I participated in the LTE World Summit Operator Mindshare event, prior to the main event itself. This consisted of several concurrent round table discussions led by operators, and examined many of the issues around LTE deployment. This included several surprising revelations about how small cells play their part, and some strong disagreements.
LTE small cells provide a key differentiator
Telefonica's delegate made the case for small cells. In a world where network performance will become more critical, they help operators differentiate and improve the customer experience. They can deliver the high capacity and infill coverage impossible through macrocell deployment alone. The specifics of how and when small cells will be installed depends on each market and spectrum available.
He didn't see the urgency for LTE yet, but expected the technology to ramp up over the next couple of years with LTE small cells being deployed from 2014 onwards. Where higher frequency spectrum is used (say at 2.6GHz), then small cells would be much more prevalent.
DoCoMo's delegate believed there must first be a stable LTE macro layer with good coverage, after which small cells should be added. He also explained that although different spectrum might be used for macro and small cell radio heads (RRUs), this broadband signal could be fed back to the same scheduler for maximum performance.
WiFi useful, but unpredictable
Several delegates had strong opinions about public Wi-Fi use. One believed that Wi-Fi is constrained to about 10 active users per hotspot, with larger numbers radically reducing its performance and customer experience. Another suggested that many Wi-Fi devices don't support the later standards versions such as 802.11n, causing congestion and poorer performance overall. A third commented that it wouldn't be secure until various aspects of Hotspot 2.0 were in place and widespread use.
However, others believed that LTE won't make a difference (to the data capacity crunch) in the short term and that Wi-Fi was required to fill the gap. Wi-Fi is compatible with most smartphones today, and the hotspots are operator independent.
It was said that in residential areas or less densely populated areas, where there is less contention, Wi-Fi can operate very effectively. However, in dense urban environments there can be anything up to 50 or 100 Wi-Fi hotspots in range all trying to share the same spectrum. This causes lots of interference and poor performance. Overall, it makes the customer experience unpredictable and uncontrollable by the operator – something that LTE (and small cells) should resolve.
Five issues affecting the speed of small cell LTE rollout
The table concluded with five main issues which would affect the speed of small cell LTE rollout:
- Backhaul, where fixed/mobile operators with access to fibre may have an advantage. In the US, a combination of cable broadband (DOCSIS) and inband repeaters may be used instead. Figures of 100Mbit/s for small cells and 500Mbit/s (increasing to 1Gbit/s) for large/macro cells were expected – all using IP/Ethernet.
- Planning, where the accuracy required to locate traffic hotspots will require the latest performance reporting and analysis tools
- Operations, which will need to scale up to roll out much larger numbers of cellsites. This will require higher levels of automation and self configuration
- Devices, where the pace of upgrade to LTE capable devices will take time. This typically only occurs as each contract is renewed, unless new equipment (e.g. a wireless tablet) is purchased. Availability of features such as eICIC on the latest LTE devices could impact the performance of the small cell layer.
- Multi-vendor interoperability (between macro and small cell layers), especially for advanced features to maximise network performance such as eICIC (enhanced Inter Carrier Interference Cancellation). This will be especially true where spectrum is shared between large and small cells.
Which RAT to kill
One table discussed which of the different Radio Access Technologies (RATs = 2G, 3G or 4G) would be shut down first. A show of hands around the table highlighted there are still huge numbers of 2G only devices in use today. Orange UK said 50% . The US is said to have around 30% while a Caribbean operator stated some 70%. It can be expected there will be lots of 2G devices around for a long time. They are cheaper and have long battery life, due to high volumes/mass production and lower IPR fees. This doesn't mean they contribute the highest revenues (ARPU) or profit, but they are a very substantial part of the user base.
After a lengthy discussion, it was voted that 3G would probably be the first to be shut down, but not for at least 10 years. When asked which RAT technologies to deploy using small cells, a surprising number plumped for LTE+2G, but a slight majority went for LTE+3G. Interesting, since the lifetime of the 3G part might be limited to 10 years!
Early trials of LTE initially identified poor battery life – as short as 50% at the start – but by tuning various parameters and turning on various features, it was possible to increase it to acceptable levels. I'd comment that a larger proportion of battery power on modern smartphones/tablets is now going into the display and processing power rather than the radio.
During the day, concerns were also raised about spectrum fragmentation and the difficulty of building devices which would be capable of handling the wide diversity of frequency bands and modes around the world. This could lead to delays in the latest products for some markets, and higher prices overall.
Pricing was briefly touched on, with Mark Newman, Head of Research at Informa, commenting that it has been difficult for operators to charge a premium for LTE. Verizon in the US charge the same as for 3G, and the Nordic countries have had to drop their price premium for higher speeds. Verizon have moved a lot of their existing 3G traffic across to LTE, freeing up 3G data capacity which is now being actively promoted to prepaid 3G smartphone users.
I also heard it suggested that where data is charged for on a per Gigabyte basis, the higher speed and faster response of LTE has tended to increase consumption which in turn can lead to higher revenues.
The key point being made was that there may not be any additional revenue stream to pay for LTE investment as such, but perhaps we will hear some further ideas on this topic later in the main conference.
All in all, a very worthwhile and thought provoking day.