A family of standards developed by the European Telecommunications Standards Institute (ETSI) to implement V2X services. ITS-G5 is an alternative to the WAVE/DSRC system defined by IEEE 1609 and SAE J2735. Both systems use the same 5.9Ghz frequency band physical wireless access layer defined in IEEE 802.11p. However, ITS-G5 is adapted to alleviate congestion when used in conjunction with the 5.8Ghz DSRC system based on EN 12253 standard which is already in use in parts of Europe. Note that there are significant differences between DSRC defined in SAE J2735, that formed part of the initial basis for ITS-G5 and DSRC defined in EN 12253 which is more specifically applicable for real time transport telematics (RTTT) which is used, for example, for wireless toll roads systems in continental Europe.