Moving 5G Indoors

Cellular networks have evolved from the legacy coverage era, where networks of high-power macro cell towers were built to provide service to a maximum portion of the population in a given geographic area, to the second era: that of densification. Densification offers overall system spectral efficiency gains and frequency reuse with low power transmitters and is responsible for bringing antennas closer to users and moving mobile service indoors. Densification has typically taken place through cell splitting—when a three-sector cell is split into six, or even nine, sectors—or small cell deployments that densified the footprint of cellular base stations considerably.

Now we stand at the threshold of the third, or convergence, era, where multiple advances in technology and architecture alternatives, along with millimeter wave (mmWave), unlicensed, and shared spectrum availability all combine to drive towards very high throughput, ultra-dense, multi-technology heterogeneous networks both indoors and outdoors.

Each of these eras offered enhancements in throughput, reduced latency, improved coverage, and lower total cost of ownership. With the rise of 5G, the convergence of Radio Access Network (RAN) architectures with multiple RAN technologies in licensed, unlicensed, and shared spectrum makes the design and implementation of in-building wireless systems challenging, as system and building owners strive to future-proof their investments to the maximum while simultaneously offering users the best possible quality of service.

Irrespective of the radio access protocol, RAN architectures will be heavily influenced by virtualization. Todays Distributed Antenna Systems (DAS) architecture, where baseband and radio functionality are centralized in a telco closet or main distribution frame in the building and the antennas are distributed throughout the building, will evolve to a Distributed Radio System (DRS) architecture where the baseband remains centralized and the radios and antennas are distributed throughout the building. 5G adopts this architecture by disaggregating RAN functions into Radio Unit (RU), Distributed Unit (DU), and Centralized Unit (CU). Small cells, which distribute baseband, radio, and antenna will also evolve to DRS. Parallel to this and leveraging virtualization, baseband functionality in the current indoor Centralized RAN (CRAN) will evolve to a Virtualized RAN (VRAN) architecture where baseband functions are run on Commercial-off-the-Shelf (COTS) data centers that are located locally, near the building. In parallel with this migration, virtualization will also be responsible for moving the compute storage and networking functions necessary for edge computing and the demands of 5G Ultra-Reliable Low-Latency Communications (URLLC) into the building at the network edge or close by.

These architecture trends are attractive to many system owners, operators, integrators, and builders because they will reduce system costs so that in-building wireless can be economically deployed in buildings with smaller floor areas than before.

RAN technologies will also converge. Today’s RANs operate in licensed spectrum. Now, operation in unlicensed and shared spectrum is becoming available. Therefore, the indoor converged RAN will incorporate today’s 4G/LTE, including LTE-M and Narrowband Internet of Things (NB-IoT), and underpin 5G for some time as 5G’s Non-Standalone (NSA) architecture is deployed in the sub 6 GHz low- and mid-bands, and the high or mmWave bands. Although 5G overlays 4G/LTE, complementary technologies will also become available. The arrival of unlicensed and shared spectrum technologies, such as Citizens Broadband Radio Service (CBRS/OnGo); Wi-Fi, MulteFire, including NB-IoT in Unlicensed spectrum (NB-IoT-U); enhanced Machine Type Communications in Unlicensed spectrum (eMTC-U); and 5G New Radio in Unlicensed spectrum (5G NR-U) in the small cell form factor will alter in-building wireless economics. The cost of achieving good indoor coverage and capacity will be lowered, which will challenge conventional in-building wireless technologies with deployment costs equivalent to Wi-Fi. This will increase the size of the market and stimulate new uses cases, such as private networks, Multiple Systems Operators/Mobile Virtual Network Operators (MSO/MVNO), and neutral hosts.

These new technologies will stimulate a transition in the ownership of indoor wireless systems from the current Mobile Network Operator (MNO) owned and operated system to a neutral host and/or venue/enterprise funding and ownership. This will spark the rise of the Building-as-a-Service (BaaS) and “Bring-Your-Own-Wireless” paradigms, and drive consolidation and partnerships between traditional indoor wireless players and building management companies, MSOs, MVNOs, and tower companies.

This represents an unprecedented number of non-mutually exclusive technologies and architectures converging to provide wireless capacity and coverage indoors. As the industry starts commercial 5G deployments outdoors in 2019, ABI Research anticipates that the requirements for good coverage and capacity indoors will drive signal sources indoors and provide momentum to the in-building wireless market.

Building owners and the connected real estate community must now move to future-proof new buildings and retrofit existing buildings to take full advantage of indoor indoors 5G. This involves installing a fiber-to-the edge architecture, accommodating high numbers of antennas, virtualizing baseband functionality offsite, and bringing edge compute closer to the user. This is a complex proposal for building owners, and they must involve domain experts from the vendor, system integrator, and third-party and commercial operator communities for maximum effectiveness.

Today, DAS and small cell vendors, system integrators, Value Added Resellers (VARs) and building management companies, MNOs, MSOs, and tower and fiber companies will all take advantage of these transformations. Mergers and acquisitions and partnerships are increasing, as companies in this ecosystem acquire the skills and Intellectual Property (IP) needed to take advantage of new opportunities in the in-building wireless ecosystem for future growth. ABI Research expects the third-party/neutral host ownership model to continue to grow and dominate over the carrier- or venue-led ownership models to represent almost two-thirds of system spending by 2023.

Already underway in many areas, the rise of the BaaS and “bring your own wireless” paradigms will spark consolidation and partnerships between traditional indoor wireless players and building management and connected real estate companies.

ABI Research’s recent 5G Indoor Deployments (AN-5099) Application Analysis Report provides a more in-depth discussion and offers recommendations for building owners navigating these complex deployment scenarios.