As we have previously mentioned, cellular telephone and broadband data services have become ubiquitous. Pricing, at least for individual users, is still rather high, but electronic tracking devices and other providers have negotiated pricing arrangements for particular services. Perhaps the best known is the GM OnStar service, which provides driver information including directions, stolen vehicle location, crash detection and emergency services notification, and other services. BMW Assist is a similar service. To date, these services have been implemented by specific vehicle manufacturers and are not available outside their vehicle brands.
However, in Europe, there are a larger number of cars and a stronger need for information services due to higher level of congestion in traffic. These features make the rate of penetration of GNSS receivers in the European car market higher than in North America, as shown in Figure 10.5 by the greater slope of line relative to Europe. On the contrary, in the commercial vehicle market, North America leads. It is assessed that the percentage of penetration of these systems by 2020 in the whole commercial vehicles market will be 50%. With regard to the use of GALILEO signals onboard commercial vehicles, it has to be noted that, in this market segment the replacement cycle of trucks or buses that have already adopted a tracking platform is longer than that in the mobile phone segment.
Perhaps the most general classification of the application of wireless communications in vehicles is to distinguish between vehicle-to-vehicle and vehicle-to-infrastructure applications, and we will discuss both in succeeding sections. Direct communication between vehicles allows information exchange without requiring any fixed infrastructure or base stations. The location and velocity of vehicles is constantly changing, and the RF communication range is of fairly short distance; therefore, the set of vehicles that can directly communicate will constantly change over a short period of time. This dictates that the physical layer and the network must be capable of operating in an ad hoc, decentralized manner, although coordination and synchronization through personal tracking device time signals are possible. Any two nodes must be able to communicate securely whenever they are within communication range.
There are existing standards for digital communication using subcarriers of standard AM and FM radio broadcast stations. Applications include channel and programming information, commercial paging systems, weather, news, and traffic information, stock market quotes, and vehicle GPS locator differential correction services. The data rate is quite low and the services often require paid subscriptions. Many of these applications are declining in popularity due to the availability of other, faster technologies. Satellite radio offers a similar unidirectional capability at much higher data rates, for example, Sirius Traffic, a subscription service for real-time traffic data. A WAVE device will be required to tune to the CCH channel at 100-ms intervals aligned with UTM second (for example, derived from a Car GPS tracker ) or derived from the switching of another nearby transceiver, and monitor the CCH for messages for a set interval, after which the device is allowed to switch to a service channel. Another option is to use multiple transceivers so that one can be continuously allocated to the CCH and the other can be used on the SCH.