Search space design for NR-U WB operations
An apparatus and a method are provided by which a configuration for a set of control resource sets and at least one search space on a bandwidth part is obtained, wherein the bandwidth part comprises at least two sub-bands, each search space is associated with a subset of at least two control resource sets, and at least two control resource sets are on different sub-bands, and mapping and monitoring each search space is performed according to the obtained configuration.
1 . An apparatus comprising
at least one processor and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform:
obtaining, from a network control element, a configuration for a set of control resource sets and at least one search space on a bandwidth part, wherein the bandwidth part comprises at least two sub-bands, respective search spaces are associated with multiple control resource sets that comprise a subset of at least two control resource sets, and the at least two control resource sets are on different sub-bands, and wherein respective ones of the set of control resource sets are associated with different listen-before-talk (LBT) sub-bands, wherein the set of control resource sets share a common set of parameters comprising at least: a control resource set length and a transmission configuration indication state; and
according to the configuration that was obtained, mapping and monitoring the at least one search space on the control resource sets associated therewith responsive to a number of sub-bands, on which the network control element transmits, being equal to a preconfigured value for the at least one search space.
2 . The apparatus according to claim 1 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform:
determining the sub-bands within the transmission bandwidth of a channel occupation time of the network control element based on an indication received from the network control element and/or by detecting a downlink demodulation reference signal.
3 . The apparatus according to claim 2 , wherein
the indication received from the network control element is a group-common physical downlink control channel, and
the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform:
mapping the search space carrying the group-common physical downlink control channel to all associated control resource sets.
4 . The apparatus according to claim 2 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform:
determine on which of the one or more associated control resource sets to map and monitor a certain search space depending on the sub-bands within the transmission bandwidth of a channel occupation time of the network control element.
5 . The apparatus according to claim 4 , wherein
the association of the search space to the control resource sets depends on a combination of sub-bands that the network control element transmits, and
the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform:
mapping a certain search space to a control resource set with the highest priority among transmitted associated control resource sets.
6 . The apparatus according to claim 5 , wherein
the associated control resource sets are defined for certain search space and the number thereof is smaller than the number of sub-bands of the bandwidth part, and
the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform:
dropping the certain search space when these control resource sets are not available.
7 . The apparatus according to claim 4 , wherein a search space is associated with multiple control resource sets, and
the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform:
mapping and monitoring the search space on all associated control resource sets if the network control element is transmitting on the sub-band corresponding to the control resource set.
8 . The apparatus according to claim 1 , wherein the control resource sets that a certain search space is associated with are ranked based on a priority.
9 . The apparatus according to claim 1 , wherein the associated control resource sets differ only in a frequency domain location within the bandwidth part.
10 . The apparatus according to claim 1 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform:
applying different mapping and monitoring strategies for different search spaces.
11 . The apparatus according to claim 1 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform:
obtaining the configuration by receiving the configuration from a network control element.
12 . The apparatus according to claim 1 , wherein the common set of parameters further comprises: a number of physical resource blocks, a demodulation reference signal strategy, an interleaving strategy and a resource element group bundle size.
13 . The apparatus according to claim 1 , wherein the mapping for respective monitoring occasions of the search space is based on an outcome of scheduling and a listen-before-talk (LBT) process on a sub-band associated with one or more control resource sets of the set of control resource sets.
14 . An apparatus comprising
at least one processor and at least one memory including computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform:
preparing a configuration for a set of control resource sets, comprising at least a primary control resource set and a secondary control resource set, and at least one search space on a bandwidth part, wherein the bandwidth part comprises at least two sub-bands, respective search spaces are associated with multiple control resource sets that comprise a subset of at least two control resource sets, and the at least two control resource sets are equally distributed among different sub-bands to provide load balancing for the at least one search space, wherein the set of control resource sets share a common set of parameters comprising at least: a control resource set length and a transmission configuration indication state; and
transmitting, after a listen-before-talk (LBT) process on a sub-band associated with the primary control resource set or the secondary control resource set, the configuration to a user equipment.
15 . The apparatus according to claim 14 , wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus to further perform:
detecting whether a channel is vacant,
determining, when it is detected that a channel is vacant for at least one sub-band, that a channel occupancy time has started,
determining a transmission bandwidth for the current channel occupancy time,
determining an association between search space and control resource set for at least one search space and the user equipment, and
transmitting at least one physical downlink control channel for the user equipment based on the determined association between search space and control resource set.
16 . The apparatus according to claim 14 , wherein the primary control resource set and the secondary control resource set are ranked based on a priority.
17 . The apparatus according to claim 14 , wherein the associated control resource sets differ only in a frequency domain location within the bandwidth part.
18 . A method comprising:
obtaining, at a user equipment from a network control element, a configuration for a set of control resource sets and at least one search space on a bandwidth part, wherein the bandwidth part comprises at least two sub-bands, respective search spaces are associated with multiple control resource sets that comprise a subset of at least two control resource sets, and the at least two control resource sets are on different sub-bands, and wherein respective ones of the set of control resource sets are associated with different listen-before-talk (LBT) sub-bands, wherein the set of control resource sets share a common set of parameters comprising at least: a control resource set length and a transmission configuration indication state; and
according to the configuration that was obtained, mapping and monitoring the at least one search space on the control resource sets associated therewith responsive to a number of sub-bands, on which the network control element transmits, being equal to a preconfigured value for the at least one search space.