Peter Jackson, Director, Europe, Communication Components Inc (CCI) says that sharing cell-site infrastructure in today’s competitive and crowded mobile environment must increasingly be accepted as standard practice by operators. By doing so, not only will they make serious opex and capex savings, but they will also attain optimum capacity and coverage levels over which to deliver the high-value content and services that, today, from their core, revenue-generating activities.

Ten years ago, ‘Focusing on core business to maximise revenues’ typically described, for a mobile operator, their race to attract new subscribers and retain hard-won existing users by rolling out network hardware, filling in coverage gaps, conducting 2G/2.5G optimisation issues and generally making sure that all was well in the land of base stations and towers, microwave links and remote electrical tilting (RET) antennas.

When a base station appeared in a town or the countryside it was typically the property of a single operator and its visible wireless furniture was restricted to a set of three or four directional planar antennas and one or two microwave radios linking it, line-of-sight, to other base stations and into the PSTN. Poor coverage, dropped calls, poor QoS were the operator’s nightmare and the major reasons for churn, hence, core focus on infrastructure.

But today, content and services are the core revenue-generating, subscriber-attracting focal points of operators, and strict ownership of infrastructure is not as essential to them as it used to be. As long as a Service Level Agreement, including such parameters as available capacity, call quality, dropped call ratio and blocked calls, is provided by the 3rd-party infrastructure provider, it is feasible that the operator will consider outsourcing, or, at least, sharing RF infrastructure.

It’s Good to Share
Sharing RF infrastructure at a time when base stations are under more stress and pressure than ever before makes good business sense for operators who need to sweat their assets to maintain revenues and remain competitive. It also means they will be able to decommission many existing cell sites – and eliminate the costs of running them – as they will no longer be needed to duplicate coverage.

With towers often awash with several operators’ antenna systems, numerous microwave radios and, on occasion, playing host to different technologies, e.g. UMTS and LTE, now is not the time for operators to ignore the smooth, cost-effective operations of their basic network building blocks; they must still keep a close eye on their infrastructure and how it’s being managed. Inefficient tower overcrowding is a surefire recipe for potential interference, and poor installation and maintenance problems increase in likelihood the more equipment is installed on any one tower.

And if a problem happens at the base station it invariably does not stay at the base station. A glitch caused by any number of equipment issues, such as a poorly sited antenna system, or by badly installed or poorly maintained powered amplifier causing passive intermodulation (PIM), can easily degrade the whole network’s performance, reduce coverage, be the cause of dropped calls, and become the root cause behind poor, churn-inducing customer experience.

Needless to say, as the daily pressure on cell sites to deliver more in terms of capacity and coverage has increased, so too have site running costs. To reduce these costs, and eliminate the risk to network performance and spectrum efficiency due to overcrowding, operators need to consider their cell-site infrastructure-sharing strategies in detail.

Efficient cell-site equipment sharing – not simply sharing a tower – can call on several solutions which are readily available and can deliver increased site capabilities without impacting network performance. Equipment such as low-loss combiners and multiplexers will help reduce capex and overall opex by enabling operators to share infrastructure viably, including RF equipment, as well as add new technologies such as LTE, without compromising network quality and performance. A new breed of passive, tuned filters for combined operations, for example, can bring operators together within the same band and with virtually no losses. Their use ensures the operators’ respective services are protected and network performance remains at least as good as it was prior to sharing. By not sharing equipment operators can find themselves at a serious disadvantage to their competitors.

To illustrate the potential problems, which can arise if operators do not share equipment such as antenna systems, let’s take a tower supporting four mobile operators in the same band. Each has its own antenna system, and in such a scenario there is usually a minimum vertical-separation requirement of 2m between antennas to avoid cross coupling and interference. If these four are not sharing antenna systems, their individual, 3m-high antennas (typical 900MHz high gain antenna length), together with the 2m vertical separation between each, will take up 18m of a 30m tower. As RF signal coverage and range will lessen the closer to the ground the antennas are, the bottom antenna will, as a result, achieve the worst propagation.

The height of the radiating element matters and is a key factor in delivering good coverage. If these four operators combined into one antenna, they would benefit from optimum height and tower positions and, therefore, optimum range and coverage. In an outsourced arrangement, the independent infrastructure provider can ensure prime antenna position and optimum level performance for all users through the use of passive filter combiners – and with lower costs all round.

Conclusion
With the right planning and the use of suitable solutions, the cost/performance benefits of site and equipment sharing to the mobile operator are potentially huge. Being able to share infrastructure right through to the RF system, without compromising network QoS, suggests an attractive alternative to the operator than one of higher costs and potentially worse coverage.
Clearly, it’s good to share.