Femtocell Opinion, comment and reviews

So what follows after the Spectrum Glut?

OverstockedThe introduction of LTE has been a profitable time for the cellular infrastructure industry. A large part of that is down to large new swathes of spectrum being made available rather than purely higher spectral efficiency or faster headline data rates. Some operators almost seem to have suffered from indigestion as they equip their networks to take full advantage. Once the quick returns from low hanging fruit have been gained, it will be the smarter decisions that determine longer-term competitive advantage.

 

 

Sub 1GHz achieves a level playing field

Access to sub 1GHz frequencies levels the playing field between late entrants who didn’t have 900MHz GSM to build on. VoLTE, not yet widely deployed, is beginning to become available. UK operator Three is rapidly deploying so-called 4G SuperVoice using a sliver of 800MHz LTE spectrum to increase coverage and improve in-building penetration. But an “outside-in” design can’t reach everyone. Despite equipping over 400 buildings, Vodafone report achieving 60% deep indoor coverage across London so there is still further progress to be made.

Higher frequencies for headline speed and capacity

Higher frequencies, such as 2.6GHz, are proving popular. EE UK assign this as their preferred band, resulting in approximately 2:1 ratio of traffic carried compared with their 1.8GHz band where both are available. They’ve still to fully deploy a further 15MHz of FDD 2.6GHz, which with Carrier Aggregation will see headline peak rates in excess of 400Mbps. Elsewhere, TIM Italy make it clear that they only expect to use these higher frequencies in cities and large towns. A few operators, such as in Korea, have combined both low and high frequencies to achieve the peak headline rates using carrier aggregation. That’s technically much more challenging because of the different RF footprints of such divergent frequencies and no doubt presents difficulties in the smartphone too. It seems unlikely that Carrier Aggregation across such bands would be used where alternatives exist.

This is one reason why in Europe I wouldn’t expect frequencies below about 1800MHz to be so widely in demand for in-building purposes in future. If anything, even higher frequencies would be introduced. The UK government has announced plans to auction a further tranche of 2.3 and 3.4GHz spectrum. The 3.4GHz band in particular would require another round of antenna and equipment upgrades, not to mention waiting for sufficient compatible smartphones to make use of it. The 2.3GHz band should be much more relevant.

Equipment investment

The new LTE spectrum has resulted in many antenna replacements and equipment upgrades. Many operators had seen this coming and invested in a “RAN Refresh”, replacing outdated basestations with fully configurable, multi-technology products. More recently, it’s been the turn of antennas, including DAS systems, to be refreshed and updated. LTE lower frequencies alone, whilst attractive in many cases, simply can’t provide ubiquitous in-building penetration to ensure coverage or capacity in many congested urban areas. Delivering that service using dedicated in-building systems releases proportionally greater capacity for macrocells to use elsewhere.

The next step will be indoors

As the limits of existing outdoor-in coverage are reached, operators can be expected to divert more of their investment indoors. Some budget is also available from property owners keen to satisfy their visitors, guests and staff with high quality and productive connectivity. Operators want to light up the LTE indicators on smartphones everywhere and deliver consistent performance to match. EE has stated a target of providing a minimum 5Mbps rate for all customers, which they already achieve over 95% of the time.

But many existing in-building deployments may not support these new LTE bands or be able to make full use of MIMO.

Two key challenges are high cost and multi-operator support. DAS has a reputation of being an expensive, custom designed solution. Small Cells are seen to be tied to a single network. Neither yet achieves both the functionality and price point the market seeks. Instead, we’ve seen investment in Wi-Fi which venues perceive to satisfy both. However for users, gaining access can be awkward, service delivered inconsistent and personal data required. Users choose it partly to save cost, partly to remain connected and rarely to take advantage of any venue specific features.

It’s my view that while carrier grade Wi-Fi continues to improve and technically can provide a much more seamless user experience, many operators would prefer to retain traffic on their networks which they can charge for and deliver a more consistent user experience. Where operators have more limited spectrum assets, appropriately engineered Carrier Wi-Fi offers a complementary capability that they could control.

The three choices

Broadly speaking, there are three technical choices for in-building wireless connectivity today: DAS, Small Cells and Wi-Fi.

DAS benefits from being inherently multi-operator. Operations departments find it easy to manage alongside their other basestations from the same vendor. Few seem to want the complexity of reconfiguration for different times of day or use cases. It’s perceived to be costly, with active DAS often driven inefficiently by full RF power macrocells. We need to see more direct connections using CPRI or similar, saving both CAPEX and OPEX, combined with smarter SON automation to optimise system performance. Some operators have a very limited set of approved equipment that they support – that range needs to expand to cope.

Small cells solutions are gaining credibility for larger buildings and environments.  Standalone enterprise Femtocells are a quick fix for small to medium sized properties. Larger buildings justify systems with centralised controllers that can make very efficient use of spectrum, achieving more seamless performance at sector boundaries and very high capacity. In some scenarios, an overlay (3G and/or LTE only) can provide differentiation for a single operator while relying on an existing 2G/3G DAS for more general service. There is also a growing argument for neutral host small cells, sharing a single operator’s spectrum to serve all network subscribers, using MOCN. The technology and regulatory approval exists, but is held back by the commercial strategy of operators who want to differentiate.

Wi-Fi has undoubtedly been extremely successful in residential and office environments. Properly engineered Carrier Wi-Fi offers the potential for a seamless service, using the latest Next Generation Hotspot features. But in many cases, venue owners want to retain a relationship with their guests or visitors through a login screen or advertising. MNOs point out that they’d prefer to make money by charging for LTE rather than giving Wi-Fi away for free. It seems to me that few European MNOs have an appetite for Wi-Fi roaming at the moment and prefer to retain customers on cellular wherever possible. Those with more limited spectrum assets may think differently.

Conclusion

The cellular industry has enjoyed boom times in recent years with the launch of LTE. A large element of that is the additional spectrum made available rather than any other specific technical benefit, and this has required upgrades to antenna systems including indoor DAS.

Once the main potential of this new spectrum has been realised, operators will need to make careful decisions on how best to achieve more ubiquitous LTE coverage, especially in-building. The three main technical options all involve investment but are not mutually exclusive.

Replacing DAS systems to be fully compatible with the new frequency bands and MIMO capable will compete with deployment of small cell overlays for 3G or LTE only. Medium to large sized Enterprises will be the major battleground, with the key competitive elements of multi-operator and lifecycle cost being forefront.

The future investment strategies of network operators will determine how these industry segments evolve. In order to scale up to meet demand, there needs to be a wider range of equipment choices approved for use; a larger set of approved installers and increased use of automation and standard processes to configure, provision and manage these systems.

Want to hear more?

David Chambers of ThinkSmallCell will be speaking on the topic of whether Wi-Fi or Small Cells are ready to displace DAS at the upcoming DAS and Small Cell Congress Europe, 8-10 Dec 2015, Munich.

You can also download a white paper on the issues around Selecting an Enterprise Wireless Solution, sponsored by SOLID, from our resources section here

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