The X2AP (X2 Application Protocol) is a signaling protocol used in LTE (Long-Term Evolution) networks. It operates between the neighboring eNodeBs (Evolved Node Bs) to support the UE (User Equipment) mobility and the load management in the E-UTRAN (Evolved Universal Terrestrial Radio Access Network).
X2AP supports the following functions and procedures:
• Handover preparation and execution
• Load balancing and overload control
• Interference coordination and management
• UE context release
• Error indication and reset
X2AP uses the SCTP (Stream Control Transmission Protocol) as the transport layer protocol, and ASN.1 (Abstract Syntax Notation One) as the encoding scheme. X2AP messages are divided into two categories: elementary procedures and criticality diagnostics. Elementary procedures are further classified into three types: initiating, successful outcome, and unsuccessful outcome. Criticality diagnostics are used to report any errors or failures in the X2AP processing.
X2AP is an essential protocol for LTE networks, as it enables the communication and coordination between the neighboring eNodeBs, which are the main components of the E-UTRAN. X2AP ensures the smooth and efficient operation and performance of the LTE network, and provides the necessary services and functions for the UE.