Method and apparatus for receiving uplink signal in train communication network

A terrestrial base station for receiving an uplink signal, comprising:

• a processor, a memory, and a radio frequency (RF) unit, wherein the processor executes a program stored in the memory to perform:
• receiving, by using the RF unit, a preamble corresponding to an orthogonal pseudo-noise (PN) sequence of a plurality of orthogonal PN sequences from an onboard wireless device in a train, wherein the onboard wireless device is connected with the terrestrial base station through a wireless backhaul link;
• recognizing an identification (ID) of the onboard wireless device from the preamble storing the recognized ID of the onboard wireless device, and allocating a temporary network ID and an uplink grant (UL grant) to the onboard wireless device;
• receiving, by using the RF unit, the uplink signal transmitted based on the temporary network ID and the UL grants;
• obtaining an ID of the onboard wireless device from the uplink signal;
• and determining whether a random access of the onboard wireless device is for a network initial access, for a network re-access, or for a handover, by comparing the obtained ID with the recognized ID of the onboard wireless device stored in advance.