With all the current hype around Wi-Fi Calling, it's important to remember this isn't the only competing technology for small cells to address in-building coverage blackspots. Repeater and Smart Booster technology is also evolving rapidly, matching multi-technology and multi-band capabilities of the radio network. I spoke with Werner Sievers, CEO of Nextivity, to get another perspective on industry evolution.
A quick recap of in-building repeater/booster technology
There are numerous wireless repeater products or boosters which relay the cellular signal by rebroadcasting it in both directions. Some repeater designs can be quite disruptive to the rest of the network, amplifying the signal disproportionately, affecting other users sharing the same sector and reducing overall system performance. They are targetted at small to medium sized buildings rather than large enterprises or public venues.
Some repeater vendors work closely with network operators to design products that are well behaved and enhance service and system capacity. Nextivity use the term "Smart Booster" to differentiate this better behaviour. The advantage is that while boosters don't require a wireline broadband connection they do need some cellular signal, even if quite weak. These smart boosters can be remotely controlled and even switched off in unusual cases where problems arise. Products can be bought by customers directly (there are a few available on Amazon) or supplied (often free) by network operators directly.
Some products are designed as a single integrated unit. Others have distinct receivers (positioned outdoors or near a window) and transmitters (positioned more centrally in the building). Nextivity's Cel-Fi is supplied as two units which communicate wirelessly using the 5GHz unlicenced band. This uses the DFS segment of that band, meaning less interference with Wi-Fi but requiring more agile frequency hopping to respect other users of those channels. The product is approved in several countries (USA, Australia, UK etc.), and they are working with regulators to expand approvals elsewhere.
How would you position Cellular Boosters vs Wi-Fi vs Small Cells?
"There is clear demand from cellphone users for better quality service indoors, both for voice and data. They don't really want to know which technology is used, but they do want seamless, high quality service. Dropped calls, voice gaps, unresponsive data, undelivered messages become annoying enough for customers to switch carriers. Some will pay directly for products that solve the problem, but most would expect the network provider to do what it takes – whether providing a free box, external macrocell equipment upgrade, updated smartphone or residential small cell.
We see there being market opportunity for all three technical solutions that address poor residential coverage (Boosters, Wi-Fi Calling and residential small cells). I think that most operators will adopt at least two of those options, and at least 60% will ultimately deploy all three."
Can you give us a real world example?
"T-Mobile USA has probably more experience of Wi-Fi Calling than anyone else. They launched their @Home service in 2007. It had many issues, limited to a subset of phones, difficulty of connecting to Wi-Fi, no handin/out etc. But it could make lengthy calls free, overcome poor indoor coverage issues at home and avoid high roaming costs when abroad. They chose to ship a dedicated broadband router box with custom software to customers which prioritised Wi-Fi voice over other users in the home.
Wi-Fi Calling using VoWiFi and IMS is already beyond the level which UMA offered and where people will adopt it. T-Mobile USA still ship router hardware as part of their program to ensure better Wi-Fi coverage and that voice calls are prioritised. AT&T likely will not want to do that - they just want Wi-Fi Calling to be a software feature.
T-Mobile USA's program is called CellSpot. If you look at both packages, they appear identical but below the branding on one box it says booster, while the other says router. It gives you the sense they don't want to have to differentiate. We estimate they're shipping high volumes of both.
Meanwhile Verizon Wireless have announced introduction of a 4G in-building small cell. This demonstrates that there is scope for all three technical approaches. Ultimately I could see each having roughly equal shares worldwide rather than one dominating outright.
What about the cost?
A lot of people in the industry focus on the unit cost. This ignores the wider context. When you take into account the cost of handling just one customer care call or increased customer loyalty over the product lifetime you get quite a different outcome. Each of these products has its own costs (even Wi-Fi calling isn't completely free).
For repeaters, cost is driven largely by the number of different frequency bands supported. Our Cel-Fi Duo supports two bands (not surprisingly given the name) but actively monitors three. This allows us to detect which bands the network is using to initiate calls and dynamically switch those in use to match.
What are your thoughts about the future evolution of boosters in the network?
We are already 6 months into our next ASIC design which will add TD-LTE, MIMO and up to 75MHz of relay bandwidth. There's demand not just for higher data rates, but also the ability to cope with speed across the ground when the booster is fitted to a fast-moving car or train. We'll also see further enhancements to antenna and hardware design.
As we install millions of these things, housekeeping becomes more important. A cloud management platform could provide the scale and simplicity to handle very large deployments.
From a wider network perspective, I think we'll also see smart boosters becoming more integrated and actively managed. The better that boosters can live within and enhance the network, the more respected they will become. I could see this extending to monitoring and control via SON (Self Organising Network) as an integral component of the network.