Frequency Allocation

ITS eSafety communication systems have strong needs for protected spectrum to provide a reasonable service quality and it is beyond all questions that such a spectrum is required on a pan-European basis to allow free movement of the communicating vehicles across borders.

COMeSafety took actively part in the European frequency allocation process for spectrum for communication between vehicles and between vehicles and roadside units. The focus was on spectrum for road safety and traffic efficiency applications, which often cannot be separated.

In the first step the European industry in ETSI developed a System Reference Document (SRDoc) to describe the requirements and basic system parameters for European wide harmonisation of spectrum to the European Conference of Post and Telecommunications (CEPT). For safety and non-safety applications a bandwidth of 70 MHz was identified in the 5.9 GHz band. The same spectrum was already available in the US and other countries like Japan assigned spectrum already in the 5 GHz band for the same purpose. Considering the existing European spectrum allocations the frequency band 5.875-5.925 GHz was identified for the deployment of safety related applications and the frequency band 5.855-5875 GHz for non-safety related applications. The safety related spectrum requires low latency communication and therefore needs a predictable sharing situation and protection against interference from other services. The non-safety applications can be operated on a non-protected/non-interference basis as given in the ISM band. The proposed maximum transmission power for the whole frequency range is 33 dBm e.i.r.p. in a 10 MHz channel.

Within the CEPT extensive compatibility studies followed with the result, that within the 30 MHz of spectrum in the frequency band 5875-5905 MHz, ITS applications will not suffer from excessive interference resulting from other services/systems. However in that frequency range ITS cannot claim protection from FSS earth stations but the usage of those stations is very limited In the remaining 20 MHz of spectrum in the range form 5.905-5.925 GHz ITS may suffer interference from the Fixed Service above 5925 MHz.

In the whole band from 5.855 – 5.925 GHz ITS is compatible with all other services providing that the unwanted emission levels are

• less than -55 dBm/MHz below 5850 MHz in order to protect the Radiolocation Services;
• less than -65 dBm/MHz below 5815 MHz in order to protect the RTTT applications;
• less than -65 dBm/MHz above 5925 MHz in order to protect the Fixed Service.

In addition a mitigation technology like Transmitter Power Control (TPC) is requested below 5.875 GHz to avoid interference with existing Broadband Wireless Access Systems.

These results lead to the conclusion, that ITS can achieve a predictable sharing situation and protection against interference from possible new systems and applications of the Fixed and Mobile Service within the band 5875-5905 MHz.

CEPT has also studied the required spectrum bandwidth for safety related ITS applications based on realistic traffic scenarios and confirmed that 30 to 50 MHz would be needed in the 5.9 GHz band.

Based on the results of the studies the CEPT developed the ECC Decision on the harmonised use of the 5875 5925 MHz frequency band for Intelligent Transport Systems (ITS) (ECC/DEC/(08)01) that designates the sub-band 5.875-5.905 GHz to ITS road safety applications on a European basis immediately and considers the sub-band 5905-5925 MHz for future extension. It is agreed that both in-vehicle and roadside units will be subject to free circulation and use all over CEPT. On-board units will be exempted from individual licensing and even if authorisation of roadside units is technically not necessary it may be considered by administrations to ensure that different ITS operators can coexist.

Additionally the ECC Recommendation on the use of the band 5855-5875 MHz for ITS (ECC/REC (08)01) suggests the CEPT administrations to make these 20 MHz of spectrum available for non-safety ITS applications on a non-protected/non-interference basis.

Frequency designation is subject to national legislation and ECC Decisions are on a voluntary basis, but administrations have to commit themselves to its implementation and consideration in the national regulation. ECC Recommendations guide administrations to a certain use of spectrum and are less binding without commitment.

While the implementation of CEPT regulations is voluntary for its 48 members, a frequency decision developed in the EU regulatory framework is binding for the 27 EU member states. Because ITS for road safety has a strong political importance in Europe the European Commission (EC) mandated the CEPT to provide technical information about the spectrum requirements and compatibility issues. Based on this information the Radio Spectrum Committee of the EC developed the Commission Decision on the harmonised use of radio spectrum in the 5875 - 5905 MHz frequency band for safety related applications of Intelligent Transport Systems (ITS), which is and close to final approval and publication is expected for autumn. By this EC Decision EU member states are forced to designate the considered 30 MHz of spectrum not later than six months after entry into force of this decision and as soon as reasonably practicable following such designation, to make that frequency band available on a non-exclusive basis.

The CEPT and as well the EC limited the maximum transmission power of ITS in the whole band from 5.855 – 5.925 to 23  Bm/MHz e.i.r.p, but absolutely not more than 33 dBm e.i.r.p..