47 CFR §90.390

1. (a)Channels. C-V2X may operate on the following band segments:
2. (b)Safety/public safety priority. The following access priority governs all C-V2X operations:
   1. (1)Communications involving the safety of life have access priority over all other C-V2X communications;
   2. (2)C-V2X communications involving public safety have access priority over all other C-V2X except those communications described in (b)(1) of this section. Roadside Units (RSUs) operated by State or local governmental entities are presumptively engaged in public safety priority communications.
3. (c)Non-priority communications. C-V2X communications not listed in paragraph (b) of this section, are non-priority communications.
   1. (1)If a dispute arises concerning non-priority communications, the licensee of the later-registered RSU must accommodate the operation of the early registered RSU, i.e., interference protection rights are date-sensitive, based on the date that the RSU is first registered (see § 90.389) and the later-registered RSU must modify its operations to resolve the dispute in accordance with paragraph (c)(2) of this section.
   2. (2)For purposes of this paragraph (c), objectionable interference will be considered to exist when the Commission receives a complaint and the difference in signal strength between the earlier-registered RSU and the later-registered RSU is 18 dB or less (co-channel). Later-registered RSUs causing objectionable interference must correct the interference immediately unless written consent is obtained from the licensee of the earlier-registered RSU.