January 24, 2017
On a regular basis, it seems that someone in the industry suggests that the mobile operators should share infrastructure to speed deployment, lower costs and/or provide better service. After all, this has been tried in other countries, some more successfully than others. The suggestion for RAN sharing usually seems to come when we are looking at a technology, spectrum auction, major network deployment or other shift in the industry. Most recently, RAN sharing has come up as part of the 5G and mmWave network discussion.
Before going further, we should define what we actually mean by ‘RAN sharing’. RAN sharing simply means that two or more mobile operators’ networks would share the same baseband, radio and antenna – same physical infrastructure but using each operator’s spectrum. The equipment could be owned by one of the operators (with access provided to the others) or by a third party. Obviously some planning is required to make this concept work. The radios and antennas would have to be flexible enough to support each of the participating operators’ spectrum needs, and this applies to current spectrum and future plans. This coordination makes RAN sharing complex and far more difficult than initially expected.
Note that RAN sharing is not colocation; colocation already occurs today and is simply when multiple mobile operators share the physical infrastructure (towers, roof tops, etc.) to mount their RAN infrastructure. As an example, colocation is when two mobile operators mount their antennas and radios on the same tower infrastructure; the tower is shared, but not the RAN equipment. Colocation is very common with macrocells and is much discussed for small cells. Allowing and encouraging mobile operators to colocate small cells on the same pole or roof top would significantly speed small cell deployment.
In the macro network, we believe RAN sharing will be difficult to achieve. But indoors will be a different case; after all, mobile operators have been sharing neutral host DAS networks in large stadiums and buildings for years. While neutral host is not as widespread as many people believe, the reality is that systems are shared indoors.
Why is the RAN more likely to be shared indoors? Simply because the building owner or manager is likely to want multiple operators offering service in the building and is unwilling or unable to fund multiple networks. Neutral host DAS can support multiple mobile operators on the same antenna array and hence provide access to multiple operator networks to those in the building.
Going forward, we expect to see an increase in indoor RAN sharing for two main reasons:
1. As more people are using their smartphones and tablets at their desks and wanting better access to LTE, property managers/owners are increasingly looking at LTE networks inside the building. Several third parties have started addressing this market and deployments are already underway. For the property manager, this means they can provide access to multiple mobile operators without having to commit to a single carrier. The third party coordinates between the operators and the property manager; essentially the third party is building the neutral host network and leasing access back to the mobile operators. This reduces the capital outlay required by the operator and gives the property manager/owner access to the networks they need. Win-win.
2. 3.5 GHz Citizens Broadband Radio Service (CBRS) band discussions. This band is being discussed for use indoors and will be a shared resource. Rather than have strict spectrum licensing and allocations as we do today, CBRS will essentially support shared access to multiple entities, some of which will share infrastructure. Note that this is just being proposed for indoor use.
RAN sharing may eventually extend to some small cell deployments, but this will likely take some time. First, the industry needs small cell colocation and then small cell infrastructure that can support multiple spectrum bands. Only then will we be able to move to small cell RAN sharing, and this will be some years off.
Until then, RAN sharing is alive and well in the U.S. with more to come; just don’t look for it on the macro tower. Look at the local mall or football stadium instead.
Iain Gillott, the founder and president of iGR, is an acknowledged wireless and mobile industry authority and an accomplished presenter. Mr. Gillott has been involved in the wireless industry, as both a vendor and analyst, for over 20 years. iGR was founded in 2000 as iGillottResearch, Inc. in order to provide in-depth market analysis and data focused exclusively on the wireless and mobile industry.