Transmitting and receiving devices for reliable reception of control messages
A transmitting device and a receiving device for reliable reception of control messages such as downlink control information is provided. The transmitting device forms a control message which comprises control information, a first CRC word (W1) and a second CRC word (W2). The control message is sent to the receiving device which obtains a first CRC check outcome based on performing a first CRC check on the control message, and a second CRC check outcome based on performing a second CRC check on the control message. Thereby, more reliable reception of control messages is possible. Furthermore, the present application also relates to corresponding methods and a computer program.
1. A transmitting device for a wireless communication system, the transmitting device comprising a processor and a memory coupled to the processor and having processor-executable instructions stored thereon, which when executed by the processor, cause the transmitting device to:
replace bits of a bit field (f n ) with padded bits to obtain control information with embedded padded bits; wherein the control information before replacing the bits of the bit field f n with padded bits comprises a plurality of information bit fields (f 1 , . . . , f n , . . . , f N ),
obtain a first cyclic redundancy check (CRC) word based on encoding the control information with embedded padded bits using a first CRC generator polynomial;
append the first CRC word to the control information with the embedded padded bits: and obtain a second CRC word based on encoding the control information with the embedded padded bits together with the appended first CRC word using a second CRC generator polynomial;
replace the embedded padded bits by the second CRC word to obtain another control information;
form a control message based on the another control information; and
transmit the control message to a receiving device.
2. The transmitting device according to claim 1 , wherein the transmitting device is configured to:
obtain the first CRC word based on encoding at least a part of a bit field (f n ) using the first CRC generator polynomial.
3. The transmitting device according to claim 2 , configured to:
replace bits of the bit field (f n ) with the first CRC word so as to obtain the control information embedded in the first CRC word;
obtain the second CRC word based on encoding the control information with the embedded first CRC word using the second CRC generator polynomial; and
form the control message based on appending the second CRC word to the control information with the embedded first CRC word.
4. The transmitting device according to claim 2 , configured to:
obtain the first CRC word based on encoding the control information with the embedded padded bits using the first CRC generator polynomial; and
append the first CRC word to the control information.
5. The transmitting device according to claim 4 , configured to:
obtain the second CRC word based on encoding the control information with the embedded padded bits using the second CRC generator polynomial; or
obtain the second CRC word based on encoding the control information with the embedded padded bits together with the appended first CRC word using the second CRC generator polynomial.
6. The transmitting device according to claim 5 , configured to:
form the control message based on replacing the embedded padded bits with the second CRC W2.
7. The transmitting device according to claim 3 , configured to:
adapt a bit length of the embedded first CRC word or the embedded second CRC word to be equal to a bit length of the bit field (f n ).
8. The transmitting device according to claim 7 , wherein adapting the bit length of the embedded first CRC word or the embedded second CRC word comprises at least one of:
puncturing bits of the embedded first CRC word or the embedded second CRC word; and
repeating bits of the embedded first CRC word or the embedded second CRC word.
9. The transmitting device according to claim 1 , configured to:
form the control message based on appending the second CRC word to the control information and the appended first CRC word.
10. The transmitting device according to claim 1 , configured to:
CRC scramble at least one of the first CRC word and the second CRC word using an identity of the receiving device.
11. The transmitting device according to claim 1 wherein the control information is downlink control information (DCI).
12. A method for a transmitting device, the method comprising:
replacing bits of a bit field (f n ) with padded bits to obtain control information with embedded padded bits; wherein the control information before replacing the bits of the bit field f n with padded bits comprises a plurality of information bit fields (f 1 . . . , f n . . . f N );
obtaining a first cyclic redundancy check (CRC) word based on encoding the control information with embedded padded bits using a first CRC generator polynomial;
appending the first CRC word to the control information with the embedded padded bits; and obtain a second CRC word based on encoding the control information with the embedded padded bits together with the appended first CRC word using a second CRC generator polynomial;
replacing the embedded padded bits by the second CRC word to obtain another control information;
forming a control message based on the another control information; and
transmitting the control message to a receiving device.
13. A non-transitory computer readable storage medium storing computer program codes that, when executed by a computer processor, causes a computer to perform the method of claim 12 .