Paul Parkinson

In-flight Internet access...and mobile phones too?

I read a business article in The Economist ('Mobile Phones on planes - Your call') during the Christmas holidays about the current developments in passenger in-flight systems, specifically the provision of Internet data access and the potential to support mobile (cell) phone voice calls during flight.

The article reports on trials of a Wi-Fi (Wikipedia) data service by JetBlue and Quantas, and a forthcoming mobile phone voice call trial by Air France (which follows on from the mobile phone SMS text messaging described in this Air France press release); it then goes on to discuss the social impact and acceptability of Internet data access and mobile voice calls during flight, which makes interesting reading.

The Internet, mobile phones and satellite communications have all been around for quite a while now, so you could be forgiven for wondering why we haven't seen these technologies rolled out across airline fleets before now? Well, maybe we are only just reaching the tipping point for technology (cost), and passenger demand (revenue)?

At present, the use of mobile phones in-flight is banned in the US by the Federal Communications Commission (and similarly by regulatory authorities in other countries) due to the potential for electromagnetic interference with aircraft avionics. If you perform a Google search, you might get the impression that this is a somewhat controversial subject with polarized views, but there is an example of hard experimental data to support the position on the UK Radiocommunications Agency website EMC Awareness page. There's also the problem that mobile phones passing over ground mobile networks at high speed could cause disruption as the networks struggle to perform handover from one cell to the next.

These new in-flight systems make use of a miniature base station on board the aircraft, known as a  picocell (Wikipedia), which connects to a satellite communications network to avoid both of these problems. This works because mobile phones transmit on increasing levels of power until they get a response - the concept is that if they receive a response from a nearby picocell they continue to transmit on low power levels, which will not interfere with aircraft avionics or reach ground-based networks thousands of feet below.

Despite this technological advance, I have to admit that I would try to avoid being on a flight where mobile voice calls were possible. This has nothing to do with the safety aspect, but because of the disruption. People tend to talk more loudly on mobile phones than on land lines because the sidetone on mobile phones is less than on landlines (sidetone is where the speech from the microphone is redirected to the speaker at a lower level, so that the person can hear what they are saying). If you now factor in the noise from the air-conditioning and jet engines, you've got a recipe for loud background chatter. The Economist article doesn't mention if these systems will support in-coming voice calls, but I certainly wouldn't welcome the sound of ringing mobile phones either, especially on a transatlantic flight, especially when I am trying to get some sleep! Maybe the reason why the airlines are being cautious about the introduction of voice calling is because they are wary of adverse passenger reaction?

On a positive note, I would very much welcome in-flight Internet data access, as it enable me to catch up on my email backlog, especially on long transatlantic flights. As an aside, my view on this isn't affected by the news story 'FAA: Boeing's New 787 May Be Vulnerable to Hacker Attack ' (Wired.com) which was posted earlier this week and was rapidly seized upon and somewhat sensationalized by the wider media. The Wired article, includes mention of "multiple networks", "isolation" and "air gaps" (i.e. physical separation) but doesn't really explain the concept of aircraft networks, which would have provided some useful context.

Basically, aircraft have a number of different type of networks, or domains, which connect systems which perform different functions; these typically include Flight Deck, OEM, and Passenger Systems. The networks have different networking requirements and are separated by firewalls for safety and security reasons (see ARINC 664 for more details) - one aircraft design already in-service is reputed to use a hardware diode to only allow the flow of data in one direction only between networks. In any case,  so I don't think this story should be a cause for concern for 787 passengers. Back to in-flight Internet access, I wonder if other laptop users would be trying to use Skype to make Voice-Over-IP (VOIP) calls? If so, I hope they don't sit near me.

So Is it finally time for take-off for in-flight Internet access?

Drive by Ethernet?

I read last week that BMW has been researching the use of the Internet Protocol (IP) over standard Ethernet (Cisco) to network automotive controllers ('BMW brings Internet protocol under the hood', EETimes).

The motivation for the research is that at present, a number of different networking technologies (including CAN, LIN, MOST and FlexRay) are used in automotive applications, and these are optimized for different types of application, but the lack of standardization results in complexity and cost.

So, I was expecting the article to say that BMW had found Ethernet to be suitable for non-critical applications, but not well-suited to critical systems. Sure enough, the article mentioned that the network had included a multimedia server and a camera (presumably for assisting reversing rather than videophone calls), but I was surprised that the BMW research group had found that:

'IP could well suit the real-time requirements even of safety-critical applications...Our experiments with prototypes demonstrated, that the real-time behaviour far exceeded the requirements — even when we ran multimedia applications across the same network'

Why was I surprised? Well, Ethernet, following its invention at Xerox PARC in the early '70s has become extremely widely used due to an ongoing favourable performance to price ratio, but it does suffer from latency and determinism problems to a certain extent, and while this has been acceptable for many uses including even some A&D mission-critical systems, safety-critical systems which require predictable latency and guaranteed delivery have often used profiled Ethernet implementations (such as ARINC 664) instead, sometimes with the additional expense of AFDX dual-redundant networking.

So, the BMW research engineers must have found away around the automotive problem? According to the article, they used Quality of Service (QOS) and traffic-shaping (wikipedia) techniques to achieve the real-time performance requirement, but unfortunately it doesn't go into details. I'm curious to know if the network profiling requirements for automotive applications have any similarities with avionics networks, or if there are major differences in terms of latencies and traffic characteristics. Maybe there's scope for more technology transfer between the two sectors (as I mentioned in my previous blog)?

There is potentially another interesting parallel between automotive and A&D - the use of multiple networks. In aircraft, multiple on-board networks are used for avionics systems, crew information systems and passenger infotainment systems, separated by firewalls for reasons of safety and security. (This also has the added benefit of reducing the safety certification burden of systems because they are not connected to the avionics network). In a car, I would expect that the automotive control systems would be on a separate network from the infotainment systems (for safety and security reasons).

According to the EETimes article, BMW doesn't have any current plans to put this technology into a production model yet, new technologies often appear in manufacturer's new high-end models, and then the technologies tend to trickle down to other model ranges.

So, unfortunately I might have to wait a while to do a back-to-back test of Ethernet-driven and conventional versions of BMW's awesome new V8-powered M3 to compare the latencies of the Dynamic Stability Control (DSC)...

Military Aerospace & Electronics Show

Yesterday, I attended the UK's Military Aerospace & Electronics technical conference and exhibition, which was held at the Heritage Motor Centre. The technical conference was split into three technical tracks, which were broadly related to avionics, land systems and technologies; and as is sometimes the case at these conferences I found that I wanted to attend some presentations which were running concurrently!

At a high-level, there were recurring themes amongst the presentations relating to modularisation, reconfigurability and of course, security. Some of the presentations discussed these issues in the context of the Future Rapid Effects System (FRES) programme, which is broadly speaking the UK equivalent of the US Future Combat System (FCS) programme. It was interesting to hear how future upgradeability through planned obsolescence and technology insertion prior to deployment, and the recognition that standards-based open architectures could facilitate this requirement.

Michael Morua of Atkins Defence Systems (MOD-appointed Systems House for FRES) gave a technical presentation on how the FRES Electronic Architecture (EA) is being implemented using a service oriented architecture, and even explained how reconfigurability would be achieved through open interface standards, and interfaces to external systems could be implemented through common data exchange middleware.

I always appreciate the opportunity to learn about emerging technologies at these conferences, so I was glad that I attended Peter Allsopp of GE Aviation's (formerly Smiths Aerospace) technical presentation 'Networked Aerospace Systems - Future Data Network Technologies'. It was interesting to hear how as data throughput requirements for avionics networks increase, the determinism, latency and availability requirements become harder to maintain with current avionics networking technologies. It appears that FlexRay, an open standard for time-triggered field bus technology may provide the way forward.

FlexRay was originally developed for safety-critical automotive applications, so it's encouraging to see that avionics can potentially benefit from the more widespread deployment of technologies in the automotive sector. This suggests that there can be cross-fertilisation between aerospace and automotive in both directions (blog: Can Automotive learn from Avionics Safety?).