Discontinuous Reception Ramp Window for Latency and Power Trade-offs
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Solution Overview
Problem
In wireless communications, user equipment (UE) may miss receiving transport blocks due to dynamic variations in processing and transmission delays, causing them to arrive outside the scheduled on-window of a discontinuous reception (DRX) cycle, leading to increased latency and power consumption.
Innovation Solution
The implementation of a ramp window within the DRX cycle, which includes a subset of wakeup slots and sleep slots, allows the UE to transition to an on-state during wakeup slots and a sleep state during sleep slots, enabling the reception of transport blocks that arrive outside the original on-window, thereby reducing latency and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the UE operates in a standard DRX cycle with fixed on-window and sleep window, then power consumption is reduced during sleep state, but transport blocks arriving outside the on-window are missed causing increased latency
Solution Approach 1:
The sleep window is segmented into multiple slots with different states: wakeup slots where the UE transitions to on-state to monitor for transport blocks, and sleep slots where the UE remains in sleep state. This segmentation allows the UE to selectively wake up only when necessary to receive data, reducing unnecessary power consumption while capturing arriving transport blocks.
Solution Approach 2:
The DRX cycle is made dynamic by allowing the UE to transition between sleep state and on-state at different slots within the sleep window based on whether a transport block is detected. The UE dynamically adjusts its reception state during the sleep window rather than maintaining a fixed state throughout.
2Reliability
If the UE extends the on-window duration to capture arriving transport blocks, then reception reliability improves, but power consumption increases due to extended on-state
Solution Approach 1:
Instead of extending the continuous on-window, the sleep window is segmented into wakeup slots and sleep slots. The UE only activates reception during specific wakeup slots within the sleep window, maintaining reliability for capturing arriving blocks while minimizing the duration of high-power on-state operation.
Solution Approach 2:
Different slots within the sleep window are assigned different qualities: wakeup slots have high reception capability (on-state) while sleep slots have low reception capability (sleep state). This local differentiation allows the UE to have high reception reliability exactly when transport blocks are likely to arrive while conserving power during periods when blocks are less likely to arrive.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A user equipment (UE may be configured to communicate with a base station in a discontinuous reception (DRX) mode according to a DRX cycle. The UE may receive signaling that indicates a configuration of a ramp window associated with the DRX cycle. The ramp window may include a set of slots that is adjacent to a sleep window of the DRX cycle and, in some examples, is adjacent to an on-window of the DRX cycle. The set of slots may include a first subset of wakeup slots and a second subset of sleep slots. During the ramp window, the UE may monitor for a transport block from the base station during the first subset of wakeup slots. If the UE receives the transport block during a wakeup slot, the UE may transition to the on-window of the DRX cycle.