The mobile backhaul set-up is an essential component of any operator’s network. In India, 80 per cent of mobile cell sites use legacy time division multiplexing (TDM)-based microwave backhaul systems between an operator’s base station and aggregation points. This is primarily due to a lack of optic fibre infrastructure. Though optic fibre is scalable for a traffic increase in 3G and broadband wireless access (BWA) networks, it is difficult to deploy, especially in dense urban or remote rural areas.

Owing to the proliferation of 3G services and the demand for various bandwidth-hungry applications, mobile operators are facing a significant increase in bandwidth demand on their backhaul networks. At the same time, operators are faced with the challenge of significantly reducing operational costs in order to compensate the decline in ARPUs, besides tackling competition and adopting new technologies.

In this context, backhaul networks of many cell sites have become bottlenecks that provide insufficient capacity to support higher bandwidths and are often expensive to upgrade.

Therefore, a comprehensive mobile network that supports 2G and 3G services (such as TDM service, clock synchronisation, multiple transport interfaces) and also accommodates long term evolution (LTE) transmissions for the future is the need of the hour. The mobile infrastructure must also support the key requirements of an LTE network, such as mesh IP traffic, support for L3 virtual private networks and high bandwidth.

However, there are a number of issues and challenges with regard to mobile backhaul that need to be dealt with.

Backhaul costs

Today, apart from traditional voice services, mobile operators are exploring a range of next-generation data services to generate revenues. However, these 3G-based services require a substantial increase in bandwidth, which, in turn, will lead to greater mobile backhaul costs. As per industry estimates, backhaul can account for as much as 30 per cent of a mobile operator’s  opex. Hence, if mobile operators were to expand the backhaul network to meet new bandwidth requirements, there could be a significant increase in the associated opex.

Almost 1.5 billion mobile subscribers are expected to be added between 2011 and 2015 as per industry estimates. Thus, more base stations, cell site connections, higher backhaul capacities, and equipment for each cell site connection would be required to meet the increase in demand for services. According to Juniper Research, operators worldwide would have to spend a combined amount of $840 billion over the next five years to upgrade their backhaul networks for the expected deluge of data demand.

Data-ready network

As the demand for data increases, an operator’s backhaul network should be able to provide enhanced service quality, accommodate bandwidth-heavy applications, support various generations of technologies and be future-proof. These elements would become increasingly important as mobile operators migrate to packet-based backhaul networks. However, according to industry analysts, the backhaul infrastructure being deployed at present would not be able to meet the growing data demand.

Analysts argue that Indian operators did not invest substantially in upgrading their legacy systems before launching 3G services, which means that their networks are not future-proof. “Being a price-sensitive market, more so at the time of launching 2G services, operators’ backhaul networks were originally built using very low-cost, often heavily low-featured, microwave equipment,” notes a market analyst.

Excess traffic

An increasing number of consumers are demanding multiple applications via the mobile network rather than over fixed connections, creating greater pressure on backhaul networks to meet the growing demand while maintaining an end-to-end user experience. This trend is set to continue as, though there are many consumers still migrating from 2G to 3G, there are some operators like Bharti Airtel that have already explored and adopted 4G technology (like LTE).

The road ahead

Several new technologies for mobile backhaul are expected to come to the fore. According to the Broadband Forum, Ethernet-based connectivity is being rapidly adopted at cell sites. This approach, in addition to being highly scalable and reliable, helps in bridging the gap between legacy and next-generation networks and services, providing the flexibility to support both.

Further, according to Juniper Research’s estimates, microwave technology will account for over 60 per cent of the world’s backhaul capacity by 2016. In India, microwave is expected to account for 87 per cent of backhaul capacity within the next five years.

According to Tejas Networks, operators are looking for a solution that takes care of both TDM and IP traffic. This demand can be met by a packet optical transport solution, which, Tejas Networks says, would dominate backhaul capacity in India by 2015.