It is no secret that data traffic is skyrocketing. Increased access to the internet through smartphones and applications such as video streaming is already putting a huge strain on 4G networks. By the end of this decade, nearly a billion more users will have access to mobile internet, predicts GSMA Intelligence. That, in turn, will lead to an explosion in data traffic rates. In 2016, the average amount of mobile data traffic generated per smartphone was just 2.1 GB per month. By 2022, Ericsson estimates that the figure will jump to a whopping 12 GB per device per month.

Looking ahead, mobile networks will have to deal with more than just smartphone traffic. Future use cases such as augmented and virtual reality (VR) and connected cars promise to add exponentially to the amount of data traffic travelling across mobile networks. Connected cars alone could generate up to 4,000 GB of data each day from hundreds of on-vehicle sensors like cameras, radars and GPS.

As capacity needs continue to grow and connectivity extends to more regions, new backhaul technologies will be required to meet the demands of 4G and future 5G networks where there is no feasible fibre-based solution. Traditional line-of-sight microwave technologies will not be able to keep pace. In such a scenario, advanced hybrid wireless technologies offer a new avenue in backhaul that can cater to the gigabit demands of today and tomorrow.

Meeting the need

According to GSMA Intelligence data, the number of global mobile internet subscribers has risen from 2.18 billion in the fourth quarter of 2012 to 3.96 billion in the fourth quarter of 2017. By the close of 2020, the total number of mobile internet subscribers worldwide will reach nearly 4.7 billion.

In order to meet the growing data de­mands, operators in mature and develo­ping markets alike are spending big on their networks. To support the impact of more devices connecting to the network and using more data over longer periods of time, as well as future 5G use cases, GSMA Intelligence noted in a recent analysis that operators will need to deploy 1,000 times more bandwidth per unit area in their networks. However, while formulating dep­loy­­ment plans, operators must balance the cost necessary to prepare a site for a new cell with the actual benefit of adding coverage in a specific area. These choices also come with significant implications for opex related to backhaul and power.

Overcoming roadblocks

Wireless backhaul is a technique that operators in both developed and developing markets are using to aid deployment in places where traditional methods are not feasible due to cost, schedule or regulation issues. In contrast to fibre, wireless backhaul presents a low-cost option that can be deployed in a matter of days or weeks. GSMA has forecasted that the use of microwave and millimetre wave backhaul will grow to account for 61.5 per cent of worldwide backhaul links by end-2019.

A step ahead: Why current systems need an upgrade

As millions more around the globe get connected, existing wireless backhaul systems will require significant upgrades in the areas of capacity and traffic management, without compromising resiliency. The advent of 5G will place even greater demands on networks globally.

  • Capacity: Legacy microwave backhaul systems can support speeds of 500 Mbps to 600 Mbps. While this figure can be doubled using dual polarisation, even this would not be enough. The increase in connections and data-heavy use cases like VR, internet of things, connected cars and 4K video streaming will demand even more capacity from a new generation of wireless links. New network technologies like edge computing will also drive the need for more capacity in wireless networks, including requirements for space and power to compute on the fringe of the network rather than in the core.
  • Traffic management: There is also a need for new wireless backhaul systems to address differences in the types of data that will be travelling across mobile networks. Until now, operators had built separate networks for cellular traffic, internet traffic and network management. But these networks will merge and be virtualised in 5G, meaning that operators will need to provision a large number of network slices within a single network to ensure quality of service (QoS) across applications.
  • Resiliency: Since 4G and 5G networks are increasingly incorporating mission-critical data, wireless backhaul systems must offer more resilience than ever be­fore. Wireless backhaul systems that rely solely on either ultra high frequency E-band spectrum or free space optics (FSO) in particular are subject to delivery interruptions caused by weather conditions. While E-band solutions remain strong in fog and smoky conditions, significant deterioration can occur in rainy weather. In contrast, FSO solutions perform better in the rain, but face challenges in limited visibility conditions, such as in instances of fog and smoke.

Case for hybrid

There are a number of hybrid solutions already in the market, many of which use a combination of E-band and microwave frequencies. However, as these hybrid solutions pair a high capacity (10 Gbps) E-band link with a low capacity (<1 Gbps) microwave link, only a portion of the data sent over the link benefits from the resiliency of lower microwave bands.

Another take on hybrid wireless backhaul combines FSO technology with E-band spectrum to deliver high capacity links with increased resiliency. As noted above, the two technologies feature complementary strengths. FSO performs well in rainy conditions that can impact E-band performance while E-band can withstand the foggy conditions that can hamper FSO delivery. And, because E-band and FSO links can both carry 10 Gbps, this hybrid option offers additional capacity benefits over those seen in hybrid E-band/ microwave systems.

What is right for a gigabit future?

Looking ahead to a gigabit future, it is important to recognise the advantages that FSO E-band hybrids offer over other backhaul solutions. FSO E-band hybrids have a capacity advantage over their E-band/ microwave counterparts because they combine two high capacity links rather than using one high capacity link alongside a lower capacity microwave spectrum. They also provide better coverage in diverse weather situations, mitigating the rainy weather stumbling block that remains present in E-band-microwave links.

FSO requires no spectrum licence for operation, while E-band licences around the globe are much cheaper than licences for lower band spectrum. In many cases, E-band licences can even be acquired for free. This means that companies looking to deploy a hybrid solution can save on what might otherwise be prohibitive spectrum costs.

Wireless backhaul solutions more generally offer time-to-market benefits as well. Where installing new fibre can take months, wireless backhaul systems can be set up quickly and with little manpower.

Getting the industry interested in hybrid

Mobile traffic has long been on the rise, but growing 4G and future 5G networks are poised to take traffic to the next level. Operators and their infrastructure will face exponentially more traffic and different types of it. Rather than defaulting to fibre, mobile stakeholders would do well to look at all the options on the table, including hybrid wireless backhaul solutions, to meet their network needs.

Hybrid systems that use E-band and FSO can continue to offer operators a solid backhaul option that can keep up with next-generation networks. Both E-band and FSO technologies support multi-gigabit capabilities that will be necessary to serve heavily burdened networks. Working together, these two technologies can overcome weather-related scattering and absorption challenges to provide operators with a reliable, high capacity link at a lower cost than fibre.

Operators like Verizon, Vodafone and Telstra, and other ecosystem partners like Nokia, Ericsson and Huawei are among those that can benefit from the use of hy­brid wireless backhaul systems. Tech giants like Facebook and Google also stand to gain from the use of hybrid wireless backhaul options for their internet connectivity initiatives.

Additionally, standards bodies including 3GPP, IEEE, Broadband Forum, Small Cell Forum, Open Networking Foundation, Telecom Infrastructure Pro­ject and ETSI are among those well placed to help define terms such as “programmable high-capacity hybrid wireless link”, set standards for operations, and ensure interoperability between systems.

Now is the time to explore these systems in earnest so that all parts of the network including backhaul can be made future proof.

Based on a whitepaper, “Advanced Wireless Backhaul for Data-driven Future”, by Collinear and Mobile World Live