The need to constantly improve network performance requires more efficient use of spectrum, not just for radio access but for backhaul as well. By continuously pushing the limits of technology, even higher frequencies have been brought into use during the past few decades, a trend that will continue in the future.
Microwave backhaul technology plays a significant role in providing reliable mobile network performance across diverse locations, from sparse rural areas to ultra-dense urban environments. This technology enables the transport of spectrum from distances ranging from as little as 100 metres to 100 km, and is well equipped to support both the growth of long term evolution (LTE) and the introduction of 5G.
The microwave backhaul industry has started preparing for the next major technology and performance leap to accommodate the projected growth in data volumes during 2025-30. Making such progress requires strong research and development (R&D) and a great deal of work on spectrum regulations. The aim is to open up spectrum beyond 100 GHz frequencies to provide up to 100 Gbps of capacity. This will support different applications and use cases within hop distances of up to a few kilometres. In the longer term, microwave backhaul spectrum is expected to serve as a high capacity complement to spectrum in other frequency bands, especially in urban and suburban areas.
As per an Ericsson Report, by 2021, 65 per cent of the world’s tower sites (excluding those in northeast Asia) will be connected through microwave backhaul technology. The constant quest to provide higher data-carrying capacities has led to the use of higher frequency bands where more spectrum is generally available. The tremendous growth in the use of spectrum in the 70/80 GHz band that is seen today was made possible by several years of R&D, and significant modification in spectrum regulations, as well as because of the experience gained from the deployment of several technologies and product generations.
Industry leaders are now working on the next major technology and performance leap, which requires long-term use of frequencies beyond 100 GHz, to support the shift to 5G by 2030. Similar efforts are under way in the microwave backhaul space for spectrum beyond 100 GHz. This is also being supported by the rapid evolution of high frequency semiconductor technologies and the introduction of promising new devices.
The way forward
Large-scale deployment of beyond 100 GHz solutions is expected to be seen between 2025 and 2030. The W-and-D bands will be able to support capacities in the 5 Gbps to 100 Gbps range, over distances of up to a few kilometres. Higher frequencies are more limited in terms of reach and coverage, but they can provide wider frequency bands and have higher data-carrying capacities.
Driven by the growing communication needs, higher frequencies have been brought into use over the years. The sector has come a long way from using frequencies of just a few GHz earlier for microwave transmission. At present, spectrum in the 70/80 GHz band to 71-76 GHz band paired with that in 81-86 GHz is rapidly gaining popularity, as it enables capacities in the 1-20 Gbps range over a few kilometres. It has taken about 15 years for such large-scale usage to take off. Similar efforts are now under way to enable the use of frequencies beyond 100 GHz for capacities in the 5-100 Gbps range over distances comparable to 70/80 GHz.
LTE is evolving rapidly and 5G is emerging as the next step for providing enhanced and diversified services and use cases. This technology evolution will put new demands on the mobile backhaul. Networks will evolve to higher throughput and lower latency, depending on the available radio spectrum and service demands.
The Ericsson Mobility report predicts that India, along with North America, will lead the way in terms of 5G subscriptions by 2022, and that 5G will accelerate digital transformation in a number of industries, enabling new use cases in areas such as internet of things, automation, transport and big data.
The groundwork for 5G technology is already in place, in terms of the platform, the radio product, modems, routers, etc. What we need is a regulatory framework and a solid backhaul technology to ensure that the reach of 5G is at a pan-Indian level.
5G is set to play a big role in fulfilling the vision of Digital India. To this end, backhaul from 100 GHz and above will prove to be the backbone for all the innovation and capabilities that 5G can bring in the future.