The overall goal is to enable full interoperability between DSRC devices throughout North America. This also includes the ability to use a single on-board radio (also known as On-Board Equipment or OBE) for any/all applications that may be implemented in the near or distant future.
In actuality, achieving 100% interoperability is not literally possible due to the various complexities of achieving interoperability. There are many levels of interoperability and this is worthy of a separate paper/presentation in itself. Thus, there may be multiple classes of on-board devices, such as one for the general public and a different one for emergency vehicles. Also, many applications will be limited in their geographic coverage and/or the users allowed access to the services provided. The more realistic interpretation of this goal is that a motorist should be able to purchase a single on-board radio that can be used for every application that they wish to utilize. In other words, no one should ever have to buy more than one OBE for a given vehicle.
This single OBE must therefor be capable of meeting all of the function and performance requirements of all of the applications to which it might be applied. Thus, the same OBE that is used for toll collection would also be used to download video data or perform any of the safety-related applications such as collision avoidance. For some of these applications, extremely short times, on the order of 50 to 100 msec, are allowed to initiate the service, transfer the necessary data, and then to close the transaction. For other applications, extremely high data rates are required, using the full 27 mbps that will be allowed. Yet in other applications, very long operating ranges are required, up to 1000 meters.
Another type of requirement consists of the various business needs for those who will be developing and selling the devices, developing the applications and systems, and the end user - the motorist. The most obvious of these needs is to keep the equipment cost as low as possible. Very much implied by the most critical applications, those that are used for the safety of the average motorist, is the need to have a very high percentage of vehicles equipped with compliant OBE. These applications also are dependent upon the widespread installation of the roadside infrastructure. Getting widespread deployment for either the vehicles or the roadside implies that costs be kept below the "pain threshold" of those who must purchase the equipment. Of course the amount of money that one is willing to spend is a function of the expected return in the form of services provided, and thus varies greatly from one user to another and from one application to another. We are therefor unable to put an exact value on the maximum that the equipment can cost, but it is obvious that the lower the cost the better. Another business case issue that had to be dealt with is the timing of the standards development program and expected dates when compliant equipment could be purchased. There are many different applications that are being planned or already under development. If we cannot have the DSRC standards completed within the next two years and with compliant product available within three years, many of these systems will resort to alternative technologies such as IEEE 802.11b or Bluetooth. This might represent a suitable solution on an individual case by case basis, but will not contribute to the overall goal of having a single OBE in a vehicle. In fact, if very many such applications should be deployed using alternative technologies, it will make it much harder to get the very widespread deployments necessary for the core public safety applications.
The standards under development were selected for their ability to meet all of these goals.