Cross-Carrier Scheduling for UE Battery Savings
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Solution Overview
Problem
In carrier aggregation environments, user equipment (UE) experiences battery drain due to the need to continuously monitor and decode control channels across multiple component carriers, leading to increased radio frequency (RF) usage and data buffering, which results in inefficient power management and potential data loss.
Innovation Solution
Implementing cross-carrier future subframe scheduling and time-skewed downlink transmission, where the UE receives downlink control indications for future subframes, allowing it to turn on the receiver only when necessary and reducing unnecessary RF 'ON' time, thereby conserving battery power and optimizing data reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE continuously monitors and decodes control channels across multiple component carriers, then data reception reliability is improved, but battery power consumption increases
Solution Approach 1:
The network provides preliminary scheduling information via PDCCH on the scheduling carrier before the actual data transmission occurs. This advance notification allows the UE to prepare selectively, turning on RF reception only for scheduled subframes rather than continuously monitoring all component carriers, thus reducing power consumption while maintaining reliable data reception.
Solution Approach 2:
The system enables self-service by having the network autonomously provide scheduling decisions through PDCCH, allowing the UE to independently determine when to activate RF reception without continuous network coordination. The UE uses the received scheduling information to autonomously manage its RF activation state, reducing unnecessary power consumption.
2Reliability
If the UE turns on the radio early to capture data samples, then data loss is prevented, but unnecessary RF activity increases power drain
Solution Approach 1:
The network provides preliminary scheduling information via PDCCH before the actual data transmission. This advance notification allows the UE to activate its RF reception at the precise moment when data transmission begins, rather than turning on early. The UE uses the scheduling information to determine the exact subframe and timing for RF activation, preventing data loss while avoiding unnecessary early activation that would waste power.
3Reliability
If the UE buffers data on component carriers, then no downlink data is missed, but memory usage and processing overhead increase
Solution Approach 1:
The network provides preliminary scheduling information via PDCCH indicating which subframes contain data transmissions. This advance notification allows the UE to selectively buffer only the data indicated in the scheduling information, rather than buffering all incoming data on all component carriers. The UE can accurately predict which data packets need buffering based on the received PDCCH schedules, reducing unnecessary memory usage and processing overhead.
4Use of energy by moving object
If cross-carrier scheduling is implemented, then power consumption is reduced, but scheduling complexity increases
Solution Approach 1:
The patent merges the control channel functionality across multiple component carriers by designating one carrier as the scheduling carrier that provides PDCCH for all component carriers. Instead of having separate control channels on each carrier, the scheduling information is consolidated on a single carrier, reducing the total number of control channels the UE must monitor and decode, thereby simplifying the overall scheduling complexity while enabling power savings.
Data Source
AI summary
A method at a user equipment having a scheduling carrier and at least one scheduled carrier, the method receiving, at a first subframe from the scheduling carrier, a downlink control indication containing a downlink assignment for the user equipment on the scheduled carrier; and turning on a receiver of the user equipment for the scheduled carrier at a future downlink subframe based on the downlink assignment. Further, a method, at a scheduling cell having a scheduling carrier, for scheduling downlink data reception on a scheduled carrier, the method setting a time skew for the scheduled carrier such that a data transmission start time for a subframe at the scheduled carrier is greater than a blind latency decode time on the scheduling carrier.