Device and method for transmitting downlink control information in a wireless communication system

1. A method for a transmitter in a communication system, the method comprising: identifying, by a transmitter, information bits in a first downlink control information (DCI) and information bits in a second DCI; appending, by the transmitter, one bit of value zero to the second DCI, if a number of the information bits in the second DCI is equal to a number of the information bits in the first DCI; appending, by the transmitter, one or more zero bits to the second DCI based on a payload size of the second DCI, if the number of the information bits in the second DCI belongs to one of ambiguous sizes; and transmitting, to a receiver, the second DCI, wherein a payload of the second DCI comprises the information bits in the second DCI and at least one zero padding bit appended to the second DCI, wherein the one or more zero bits are appended to the second DCI until the payload size of the second DCI does not belong to one of the ambiguous sizes and the payload size of the second DCI is not equal to a payload size of the first DCI, and wherein the transmitted second DCI is received based on the payload size of the second DCI.

2. The method of claim 1 , wherein the ambiguous sizes comprise one of 12, 14, 16, 20, 24, 26, 32, 44, and 56 information bits.

3. The method of claim 1 , wherein the first DCI comprises a DCI format 0 and a DCI format 1A and the second DCI comprises a DCI format 1, and

wherein identifying the information bits in the first DCI and the information bits in the second DCI comprises:

appending at least one zero bit to the DCI format 1A until the payload size of the DCI format 1A equals the payload size of the DCI format 0, if a number of information bits in the DCI format 1A is less than a number of information bits in the DCI format 0; and

appending one zero bit to the DCI format 1A, if the number of the information bits in the DCI format 1A belongs to one of the ambiguous sizes.

4. The method of claim 3 , wherein identifying the information bits in the first DCI and the information bits in the second DCI further comprises:

appending at least one zero bit to the DCI format 0 until the payload size of the DCI format 0 equals the payload size of the DCI format 1A, if the number of the information bits in the DCI format 0 is less than the payload size of the DCI format 1A.

5. A method for a receiver in a communication system, the method comprising:

receiving, by a receiver from a transmitter, control information comprising at least one of a first downlink control information (DCI) and a second DCI; and

decoding, by the receiver, the control information based on a payload size of the second DCI,

wherein one bit of value zero is appended to the second DCI by the transmitter, if a number of information bits in the second DCI is equal to a number of information bits in the first DCI,

wherein a payload of the second DCI comprises the information bits in the second DCI and at least one zero padding bit appended to the second DCI,

wherein one or more zero bits are appended to the second DCI based on the payload size of the second DCI by the transmitter, if the number of the information bits in the second DCI belongs to one of ambiguous sizes, and

wherein the one or more zero bits are appended to the second DCI until the payload size of the second DCI does not belong to one of the ambiguous sizes and the payload size of the second DCI is not equal to a payload size of the first DCI.

6. The method of claim 5 , wherein the ambiguous sizes comprise one of 12, 14, 16, 20, 24, 26, 32, 44, and 56 information bits.

7. The method of claim 5 , wherein the first DCI comprises a DCI format 0 and a DCI format 1A and the second DCI comprises a DCI format 1,

wherein at least one zero bit is appended to the DCI format 1A until the payload size of the DCI format 1A equals the payload size of the DCI format 0 by the transmitter, if a number of information bits in the DCI format 1A is less than a number of information bits in the DCI format 0, and

wherein one zero bit is append to the DCI format 1A by the transmitter, if the number of the information bits in the DCI format 1A belongs to one of the ambiguous sizes.

8. The method of claim 7 , wherein at least one zero bit is appended to the DCI format 0 until the payload size of the DCI format 0 equals the payload size of the DCI format 1A by the transmitter if the number of the information bits in the DCI format 0 is less than the payload size of the DCI format 1A.

9. A transmitting apparatus in a communication system, the apparatus comprising: a transmitter for transmitting a signal to a receiver; and a controller coupled to the transmitter and configured to: identify information bits in a first downlink control information (DCI) and information bits in a second DCI, append one bit of value zero to the second DCI, if a number of the information bits in the second DCI is equal to a number of the information bits in the first DCI, append one or more zero bits to the second DCI based on a payload size of the second DCI, if the number of the information bits in the second DCI belongs to one of ambiguous sizes, and transmit, to a receiver, the second DCI, wherein a payload of the second DCI comprises the information bits in the second DCI and at least one zero padding bit appended to the second DCI, wherein the one or more zero bits are appended to the second DCI until the payload size of the second DCI does not belong to one of the ambiguous sizes and the payload size of the second DCI is not equal to a payload size of the first DCI, and wherein the transmitted second DCI is received based on the payload size of the second DCI.

10. The apparatus of claim 9 , wherein the ambiguous sizes comprise one of 12, 14, 16, 20, 24, 26, 32, 44, and 56 information bits.

11. The apparatus of claim 9 , wherein the first DCI comprises a DCI format 0 and a DCI format 1A and the second DCI comprises a DCI format 1, and

wherein the controller is further configured to append at least one zero bit to the DCI format 1A until the payload size of the DCI format 1A equals the payload size of the DCI format 0 if a number of information bits in the DCI format 1A is less than a number of information bits in the DCI format 0 and to append one zero bit to the DCI format 1A if the number of the information bits in the DCI format 1A belongs to one of the ambiguous sizes.

12. The apparatus of claim 11 , wherein the controller is further configured to append at least one zero bit to the DCI format 0 until the payload size of the DCI format 0 equals the payload size of the DCI format 1A if the number of the information bits in the DCI format 0 is less than the payload size of the DCI format 1A.

13. A receiving apparatus in a communication system, the apparatus comprising:

a receiver for receiving a signal from a transmitter; and

a controller coupled to the receiver and configured to:

receive, from a transmitter, control information comprising at least one of a first downlink control information (DCI) and a second DCI, and

decode the control information based on a payload size of the second DCI,

wherein one bit of value zero is appended to the second DCI by the transmitter, if a number of information bits in the second DCI is equal to a number of information bits in the first DCI,

wherein a payload of the second DCI comprises the information bits in the second DCI and at least one zero padding bit appended to the second DCI,

wherein one or more zero bits are appended to the second DCI based on the payload size of the second DCI by the transmitter, if the number of the information bits in the second DCI belongs to one of ambiguous sizes, and

wherein the one or more zero bits are appended to the second DCI until the payload size of the second DCI does not belong to one of the ambiguous sizes and the payload size of the second DCI is not equal to a payload size of the first DCI.

14. The apparatus of claim 13 , wherein the ambiguous sizes comprise one of 12, 14, 16, 20, 24, 26, 32, 44, and 56 information bits.

15. The apparatus of claim 13 , wherein the first DCI comprises a DCI format 0 and a DCI format 1A and the second DCI comprises a DCI format 1,

wherein at least one zero bit is appended to the DCI format 1A until the payload size of the DCI format 1A equals the payload size of the DCI format 0 by the transmitter if a number of information bits in the DCI format 1A is less than a number of information bits in the DCI format 0, and

wherein one zero bit is append to the DCI format 1A by the transmitter if the number of the information bits in the DCI format 1A belongs to one of the ambiguous sizes.

16. The apparatus of claim 15 , wherein at least one zero bit is appended to the DCI format 0 until the payload size of the DCI format 0 equals the payload size of the DCI format 1A by the transmitter if the number of the information bits in the DCI format 0 is less than the payload size of the DCI format 1A.