A familiar problem of modern connected society the world over is "signal failure" i.e. reception issues when trying to connect to wireless services, be they 4G, 3G, cellular or WiFi networks or indeed even GNSS (GPS / GLONASS etc.) services.
Modern building construction techniques, especially in new commercial/industrial builds, often use materials for cladding, insulation etc. that have RF reflective properties which can inhibit the penetration of public wireless services into areas where is network connectivity is required.
Aside from commercial buildings, the "signal failure" phenomenon can also be found in holiday cottages and cabins, home offices, old buildings with thick walls, narrow boats, site offices (often metal containers) as well as automated installations using wireless services such a vending, CCTV, security systems and metering to name but a few.
Network operators, as part of acquiring their licences from national governments, have more often than not committed to defined network coverage levels. However, even if these coverage commitments are calculated by a percentage of the population rather than a geographic area, there remains a significant number of environments where the signal is not sufficient for a reliable wireless communications. In percentage terms of the population this may seem like a low number, but when mobile phone penetration is at saturation point i.e. nearly everyone in the country has a mobile phone (without taking into consideration if they also have a data device (tablet, blackberry, netbook etc.) that small percentage of "signal failure" cases is actually a large absolute number. Add to that the number of data installations using cellular networks (known as M2M or machine to machine) and you realise that absence of reliable network signal is an all too common problem.
There are number of ways to address the symptoms of "signal failure". In the very worst case the user or device maybe so remote the only way to connect to a network may be via a satellite service. This is can be very costly, especially if you have a high volume of calls or a large amount of data traffic. That scenario aside, there are typically three ways to bring about reliable communications to these areas of weak coverage.
One method is to deploy active signal repeaters. In simplified terms, these products use amplifiers to boost signals into a space that was previously without coverage. A donor antenna antenna outside the building is connected to the repeater via low loss RF cable and the repeater then amplifies the signal. From the repeater, the signal is re-broadcast via a client antenna located in the space that requires coverage. This princpal is the same for professional distributed antenna systems (DAS) that facilitate coverage into public spaces, buildings, hotels, stadiums etc. The advantages of repeaters is that they really re-broadcast functionality so wireless users remain so and can move around the coverage space without wires or constraints. The disadvantages are that repeaters can be expensive and maybe hard to justify for home, leisure or small office installations as well as prohibitive for M2M applications. In addition, in many countries it is still illegal to use cellular repeaters unless you have explicit permission from the network operator(s).
Connecting a quality high gain external antenna and connecting it to the device is a more cost-effective approach. The external antenna is mounted outside (the same way a donor antenna is deployed for a repeater) and via a low loss RF cable it is directly connected to the wireless device. This works very well when the device has a dedicated antenna port - many 4G and 3G routers, modems and gateways do. This method is really suitable for data applications where the device or terminal can be fixed in one place and connected to the external antenna. Often the 4G/3G router or terminal will also offer WiFi capability so the cellular network services can be accessed via local WiFi (unfortunately this doesn't help mobile phone or Smartphone users making calls). The high gain antenna approach works well in terms of price performance for M2M applications and it has been known to run over 50M of low loss cable from the donor antenna to the M2M device underground (think parking garage, pumping station etc.) and still effect a reliable service to the device.
For Smartphone and mobile phone users wanting to make calls and not wanting to invest in repeater technology, then things get a little more complicated! As most mobile phones and Smartphones nowadays do not have an external antenna port, it is not possible to connect a high gain donor antenna directly into a connector on the phone. A way to overcome this is to use a signal docking station or a antenna coupler. Both products use the same principal to "connect" with the antenna in your phone and route the signal via an external donor antenna. Couplers are generally more fiddly and are designed to wrap around the phone, a signal docking station typically offers a cradle pad for the phone (or indeed 2 phones) to sit on. The docking station or coupler is then connected to the external antenna located outside. In both cases, it is advisable to use the phone's handsfree functionality or a bluetooth headset to make calls because as soon as you remove the phone from the cradle or the coupler, you are removing the connection to the high gain antenna.
For those of you that need coverage, but have decided that you do not want to deploy any of the above, you could always wait for the network operators to improve their network coverage, but the bottom line is that there are always going to be many locations, most of them indoors where users reside, where network connectivity is not possible due to very weak signal or no signal at all.
