The present document specifies the standards allowed to implement layer 1 on the Xn interface. The specification of transmission delay requirements and O&M requirements are not in the scope of the present document. In the following, 'layer 1' and 'physical layer' are assumed to be synonymous.

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.

• References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific.
• For a specific reference, subsequent revisions do not apply.
• For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.

For the purposes of the present document, the abbreviations given in TS 38.411 apply.

The Xn Layer 1 shall comply with the requirements of clauses 4 through 6 in TS 38.411.