Compact downlink control information messages

1. A network node for communicating with a wireless device, WD, the network node comprising processing circuitry that causes the network node to:

select between a first mode of operation and a second mode of operation; and

operate in the selected mode:

the first mode of operation including one of selecting and generating a first downlink control information, DCI, message having a first number of bits; and

the second mode of operation including one of selecting and generating a second DCI message having a second number of bits less than the first number of bits in at least one of the following fields:

a modulation and coding scheme, MCS, field, the MCS field indicating an MCS subset of a table of configurable modulation and coding schemes, the MCS subset being selected based in part on a measure of channel quality;

a redundancy version, RV, field; and

a hybrid automatic repeat request, HARQ, process field; and

the first and second DCI messages including scheduling messages for scheduling one of a data transmission and a physical downlink shared channel, PDSCH, transmission.

2. The network node of claim 1 , wherein the second DCI message has fewer than 5 MCS bits.

3. The network node of claim 1 , wherein the RV field has one of one bit and no bit, one bit indicating two RVs and no bit indicating one RV.

4. The network node of claim 1 , wherein the HARQ process field has one of two bits, one bit and no bit, indicating one of four, two and one HARQ processes, respectively.

5. A method implemented in a network node, the method comprising:

selecting between a first mode of operation and a second mode of operation; and

operating in the selected mode:

the first mode of operation including one of selecting and generating a first downlink control information, DCI, message having a first number of bits; and

the second mode of operation including one of selecting and generating a second DCI message having a second number of bits less than the first number of bits in at least one of the following fields:

a modulation and coding scheme, MCS, field, the MCS field indicating an MCS subset of a table of configurable modulation and coding schemes, the MCS subset being selected based in part on a measure of channel quality;

a redundancy version, RV, field; and

a hybrid automatic repeat request, HARQ, process field; and

the first and second DCI messages including scheduling messages for scheduling one of a data transmission and a physical downlink shared channel, PDSCH, transmission.

6. The method of claim 5 , wherein the second DCI message has fewer than 5 MCS bits.

7. The method of claim 5 , wherein the RV field has one of one bit and no bit, one bit indicating two RVs and no bit indicating one RV.

8. The method of claim 5 , wherein the HARQ process field one of two bits, one bit and no bit, indicating one of four, two and one HARQ processes, respectively.

9. A wireless device, WD, for communicating with a network node, the WD comprising processing circuitry that causes the WD to:

select between a first mode of operation and a second mode of operation, the selecting being based on signaling from the network node; and

operate in the selected mode:

the first mode of operation including receiving and decoding a first downlink control information, DCI, message having a first number of bits; and

the second mode of operation including receiving and decoding a second DCI message having a second number of bits less than the first number of bits in at least one of the following fields:

a modulation and coding scheme, MCS, field, the MCS field indicating an MCS subset of a table of configurable modulation and coding schemes, the MCS subset being selected based in part on a measure of channel quality;

a redundancy version, RV, field; and

a hybrid automatic repeat request, HARQ, process field; and

the first and second DCI messages including scheduling messages for scheduling one of a data transmission and a physical downlink shared channel, PDSCH, transmission.

10. The WD of claim 9 , wherein, when there is no RV field, the WD assumes only one RV.

11. The WD of claim 9 , wherein, when there is no HARQ process field, the WD assumes only one HARQ process.

12. A method implemented in a wireless device, WD, the method comprising:

selecting between a first mode of operation and a second mode of operation, the selecting being based on radio resource control, RRC, signaling from the network node; and

operating in the selected mode:

the first mode of operation including receiving and decoding a first downlink control information, DCI, message having a first number of bits, and

the second mode of operation including receiving and decoding a second DCI message having a second number of bits less than the first number of bits in at least one of the following fields:

a modulation and coding scheme, MCS, field, the MCS field indicating an MCS subset of a table of configurable modulation and coding schemes, the MCS subset being selected based in part on a measure of channel quality;

a redundancy version, RV, field; and

a hybrid automatic repeat request, HARQ, process field; and

the first and second DCI messages including scheduling messages for scheduling one of a data transmission and a physical downlink shared channel, PDSCH, transmission.

13. The method of claim 12 , wherein, when there is no RV field, the WD assumes only one RV.

14. The method of claim 12 , wherein, when there is no HARQ process field, the WD assumes only one HARQ process.