Sidelink Resource Allocation Using Active Time Indicators
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Solution Overview
Problem
In sidelink communication, resource allocation is challenging when user equipment operates in discontinuous reception mode, as the network may not have sufficient information about the active time of the receiving UE, leading to unsuccessful transmissions.
Innovation Solution
The transmitting UE determines the active time of the receiving UE and includes an active time indicator in the resource allocation request, allowing the network to allocate resources within the active time period, and if the allocated resource is not within the active time, the UE can select an alternative resource from a pool to ensure successful transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network schedules sidelink transmissions without visibility of Rx UE's active time, then resource allocation can be performed, but the transmission reliability deteriorates because the transmission may occur outside the active time window
Solution Approach 1:
The transmitting UE performs preliminary determination of the receiving UE's active time before requesting resource allocation. The active time indicator is prepared in advance and included in the resource allocation request message, allowing the network to schedule transmissions within the active time window without needing real-time visibility of DRX cycle variations.
Solution Approach 2:
The active time indicator acts as an intermediary information element that bridges the knowledge gap between the transmitting UE (which knows the active time) and the network (which needs to schedule resources). This indicator is carried within existing uplink control messages such as BSR or SRI, enabling the network to make informed scheduling decisions without direct visibility of the Rx UE's DRX state.
2Loss of time
If the transmitting UE waits for network resource allocation, then resource management is centralized, but transmission delay increases when the network cannot determine appropriate timing due to unknown active time
Solution Approach 1:
The transmitting UE determines the active time and prepares the active time indicator before submitting the resource allocation request to the network. This preliminary action enables the network to perform rapid resource allocation without needing to query or infer the active time, significantly reducing the time loss while maintaining centralized resource management.
3Productivity
If sidelink transmissions are scheduled outside the active time window, then resource utilization can be maximized, but the probability of successful reception decreases
Solution Approach 1:
By determining and indicating the active time in advance, the system ensures that scheduled transmissions occur within the active time window, maximizing successful reception probability. The network uses the active time indicator to select resources that fall within the indicated window, achieving both reliable delivery and efficient resource utilization.
Data Source
AI summary
A method and apparatus are provided for determining an active time of a user equipment to which a sidelink communication is to be sent. A sidelink resource allocation request is generated requesting allocation of a resource for transmitting this sidelink communication, the sidelink resource allocation request having an indicator indicative of the determined active time of the user equipment.