Scheduling Request Collection After DRX Period in mmW Systems
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Solution Overview
Problem
In wireless communication systems operating in millimeter wave (mmW) spectrum, user equipment (UE) devices configured for discontinuous reception (DRX) face challenges in transmitting scheduling requests due to directional beamforming, which prevents them from receiving physical downlink control channel (PDCCH) transmissions during sleep mode, thereby hindering resource allocation for uplink data transmission.
Innovation Solution
The UE identifies a random access time period after awakening from sleep mode and transmits scheduling requests during this period, using either random access channel (RACH) resources or resources not associated with RACH, based on the length of the DRX sleep period, and utilizes directional synchronization subframes to determine the appropriate transmission resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a UE enters DRX sleep mode to conserve battery power, then power consumption is reduced, but the UE cannot receive PDCCH transmissions for scheduling grants
Solution Approach 1:
The UE transmits the scheduling request before entering sleep mode or during the transition from sleep mode, ensuring the base station has advance notice of the uplink data transmission need. This preliminary action allows the base station to prepare and send scheduling grants during the UE's active periods, resolving the contradiction between power saving and reliable control channel reception.
2Productivity
If a UE transmits scheduling request during DRX sleep mode in mmW spectrum, then uplink resource allocation can be initiated, but the transmission may be blocked due to directional beamforming
Solution Approach 1:
The patent implements dynamic resource selection where the UE adapts its scheduling request transmission resources based on the DRX cycle length. For longer DRX cycles, the UE uses random access resources with more robust transmission configurations, while for shorter cycles, it uses conventional PUCCH resources. This dynamic adaptation ensures reliable transmission across varying operational conditions.
Solution Approach 2:
The UE changes transmission parameters including frequency resource selection and transmission power based on the DRX sleep period duration. By adjusting these parameters dynamically according to the specific DRX configuration, the system maintains reliable scheduling request transmission while optimizing for the directional beamforming constraints of mmW spectrum operation.
3Reliability
If a UE uses random access resources for scheduling request transmission, then transmission robustness is improved for long DRX periods, but resource availability is reduced
Solution Approach 1:
The UE selectively uses random access resources only when necessary (i.e., during long DRX sleep periods), rather than continuously. This partial action approach allows the system to maintain robust transmission capability when needed while preserving conventional PUCCH resources for normal operation, thus balancing reliability requirements with resource availability.
Data Source
AI summary
A wireless device configured for discontinuous reception (DRX) may and operating in a system that uses directional beamforming may identify a random access time period after awaking from a DRX sleep mode. The device may then transmit a scheduling request during the random access time period. In some cases, the device may transmit the scheduling request using frequency resources also associated with random access transmissions. In other cases, the device may utilize resources that are not associated with random access. The determination of which frequency resources are used may depend on the length of the DRX. That is, if a device has been in a sleep mode for a long time, it may use random access frequency resources that are associated with a more robust transmission configuration.