The highest 5G speeds will require deployment in millimeter wave spectrum bands, causing some industry observers to question how widely such deployments will occur in rural areas. The concern is that distances covered in millimeter wave spectrum bands are less than in lower-frequency bands, potentially making 5G millimeter wave rural deployments unfeasible.
Sharing cellular RAN (radio access network) infrastructure potentially could address this concern, notes CoBank Knowledge Exchange in a new report. Researchers also see strong potential for network sharing in the CBRS spectrum band.
Cellular network sharing can take a variety of forms, but CoBank researchers focused on deployments in which multiple service providers share a radio access network (RAN). Traffic from the access network is then delivered to and from each provider’s core network.
Traditionally, each provider has operated its own RAN, requiring providers to deploy cell tower equipment that duplicates one another. But the researchers note that in other parts of the world, providers have begun to share RAN infrastructure with each other. The concept could catch on here, considering that 5G millimeter wave deployments are likely to require hundreds of thousands of small cells, the researchers note.
A neutral host provider could enhance the appeal of RAN sharing by acting as a neutral third party to work with providers to determine cellsite locations, work with tower operators to negotiate space on the towers, procure network equipment and work with construction companies to deploy the equipment and establish backhaul connections, according to CoBank. The neutral host provider also would manage ongoing network operations and charge providers for network access.
The RAN sharing concept also could get a boost from the opening of the CBRS band for commercial deployments. The CBRS band already uses a different form of network sharing: Providers must deploy equipment that works with a spectrum access system (SAS) to assign users only to frequencies that are not in use by the U.S. military which, until recently, had sole use of a large part of the spectrum band.
SAS technology enabled the FCC to free up mid-band spectrum in the CBRS band between 3550 – 3700 MHz for commercial use, about half of which will be available to all service providers on a lightly licensed basis. As the CoBank report notes, RAN sharing traditionally was impractical, at least in part, because providers had licenses for different spectrum bands, with few bands available to all providers. But because the CBRS band will be available to all providers, it could motivate providers to share RAN infrastructure, the researchers argue.
It would have been interesting to see the researchers do an economic analysis comparing a go-it-alone approach to RAN infrastructure deployment with a shared RAN approach. Nevertheless, it would seem to be an area worth further exploration.
The CoBank report comes at a time when the FCC is making plans for a Rural 5G Fund that would help cover the cost of deploying 5G in areas lacking high-speed mobile service today. The fund is predicated on the idea that there are some rural areas where there isn’t enough business to justify network investment without some level of government support – even if only a single provider serves the area, thereby getting all the business for the area.
The RAN sharing solution would appear best suited to less remote rural areas that would have enough business to support more than a single operator.