Grant-Free Uplink Activation for URLLC Latency Reduction
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing ultra-reliable low-latency communications (URLLC) due to stringent latency and reliability requirements, sporadic or periodic traffic patterns, and varying packet sizes, which demand flexible radio resource allocation.
Innovation Solution
The implementation of a grant-free (GF) radio resource pool that allows wireless devices to transmit data without a prior uplink grant, enabling flexible allocation of exclusive or partially overlapped radio resources for URLLC transmissions, and utilizing preambles for device identification within the GF resource pool.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional grant-based uplink resource allocation is used, then resource allocation control is simplified, but latency increases and signaling overhead increases
Solution Approach 1:
The base station pre-configures a set of uplink resources (time-frequency resources) and transmits configuration information to the wireless device before actual data transmission. The wireless device can immediately use these pre-configured resources without waiting for dynamic grants, thereby reducing latency while maintaining manageable control complexity through the structured configuration approach
2Loss of energy
If traditional grant-based uplink resource allocation is used, then resource allocation is controlled centrally, but signaling overhead increases
Solution Approach 1:
The base station performs preliminary configuration of uplink resources and transmits this configuration information to the wireless device in advance. This eliminates the need for continuous dynamic grants and reduces signaling overhead significantly, as the wireless device can autonomously use the pre-configured resources without requiring repeated control signals from the base station
3Adaptability or versatility
If flexible radio resource allocation is implemented for varying packet sizes, then URLLC traffic requirements are met, but resource management complexity increases
Solution Approach 1:
The uplink resources are segmented into multiple time-frequency resource blocks within the configured pool. The wireless device can select appropriate resource blocks based on its packet size requirements, enabling flexible adaptation to varying packet sizes while the base station manages the overall resource allocation through structured configuration rather than complex real-time management
4Productivity
If grant-free resources are allocated exclusively or partially overlapped, then resource utilization improves, but device identification complexity increases
Solution Approach 1:
A preamble is introduced as an intermediary signal that the wireless device transmits before data transmission on the grant-free resources. The base station uses this preamble to identify the wireless device, enabling reliable device identification in the shared grant-free pool while allowing multiple devices to use the same resources simultaneously without complex identification mechanisms
Data Source
AI summary
Systems, apparatuses, and methods are described for wireless communications. A base station may send a message to a wireless device to activate uplink transmissions for a non-activated cell. The wireless device may receive the message and activate a previously non-activated cell.