Downlink control channel monitoring

Abstract

Various communication systems may benefit from the appropriate monitoring of communication channels. For example, certain wireless communication systems may benefit from downlink control channel monitoring optimized for discontinuous reception mode and/or narrowband operation. A method can include selecting a search space configuration from a plurality of search space configurations for a user equipment. The method can also include operating the user equipment in the selected search space configuration.

1 . An apparatus comprising:
 at least one processor; and   at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform:
 selecting a search space configuration from a plurality of search space configurations for a user equipment; and 
 operating the user equipment in the selected search space configuration, 
 wherein the plurality of search space configurations can respectively cover at least two different bandwidths. 
   
     
     
         2 . The apparatus according to  claim 1 , wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform:
 switching between search space configurations.   
     
     
         3 . The apparatus according to  claim 1 , wherein the selecting is based on at least one of need for bandwidth or based on an explicit indication from an access node. 
     
     
         4 . The apparatus according to  claim 2 , wherein the switching is based on at least one of a change in need for bandwidth, an expiration of a timer, or an explicit indication from an access node. 
     
     
         5 . The apparatus according to  claim 2 , wherein the switching comprises switching from configuration A to configuration B or switching from configuration B to configuration A. 
     
     
         6 . The apparatus according to  claim 5 , wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform:
 relying on a timer when switching from the configuration A to the configuration B, or relying on an additional synchronization signal when switching from the configuration B to the configuration A.   
     
     
         7 . The apparatus according to  claim 5 , wherein the configuration A comprises one or more of the following attributes: search space(s) covering a wide bandwidth; search space(s) covering a high number of control channel elements; user equipment operating with a high number of physical downlink control channel blind decoding attempts per slot or per mini-slot or per subframe; user equipment monitoring all required physical downlink control channel from both slots and mini-slots; user equipment operating with radio frequency bandwidth up to a bandwidth corresponding to maximum channel bandwidth; or user equipment having a large data volume in at least one link direction, either downlink or uplink. 
     
     
         8 . The apparatus according to  claim 5 , wherein the configuration B comprises one or more of the following attributes: search space(s) covering a narrow bandwidth; search space(s) covering a low number of control channel elements; user equipment operating with a low number of physical downlink control channel blind decoding; user equipment monitoring physical downlink control channel at maximum with slot resolution at least in discontinuous reception mode; user equipment operating with radio frequency bandwidth corresponding to a subset of the maximum channel bandwidth; or user equipment supporting a limited data volume in at least in at least one link direction, either downlink or uplink. 
     
     
         9 . The apparatus according to  claim 1 , wherein the plurality of search space configurations comprise at least one of a first search space configuration configured to support the user equipment in active data transmission, a second search space configuration configured to support the user equipment in discontinuous reception mode or in a low data rate service mode. 
     
     
         10 . The apparatus according to  claim 1 , wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform:
 receiving configuration of the plurality search space configurations by higher layer signaling.   
     
     
         11 . The apparatus according to  claim 1 , wherein the plurality of search space configurations comprise at least one of a first search space configuration configured to cause the user equipment to follow all physical downlink control channel aggregation levels, a second search space configuration configured to cause the user equipment to follow only a subset of physical downlink control channel aggregation levels, a first search space configuration configured to cause the user equipment to follow both a common search space and a user specific search space, a second search space configuration configured to cause the user equipment to follow only a common search space, or different user specific search spaces from one another. 
     
     
         12 . The apparatus according to  claim 1 , wherein the operating of the user equipment comprises performing physical downlink control channel blind detection. 
     
     
         13 . An apparatus comprising:
 at least one processor; and   at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, with the at least one processor, cause the apparatus at least to perform:
 selecting a search space configuration from a plurality of search space configurations for a user equipment; and 
 indicating, to the user equipment, the selected search space configuration, 
 wherein the plurality of search space configurations respectively cover at least two different bandwidths. 
   
     
     
         14 . The apparatus according to  claim 13 , wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform:
 sending an indication to the user equipment to switch to a different search space configuration of the plurality of search space configurations.   
     
     
         15 . The apparatus according to  claim 13 , wherein the selecting is based on at least one of need for bandwidth. 
     
     
         16 . The apparatus according to  claim 14 , wherein the switching is based on at least one of a change in need for bandwidth, the expiration of a timer. 
     
     
         17 . The apparatus according to  claim 14 , wherein the switching comprises switching from configuration A to configuration B or switching from configuration B to configuration A. 
     
     
         18 . The apparatus according to  claim 17 , wherein the at least one memory and the computer program code are further configured to, with the at least one processor, cause the apparatus at least to perform:
 relying on a timer when switching from the configuration A to the configuration B, or relying on an additional synchronization signal when switching from the configuration B to the configuration A.   
     
     
         19 . The apparatus according to  claim 17 , wherein the configuration A comprises one or more of the following attributes: search space(s) covering a wide bandwidth; search space(s) covering a high number of control channel elements; user equipment operating with a high number of physical downlink control channel blind decoding attempts per slot or per mini-slot or per subframe; user equipment monitoring all required physical downlink control channel from both slots and mini-slots; user equipment operating with radio frequency bandwidth up to a bandwidth corresponding to maximum channel bandwidth; or user equipment having a large data volume in at least one link direction, either downlink or uplink. 
     
     
         20 . The apparatus according to  claim 17 , wherein the configuration B comprises one or more of the following attributes: search space(s) covering a narrow bandwidth; search space(s) covering a low number of control channel elements; user equipment operating with a low number of physical downlink control channel blind decoding; user equipment monitoring physical downlink control channel at maximum with slot resolution at least in discontinuous reception mode; user equipment operating with radio frequency bandwidth corresponding to a subset of the maximum channel bandwidth; or user equipment supporting a limited data volume in at least in at least one link direction, either downlink or uplink.