Random Access Method and Apparatus and Communication System

A terminal comprising:

• a processor circuit configured to:
• configure at least two uplink bandwidth parts (UL BWPs) and at least two downlink bandwidth parts (DL BWPs), wherein the at least two UL BWPs and the at least two DL BWPs are of one-to-one correspondence based on value of BWP index;
• determine an active DL BWP of the at least two DL BWPs, the active DL BWP having a corresponding UL BWP of the at least two UL BWPs, wherein the corresponding UL BWP is configured with at least one time-frequency resource to transmit a preamble;
• select a time-frequency resource from at least one time-frequency resource allocated for preamble transmission in the corresponding UL BWP corresponding to the active DL BWP;
• and
• select a first preamble from at least one preamble allocated for preamble transmission corresponding to the active DL BWP;
• a transmitter configured to transmit the first preamble, on the selected time-frequency resource, to a network device;
• and
• a receiver configured to receive a random access response (RAR) on the active DL BWP.

A communication system, comprising;

• a User Equipment (UE) configured to:
• configure at least two uplink bandwidth parts (UL BWPs) and at least two downlink bandwidth parts (DL BWPs), wherein the at least two UL BWPs and the at least two DL BWPs are of one-to-one correspondence based on value of BWP index;
• determine an active DL BWP of the at least two DL BWPs to receive a random access response (RAR), the active DL BWP corresponding to the UL BWP of the at least two UL BWPs, wherein the corresponding UL BWP is configured with at least one time-frequency resource to transmit a preamble;
• select a time-frequency resource from at least one time-frequency resource allocated for preamble transmission in the corresponding UL BWP corresponding to the determined DL BWP;
• select a preamble from at least one preamble allocated for preamble transmission according to the determined DL BWP;
• and
• transmit the preamble, on the selected time-frequency resource, to a network device;
• and
• the network device configured to:
• configure at least two UL BWPs and at least two DL BWPs wherein the at least two UL BWPs and the at least two DL BWPs are of one-to-one correspondence based on value of BWP index;
• receive the preamble transmitted by the UE;
• determine, according to the received preamble, the DL BWP in the at least two DL BWPs according to the UL BWP in which the preamble is received, the DL BWP corresponding to the UL BWP of the at least two UL BWPs;
• and
• transmit a RAR corresponding to the received preamble on the determined DL BWP, wherein the UE is further configured to receive the RAR on the DL BWP.