Base station, user equipment, and method for early data transmission

1. A user equipment for performing a random access procedure with a base station, comprising:

a transceiver, being configured to receive a system information block and a random access response message from the base station; and

a processor, being electrically coupled to the transceiver and configured to determine whether to carry early uplink data in a radio resource control (RRC) connection request message which is to be transmitted to the base station according to a maximum transport block size included in the system information block;

wherein if the processor determines to carry the early uplink data in the RRC connection request message, the processor selects a candidate transport block size from a plurality of optional transport block sizes according to the number of resource units indicated by the random access response message, and the transceiver transmits the RRC connection request message including the early uplink data to the base station with all or a part of the number of resource units according to the candidate transport block size;

wherein each of the optional transport block sizes is not greater than the maximum transport block size;

wherein the number of resource units indicated by the random access response message corresponds to a plurality of pre-configured transport block sizes, and the processor selects the plurality of optional transport block sizes from the plurality of pre-configured transport block sizes so as to select the candidate transport block size from the plurality of optional transport block sizes; and

wherein with a minimum difference between adjacent transport block sizes, the processor selects a minimum optional transport block size, a maximum optional transport block size, and at least one intermediate optional transport block size which is between the minimum optional transport block size and the maximum optional transport block size from the plurality of pre-configured transport block sizes.

2. The user equipment of claim 1 , wherein the maximum transport block size corresponds to a coverage enhancement level of the user equipment.

3. The user equipment of claim 1 , wherein the number of resource units indicated by the random access response message is associated with a coverage enhancement level of the user equipment.

4. The user equipment of claim 3 , wherein the higher the coverage enhancement level of the user equipment is, the greater the number of resource units indicated by the random access response message is.

5. A method for early data transmission during a random access procedure, comprising:

receiving, by a user equipment, a system information block from a base station;

determining, by the user equipment, whether to carry early uplink data in a radio resource control (RRC) connection request message which is to be transmitted to the base station according to a maximum transport block size included in the system information block;

selecting, by the user equipment, a plurality of optional transport block sizes from a plurality of pre-configured transport block sizes so as to select a candidate transport block size from the plurality of optional transport block sizes; and

selecting, by the user equipment, the candidate transport block size from the plurality of optional transport block sizes according to the number of resource units indicated by a random access response message transmitted by the base station, and transmitting, by the user equipment, the RRC connection request message including the early uplink data to the base station with all or a part of the number of resource units according to the candidate transport block size, if the user equipment determines to carry the early uplink data in the RRC connection request message;

wherein the number of resource units indicated by the random access response message corresponds to the plurality of pre-configured transport block sizes; and

wherein the step of selecting the plurality of optional transport block sizes further comprises: selecting, by the user equipment, a minimum optional transport block size, a maximum optional transport block size, and at least one intermediate optional transport block size which is between the minimum optional transport block size and the maximum optional transport block size from the plurality of pre-configured transport block sizes, with a minimum difference between adjacent transport block sizes.

6. The method of claim 5 , wherein the maximum transport block size corresponds to a coverage enhancement level of the user equipment.

7. The method of claim 5 , wherein the number of resource units indicated by the random access response message is associated with a coverage enhancement level of the user equipment.

8. The method of claim 7 , wherein the higher the coverage enhancement level of the user equipment is, the greater the number of resource units indicated by the random access response message is.

9. A base station for performing a random access procedure with a user equipment, comprising:

a transceiver, being configured to transmit a system information block indicating a maximum transport block size and a random access response message indicating the number of resource units to the user equipment, and receive an RRC connection request message including early uplink data from the user equipment; and

a processor, being electrically coupled to the transceiver and configured to blindly decode the RRC connection request message including the early uplink data according to all or a part of the number of resource units and a plurality of optional transport block sizes;

wherein the number of resource units indicated by the random access response message corresponds to a plurality of pre-configured transport block sizes, and the processor selects the plurality of optional transport block sizes from the plurality of pre-configured transport block sizes so as to blindly decode the RRC connection request message including the early uplink data according to all or a part of the number of resource units and the plurality of optional transport block sizes; and

wherein with a minimum difference between adjacent transport block sizes, the processor selects a minimum optional transport block size, a maximum optional transport block size, and at least one intermediate optional transport block size which is between the minimum optional transport block size and the maximum optional transport block size from the plurality of pre-configured transport block sizes.

10. The base station of claim 9 , wherein the maximum transport block size corresponds to a coverage enhancement level of the user equipment.

11. The base station of claim 9 , wherein the number of resource units indicated by the random access response message is associated with a coverage enhancement level of the user equipment.

12. The base station of claim 11 , wherein the higher the coverage enhancement level of the user equipment is, the greater the number of resource units indicated by the random access response message is.