Methods, apparatuses, user equipment and base stations for sending and receiving system information

A method of sending system information (SI), comprising:

• sending first class SI which carries scheduling information of second class SI so that user equipment is enabled to determine a receiving window associated with target second class SI to be requested by the user equipment;
• in response to receiving a preamble sent by the user equipment, determining the target second class SI and a receiving window associated with the target second class SI;
• and
• after the preamble is received, sending the target second class SI within the receiving window associated with the target second class SI.

User equipment, comprising:

• a processor;
• and
• a memory for storing instructions executable by the processor;
• wherein the processor is configured to:
• determine a receiving window and a preamble associated with to-be-requested system information (SI) in response to receiving first class SI broadcast by a base station, wherein the to-be-requested SI belongs to second class SI;
• send the preamble in an uplink subframe configured for sending the preamble in response to arrival of the receiving window associated with the to-be-requested SI;
• and
• receive the to-be-requested SI within the receiving window associated with the to-be-requested SI, wherein the to-be-requested SI is sent by the base station according to the receiving window.