On 18 February 2015, Frost & Sullivan hosted a virtual panel on 5G featuring speakers from National Instruments, Alcatel-Lucent, and NYU Wireless, which are among the leading companies and research institutions at the forefront of 5G technologies working to move forward the 5G agenda. A number of companies and academic institutions notably in Europe and Asia but also in America are making significant R&D efforts on 5G technologies aiming to make it a reality by 2020. This article highlights the key points regarding technology issues brought to bear during the panel discussion.

In contrast to previous cellular technologies for which the roadmap was relatively set for years ahead, there are significant opportunities for contribution with 5G, which has captured the imagination of the research community. NYU Wireless, for example, has focused on moving the cellular standards to higher frequency bands (28 GHz and above). It has made initial measurements in the NYC area demonstrating viable connections could be made and significant improvements in capacity could be achieved through the use of very high frequencies. National Instruments is currently working with about 25 to 30 organizations to advance 5G technologies including NYU Wireless on millimeter wave (mmwave), Lund University on real-time Massive multiple-input multiple-output (MIMO) concepts, and TU Dresden on generalized frequency division multiplexing (GFDM). The company has developed prototyping platforms using software-defined radio (SDR) technology. It has released a special version of LabVIEW to enable researchers to prototype faster and move their algorithms directly to the hardware to prove their designs in real-world conditions.

A key issue with 5G currently remains to find a suitable replacement for orthogonal frequency division multiplexing (OFDM), which is an issue on which Alcatel-Lucent’s Bell Labs has spent a significant amount of time and resources. 5G needs a flexible air interface where parameters like sub-carrier spacing may be optimized for a specific need and vary in different sub-bands. With 5G, some devices could communicate with open-loop communication while others may use closed-loop communication requiring parameter optimization but this is likely to translate into interference, which is difficult to address with OFDM. Candidate waveforms include GFDM, filter bank multicarrier (FBMC), and universal filtered multicarrier (UFMC). The difficulty in using FBMC for control channels and short packets has led some organizations to shift their focus to UFMC (also called UF-OFDM) as it applies filters to a set of sub-carriers, and this can be adjusted depending on the application.

Another important issue with 5G that stirs up much debate is about the best-suited high frequencies for 5G. While many think 60 GHz is most adequate, its ability to absorb radio waves makes it unlikely to be a good fit for 5G. Other frequencies are better positioned to handle long-range links in the order of hundreds of meters, making them more adequate. These frequencies include 15 GHz, 24 GHz, 38 GHz, and the C band (71–76 GHz) although the use of 10 to 24 GHz frequencies for backhaul may lower their chances of becoming the frequencies of choice for 5G. In addition, there are other spectral opportunities below 6 GHz as 6 GHz is not exhausted.

The different 5G technologies are at different stages of maturity; mmWave requiring more research than others. As a result, higher band technology is expected to come later in the standardization process. While these bands have been used for backhaul, they have not been used for access, and their harsh propagation conditions require significant research to be performed. While the focus currently is heavily on prototyping platforms due to the nascent nature of 5G technologies, the move to higher frequencies is expected to increase demand for test equipment with a higher frequency range. While there is test equipment with a high frequency range available in the market, the offering is much more limited than below 6 GHz.

With ambitious targets that go far beyond increasing data rates, 5G certainly provides research institutions and industry participants with significant challenges. Massive MIMO systems with hundreds of antennas present significant challenges in terms of data throughput, signal processing, computing capability, and synchronization. These challenges also have ripple effects like pilot pollution. Synchronization in Massive MIMO is especially challenging for researchers due to the clock distribution. However, 5G technologies are not mutually exclusive, and some can help alleviate the challenges posed by others. For example, high frequencies can help alleviate the challenge of very large antennas as antenna dimensions scale with the wavelength.

Despite the technological challenges posed by 5G technologies, progress is being made constantly. There have been demonstrations of massive MIMO. Prototypes have been built achieving 5 Gb/s or even higher, which already represents a significant improvement over 4G. Recently, Samsung demonstrated a very high rate production with mobility using mmwave technology. Prototypes for candidate waveforms including FBMC and GFDM have also been built and run in real-time. Looking back at the evolution of previous cellular technology, 2020 for the first deployments is a realistic objective. Around that time, some users are expected to receive a cellular experience radically different from today.

 For more insights regarding these aspects and others such as 5G targets, standardization, potential restraints, and early deployments, click here to listen to the full webcast.