Communications Device RACH Recovery Using 2-Step and 4-Step Grants
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Solution Overview
Problem
Existing wireless communications networks face challenges in efficiently handling uplink data transmission using random access procedures, particularly with the increasing use of diverse devices and traffic profiles, where 2-step RACH procedures may fail, leading to inefficient recovery through fallback to 4-step RACH, which prolongs connection times and can result in dropped connections.
Innovation Solution
A communications device configured to initiate a 2-step random access procedure but upon failure, continues as if it started a 4-step procedure by transmitting additional data according to a 4-step random access response, allowing seamless transition without resource partitioning, thereby reducing recovery time and maintaining network efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a 2-step random access procedure is used for uplink data transmission, then connection setup time is reduced and data transmission efficiency is improved, but the procedure may fail and recovery through fallback to 4-step RACH prolongs connection time
Solution Approach 1:
The patent applies preliminary action by having the communications device prepare and transmit both the random access preamble and the complete uplink data payload in advance as part of the 2-step procedure. This pre-preparation of data transmission resources before the actual data transfer reduces the overall connection setup time while maintaining reliability through the efficient use of allocated resources.
Solution Approach 2:
The patent implements dynamics by enabling the communications device to adaptively switch between 2-step and 4-step random access procedures based on real-time conditions. The device dynamically adjusts its behavior based on network response and procedural success/failure, optimizing the connection setup process while maintaining reliability through flexible procedural selection.
2Reliability
If fallback to 4-step RACH is performed after 2-step RACH failure, then connection reliability is maintained, but recovery time increases and network resources are inefficiently utilized
Solution Approach 1:
The patent applies preliminary action by having the network element prepare and transmit a random access response message with uplink grant resources in advance, even before the complete 2-step procedure succeeds. This pre-allocation of resources allows the communications device to continue transmission without waiting for full procedure completion, reducing recovery time while maintaining reliability.
Solution Approach 2:
The patent implements continuity of useful action by enabling the communications device to continue transmitting uplink data using the granted resources from the random access response message, rather than stopping and restarting the entire RACH procedure. This continuous transmission approach maintains connection stability while significantly reducing recovery time and network resource consumption.
3Productivity
If resource partitioning is used to separate 2-step and 4-step RACH procedures, then procedure efficiency is improved, but device complexity and implementation difficulty increase
Solution Approach 1:
The patent applies universality by designing a unified random access response message structure that serves multiple functions: it can respond to both 2-step and 4-step procedures, and can be used for both successful completions and failure recoveries. This multi-functional approach maintains procedural efficiency while reducing implementation complexity by eliminating the need for separate resource partitioning mechanisms.
Data Source
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AI summary
A communications device for transmitting data to a wireless communications network is configured to transmit a random access preamble, and to transmit uplink data in an uplink shared physical channel associated with the preamble according to a 2-step random access procedure, the association between the preamble and the uplink shared channel being known to the wireless communications network. The communications device is configured to detect, in response to transmitting the preamble and the uplink data, a random access response message providing timing advance information and uplink grant of resources of the uplink shared channel according to a 4-step random access procedure. In response to detecting the random access response message, the communications device is configured to transmit uplink data in the uplink resources granted in the random access response message according to a 4-step random access procedure, as if the communications device was continuing with a 4-step RACH procedure having started with a 2-step RACH procedure. As such there is no requirement to fall-back to a full 4-step random access procedure, if a 2-step random access procedure has failed, thereby saving time and communications resources.