Optimizing uplink synchronization via dynamic PRACH configuration

In a wireless communication system in which a base station of a cellular radio access network (RAN) serves a plurality of user equipment devices (UEs) over an air interface and the air interface defines a physical random access control channel (PRACH) instance for carrying UE access requests, a data system comprising:

• a network communication interface through which the data system is configured to receive a log of subband CQI reports from the base station, wherein the log of subband CQI reports comprises one or more subband CQI values reported to the base station by each of the plurality of UEs respectively, and wherein each of the subband CQI values corresponds to a respective range of resource blocks such that the received log of subband CQI reports comprises at least one CQI value for each of a plurality of ranges of resource blocks;
• and
• a controller arranged to:
• (i) determine, based on an evaluation of the subband CQI values for the plurality of ranges of ranges of resource blocks, that a particular range of resource blocks of the plurality of ranges of resource blocks has a highest reported downlink air interface quality of the plurality of ranges of resource blocks, wherein the particular range of resource blocks is located within a single subframe, and (ii) based on the determination, cause the base station to configure the PRACH instance in the particular range of resource blocks having the highest reported downlink air interface quality.

In a wireless communication system in which a base station of a cellular radio access network (RAN) serves a plurality of user equipment devices (UEs) over an air interface and the air interface defines a physical random access control channel (PRACH) instance for carrying UE access requests, a method for configuring a position of the PRACH instance based on air interface conditions within an environment, the method comprising:

• the base station receiving one or more subband channel quality indicator (CQI) values from each of the plurality of UEs respectively, wherein each of the subband CQI values corresponds to a respective range of resource blocks;
• the base station providing to a data system in the wireless communication system a log of a plurality subband CQI values received from the plurality of UEs, wherein the log of the plurality of subband CQI values comprises at least one CQI value for each of a plurality of ranges of resource blocks;
• responsive to providing the log of the plurality of subband CQI values to the data system, the base station receiving from the data system an instruction to configure the PRACH instance in a particular range of resource blocks of the plurality of ranges of resource blocks, wherein the particular range of resource blocks is located within a single subframe;
• and
• the base station broadcasting to the plurality of UEs a system information message that defines the PRACH instance as being at the particular range of resource blocks.