With the growth rate of data demand and usage in the country shooting skywards, the capacity crunch is becoming more pronounced. The introduction of high speed services like 3G and 4G has made backhaul as important for operators as access networks. In the absence of adequate backhaul links, users cannot avail of high speeds, irrespective of the access network deployed by an operator. Backhaul networks are also needed for handling a range of new functionalities like quality of service and resilience management.

As a result, revamping backhaul set-ups has become a priority area for many operators and this has resulted in a number of new trends in the backhaul space. Key among these is a strategic shift in favour of deploying more fibre in backhaul networks. Even though expecting microwave links to give way to fibre in the medium or long term will be wishful thinking as the former continues to dominate, the two technologies have started coexisting in a major way. In recent times, the microwave-fibre mix adopted by operators has shown a fairly healthy share of fibre deployment, at least in urban areas.

Operator strategies

Given the growing bandwidth demand, existing backhaul networks at many cell sites have themselves become bottlenecks for mobile operators and are affecting their ability to offer quality networks and data services. Without an efficient mobile backhaul strategy, 3G and 4G operators will find it extremely difficult to offer an uninterrupted user experience to smartphone owners who demand high speed internet data downloads on the move.

While the current 3G and 4G subscriber figures are not up to industry expectations, they will only grow in the future. Operators are accordingly fine-tuning their backhaul strategies to make their networks future-ready. The strategies that are being adopted are taking factors like total cost of ownership, technology and network complexity into consideration.

Operators are migrating from separate legacy ATM (asynchronous transfer mode) and TDM (time division multiplexing) backhaul networks to more cost-effective, converged, multipoint label switching (MPLS)-enabled and multi-purpose infrastructure. Apart from reducing operational costs, MPLS-based networks will serve as the best-suited future-proof platforms for delivering next-generation services. In the long run, a fully integrated network will also be able to handle several types of traffic on a single cell site. Another focus area is the deployment of hybrid or all-IP network equipment in the transmission segment. Operators need to take a new approach to transport planning for a successful and cost-effective migration to an all-IP network. However, they are more inclined to opt for all-IP backhaul while upgrading their existing infrastructure.

Operators have also started deploying hybrid microwave and fibre in secondary routes and connecting a growing number of sites through fibre to meet bandwidth and latency requirements. To a large extent, the quantum of spectrum available for long term evolution services will be a key factor in the decision made by operators on the mix of backhaul technologies.

Another alternative is backhaul sharing. However, only a few operators seem to be interested in this, for sharing fibre infrastructure in particular. Partnering with each other and dividing areas geographically for backhaul deployment can bring in synergy and lead to cost and time savings. Given the challenges faced in rolling out fibre networks in India, operators often perceive having a robust optical fibre network infrastructure as an  edge over competitors.

Other options that service providers can explore include aggressively building fibre aggregation hubs in order to backhaul traffic from three to five sites to central core nodes using fibre networks and intra-city fibre deployment in Tier II cities across the country.

Changing microwave-fibre backhaul mix

At around 100 Mbps, the bandwidth requirement for 3G and 4G is very high. As a result, 3G and 4G players across the world prefer to use optical fibre technology for backhauling the huge capacity. Wi-Fi hotspots also require fibre backhaul networks for carrying traffic. As these technologies get inducted into the mainstream, the need for Indian backhaul networks to undergo fiberisation is becoming more pronounced than ever. The industry has started witnessing a significant shift in the microwave-fibre backhaul mix, particularly in the case of large operators as several of them move their metro backhaul to fibre.

The growth in mobile data traffic is also expected to have an impact on the microwave-fibre mix deployed by operators. As per industry estimates, the country witnessed about 70 per cent growth in mobile data traffic in 2014, and the trend is expected to continue. Mobile data is expected to grow from 88 petabytes per month in 2014 to 1.1 exabytes per month in 2019. Thus, fibre has become the preferred mode for 4G deployment, as well as for high-traffic 3G sites. As per industry reports, the fibre to microwave ratio for some operators has started shifting from 1:5 to around 1:2. However, operators continue to adopt a selective approach while upgrading their backhaul networks, as a result of which the intent to connect every tower with fibre is lacking. A major impediment faced by mobile operators is the high cost of rolling out fibre networks. Seeking right of way is both an expensive and complex proposition, and the policy guidelines require a high degree of transparency and uniformity.

That said, fibre is expected to improve its share in the mix. At present, microwave accounts for about 80 per cent of an operator’s backhaul requirement, which could come down to 60-70 per cent over the next five years. The growing share of fibre in the backhaul mix, however, is not an indicator of microwave taking a back seat. The capability of microwave link-based backhaul has also improved significantly over the years owing to the development of innovative solutions and advanced models of existing products.

The way forward

Operators are looking to upgrade their backhaul bandwidths to meet the growing user demand for voice and data services. This is reflected in their constant endeavour to upgrade backhaul networks in line with new technologies. Going forward, the industry is likely to witness a significant representation of fibre in the backhaul mix. The coexistence of fibre with microwave will be crucial for supporting next-generation technologies, and for delivering a quality experience to users. Wireless technologies are the best means for providing last mile connectivity, and need to be supported by fibre backhaul networks for onward connectivity to national and international backbones. In the long run, only operators that make a timely transition to network IP-fication will stand to gain from the data deluge being witnessed in the country.