Further key technology for these systems will include equipping the vehicle with the ability to know where it is and to report this information, as well as its speed, to service providers that will supply real-time traffic updates. Positional information could also be used to enable road-tolling systems.

Since the driver information system is very likely to be integrated into the slot currently occupied by the car radio, it is therefore going to be important to look at the best architecture to provide a low-cost route to integrating the communications capability, positional information and user interface with the traditional functions found in a car audio system. Current systems already include AM/FM, Radio Data System, cassette and often a CD player. The advent of digital audio formats such as MP3 and Internet download will also play an important part in extending the capabilities of these systems.

Interfacing to the Web

Web connectivity is going to be an important element for in-car information systems, to enable the download of traffic and weather reports, up-to-date maps and digital audio content. The current data rates available today (GSM is 9,600 bits/second) significantly limit the quantity of data that can realistically be provided to the vehicle. However, as higher bandwidths of 384 kbits/s become available via GPRS, Edge and 3G wireless standards, this bottleneck will be removed. This kind of data rate is more than six times that available for most home Internet connections today, and with standards from GPRS supporting packet-based data services, the possibilities for Internet content delivery to the car are enormous. Taking a simple example of downloading MP3 files: Over a GSM data connection a typical 4-Mbyte file could take more than 15 minutes, compared with just 15 to 20 seconds using a 3G link.

If the driver's mobile phone is a link to the wider network, then Bluetooth may prove to be a useful technology to link the mobile phone to the driver information system, without requiring ugly fixed cradles in the car interior. Bluetooth has been architected to work in the unlicensed 2.4-GHz spectrum and achieves excellent robustness using a packet-switched protocol based on a frequency-hopping scheme. It also incorporates error detection and correction to improve data integrity. This makes it an ideal technology for use in a noisy environment such as a car.

Since Bluetooth is capable of mixing voice and data over the same link, there are a variety of possible uses. The total bit rate supported by Bluetooth is 721 kbits/s. That means, for example, that the driver can use a headset to make or receive a voice call (Bluetooth can support multiple 64-kbit/s CVSD-encoded voice channels), while data from the Internet is also being retrieved. Complexity will increase if there are multiple Bluetooth mobile devices in the car-for example, if one or more of the passengers is also using a handset or a headset. Bluetooth has the capabilities to enable it to handle these complexities, by setting up ad-hoc networks known as piconets.

User-interface challenges

Safety is becoming more of an issue as the driver gets presented with ever increasing quantities of information. For example, it would improve safety if incoming phone calls were blocked during an emergency situation when the ABS system is in operation. To enable this, the driver information system must be able to talk with the electronics monitoring and controlling the rest of the car. A controller-area network (CAN) gateway is already part of many car entertainment systems, and it is via the CAN network that the in-car information unit will be party to chassis and engine information. CAN is generally aimed at low-speed control information, currently up to 1 Mbyte/s, although it often is used at slower bit rates. However, for some applications, 2-Mbyte CAN is being considered.

Local storage

In the very cost-sensitive automotive environment, local data storage vs. network-based storage is a difficult trade-off, one that is made more difficult given the high-reliability demands that are made by customers. CD and now DVD mechanisms are already well-proven in the automotive environment. They are able to meet the harsh vibration and temperature specifications. For read/write storage (for example, encoding CDs onto some local storage), then the trade-off is between solid-state storage media such as MultiMedia Card and Memory Stick, or ruggedized hard-disk drives. Solid-state devices potentially offer a more reliable option, although they are currently a long way from the storage density achieved by disks. Indeed, some in-car equipment such as the EMPEG car MP3 player is already using a hard disk due to its superior storage capability in comparison to solid state, and this could drive the disk drive industry toward targeting its products at the automotive market in the future.

When considering the local storage of content, it is also important to consider copyright issues, and the inclusion of digital rights management software is likely in this type of product to ensure that it complies with the specifications of the Secure Digital Music Initiative (SDMI).

Wanted: more integration

All of the services and data available will have a significant impact on the integration levels required to make an affordable in-car unit. The current solution in high-end vehicles is to add modules that provide standalone functions such as global positioning system (GPS), audio and cellular communications to the on-board information system. This kind of solution is not suited to the volume car market, which is very cost sensitive. Manufacturers of future in-car information units must look toward more integrated solutions, utilizing where possible system-on-chip technology to reduce the number of devices required to implement the system.

The increasing complexity of the driver information system may well accelerate the use of leading-edge semiconductor manufacturing processes in automotive electronics. Operating conditions will be significantly less hostile than the traditional automotive electronics modules such as the engine controllers, and this combination of advancing system requirements and more relaxed operating conditions will enable more aggressive technology to be used earlier in the cycle.

To bring a broad range of in-car services to the mass market, low-cost driver information terminals will be required, and system-on-chip technology will be an important element in making this a reality.