Method and apparatus for cross link establishment

A method for detecting radio link failure (RLF), implemented by a terminal wireless transmit/receive unit (T-WTRU), the method comprising:

• communicating, using a cross link (XL), with a helper WTRU (H-WTRU);
• detecting RFL of the XL;
• starting a timer;
• performing neighbor discovery or cell selection or reselection;
• and
• determining whether a backup H-WTRU or a cell is found before the timer expires.

A method, implemented by a helper wireless transmit/receive unit (H-WTRU), for establishing a cross link (XL) with a terminal WTRU (T-WTRU), the method comprising:

• receiving an RRC reconfiguration message from a base station, the RRC reconfiguration message including configuration information for a mapping between a radio bearer (RB) of the H-WTRU on the XL and a RB of the H-WTRU on the traditional link (TRL), wherein a signaling radio bearer (SRB) on the XL is mapped to a data radio bearer (DRB) on the TRL and a DRB on the XL is mapped to a DRB on the TRL;
• configuring the RB of the H-WTRU on the XL and the RB of the H-WTRU on the TRL based on the configuration information;
• and
• tunneling the RB on the XL on to a RB on the TRL.