Meanwhile, several operators are transforming their infrastructure based on traditional switching technologies (public-switched telecom network) to packet- switched all-IP owing to the increasing data traffic on networks. An all-IP network will not only support growing data traffic but will also help reduce complexities that arise during network planning and management. Also, operators are modernising their backhaul network to support LTE downstream speeds. For instance, South Korea-based SK Telecom has deployed an IP-based mobile backhaul solution to support speeds offered by LTE and LTE-Advanced services. Similarly, Zain Kuwait has installed an IP mobile backhaul system through the adoption of 100G IP and optical transport network integrated technology to provide high speed broadband services.

In the future, operators are likely to implement innovative backhaul solutions to provide greater bandwidth support at lower costs. Of the current trends, deployment of a self-organising network (SON) and leasing of backhaul infrastructure are gaining traction among operators.

tele.net takes stock of the current trends in the global backhaul network industry…

Microwave-based backhaul remains the most widely deployed technology

Backhaul networks have been deployed through both wireless and wireline technologies by operators across the world. While operators in the North American region have primarily used wired backhaul networks based on copper or fibre technologies, the deployment of microwave-based backhaul is increasing due to the benefits offered by the latter (such as lower opex and short time-to-market). Moreover, many service providers lease fibre infrastructure from local transport carriers instead of setting up their own network due to high upfront costs and expansive infrastructure of lessors.

In contrast, the majority of the backhaul network in Europe and Asia is based on microwave technologies and operators use spectrum in various high frequency bands due to the high roll-out cost of the wireline network. In Africa, most operators resort to satellite and microwave technologies for their backhaul infrastructure.

Despite the capacity constraints faced by existing networks, operators have been reluctant to deploy fibre technology for backhaul support. This is because while fibre-based backhaul is scalable in capacity terms and is reliable, it involves several challenges. The high investments associated with fibre network roll-out have been the biggest impediment to its adoption. Operators are facing severe margin pressure due to a decline in profitability, and, therefore, any investment in fibre-based backhaul will have to be justified to the investors. This has become all the more important as it has been witnessed that while data traffic has grown almost tenfold over the past few years, data service revenues have increased by only 20-30 per cent due to operators’ inability to monetise these services efficiently. Moreover, setting up a fibre network is not feasible in several areas, especially in urban regions where securing right of way (RoW) is the biggest challenge.

In contrast, deploying backhaul network using microwave technology is relatively easy and inexpensive, and involves considerably less time, thereby enabling service providers to gain a competitive edge. In addition, microwave can support several Gbps of bandwidth and can be scaled in a cost-effective manner using aggregated link technologies. However, one of the downsides of microwave is the declining availability of spectrum in the high frequency bands, which could force operators to partly switch to fibre technologies. However, microwave will continue to be preferred over fibre till the latter’s deployment costs reduce substantially.

Infrastructure leasing for cost optimisation

Even as operators are upgrading their primary backhaul infrastructure, the majority of them are increasingly opting to lease infrastructure due to challenges involved in setting up additional networks. Moreover, this significantly reduces the time-to-market, which has become one of the biggest determinants for the success of service launches. The trend, which started in the US, is now becoming prevalent across the world. Several companies have realised that leasing infrastructure is the most cost-effective solution to support an unpredictable rise in bandwidth requirements. For instance, Telefonica UK (O2) has signed an agreement with Virgin Media Business to lease the latter’s fibre-based backhaul network to support the growing demand for mobile data services. Similarly, Orange Poland is using over 1,100 optic fibre backhaul links of Telekomunikacja Polska for providing high speed broadband services.

Innovative backhaul solutions for small cell deployment

Operators across the world are planning to set up small cells in addition to the macro network in a HetNet set up for providing higher capacity to customers in dense areas. This is because small cells will not only reduce congestion on macro networks but will also enable operators to use spectrum efficiently. However, providing backhaul support to these outdoor cell sites is becoming a major issue, as is evident from the trials conducted by operators. In fact, small cells have more stringent backhaul requirements than macro cell sites and, therefore, operators need to plan carefully to achieve higher capacity at low costs. Moreover, given the RoW issues in urban areas and high investment requirements, fibre-based backhaul will not be feasible for small cells. Also, due to spectrum shortage, operators would not be willing to use only microwave-based backhaul for small cells. Consequently, several operators are expected to provide backhaul to small cells through fibre and microwave technologies, but the spread between the two options will depend on local demographics, installation costs, infrastructure, etc. While fibre is likely to be the preferred option among various wireline solutions, line of sight (LoS) and non-LoS (NLoS) will be used for wireline-based backhaul support. Both LoS and NLoS have their advantages and drawbacks. LoS architecture offers higher capacity and adequate spectrum (60 GHz and 80 GHz), but its deployment is more expensive. On the other hand, while NLoS architecture roll-out does not involve high costs, limited spectrum availability (sub-6 GHz) is an issue.

In addition, an emerging technology solution for providing backhaul support to small cells is self-organising systems. According to consulting firm Senza Fili, Cambridge Communication Systems (CCS) offers a self-organising small cell backhaul system that uses a combination of point-to-point and point-to-multipoint links, which auto-configure and change dynamically based on the backhaul terminal location and network traffic. These two features of this backhaul system result in cost savings on account of fewer installation and operation hassles as well as non- requirement of backhaul radio frequency planning/manual realignment during the deployment of new small cells. One of the companies to deploy CCS’s self-organising small cells backhaul system is China Mobile. Going forward, successful performance of these systems will go a long way in creating a significant demand for them and developing the roll-out configurations of future data networks.

The way forward

With LTE and LTE-Advanced deployments likely to gain momentum, operators will be challenged to support the high bandwidth requirements of these technologies. They will need to upgrade their backhaul infrastructure through fibre deployment or use of additional microwave spectrum. Meanwhile, operators will have to ensure that network upgradation does not result in high expenses as data service revenues are likely to remain modest in the near term. To this end, new solutions such as self-organising networks can help operators reduce their cost per bit through proper network management and maintenance as well as automation of operations. Leasing and sharing backhaul infrastructure will also enable operators to provide high speed broadband services at lower costs.