Recent market statistics show a significant upturn of in-building digital cellular solutions. The simplicity, flexibility and ease of installation are all much better than legacy choices. Costs are further reduced when the signal source is integrated within the digital solution, allowing this approach to provide the best business case and platform for future growth.
Mainstream vendors turn to indoor digital solutions
In earlier years, large buildings were equipped with analogue DAS that distributed signals from standard cellular basestations. These provided good coverage and high compatibility with existing outdoor basestation equipment. The trade-off was providing simplified operations and management for each network operator at the expense of equipment and complexity.
Active DAS systems have been developed over recent years that distribute the radio signals using fibre and/or Ethernet cables. This simplifies the wiring and physical installation of remote radio heads, significantly reducing cost and timescale for implementation. However, the signal source has usually remained as external macrocells or picocells connected via analog RF which isn’t particularly efficient or cost effective.
Several small cell vendors have developed a variety of in-building solutions which are commonly interconnected by structured cabling, benefitting from both the simplicity of Ethernet backhaul and an integrated signal source.
Huawei is one of several mainstream RAN vendors who have developed a Distributed Radio System which integrates both the basestation (signal source) with a set of remote radio heads. Their LampSite solution can also accept RF from third party basestations, effectively combining the benefits of integrated signal sources with multi-vendor interoperability. Ericsson has a similar product in Radio Dot but as we’ve discussed before, is not yet quite as advanced.
Characteristics of an indoor digital system
Whereas older analogue DAS systems distributed the RF signals over thick coax cables, today’s modern indoor digital systems use fibre and/or Ethernet cables. The use of structured wiring is common today, allowing cellular services to share the same cabling trays that support other building services. Where fibre used to be unusual, it is now a more common sight in modern buildings so that electricians and maintenance staff are much more familiar with installation and operation.
Ethernet cabling can be used throughout; alternatively fibre can be fed to a central equipment closet on each floor from which signals to nearby radio heads/small cells are distributed.
Digital systems bring other benefits too:
- Distances between the central equipment room and remote radio heads can be greatly extended. The same room can serve multiple buildings in the same campus or neighbourhood.
- Expansion is easier because of the native high capacity Involved. The RF frequencies used are independent of the physical cable.
- End to end O&M assures high network efficiency, with good visualisation for technicians to diagnose and rectify faults.
Satisfying growing demand
Evidence of pent-up demand for in-building capacity has been demonstrated from traffic statistics measured before and after installation of a digital in-building solution. It is not uncommon to see data traffic grow by 3 to 4 times. This is not just because of the faster speeds, but also ease of access and the greater utility provided.
Technical upgrades are much easier when signals are distributed digitally. The transmission and head-end can support not just higher data rates but also advanced features such as MIMO and additional frequency bands. Evolution to later 3GPP standards and even to 5G is possible, significantly extending the lifetime of the equipment and maximising the return on investment.
Management of digital systems is simpler due to greater visibility and control of each active node.
Longer term investment
Whether building owners or network operators fund an in building solution, the business case is much improved if its lifetime can be extended. This is where a choice of digital technology and standard cabling stands out. If a system can be easily upgraded to support new cellular features, greater capacity and even 5G then it has a much higher value. Don’t discount the disruption and downtime that might otherwise be encountered if major recabling is required for a subsequent upgrade.
Adding value beyond connectivity
Larger buildings can benefit from a range of value added services based on some knowledge of the location, movement and behavior of visitors. This can be reported in aggregate form, identifying the best locations for advertising boards or to identify when more staff are needed. More specific Apps have been developed for specific market verticals, such as Healthcare, Retail or Industrial.
Digital in-building solutions are better for the longer term, being both easier to install and much easier to upgrade, leading to an overall better business case.
The higher cost of some digital in-building solutions has been due to standalone basestations driving the DAS. Lower cost alternatives are now available that integrate the signal source (e.g. Small Cell or Picocell) and directly distribute a digital signal to remote radio heads.
Such indoor digital systems can also provide neutral-host multi-operator service with high capacity at lower cost. Some markets are ready for this while other network operators prepared to accept much higher price for duplicate/separate wholly owned systems.
Significant volumes of indoor digital systems now being shipped, for example Huawei have supplied over 1,000,000 LampSite radioheads to date and are forecasting another 1,000,000 before end 2018.
Everyone wants higher quality, more reliable and faster cellular service. Mobile operators, equipment vendors, and service providers are all recognizing that indoor digital technology serves this need and are increasingly adopting this approach.