Methods and apparatus for encoding and decoding a downlink control channel transmission

A method in a user equipment for decoding a downlink control channel transmission, comprising:

• receiving a downlink control channel transmission from a network node, wherein the downlink control channel transmission carries one or more predetermined control information bits or omits one or more predetermined control information bits such that the downlink control channel transmission carries a reduced number of control information bits;
• determining that channel conditions are below a threshold level;
• and
• in response to determining that channel conditions are below the threshold level, decoding the downlink control channel transmission based on knowledge that the one or more predetermined control information bits are to have one or more respective values when channel conditions are below the threshold level.

A network node configured for use in encoding a downlink control channel transmission to a user equipment, the network node comprising:

• transceiver circuitry;
• and
• processing circuitry configured to:
• determine that channel conditions are below a threshold level;
• in response to determining that channel conditions are below the threshold level:
• encode, into the downlink control channel transmission, one or more predetermined control information bits whose one or more respective values are known to the user equipment, or
• encode a reduced number of control information bits into the downlink control channel transmission by omitting one or more control information bits, wherein the one or more omitted control information bits are one or more predetermined control information bits whose one or more respective values are known to the user equipment;
• and
• transmit, via the transceiver circuitry, the downlink control channel transmission to a user equipment;
• wherein the one or more predetermined control information bits whose one or more respective values are known to the user equipment are one or more control information bits that the user equipment knows are to have the one or more respective values when channel conditions are below the threshold level.

A user equipment comprising:

• transceiver circuitry;
• and
• processing circuitry configured to:
• receive, via the transceiver circuitry, a downlink control channel transmission from a network node, wherein the downlink control channel transmission carries a number of predetermined control information bits or omits one or more predetermined control information bits such that the downlink control channel transmission carries a reduced number of control information bits;
• determine that channel conditions are below a threshold level;
• and
• in response to determining that channel conditions are below a threshold level, decode the downlink control channel transmission based on knowledge that the one or more predetermined control information bits are to have one or more respective values when channel conditions are below the threshold level.