Providing indoor coverage, or "inside buildings", means providing coverage of areas (e.g. basement areas, buildings with thick walls, etc.) that are not naturally covered by conventional networks.
Indeed, the propagation of waves emitted by conventional outdoor antennas can be disrupted by obstacles and certain materials. For example, if a home is well insulated, its insulation will reduce mobile indoor reception.
As mentioned above, within a building itself, the so-called "natural" mobile coverage, which results from the emission of radio waves by external relays, cannot be guaranteed.
Indeed, the attenuation of the signal depends on several factors: distance of the relay from the building in question, topography of the premises, overground, built in dense urban areas and the very nature of the construction. This masking phenomenon has become more pronounced in recent years with the emergence of new environmental standards, limiting the penetration of the signal into buildings.
In addition, even if the level of coverage could be satisfactory due to the immediate proximity of a relay, it is often observed, particularly in dense urban areas where traffic is high (e.g. the Parisian metro), that the performance obtained in buildings is degraded, particularly in terms of data flow rates. These phenomena can be explained by a saturation of the external relays.
For all these reasons, the deployed external relays cannot guarantee a good quality of service for mobile applications within buildings, especially in dense urban areas.
Why are we now talking about connectivity defects in what could be called "white indoor zones"? This is because today, a third of French people use their smartphones in shopping malls, 40% say they use them in transport, and 60% at work (Omnicom statistics; SFR Group; PHD; Baromobile 2015). In total, 80% of all telephone calls would be made indoors. Differences in connectivity quality across locations can therefore affect users, both business and residential, who are hindered in their activities and productivity.
The increase in the number of smartphones, the increased portability of objects, but also the increasing use of comfort sensors (e.g. temperature, maintenance, etc.) may also explain the highlighting of this issue: most of the technologies that have emerged over the past decade require the implementation of reliable and seamless network coverage in order to exploit their full potential.
Indoor coverage is therefore a new connectivity issue, which requires solutions that do not exclude any territory, any user, in order to support the growth of our country.
Several solutions exist to meet the challenges of indoor coverage, both for voice and data services, and for individuals and businesses.
The DAS (Distributed Antenna System) is a so-called "all-active" solution, which makes it possible to cover sites with large surfaces and/or buildings with several floors.
This solution consists in creating a mobile network within a building, independently of the external network. The broadcast antennas are therefore active and have a similar appearance to Wi-Fi hotspots. The intermediate equipment between the core network and the antennas operates in a similar way to routers.
Developed very recently to provide mobile phone service coverage for commercial buildings. They are not intended to systematically replace traditional solutions, but rather to meet a need for mid-size structures (e.g. office buildings).
Another solution for indoor coverage can be the cellular amplifier, or repeater. This amplifier makes it possible to reinforce the weak initial reception of the external mobile signal by repeating it inside a building. It therefore consists of a receiving antenna (usually located outside) and a transmitting antenna, both of which are connected by a wifi connection.
However, this type of solution is subject to operator authorization. However, they see in these devices a source of interference to their external relays, especially in dense areas, because the repeater is likely to generate noise on the rising track and thus degrade the performance and proper functioning of the relays.
FEMTO, or FEMTOCELL, is a relatively recent product that has been developed to address coverage gaps in small spaces, such as a meeting room, a work platform, or an auditorium.
In concrete terms, it is a box that connects to the fixed Internet network to transmit a low-power signal (100 mW maximum). The building must be eligible for a fixed broadband offer (512 kbit/s or more), but this criterion is already met by 99.7% of fixed lines. If its operation does not require the intervention of professional installers, to benefit from it, it may be necessary to declare in advance, on the operator's Internet space, the different mobiles to be connected to the equipment.
With this technology, telephone calls or web page consultations on the smartphone will be made via the fixed Internet line (ADSL or fibre) and no longer via the mobile network.
The advantages of FEMTO:
The disadvantages of FEMTO
The deployment of a Wi-Fi architecture
Wi-Fi is a set of wireless communication protocols governed by the IEEE 802.11 group of standards (ISO/IEC 8802-11). A Wi-Fi network allows several devices (computer, router, smartphone, Internet modem, etc.) to be connected by radio within the same computer network, in order to allow data transmission between them.
VoWi-Fi, or voice over Wi-Fi, is the use of the Wi-Fi network to benefit from mobile services and thus carry voice and not just data.
More precisely, calls made via a smartphone will therefore be made transparently over the Wi-Fi network and no longer over the mobile network, while allowing call continuity between these two networks. However, voice over Wi-Fi requires a compatible phone because calling/SMS will be processed without additional application on the operators' mobile network core.
This technology has recently benefited from the VoLTE (voice service on the 4G network) feature: customers affected by this update can now make all their phone calls over a recorded Wi-Fi network for better quality, this is the "Wi-Fi Calling" feature. The cut-off rate observed by operators is a maximum of 5%.
While this solution has the advantage of being able to compensate for a lack of mobile coverage in an area already covered by Wi-Fi, it has disadvantages:
Thus, the user experience is not guaranteed, and this solution is more of a one-time palliative than a sustainable approach.
The evolution of the standard has made it possible, over the years, to offer higher speeds and new uses have developed (e.g. the interoperability of Wi-Fi networks).
The objective here is therefore to facilitate mobile Internet access for the general public by offering increasingly high speeds. The latest consumer evolution is the 802.11ac standard, which offers a theoretical throughput of 1,300 Mbit/s using 80 MHz channels in the 5 GHz band.
Unfortunately, this evolution has also been accompanied by an increase:
These disadvantages rather encourage caution when deploying Wi-Fi solutions.
In order to meet more precise sizing and performance requirements, the actors responsible for implementing Wi-Fi networks are increasingly using:
These tools make it possible to provide guarantees on the achievement of indoor coverage objectives.
One of the promises of the Internet of Things or IoT networks, and in particular narrowband networks (LPWANs), is to make it easier to cover buildings from the relays of the external network.
This is true to a certain extent, because in the case of large buildings, this coverage remains difficult.
To overcome these problems, network operators are occasionally required to deploy micro-relays in buildings. This solution remains inexpensive as the micro-relays are able to provide coverage over very large areas.
Some practical tips to improve indoor coverage
The tremendous adoption of 4G technology now makes it essential to integrate mobile networks into all building construction or redevelopment projects.
It is therefore important to study the implementation of mobile networks as soon as possible when a construction or redevelopment project is initiated. Good anticipation facilitates the integration of network infrastructures.
Listening to needs
It is essential to collect all the needs and expectations regarding wireless networks at the start of a project, and to determine the dimensioning data for each of them (e.g. traffic, surface area, etc.).
Several types of solutions exist and must therefore be considered. Similarly, several types of potential providers exist and must be consulted.
Joint processing of network implementation projects opens up opportunities for synergy, whether it is the sharing of network equipment (e. g. antenna, fibre, etc.) or the sharing of development equipment (e. g. technical room, cable tray, etc.).
It also makes it possible to apprehend as soon as possible any problems of electromagnetic cohabitation (EMC) that could degrade the performance of networks and to propose appropriate precautionary measures.
The lifespan of a real estate project is generally around fifteen years. The implementation and operation of mobile networks must be based on an equivalent period of time. It is therefore necessary to compare solutions based on their cost price over this time horizon, as well as by anticipating developments and the treatment of obsolescence.
A question about Indoor coverage ? Need to remove doubts in view of a future project? Send an email to Benjamin Fradelle, Tactis Associate Director.