical layer—we must maintain a full link, which includes the physical layer as well as the medium access control (MAC), radio-link control (RLC), and Packet Data Convergence Protocol (PDCP)."

Going standalone
On December 19, Keysight announced with Qualcomm a trial that used a standalone 3GPP Release 15.3.0 5G NR to send IP packets, similar to Anritsu's recent announcement with Qualcomm. The test setup consisted of a Keysight 5G network emulator communicating with a smartphone form-factor test device that uses a 5G modem and antenna modules.

Electromagnetic device models
If you design devices that will connect to 5G networks, you'll probably need simulations. To that end, Modelithics and Ansys have begun work on models for inductors, capacitors, connectors, packaged filters, and other devices that you'll need to simulate your circuits. The models will work with the Ansys HFSS 3D Electromagnetic Field Simulator for RF and Wireless Design.

Power amplifier design
Power amplifiers (PAs) are a critical component of 5G base stations and user equipment. Because 5G's emphasis on power savings, engineers are designing PAs using GaN power transistors with some using the Doherty amplifier architecture. National Instruments' AWR Group has produced an application note, "Design of a High-Efficiency Broadband GaN HEMT Doherty Amplifier for New-Generation Cellular Transmitters" that describes how to use AWR software to design a 200-W Doherty amplifier using GaN HEMT technology. Frequency range is 1.8 GHz to 2.7 GHz.

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The Doherty RF amplifier achieves better efficiency by using an auxiliary amplifier to vary the load impedance on the primary amplifier. This approach allows the primary amplifier to continue to swing a large signal, dissipating less power in the amplifier. If the auxiliary amp lowers the load impedance on the primary amplifier, the primary amplifier delivers more power.

Martin Rowe covers test and measurement for EDN and EE Times. Contact him at martin.rowe@aspencore.com