Interview: Rob Joyce, head of LTE, O2

O2's 4G guru talks to Computing about the future of mobile wireless in the UK, high bandwidth applications, and where 4G fits in alongside 3G and Wi-Fi coverage

Mobile operator O2 announced a trial of fourth-generation (4G) Long Term Evolution (LTE) wireless technology, the successor to 3G, in London late last year.

The six-month pilot will upgrade more than 25 existing masts covering 15 square miles in Canary Wharf, Soho, Westminster, South Bank and King's Cross connecting up to 1,000 hand-picked users at peak rates of up to 100Mbit/s.

Computing: How will the London 4G tests differ from the O2 trials already conducted in Slough? What have you learned so far?

Joyce: We did both static and mobile tests in the labs and office, as well as driving around Slough itself. LTE handover is much quicker than on HSDPA+ as it is designed as mobile packet technology, so it is much better at handling mobility and is not challenged by speed, at least at a standard 50km/h.

Any technology struggles to keep the bit rate high when the user is travelling at greater speed, although the next version [of LTE] goes up to 500km/h, with some vendors demonstrating the technology on the Beijing Express in China.

What we did learn in Slough is what the network looks like loaded. We did not see a limit there [on how many users can be simultaneously connected to one cell]. The network equipment vendors say it is 3,000 and we will hopefully get close to testing that limit in the London trial. We think the minimum throughput for the guy standing at the cell edge will be 5Mbit/s, with closer to 100Mbit/s peak rates for those at the centre, but typical throughput will be 30-50Mbit/s. We do not think everybody is going to be streaming 10Mbit/s - people will be hitting their email and browsing the web then dropping off, those closest to the cell will get peak rates.

What sort of applications need the sort of bandwidth 4G can potentially provide?

It's up to end users really. You would probably have said that 10Mbit/s [of mobile bandwidth] was too much 10 years ago, but if you don't have 10Mbit/s for an iPhone iOS update today, you would be sitting there for hours. You also need more bandwidth for virtual private networks (VPNs), logging on remotely when somebody is sending a 4-5MB presentation - corporates and over-the-air updates will eat bandwidth. Not everyone might be streaming 10Mbit/s from the BBC iPlayer, but if everyone is streaming 1Mbit/s you need a system to cope with that.

Two examples came out of a trial using a dongle. The most power-hungry apps were cloud-based games - the commands sent from the handset use low bandwidth in the uplink, but you need fast bandwidth to get instructions and download the streaming high-definition images of where the player is positioned in the game.

Interview: Rob Joyce, head of LTE, O2

O2's 4G guru talks to Computing about the future of mobile wireless in the UK, high bandwidth applications, and where 4G fits in alongside 3G and Wi-Fi coverage

Another example saw media people who often have to send video backups, like after the Mobile World Congress for example, for live streaming of video outdoors. To book a satellite channel for an hour would cost hundreds of pounds, but with LTE you could do it with a 50Mbit/s link, which means you don’t have to carry the satellite equipment around.

Where does 4G leave other mobile wireless technology like Wi-Fi hotspots, HSDPA+ and WiMAX?

The 3G network now is HSDPA+ though we have not waved the flag on that too much, so we see that as coming into 3G handsets. It will be a couple of years before we get to LTE so we might as well take advantages of that [HSDPA+] now. WiMAX was not something that O2 was looking at in the UK, though Telefonica [O2’s telco parent] has an interest. WiMAX has fixed mobile access applications but we have decided that LTE is the global standard for mobile 4G, a bit like GSM became the global standard for 3G in the end.

O2 does not stop with the Wi-Fi rollout. With LTE there is an auction, a network to build and devices [to emerge], and it is three to four years away from mass market. Wi-Fi is a shared access technology and a shared spectrum, and I would be surprised if you got 5Mbit/s in central London unless you were standing underneath the access point. That said, the thing about LTE is that it is a wide area technology: when we put it up a site will cover the whole of Oxford Street and a city block, so we are not going after the Wi-Fi market. Both systems will work in parallel to serve the customer depending on where they are. Those after cheaper [mobile data] subscriptions may be better on Wi-Fi. We also expect Wi-Fi to be spectrally challenged in five years’ time.

What other strategies is O2 employing to handle the anticipated surge in demand for mobile bandwidth?

There are forecasts from various sources, such as Cisco, which predict 50 times the mobile network traffic there is today. You can attack that traffic growth in two ways, either building more cells, pipes etc, or sticking with what you have – either a more spectrally efficient technology or building more infrastructure. Our view is to do more, but building towers is expensive and it is cheaper to sweat what you have. That is why we will reframe the technology to take 5MHz of the 900MHz frequency spectrum and use it for 3G and HSDPA+ – O2 is the first operator to do this – which will add 50 per cent capacity to the 3G network.

Over 60 per cent of new connections are 3G smartphones and as we see more traffic migrate to those from GSM we will suffer some sort of capacity crunch if we do not acquire more spectrum. In the short term we can use smaller cells – we are planning 800 microcells in central London – but we do intend to acquire new spectrum. It will not be old point-to-point technology, but 4G equipment operating in the 800MHz and 2600MHz frequency wavebands from day one.

How do you think the forthcoming auctions for 4G spectrum will go?

I am not involved in the ins and outs of the auction but I understand we [O2] just want a fair and open auction with no rules in terms of having to have that spectrum. There are a few caps and caveats for others in the auction, so we prefer there to be no preferential treatment and that the people who want the spectrum the most are the people who will pay the most. If there is a rule that a block is given away and nobody else will bid for it, it could be sold later for a couple of hundred million more.

Interview: Rob Joyce, head of LTE, O2

O2's 4G guru talks to Computing about the future of mobile wireless in the UK, high bandwidth applications, and where 4G fits in alongside 3G and Wi-Fi coverage

What sort of MiFi routing device will be used in the 4G trial?

The MiFi device is the size of a small iPhone with a 4G modem inside to handle the internet connection. We have not announced any original equipment manufacturer (OEM) names but there are products which are desk based that can cover a whole house or office.

What changes is O2 making to its own network infrastructure to support the trial?

We are upgrading the existing 3G towers in London – putting extra equipment in at the base but not an additional antennae. We will swap out the 3G/GSM antennae for a 4G equivalent, which will use the 2600MHz frequency band.

Ofcom has given us a 20Mbit/s test and development waveband. Each band normally needs a different piece of equipment, 900MHz and 2100MHz for 3G today, but dual-band 800MHz and 2600MHz [for 4G], which means two radios, but we will probably connect back to a common box of electronics to do the traffic management and signal processing, which could be either or: we could choose to go to 2600MHz only or wide band out in suburbia and beyond.

Will LTE be used in rural areas to fill in gaps in wired broadband provision?

That is the crux of the matter – there is no official strategy for LTE rollout. People say you can throw away a fibre connection and you could, but if you serve every house every evening you will do it with fibre. You could probably use LTE in a rural village, but it [LTE] is not going to replace fibre [anywhere else].

There are economics there, however, which is why none of the operators roll out to the network edge. You could do it with LTE today at the network edge, but you could do it with 3G too and get much better service. 900MHz HSDPA+ will roll out in rural areas in the coming years. There are government initiatives, and O2 is keen to speak with them and work with this.

Telefonica has been trialling 4G on the 800MHz and 2600MHz spectrum for rural areas in Germany since 2009 and we have to cover the not-spots there first. There are also trials going on in Argentina, Brazil and other places, where we are using different manufacturers' network equipment, like Alcatel Lucent, Ericsson and Huawei, and though there is clearly a distinction in how advanced those commercial deployments are, we can also see how the different technology works in different bands.