Random Access Response Timing Verification
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Solution Overview
Problem
In wideband radio access systems, user equipment may erroneously receive a random access response intended for another user equipment, leading to incorrect time synchronization and potential resource collisions.
Innovation Solution
A method is introduced where the random access response includes time-related information, such as the subframe number at which the random access preamble was transmitted, allowing user equipment to accurately identify whether the received response is intended for it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If user equipment waits for random access response without accurate time interval identification, then the system can operate with simple timing, but user equipment may erroneously receive response of another user equipment
Solution Approach 1:
The base station preliminarily embeds timing information (subframe number) into the random access response message before transmission. This allows user equipment to verify the response timing in advance by comparing the embedded subframe number with its own transmission timing, preventing erroneous response identification without requiring complex post-reception timing analysis.
Solution Approach 2:
The random access response includes feedback information about the timing when the corresponding random access preamble was detected by the base station. User equipment uses this feedback to verify whether the response is intended for it by comparing the feedback timing with its own transmission timing, creating a closed-loop verification mechanism.
2Reliability
If random access response includes time-related information, then user equipment can accurately identify its response, but the response message becomes more complex
Solution Approach 1:
The subframe number field in the random access response serves multiple functions: it identifies the timing when the preamble was detected, enables user equipment to verify response ownership, and provides timing synchronization information. This multi-functionality reduces the need for separate verification fields, minimizing message complexity while maintaining reliability.
3Adaptability or versatility
If user equipment uses random sequence in each RACH slot, then access flexibility is improved, but response misidentification risk increases
Solution Approach 1:
User equipment preliminarily records the subframe number when it transmits the random access preamble. This preliminary timing record serves as a reference for later verification when receiving the random access response, enabling accurate response identification even when using random sequences in different RACH slots.
Data Source
AI summary
A base station transmits a random access response in response to a random access request (random access preamble) of a user equipment. The random access response indudes information about a time when the random access request is transmitted and sequence number information of the random access request (random access preamble). The user equipment checks whether the received random access response is the response of the random access request transmitted by the user equipment, using the information about the time when the random access request is transmitted and the sequence number information included in the received random access response.