Significant investments were made in deploying telecom backhaul infrastructure to meet the demand for 2G voice services. With the industry now moving towards 3G and 4G technologies, backhaul networks need to be augmented so that they are capable of handling increasing data traffic and categorising services based on priority and traffic volumes. The key differentiators for a sustainable backhaul network are better quality of service (QoS) and low latency.

Telecom operators in India are taking various approaches to deploy 3G and 4G backhaul networks. While some are rolling out a pure packet carrier Ethernet network, others are adding packet processing capabilities on their 2G networks. The difference in the approach is based on the existing network infrastructure, which varies across operators. While the large incumbent operators own end-to-end networks, most of the new entrants lease bandwidth from third parties to optimise costs.

According to research firm Ovum, Indian operators will continue to spend significantly on their backhaul networks. It is estimated that the backhaul market in the country would witness a compound annual growth rate of 15 per cent from $359 million in 2010 to $825 million in 2016.

tele.net takes a look at the key technology trends and operator strategies as they make a transition towards next-generation backhaul networks...

Operators undertake IP-fication and packetisation

Telecom operators have realised the need for IP-fication of networks to provide a quality data experience to users. Most operators, which have been using time division multiplex (TDM)-based networks, are now shifting to packet-based ones.

For example, Idea Cellular plans to migrate its existing TDM-based network to an all-IP domain in the top 100 towns to meet the growing demand for 3G services and support the uptake of 4G services. The operator has already converted the majority of its 3G network into an all-IP network and its 3G sites are based on IP-powered radio technology. Bharti Airtel has also migrated to a CEN-based IP access network which meets the higher bandwidth requirements of 3G, 4G and DSL broadband subscribers.

Globally, the transition to all-IP infrastructure has been a gradual process. By and large, players can explore three approaches while migrating their TDM-based networks to an IP-based platform. In the first case, operators can continue to use their traditional backhaul infrastructure, aggregate leased lines, share bandwidth between 2G and 3G networks, optimise networks and subsequently switch over to packet infrastructure. In the second approach, they can adopt a hybrid infrastructure that uses TDM technology for supporting voice services and offloads HSPA data traffic to a separate packet network. In the third approach, operators with deep pockets can directly migrate to an all-IP backhaul and in turn save infrastructure costs.

The hybrid approach adopted by European operators is best suited for Indian operators, who have a huge debt burden and limited resources to modernise their networks. This approach helps operators address the issue of managing growth in data traffic while safeguarding their investment in the current backhaul infrastructure.

Meanwhile, new entrants or players that do not have TDM-based backhaul, can directly migrate to Ethernet backhaul. Videocon Telecom, one of the latest entrants in the Indian telecom market, has followed this strategy by building its backhaul infrastructure using IP and MPLS technologies. The company replicated the success story of global operators such as Japan’s EMOBILE, which bypassed the TDM-based network in favour of a packet-based network. EMOBILE currently offers high speed broadband connectivity to subscribers through HSDPA and the operator backhauls all traffic over Ethernet using asynchronous transfer mode pseudo-wires.

Optimising fibre deployment

Despite cost- and technology-related concerns, Indian operators are investing in upgrading their legacy networks to support high speed 4G services. Following in the footsteps of their global counterparts, they are realising the need to invest in fibre technology. For example, the majority of telecom networks in Europe and North America are already evolved to support 3G and long-term evolution (LTE) services. About 50 per cent of the telecom sites in these markets are connected through fibre, while in India, fibre penetration stands at 15-20 per cent. However, operators are now stepping up efforts to modernise their networks and making significant investments to use fibre as the backbone of their backhaul networks.

While ensuring that they optimise the available and new deployments, operators are careful of not overspending on greenfield deployments. A key strategy has been the signing of network sharing agreements. One of the most awaited 4G players, Reliance Jio Infocomm Limited (RJIL) signed an infrastructure agreement with Reliance Communications (RCOM) and has gained access to the latter’s large optic fibre cable (OFC) network of 120,000 km. RJIL will lease capacity on RCOM’s nationwide intercity OFC network for a one-time payment of Rs 12 billion, while RCOM will have access to RJIL’s OFC infrastructure. Since fibre backhaul is crucial for supporting high bandwidth services, RJIL is currently laying fibre in major metros including Mumbai and Kolkata. At present, the operator is laying 1,750 km of OFC in and around Kolkata.

The country’s leading operator and the first player to introduce 4G services, Bharti Airtel has also been augmenting its OFC network over the past few years. At present, the operator has 120,000 km of fibre networks. Other players including Idea Cellular and Vodafone India have also been expanding their OFC networks, which cover 74,000 km and 120,000 km respectively.

Strengthening microwave backhaul

Although fibre is capable of handling the traffic growth on 3G and LTE networks, it involves deployment-related challenges, especially in dense urban or remote rural areas. Therefore, dependence on microwave backhaul will increase in the future. Recent innovations in microwave technology, in particular the use of multiple antennas and higher-order modulations, have resulted in a significant increase in the capacity of microwave links. According to equipment vendors, the peak capacity of LTE base stations on 20 MHz bandwidth is 300-350 Mbps. Microwave backhaul, on the other hand, can deliver 1 Gbps links.

While this may not be adequate to support data traffic in dense urban areas, new and improved microwave backhaul networks can become a major component of the telecom network connecting rural towns for both mobile and data coverage. According to Heavy Reading’s “Backhaul Strategies in India” report, femtocell and E-band technologies are also likely to play a major role in microwave backhaul deployments as they will help in reducing congestion. These systems can be used as an overlay on existing microwave backhaul networks to meet capacity needs.

The way forward

The demand for mobile data has increased following the launch of 3G services. Further, with the upcoming large-scale launch of 4G LTE, these high speed services are expected to account for the highest share of data traffic.

Going forward, as the uptake of smartphones, tablets and other devices increases over the coming years, the number of broadband users is likely to increase significantly. Several applications and devices like smartphones and dongles are currently operating at speeds of 21 Mbps, which may go up to 100 Mbps once 4G LTE gains traction. In this scenario, an efficient mobile backhaul strategy is required for offering an uninterrupted user experience.

Given the current trends, future backhaul networks in India are likely to be a hybrid of fibre and microwave links, with carriers using microwave only where fibre is not available and/or affordable. However, building robust and scalable backhaul capacity will be key to deploying high performance 3G and LTE networks, regardless of the technology used.