5G aims to increase data rates, carrier bandwidths, latency values and more to support the ever-increasing number of connected devices. Compared to previous generations of mobile networks, 5G represents a momentous shift in the development and implementation processes.
Traditionally, mobile network testing activities take place once commercial networks are up and running. But every new generation and technology starts in the lab, with research and development conducted in early trial networks. The same applies to base stations and smartphones. Yet despite extensive network simulations, it is often unclear how a new technology behaves in real environments. Trials are the only way to provide insight.
The most interesting parameter in these early mobile network trials is coverage. It is of utmost importance to get real-world information about a mobile network’s coverage to understand the new technology and tune algorithms, for example in network planning tools. Today, network test tools from Rohde & Schwarz mobile network testing, support ongoing trials and pre-commercial 5G use cases.
Testing considerations include the combination of millimeter wave utilization, multiple input multiple output (MIMO), and beamforming. The short wavelength of millimeter wave frequencies and the higher losses in circuits necessitate a tight integration, making it impractical to supply connections for testing. This means over the air testing must be applied. Through the use of many more antennas, massive MIMO and beamforming combat the effects of higher attenuation at higher frequencies and improve capacity. More antennas mean more testing to ensure that all integrated antennas are operating correctly.
Testing Example
The U.S. operator Verizon Wireless got spectrum in the 28 GHz band via an acquisition and decided to use it for a Fixed Wireless Access (FWA) application. Together with Korean operators and other industry players, they created a specification called 5GTF, published in June 2016. The 5G task force adapted the 3GPP Release 12 LTE specification and specified 100 MHz bandwidth signals with the following characteristics:
- OFDMA used also in the uplink
- Simple form of beamforming: Beam Reference Signal, Beam Refinement Reference Signal
- Phase Noise compensation reference signal defined for downlink and uplink
- PHY/L1, MAC/RLC adaptations, new physical signals and new or extended PHY channel/functionality
Since the FWA application is designated for customer premises equipment (CPE), mobility is neither targeted nor specified. The focus is on overcoming the higher path loss in the 28 GHz band in order to provide high user data rates to be able to compete in the fixed network area (see image above). For more information on the fixed wireless access test click here.
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