Cross-Cell Random Access Initiation via Primary Cell Signaling
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Solution Overview
Problem
In wireless communication systems, the delay in initiating a random access process by a terminal device in a secondary cell is significant due to the need for the network device to wait for the secondary cell to be activated before sending a PDCCH order, which reduces resource efficiency and increases latency.
Innovation Solution
The terminal device receives control information from a network device in a primary cell to initiate a random access process in a secondary cell, allowing the process to be triggered before the secondary cell is fully activated, using a random access parameter associated with an identifier included in the control information, thereby reducing delay and saving transmission resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network device waits for the secondary cell to be activated before sending the PDCCH order to initiate random access, then the random access process can be reliably initiated in the correct cell, but the delay increases and resource efficiency decreases
Solution Approach 1:
The network device sends the PDCCH order to initiate random access in the secondary cell before the secondary cell is fully activated. The terminal device receives this order through the primary cell and prepares for random access in advance, performing the action before the typical activation condition is met, thus reducing delay while maintaining reliability through proper parameter association.
2Loss of time
If the network device sends the PDCCH order through the activated primary cell instead of waiting for secondary cell activation, then the delay is reduced and resource efficiency improves, but the system complexity increases
Solution Approach 1:
The primary cell acts as an intermediary to transmit the PDCCH order that intends to initiate random access in the secondary cell. Instead of requiring direct signaling through the secondary cell, the primary cell mediates the transmission, allowing the terminal device to receive the order and understand which cell to access through associated parameters, thus reducing delay without significantly increasing complexity.
Solution Approach 2:
The PDCCH order format is designed to be universal and flexible, capable of indicating random access initiation in different cells through parameter association. The same PDCCH order structure can trigger random access in the primary cell or indicate the secondary cell through associated parameters, providing multi-functionality without requiring separate signaling mechanisms for each cell.
3Measurement precision
If additional identifiers are configured to associate with random access parameters for clear cell identification, then the accuracy of random access initiation improves, but the transmission resource overhead increases
Solution Approach 1:
Existing cell identifiers are configured to serve multiple functions: they identify the cell for scheduling purposes and simultaneously serve as the first identifier to associate with random access parameters. This multi-functionality allows accurate cell identification without requiring additional dedicated identifiers, thus avoiding extra transmission overhead while maintaining precision.
Solution Approach 2:
Instead of creating new dedicated identifiers for random access parameter association, the system reuses existing cell identifiers that are already part of the configuration. These identifiers are 'recovered' and put to dual use, eliminating the need for additional signaling resources while maintaining the ability to accurately identify the target cell for random access.
Data Source
AI summary
This application discloses example communication methods and example apparatuses. One example method includes receiving control information from a network device in a first cell, where the control information indicates to initiate a random access process in a second cell, and the control information includes a first identifier of the second cell. A random access process can then be initiated, based on the control information, in the second cell by using a random access parameter associated with the first identifier.