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Redefining Backhaul: Need to move to an optimum fibre-microwave mix

May 12, 2017


The telecom backhaul ecosystem is undergoing a major change as capacity requirements grow exponentially on the back of increased 4G uptake. While fibre is becoming a necessity to support future data demand, operators are also exploring new microwave bands for a quick fix solution. Industry experts comment on the key trends in backhaul network deployment, operator strategies and key growth drivers…

(From left) Aditya Chaudhuri, Managing Director and Lead, Accenture's Communication, Media and Technology Group in India; and Vishant Vora, Chief Technology Officer, Vodafone India

How have operators’ backhaul strategies changed with the growing demand for data? What backhaul solutions are they currently using?

Aditya Chaudhuri

E1/T1 systems were used about 15 years back when operators were expanding their 2G footprint. These circuits, when configured in parallel, provided additional capacity. At the time, the maximum backhaul requirement per site was 2 Mbps, which was even shared among three or four sites where the utilisation was less. These systems are still used extensively across the country along with newer technologies. Most of these (over 75 per cent) are being fed by microwave-based backhaul. Older generation microwave backhaul is adequate for voice, but not for high-traffic loads as in the case of 3G and long term evolution (LTE) data networks. Here, the lack of bandwidth severely impacts latency, which is the key requirement for supporting heavy data traffic. While the peak capacity of LTE base stations on the 20 MHz bandwidth is in the range of 300-350 Mbps, according to equipment vendors, new age microwave backhaul can already deliver up to 1 Gbps links. It is therefore more capable of supporting the current pace of data uptake in India. As data uptake rises with increasing 4G deployments, the need for backhaul technology to support centralised and cloud radio access network, distributed and cloud mobile core and multi-access edge computing will increase further. This necessitates dynamic optimisation of bandwidth. To this end, operators are now focusing on fibre and advanced microwave systems with higher-order modulations to deliver increased capacity.

Vishant Vora

The introduction and adoption of 4G have transformed operators’ backhaul strategies. This has not only forced them to upgrade their networks in terms of capacity but has also led to a transformation to an all-packet transport infrastructure. Vodafone, because of its global best practice sharing, underwent this transformation early during the introduction of 3G networks and started investing strategically in creating a high capacity packet backhaul infrastructure that is also future fit. We are seeing a significant growth in the backhaul utilisation space. Owing to an efficient backhaul design, we have also been able to roll out our LTE networks in double-quick time without compromising on the quality of networks, or on the customer experience.

What is the current microwave-fibre mix in operators’ backhaul network? How do you see it change in the future?

Aditya Chaudhuri

Mobile backhaul accounts for 25-40 per cent of an operator’s capex and a significant part of the opex. The current mix is still heavily in favour of microwave, as much as 75-80 per cent. Going by the evolution of backhaul technologies in developed economies, a mix of microwave and fibre would be the ideal choice for India. Even advanced microwave backhaul will not be able to sustain the bandwidth requirements of LTE Advanced (LTE-A) and 5G and therefore, it is imperative for operators to move to fibre. Operators like Reliance and Bharti Airtel have recognised this need and have started undertaking large-scale fibre roll-outs. In order to complement their fibre backhaul infrastructure, the sharing/ leasing of fibre-based networks of local cable companies, particularly in Tier II/Tier III cities, is a strong likelihood. This will result in reduced capex and fewer right-of-way (RoW) issues. In remote areas, wired backhaul will be expensive and difficult to deploy. In such cases, wireless or satellite could be a more viable option with a multi-hop architecture to create large and efficient coverage areas.

Vishant Vora

In the current microwave-fibre mix, fibre accounts for over 35 per cent in top town metros and about 20 per cent in Tier II and Tier III towns. This is likely to see significant growth (at least 2x), despite the potential introduction of E-band/V-band microwave later this year. Any delay in the regulation around E-band/V-band would have a greater impact on fibre requirements.

What are the key challenges faced while upgrading backhaul networks? How can these be resolved?

Aditya Chaudhuri

Microcell performance can be improved by boosting baseband processing power, adding small cells and deploying dedicated indoor solutions based on the 3GPP standard. This approach can include the use of microcells, picocells or low-power remote radio units along with Wi-Fi. However, the deployment of small cells as part of a heterogeneous network solution will involve the installation of thousands of new sites. Managing the deployment of such a large number of radio and backhaul sites will be a key challenge to deliver on budget.

The cost of installing and maintaining the chosen backhaul solution needs to match the anticipated volume of data traffic and revenues without compromising on the desired quality of service. A major challenge here pertains to forecast accuracy and the effort required in capacity optimisation to maximise the return on investment in existing network nodes. This becomes particularly relevant in areas where the network is serving a small subscriber base. It is important to enable dynamic flexibility in backhaul networks and ensure reuse of existing resources to support short time to market at the right cost. A self-organising network would be a major enabler in driving automation and flexibility in planning, installation, maintenance and optimisation.

Vishant Vora

The challenges in the backhaul space mainly revolve around regulation, be it the licensing for E-band/V-band microwave spectrum or the high RoW charges that are subject to the regulations of various municipal bodies and PSUs. While the government has attempted to address this issue, a lot more simplification and optimisation are required in this space. The other challenges in backhaul augmentation are linked to practical considerations around infrastructure availability and permissions for trenching for fibre.

Going forward, what new trends, solutions and growth drivers are likely to emerge in the Indian backhaul market?

Aditya Chaudhuri

Carrier Ethernet has become a widely used technology as it provides significant bandwidth based on the industry standard interface/protocol. It can be carried over copper, fibre or microwave. Of late, operators have also started using digital subscriber line and asymmetric digital subscriber line (ADSL) for offloading backhaul traffic. This allows mobile phones to use Wi-Fi when in the range of a hotspot. Femtocells are also finding use in cases where ADSL is used for mobile backhaul.

With the proliferation of smart cities and internet of things, there will be a need to redefine the backhaul infrastructure. The ideal strategy would be a mix of technologies that best manages the backhaul traffic. This, in turn, would depend on the spectral efficiency of the radio equipment and the type of traffic (voice or data). The growth of microwave and fibre backhaul in metropolitan, urban and suburban areas will be largely driven by small cell solutions. Since operators will choose their technology, there will be a natural tendency to move towards backhaul infrastructure sharing in order to reduce the total cost of ownership.

Vishant Vora

Backhaul architecture will continue to evolve at a rapid pace with the increasing demand for bandwidth at every site and fronthaul becoming another buzzword.

How will operators’ backhaul needs change with the roll-out of 5G? What will be the optimum mix of backhaul technologies for 5G?

Aditya Chaudhuri

In order to support 5G networks, operators will have to move to fibre for backhaul. This will help meet new requirements for security, timing, latency and QoS. However, in India, since data usage continues to be a matter of concern with not more than 50 per cent of 3G capacity being utilised and continued customer reliance on voice communication, microwave will remain a technology choice for backhaul to support the resultant heterogeneous networks. We are, therefore, likely to see more advanced millimetre-wave line-of-sight systems being deployed with point-to-multipoint hub-and-spoke architectures to support the backhaul requirements. Following the deployment of 5G or LTE Advanced, we are likely to witness a steady growth in fibre backhaul, accounting for 30 per cent of the backhaul networks by 2020.

Vishant Vora

The investments in the backhaul/front space will continue to grow as operators prepare their networks for LTE-A Pro and beyond. Fibre will be the mainstay for creating versatile heavily layered radio networks with support from V-band/E-band and other millimetre-wave microwave technologies. From a technology perspective, Vodafone sees packet/Ethernet as the predominant technology in both the backhaul and fronthaul spaces.



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