DRX Cycle Control via Zero BSR Detection
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Solution Overview
Problem
In 4G and 5G wireless networks, Connected Mode Discontinuous Reception (C-DRX) systems face inefficiencies due to the unnecessary restart of inactivity timers when a UE has a Buffer Status Report (BSR) of zero, leading to increased battery usage and power consumption, especially when transmitting CSI reports or BSRs with empty buffers.
Innovation Solution
Implementing proprietary timers and configuring wireless devices via RRC signaling or MAC CE to prevent the restart of inactivity timers when a BSR is zero, using a data-inactivity-timer and data-short-cycle-timer to manage DRX states, and transmitting DRX Command MAC CEs to control the DRX cycle, allowing the UE to transition to long cycles and reduce unnecessary monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inactivity timer is restarted whenever a PUSCH transmission occurs (including when BSR is zero), then the UE maintains readiness for data transmission, but the UE power consumption increases due to unnecessary monitoring
Solution Approach 1:
The patent introduces a new parameter (BSR value) to distinguish between different types of PUSCH transmissions. By checking whether the BSR indicates empty buffer (zero), the system can change the timer restart behavior accordingly, allowing the UE to enter DRX mode when no data is actually present while maintaining readiness when data is expected
Solution Approach 2:
The patent uses the BSR feedback mechanism to determine whether to restart the inactivity timer. The BSR acts as feedback information about the UE's buffer status, enabling the network to make intelligent decisions about whether the UE should remain active or can transition to DRX mode, thus balancing reliability and power consumption
2Speed
If the UE monitors PDCCH continuously to check for data transmission, then data can be received promptly, but battery life is reduced due to continuous monitoring
Solution Approach 1:
The patent implements periodic DRX cycles where the UE alternates between active monitoring periods and sleep periods. Instead of continuous monitoring, the UE monitors PDCCH periodically according to DRX configuration, significantly reducing power consumption while maintaining the ability to receive data when it arrives
Solution Approach 2:
The patent makes the monitoring behavior dynamic by adjusting the DRX cycle parameters based on the BSR indication. When the BSR indicates empty buffer, the system can transition to more aggressive DRX modes with longer off-duration, while maintaining the ability to switch to continuous monitoring when data transmission is detected, thus optimizing between speed and energy consumption
3Use of energy by moving object
If the UE transitions to long DRX cycles to reduce monitoring, then power consumption decreases, but the UE may miss timing information for data transmission
Solution Approach 1:
The patent uses preliminary BSR indication before actual data transmission to prepare for DRX cycle transition. By checking the BSR in advance and seeing that the buffer is empty, the system can safely transition to long DRX cycles without risking missed timing information, as there is no imminent data transmission that would require immediate UE response
Data Source
AI summary
A method by a network node is provided for controlling a DRX state of a wireless device configured with a long DRX cycle and in a connected state. The method includes transmitting, to the wireless device PDCCH for scheduling DL or UL data transmission. At a first time, the network node transmits new user data on a PDSCH or receives new user data on a first PUSCH. At a second time, the network node receives a second PUSCH that includes only a BSR with a value that is zero and transmits a DRX Command MAC CE to the wireless device when no pending SRs or PUSCH transmission exist for the wireless device and at least one of: a set time has elapsed after user data was transmitted on the PDSCH or received on the first PUSCH, or a set time elapsed before reception of the second PUSCH.