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Conflicting agendas drive new CBRS Alliance

Mobile players old and new join forces to target newly opened 3.5 GHz band for LTE capacity expansion

A collection of uneasy bedfellows has formed the latest wireless industry group, the CBRS Alliance, which aims to promote and accelerate uptake of LTE services in the US’s newly opened 3.5 GHz band (now labelled the Citizens Broadband Radio Services band).

New spectrum was once of interest only to the traditional mobile players, and indeed, Nokia and Qualcomm are among the founders of the new alliance. But the innovative tiered system of access to the 3.5 GHz band makes it of potential value to newer mobile players, so we see Alphabet Access Technologies and Federated Wireless – both would-be disruptors of the old wireless order – and also, from the enterprise side, Intel and Brocade’s Ruckus Wireless.

These companies may have very different agendas when it comes to new spectrum, but their combined weight should at least overcome some doubts about the level of interest in deploying in 3.5 GHz. The establishment of the Alliance follows a preliminary move in February, when the six firms made a joint commitment to expand the range of LTE-based services available in the CBRS band.

The US regulator, the FCC, has freed up 150 MHz of spectrum in the 3550 MHz to 3700 MHz range for commercial use. While the 3.5 GHz/3.6 GHz bands are commonly used in many parts of the world for fixed, and increasingly for mobile, wireless access, in the US they were mainly reserved for federal agencies, apart from the lightly licensed 3.65 GHz portion.

The CBRS band now offers three levels of access. At the top, the federal incumbents have the highest level of priority and protection from interference.  Up to seven three-year Priority Access Licences (PALs) will be awarded per region, with 10 MHz each. These will take priority over the GAA (General Authorized Access) users which are licence-exempt. The levels of priority are protected by a new Spectrum Allocation System (SAS) and the previously available 3650 MHz-3700 MHz section remains entirely for GAA use.

The flexible system means that traditional and non-traditional operators could move into this spectrum. For the former group, the CBRS spectrum is becoming available at a timely moment, when operators are switching their attention from coverage to capacity, which entails a heavier focus on higher frequency capacity bands.

For enterprise providers, the PAL portions of CBRS, in particular, could provide a solution to the shortage of in-building capacity and coverage by supporting a dedicated, quality-controlled band whose high frequency makes it best suited to small cells.

And the flexible access options – even the PAL licences are likely to be very affordable in most areas – mean that new players can enter the space. The cablecos have shown interest in LTE in both 3.5 GHz and 5 GHz as a potential complement to their fixed-line and WiFi installations, especially indoors.

Some players have argued that the 3.5 GHz band is a better target for in-building and flexibly licensed LTE than pushing LTE-U into the 5 GHz band, with the accompanying conflicts with well-established WiFi interests. Like 5 GHz, 3.5 GHz is well suited to a separate, largely indoor network of small cells – if it is fully controlled within an enterprise it can even get round the QoS concerns of the GAA approach and it can be anchored by the conventional macro network.

The band supports TDD-LTE, which operators round the world are increasingly looking to use to complement their FDD-LTE networks, since unpaired spectrum is well suited to data-intensive, download-centric and small cell patterns of deployment. Although adopting a very different band plan to other countries, there is potential for international roaming between these small cell networks, and that would encourage a device ecosystem to develop – the critical barrier for any new band to overcome.

This will be one of the top priorities for the new Alliance, with Qualcomm and Alphabet (via Google Android) being the obvious influencers on that front.

In a statement, the members said they believe the CBRS band will become essential to meet growing demand for wireless data services, and that shared spectrum will help deliver capacity expansion “at massive scale” indoors and outdoors. They noted that several countries are preparing to allocate spectrum in the 3400 MHz to 3600 MHz band for IMT services. Others already have TDD-LTE (often in fixed mode), WiMAX or legacy technology installed and are looking to migrate to mobile 4G.

Neville Meijers, VP of business development at Qualcomm Technologies and chairman of the Alliance, said there was “ever-growing demand for LTE-based solutions in 3.5 GHz bands and expansion of the wireless footprint”, adding that the new group “aims to enable the entire industry to address demand by expanding the capacity of new technologies”.

The partners will also seek to kickstart the infrastructure ecosystem and is developing an official certification process as well as a program of field tests of LTE-enabled CBRS from later this year.

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