Even as 4G cellular systems – long term evolution (LTE) and LTE-Advanced technology – are being deployed, development is well under way on 5G wireless communications systems. 5G mobile networks offer a vision of “everything, everywhere, and always connected”. Key attributes include a dense, highly-integrated network comprised of small cells supporting data download rates of up to 20 Gbps and over-the-air latency of 1 ms or less. 5G standards are based on a unified air interface, which will operate into the millimetre frequencies. The use of high-order spatial multiplexing techniques such as multiple input multiple output (MIMO) will enhance capacity and data throughput.
One of the biggest challenges in 5G development today is the presence of many different waveform scenarios across higher frequencies and wider bandwidths. While 5G New Radio (NR) Release 15 in June 2018 specifies frequencies up to 52.6 GHz and bandwidths up to 1 GHz with carrier aggregation, standardisation will not stop with Release 15. NR will continue to evolve through Release 16 and beyond, where higher frequencies, wider bandwidths and new waveforms will likely be added to the specification. These introduce new test challenges for 5G signal generation and analysis, where fidelity and flexibility are key for today’s 5G development.
Making the leap from aspirational predictions to practical implementation starts with the creation, generation and analysis of 5G NR signals. Signal impairments become more problematic at higher frequencies and with wider bandwidths. These impairments can distort the modulated signal, making it difficult for the receiver to accurately demodulate the signal.
This is why fidelity and flexibility are paramount – they enable analysis to be performed in the evaluation of early designs with 5G waveforms that may use a variety of modulation schemes at many different frequencies and modulation bandwidths. For developers, the risk of choosing the wrong path further reinforces the need for flexibility, especially in the form of signal-creation and signal-analysis tools that enable rapid changes in direction as new frequencies, bandwidths and waveforms emerge in the evolution of 5G.
5G presents a myriad of new challenges in research and development. Some of the key discussions fall into a set of six technology characteristics: 1000X higher mobile data volume per geographical area; 10 to 100X more connected devices; 10 to 100X higher user data rate; 10X lower energy consumption; end-to-end latency of < 1 ms; and ubiquitous 5G access including in low-density areas. The technology must be capable of supporting a greater density of users, higher data throughput, and more efficient utilisation of allocated spectrum. New waveforms supporting these goals may require advanced signal processing and adaptive channel estimation, as well as equalisation to improve signal robustness and improve immunity from interference. The minimisation of self-interference helps contribute to better receiver sensitivity. Multi-antenna technologies such as MIMO will be critical to support high data throughput and user density, and advanced techniques such as massive MIMO and adaptive beamforming will be used to improve capacity. Both MIMO and adaptive beamforming require sophisticated algorithms that need to be tested and validated. Some devices will need to operate across multiple frequency bands with new and legacy 4G radio access technologies, including 5G millimetre-wave frequency band extensions for high data throughput applications.
The pursuit of higher data throughput is a constant in the evolution of wireless standards. In 5G, this points towards the use of multi-carrier waveforms, millimetre-wave frequencies and wider modulation bandwidths. Some of the desired characteristics include flexible and scalable waveforms, optimised multiple-user access, the efficient use of allocated spectrum, low latency, simultaneous operation of synchronous and asynchronous traffic, and coexistence with legacy waveforms.
As developers characterise and validate their designs, a high performance, highly flexible testbed will enable them to evaluate diverse waveform scenarios with prototype algorithms and hardware. It will also make it possible to quickly and easily transition from simulation to physical testing of the prototype algorithms and hardware. More specifically, fidelity and flexibility are needed in three key areas of 5G early testing: generating and analysing new waveforms; supporting a wide range of modulation bandwidths from several megahertz up to tens of gigahertz; and supporting a wide range of frequency bands, from RF to millimetre-wave.
5G will be far more accessible than any other generation of network before it, due to better infrastructure and new advancements in wireless technology. Today, service providers, network equipment manufacturers, chipset and device makers are all working hard to facilitate the 5G revolution. The specifications for new radio technologies (like millimeter-wave and others) to be used will continue to evolve, but the industry as a whole is moving fast and is committed to 5G globally.