The battle for 6G is on, and both China and the US are eagerly vying for the top spot. As 5G is gradually rolled out across the globe, anticipation is already building for the next generation of mobile communications technology, 6G. Over the coming decade, we can expect to see a race between vendors, operators, research bodies, and academia, competing to define the landscape of 6G. One of the key questions that research into 6G will investigate is whether it will require a new waveform.
OTFS: the new waveform?
Currently, both 4G and 5G are based on the Orthogonal Frequency Division Multiplexing (OFDM) waveform. This modulation format while effective for many use cases, is prone to signal degradation in high-mobility scenarios, such as streaming while on the move, hence it is not suitable for critical communications at very high speeds. 6G will be developed with these types of use cases in mind, therefore one of the first major specifications for 6G is likely to be that it uses a different waveform. One interesting candidate is Orthogonal Time Frequency and Space (OTFS).
OTFS is a new waveform giving rise to a powerful two-dimension modulation format. Compared to the existing OFDM modulation format used by 4G and 5G, OTFS provides 3-7 dB performance gains in high mobility scenarios as it enjoys resiliency to high Doppler shifts. Among the benefits of OTFS are its capacity to exploit full time-frequency (TF) diversity and its ability to work well in high Doppler fast-fading wireless channels. In other words, the OTFS waveform is adaptive to complex methods of communication enabling a range of high-mobility use cases that are already being associated with 6G. This also includes immersive technologies such as AR and VR, further sophistication of artificial intelligence, and the use of robotics.
Mass mobility
Advanced technologies, such as those mentioned above, require waveforms adapted to high mobility like OTFS. While 5G was originally touted to be high mobility, its PHY (physical) layer has ended up occupying the same waveform as 4G before it. It looks like mobility will be a key benchmark for future connectivity, and it is encouraging to see that people are linking the sixth generation of mobile connectivity with extreme mobility. 6G will likely become a multi-waveform standard fusing together previous generations, such as 4G and 5G. Fortunately, OTFS is a flexible format that can be seamlessly integrated with legacy 4G and 5G. Therefore, we can expect to see the fusion of these technologies over the next few years. If 5G does not live up to its expectations, then the development of 6G, incorporating new waveforms such as OTFS will be accelerated.
The geopolitics of 6G
The development of innovative new PHY technologies, such as OTFS, has implications for the wider geopolitical context. Tensions between China and the US have been exacerbated by the competition for the future of connectivity. As the race for 6G picks up pace, it will be the development of these new technologies that could enable operators to obtain a head-start in defining the future connectivity standard. China has taken the lead in 5G, and a Chinese telecoms giant recently boasted its plans for 6G to the rest of the world, releasing an ambitious statement announcing that the company aims to launch its 6G products by 2030.
The promise of OTFS
OTFS has the potential to give operators a significant leg up. It has already been widely endorsed as a promising candidate for the foundation of 6G by the global research community, leading mobile operators and vendors. OTFS can facilitate the differentiation of the sixth-generation connectivity standard as it offers enhanced performance in high mobility with robustness to channel distortions, thus delivering better performance for consumers and enhancing overall spectral efficiency for operators that are already investing billions in spectrum licenses. In addition, OTFS can be integrated into the mobile network using existing methodologies developed for previous generations as OFDM and CDMA. Beyond integration, the key challenge is to illustrate the potential value of 6G in general and OTFS in particular to society.
