Random Access for Uplink Reliability in LAA
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Solution Overview
Problem
In LTE systems, uplink data transmission reliability and timeliness are compromised in LAA cells due to interference and the need for successful LBT before data can be sent, especially when carrier aggregation is performed with licensed spectrum cells, leading to delays and unreliability in uplink reporting.
Innovation Solution
Implementing a communication method that includes receiving random access preamble information, sending a random access preamble, and obtaining an uplink asynchronous HARQ process identifier in the random access response to enable non-contention-based random access on LAA cells, allowing for uplink transmission based on unlicensed-spectrum channels, even if LBT fails initially.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LBT process is performed before uplink transmission on LAA cell, then channel access reliability is improved, but transmission timeliness deteriorates due to additional listening time required
Solution Approach 1:
The base station performs LBT in advance and pre-allocates uplink resources to the terminal through random access response before the terminal needs to transmit data. This preliminary channel access and resource allocation eliminates the need for the terminal to perform separate LBT, reducing transmission delay while maintaining reliability through the base station's prior channel assessment
Solution Approach 2:
The base station acts as an intermediary that performs LBT on behalf of the terminal and mediates resource allocation. Instead of the terminal directly performing LBT and accessing the channel, the base station intermediates by listening first and then granting uplink resources, thereby resolving the contradiction between reliability and timeliness
2Adaptability or versatility
If existing uplink transmission procedure is used on LAA cell, then protocol compatibility is improved, but transmission reliability deteriorates due to LBT failure blocking data reporting
Solution Approach 1:
The base station intermediates the LBT process and resource allocation, performing channel access before granting uplink resources. This mediation ensures that terminals receive pre-validated uplink grants, eliminating LBT-related reliability issues while maintaining standard random access procedures
Solution Approach 2:
The base station performs preliminary LBT and resource allocation through the random access response message, establishing uplink resources before the terminal attempts data transmission. This preliminary action ensures reliable data reporting by guaranteeing channel access validity before actual uplink data transmission occurs
Data Source
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AI summary
Embodiments of the present invention provide a communication method used for random access, including: receiving, by a terminal, random access preamble information sent by a base station; and before sending random access to the base station based on the random access preamble information, receiving, by the terminal, a random access response sent by the base station, where the random access response includes an uplink asynchronous hybrid automatic repeat request HARQ process identifier, and the uplink asynchronous HARQ process identifier is used by the terminal to send uplink data to the base station. Compared with the prior art, the communication method provided in the embodiments of the present invention can ensure to some extent that uplink data is transmitted timely and can effectively improve uplink data transmission reliability.