The idea of true mobile data is very attractive. The idea that we can have seamless access to all our corporate data any time, any place, anywhere (to borrow and old advertising slogan), without having to worry about finding a spare network access point or telephone socket for our modem. Or the idea that we can send and receive e-mail, or even browse the Internet, whilst travelling by train to our next appointment. And these concepts are not just of interest to the permanently mobile sales executive – in effect anyone who uses a PC on a regular basis could make good use of effective mobile data communications.

So why are there so few "active" mobile users? Leading laptop manufacturers are targeting 30 per cent GSM connectivity sales with new machines, clearly aimed at data applications. Add to that the number of smart phones out there which contain "soft modem" technology or are capable of fax and data communications in their own right, and the potential for mobile data applications is significant. You can even find operators – Cellnet, for instance – which offer a "data only" service in recognition of the pent-up demand. Yet how often do you see anyone connecting their phone and portable computing device together and actually using the technology?

The problem is that, to date, most users have played around with the data capabilities and found them lacking for various reasons – lengthy call set-up times (20 to 30 seconds), slow data transmission (9600bps), and unreliable connections being the main objections. Taking these one at a time, however, we can soon dispel the myth that GSM is not a viable proposition for a corporate mobile datacomms strategy.

Follow The Digital Path

As far as lengthy call set-up times are concerned, a solution is already available. The problem with some GSM operators is that the digital path stops at the network. From there to the modem at the head office host computer, the system relies on standard analogue modem technology. While modem-terminated GSM frees the user from the need for special data lines into the network, it does introduce further delays into the call set-up procedure before data can be exchanged. As well as being irritating, this can be costly over time, too, since the user is paying for the call time whilst the modem training is going on.

To beat this problem, initial service offerings from the major GSM operators include ISDN capabilities within the GSM "cloud" in order to provide end-to-end digital communications from handset to corporate network. Two-way ISDN QuickConnect from Cellnet, for instance, provides increased reliability and performance together with a significantly reduced call set-up time fast connection to corporate LAN’s and the internet. From a cost point of view, the end-user now only pays from the time the data begins to flow.

Even smart phone users can benefit from V.110 ISDN-terminated GSM. For example, I use a Nokia 9000i for my mobile data communications instead of lugging around a bulky laptop (if I want to work on a PowerPoint presentation, my laptop is fine – otherwise why suffer a dislocated shoulder if all I want is basic note taking, contacts database, calendaring, fax, e-mail and Web browsing?) Connecting via Cellnet to my Pipex Dial account was taking upwards of 30-40 seconds from initiating the call to the point where the Nokia started downloading the message headers. As it happens, Cellnet and UUnet have ISDN links between their networks, so after making a couple of changes on the Nokia configuration I tried again using the new service. The results were astounding, with initial connection time reduced to less than 5 seconds.

More Speed, Scotty!

The objection regarding slow data transmission is a little harder to blow away. After all, when most of us are surfing the ‘Net using at least 28800bps modems, and some are languishing on-line at the heady speeds of 56Kbps or even 64Kbps (and beyond), then the paltry 9600bps offered by GSM seems somewhat lacking.

However, just stop to think for a moment what you would use GSM data services for. What if you are trying to gain remote access to a mainframe application running on a 3270? The 3270 terminal controller only runs at 9600bps itself, making GSM eminently suitable for such a task. Or perhaps you just want to do some simple messaging. Unless you need to download huge binary attachments, it is unlikely that GSM will prove too much of a bottleneck in such applications. Granted, there will always be the odd mobile application which will require more bandwidth, but even there things can only get better. Compression will help achieve greater throughput in most cases, and raw speed is set to increase to 14400bps in the near future, followed by even higher throughput (up to 64Kbps in theory) using new technologies such as multi-slot and GPRS.

Resilience Is King

The thing is, that speed is only important if reliability is maintained, and that is one area where standard GSM fails miserably at present. With any kind of RF communication, it is the radio link between handset and base station which remains the weakest part of the chain – if conditions are unfavourable, or you move into a tunnel during a call, or if there simply isn’t a cell within range, you will lose the connection. This is irritating enough with voice calls, but at least there you can redial and pick up the conversation where you left off. If you had downloaded 9MB of a 10MB file when the connection disappeared, however, you would be forced to start over from scratch, even down to logging in again and re-starting the transfer.

"There is no session recovery available in GSM, Tetra, PMR, satellite or Mobile IP-based networks, and this is the main reason people think GSM is such a poor performer," explains Martin Kendrick, MD of GSM-specialists Brand Communications. "The apparently slow data transfer rate is the least of the problem if a connection is lost five times during a call, with the transfer having to be initiated from scratch each time".

Brand has a solution, however, in the form of the Apollo Router, which is available either as a PC-based expansion card, or as a software-only solution for the mobile user. Plenty of on-board processing coupled with some clever software design allows the Apollo to achieve high levels of compression to boost performance. But this is coupled with advanced session spoofing and error recovery in order to provide the highest levels of reliability from the GSM network. Using the Apollo, a virtual session is established for the user and spoofed, providing two important benefits. The first is reduced cost, since if no data traffic is flowing across the link then the router drops the connection – thus saving money – but keeps the session alive. When either end of the link attempts to send data, the session is quickly re-established and the session continues as if nothing had happened. Furthermore, routing packets which would normally bring the line up are also spoofed, meaning that air time is used for actual data transmission only, and not for routine IP, IPX and SPX packets.

It is easy to see the benefit this provides in the event of a communications failure. Should the signal be lost, the session remains spoofed at the router. Once the GSM signal is regained, the session is re-established and the data flows from the last bit sent – no more logging in to the network and re-initiating the transfer from the beginning. Tests performed by Cellnet using the Apollo router demonstrate anything from 40 per cent cost savings (assuming no call loss) as a result of the increased reliability and performance, to over 500 per cent when calls are dropped repeatedly. From a security angle, Apollo also includes a fully-functional firewall which can resist all known Denial Of Service attacks, and a range of authentication options is supported, including PAP/CHAP, CLI, RADIUS and TACACS+.

The software-only Apollo Emulator features the same code as the hardware-based router, but runs on a range of portable devices to make anything attached to the serial port – whether that is a standard modem, an ISDN Terminal Adapter or a GSM phone – look just like a standard Network Interface Card (NIC).

"The original concept behind the Brand solution is based on the fact that there is no such thing as a remote user – only a LAN user," says Kendrick. "When I am on the move, I want to be able to do everything exactly the same as when I am on the LAN, with common, seamless interfaces". No more firing up remote clients, or developing mobile-specific applications – the Apollo is both application and protocol independent. Any application which runs on a LAN will run in an identical manner over Apollo, allowing companies to deploy their line of business applications to field sales staff in order to enhance their productivity and demonstrate a more real-time control over their customer order cycle.

Value Added Data Networks

So if we now have the ability to make every device look like a LAN client – whether it is a PC, laptop, PDA, smart phones or even a vending machine or a car – the service operators have the means to provide additional services.

For instance, push technology could bring your daily newspaper down to a hand-held device to read on the train. Motorist organisations are already on their way to providing on-line network access to their field maintenance staff and vehicles for greater efficiency and improved customer service. The RAC in particular has taken a pioneering lead into the study of "smart cars" with on-board diagnostics and driver information systems over GSM, the aim being to allow maintenance staff to gain access to the car remotely to determine faults in advance of arriving at the scene.

Retail organisations with on-site vending equipment such as drinks or cigarette machines are also making use of GSM technology. If there is a fault or if the machine runs low on stock an alert is sent to a central location via a GSM phone mounted inside the cabinet. Bi-directional communications allows the central office to interrogate the unit further if necessary before taking action – a fruit machine operator, for instance, can be alerted if a machine is paying out too often and can change the odds via GSM thus eliminating the need for a site visit. Prior to GSM, such remote operation required a dedicated PSTN connection for each machine – not always practical, and a real pain to manage if the machines have to be moved for any reason.

Even more attractive is the ability to provide (and charge for) dedicated communications links – BRI, PRI or even T1 – from the operator’s network to a customer’s own network, effectively making the GSM cloud a part of the corporate LAN.

But to provide these services, the operators need a new kind of infrastructure within the GSM "cloud" (see diagram SLIDE 2). Based on the Apollo router software running under NT, the Apollo Access Servers provide up to 240 physical ISDN inputs per box, made up of eight PRI interfaces. Two additional DSP cards handle the V.110 rate adaption, and connectivity to the internal network is provided by any generic LAN card. Any number of Access Servers can be installed depending on the number of clients to be serviced, and since user connections are raised and dropped (though spoofed) on a random and frequent basis, an almost unlimited number of users can have logical connections to one Access Server.

Dual Gigabit backbones provide connectivity to the smaller number of Service Access Servers, which provide all the spoofing capabilities for the Access Servers as well as connectivity to corporate networks - one Service Access Server can support between six and ten corporate LAN leased line connections. This division of labour between the two types of server creates what is, in effect, a "distributed router" capable of scaling to a million concurrent data users with little or no degradation in performance. Given the normal 20 or 50 to 1 contention ratio typical in such installations, the Brand solution is capable of servicing the entire population of the UK. At the other end of the scale, a single Access Server can stand alone in "smaller" implementations requiring from 30 to 240 ports.

It is a simple matter to install third party servers on the backbone in order to provide Value Added Services. The diagram, for instance, shows a Backweb Push Server and a Spyglass Proxy Server integrated in the architecture. The Spyglass server provides a unique Web content reduction capability which allows bandwidth-limited devices such as the Nokia Communicator to view standard Web pages, a facility which would attract extra revenue for the network operator, especially as the number of smart phones in general use increases (see box).

The Brand architecture is already being deployed in major networks in Europe, Scandinavia and Asia. It enables the operators to provide a packet-switched service from end to end – from mobile client to corporate LAN – which is far more flexible and economical than the current circuit-switched model.

As more carriers deploy this type of architecture, international travellers can have the ultimate in "roaming" capabilities. This is achieved via the fact that wherever they are in the world they can make a local call and establish a secure VPN back to corporate HQ, since with this model the entire carrier network looks like one big LAN.

Summary

So, what is holding us up? Vendors and analysts keep talking about the "killer mobile application", in the same way that they talk about the killer application for videoconferencing or other such niche technologies.

The fact of the matter is that there is no such thing as the killer application for mobile data. The fact that sales of laptop, sub-notebook and palmtop PC devices is at an all time high proves that today’s computer user needs to do his or her computing on the move. After being used to constant network connectivity in the work-place, those mobile users are often at a loss when disconnected.

Given the commoditised nature of voice communications of GSM, most network operators are beginning to concentrate on the more lucrative data market, and are targeting 10 per cent data traffic by the year 2000. Brand Communications’ Martin Kendrick believes this is a conservative target: "Corporates have been waiting for the industry to deliver effective mobile solutions for the last three years, and so I believe that the pent up demand is much bigger than the network operators realise. I foresee that by the year 2000, 20 to 30 per cent of all GSM network traffic will be data, rising to 80 per cent by 2004."

Effective mobile communications will allow users to remain connected and in touch no matter where they are (as long as there is GSM coverage, of course). And that means that everything we do today on our PC’s is the "killer application" for the mobile data market place.

Brand Communications can be contacted on 01480 442100  

GSM Smart Phones Are Getting 'Smarter'

Devices such as the Nokia Communicator have caught the imagination of the mobile data user, but wireless e-mail application may soon be found on a number of GSM-based phones

Alcatel, Schlumberger, and Sendit - all leaders in their respective fields - have signed a Memorandum of Understanding to create the first wireless e-mail application based on GSM smart cards – the SIM’s (Subscriber Identity Modules) that are contained within your GSM phone. This is possible because processor-equipped smart cards are capable of performing reasonably sophisticated computing operations independent of the processor resident in the phone.

The idea is that the application on the SIM, in this case electronic mail, uses so-called 'pro-active' commands which are part of the latest Phase2+ GSM specification, thus enabling applications to take advantage of the processing and memory features of the SIM. While the application runs independently, it can still make use of the phone's user interface - most likely an LCD screen - enabling advanced text-based applications such as e-mail, as well as other Internet-style services.

New applications can even be sent and programmed into a subscriber's phone over-the-air, following purchase of the device. The result will likely be 'smarter' phones with a broader range of application services. Already, Alcatel is offering a smart phone based on the Phase2+ specification - the One Touch PRO. Likewise Schlumberger is supplying the smart card technology, and Sendit the Internet server system.

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