Network Sharing: The goal is lower costs

April 14, 2022 | In last week’s blog I provided an overview of neutral host networks. This week, I’ll provide a similar overview of three approaches to mobile network sharing (MOCN, GWCN and MORAN) which could enable neutral host networks.

The 3GPP has defined 2 types of network sharing:

• Multi-Operator Core Network (MOCN): Two operators share the RAN and all the associated hardware (antennas, cables, power, backhaul, etc.) along with the radio frequency spectrum (licensed, etc.). But, the carriers control their own core networks which are connected to the shared eNodeBs via separate S1 interfaces. In MOCN, the carriers broadcast their unique PLMNs on the same RF spectrum to user devices (owned by subscribers). The devices then attach to the carrier with whom they have service.
• Gateway Core Network (GWCN): operators share base stations, spectrum, and element(s) of the core network. In LTE, providers would share the core’s mobility management entity (MME). In 5G core networks, each network function (which can be virtualized and hosted with hyperscalers) is interconnected via the 5G Service-based Architecture (SBA). I am not clear on why sharing a single NF, particularly as carriers begin introducing 5GC into their networks, provides much benefit.

With Multi-Operator Radio Access Network (MORAN), which is not a 3GPP-defined specification, all elements of the cell site (just as in MOCN and GWCN) are shared except the spectrum.

Note that both MOCN and GWCN require the sharing of spectrum for which, obviously, U.S. MNOs (and others) have paid billions over the years. Sharing spectrum could work out a few ways:

• One operator shares its spectrum with other operators via a leasing agreement; the hardware build costs, along with operating costs, are also shared.
• Several operators pool their spectrum bands and share it among themselves. This is one avenue for mmWave buildouts since high-band spectrum shares physical characteristics (e.g., low propagation) and site-based challenges (e.g., need many sites, fiber connections). U.S. operators, since they have yet to build out significant, mobility-focused mmWave-based networks, could achieve cost savings if they, at least, share sites if not multi-band radios and antennas.
• An already shared band (e.g., CBRS in the U.S.) is used by multiple operators. Since the GAA portion of the CBRS band can be used by anyone, service providers could share the cost of building and operating a CBRS-based neutral host network.

As mentioned, sharing allows a service provider to avoid some build and operate costs such as radio equipment, antennas, etc. Note that some infrastructure (e.g., tower space) are already shared because multiple operators collocate at tower sites. But by sharing the “active” elements of the RAN, service providers could:

• Reach subscribers in underserved / unserved markets more cost-effectively.
• Improve coverage/capacity in existing markets for less total investment than if they were to build out the network by themselves.

The technology needed to share a RAN is established and well understood even though there are relatively few examples. The real challenge in network sharing lies in figuring out the cost/benefit of network sharing and then negotiating the agreement(s) between the interested parties. The advent of lightly licensed / shared spectrum, such as CBRS, may help foster the neutral host network model.

In the U.S. , as already mentioned, the MNOs have paid billions for their spectrum and compete aggressively for every last connection. It would seem therefore, without a major change in business economics or a significant new competitor disrupting the market, that the U.S. MNOs would be unlikely to share spectrum. Network sharing using MORAN therefore seems the most likely on the macro network. But MOCN could be used for in-building solutions, especially where a third party owns the spectrum.

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