Perry Yang, president of Huawei's microwave product line, is adamant that microwave backhaul is here to stay. Not only in supporting carriers' evolution paths from 4G to 5G, but also on their longer term journey. Microwave backhaul is a safe investment, he insists, because it can meet spiralling demand for more capacity and low-latency connections in places where it is economically not feasible to roll out fiber.
"Many mobile operators don't have sufficient fiber infrastructure, which is where microwave comes in," he enthuses. For him, microwave backhaul is future-proof.
Yang is far from being a lone industry voice. A recent report published by the GSMA – Wireless backhaul evolution: delivering next-generation connectivity – anticipates that microwave backhaul, with around a 65% market share, will account for the majority of global backhaul links from 2021 to 2027.
Huawei's expectation of continual improvements in microwave backhaul performance chimes with the report's market-share projections. "We're going to introduce lots of interesting new innovations to substantially increase bandwidth and transmission distances," promises Yang.
Huawei intends to increase current capacity of E-band (71GHz–76GHz and 81GHz–86GHz) from between 10Gbit/s and 20Gbit/s – which already gives many carriers plenty of bandwidth headroom – to 50Gbit/s. Further down the road Huawei is aiming to develop products for D-band at 130GHz. "We're looking to provide D-band capacity of 100Gbit/s while supporting signal distances of 1km," says Yang.
It is not just the prospect of greater capacity that should reassure carriers, he maintains, but lower rollout costs and quicker time-to-market in comparison with fiber buildouts. "Our work on microwave is designed to provide the most cost effective backhaul solution to support greater capacity and a long transmission distance," says Yang. He thinks microwave will develop in tandem with fiber. "Microwave and fiber are complementary," he says.
A main driver behind Huawei's microwave backhaul R&D, emphasizes Yang, is to "give operators greater value for their money." Another factor is the welcome socio economic benefit of enabling operators to provide rural areas and villages with a high-speed Internet service – something that is not economically feasible if solely relying on fiber.
Make E-band go the distance
While E-band is an ideal mobile backhaul frequency range in many ways – low spectrum and equipment costs, points out Yang, and an ability to provide high capacity – its Achilles Heel is comparatively short transmission distances. Places where there is high rainfall can also restrict E band reach. But Huawei, reassuringly for carriers, is already well down the innovation path when it comes to tackling this shortcoming.
At the 2020 Global Mobile Broadband Forum held in Shanghai last November, Huawei unveiled its long-reach E-band Solution. By using a combination of Huawei's intelligent beam tracking (IBT) antenna and its high-power E-band solution, the long-reach product is able to increase E-band transmission distances from 3km to 5km while still maintaining 20Gbit/s capacity.
Because it is a high-frequency band, an E-Band link is very narrow and so susceptible to misalignment. This is especially the case when masts are not steady, and antennas are exposed to high winds. Huawei's innovative IBT, however, self-corrects the antenna in the event of misalignment. This is a game-changer.
Antenna sizes have traditionally been restricted to 0.3m and 0.6m in diameter in an attempt to reduce the risk of being dislodged and causing beam misalignment, but Huawei, courtesy of IBT – industry's first active microwave antenna – was able to introduce a 0.6m antenna last year that is much more stable than previous dishes of that size. A 0.9m version is slated for availability in the second half of this year. Moreover, larger antenna sizes allow transmit power to increase by 6dB for E-band signals.
As carriers no longer need to rely on sturdy, unswaying masts to support bigger antennas, it means shorter time-to-market, more reliability, and an easing of pressure to pay for top-notch tower infrastructure. "In the next two years," maintains Yang, "the transmission distance of E-band will increase between 50% and 100%, providing greater capacity at lower cost."
The multiband option
While long-reach E-band can be an ideal solution in urban areas, it is not necessarily suitable for sprawling suburban environments.
"In many regions microwave needs to travel a distance of 10km or even 20km while providing high capacity, so E-band will not be sufficient," says Yang. "We needed another solution to provide greater capacity while still travelling long distances, which is why decided to bond different frequency bands."
Cue Super Link, a multiband antenna solution. Another microwave backhaul innovation from Huawei, and showcased at HAS 2021, Super Link was developed in response to carrier requirements and can support three frequency bands using a single antenna.
By not having to deploy different antennas for different frequency bands, Yang says carriers can reduce costs by between 30% and 40% when compared with traditional dual-band solutions, helped along by lower tower-rent expenses. "Our Super Link multiband offering can support 10Gbit/s capacity at a distance of 20km," he adds. "This can help carriers connect small villages and towns together, while still providing high capacity."
In 2019, at the Global Mobile Broadband Forum held in Zurich, Huawei released SuperHub. An innovative solution, SuperHub improves spectrum efficiency at aggregation sites or "hubs."
It does this by enabling spectrum, traditionally used only once within a 90-degree range, to be multiplexed three times. That capability, however, used to be only available to carriers that replaced their old antennas with new ones that were SuperHub-compliant. It is a requirement that no longer exists. Huawei has released a software-based version of SuperHub allowing carriers to reuse existing antennas to take advantage of the greater spectral efficiency on offer.
"The frequency band can be multiplexed every 30 degrees with SuperHub because of our interference cancellation algorithm, which means we can increase capacity at single hub side by nearly threefold," continues Yang. "In the future we'll be able to achieve 15-degree multiplexing."
With a series of microwave backhaul innovations under its belt, and more in the pipeline, Huawei seems well placed to satisfy carrier requirements for less costly alternatives to fiber in the backhaul without jeopardizing high-speed Internet experiences.
"Microwave backhaul has clear opportunities in the 5G era and beyond," says Yang.
This content is sponsored by Huawei.