Random Access Group Identifier Generation Using Subframe Serial Numbers
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Solution Overview
Problem
In cellular radio communication systems, terminals face challenges in rapidly and accurately accessing the system during handover processes due to the reliance on absolute system time for calculating group identifiers in random access response messages, leading to delays and inefficiencies.
Innovation Solution
A method to generate group identifiers based on the serial number of the subframe and the random access channel in which the random access time slot is located, using the formula group identifier=Sn+m×10, allowing terminals to access the system without needing to read the absolute system time, especially during handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the group identifier is calculated based on the absolute system time (SFN), then the terminal can identify the random access response message, but the terminal cannot rapidly access the system during handover because it needs to read the absolute system time first
Solution Approach 1:
The patent extracts the handover scenario from the general random access process and provides a specialized solution. During handover, the terminal uses the downlink time slot information (which is already synchronized) to calculate the group identifier directly, without needing to read the absolute system time from the target cell. This extraction of the time reference from the absolute system time to the relative downlink time slot information resolves the contradiction by maintaining calculation accuracy while eliminating the time delay associated with reading SFN.
Solution Approach 2:
The patent applies preliminary action by having the terminal acquire the downlink time slot configuration information in advance during the handover preparation phase. This information is then used to calculate the group identifier for the random access response message without requiring additional real-time operations. By preparing the time reference information beforehand, the system eliminates the delay that would otherwise occur during the actual handover execution.
2Measurement precision
If the terminal reads the absolute system time to calculate the group identifier, then the calculation is accurate, but the access process becomes slower and less efficient
Solution Approach 1:
The patent introduces an intermediary approach by using the downlink time slot information as an intermediate reference instead of directly using the absolute system time. The downlink time slot information serves as a mediator that connects the terminal's time reference with the random access response identification requirement. This intermediary mechanism maintains the accuracy needed for group identifier calculation while significantly improving access speed, as the terminal already has this time information from downlink synchronization without needing additional SFN reading operations.
3Adaptability or versatility
If multiple random access channels are configured in TDD mode, then more random access opportunities are available, but the group identifier calculation becomes more complex
Solution Approach 1:
The patent applies segmentation by dividing the group identifier calculation into distinct components based on the random access channel type. For TDD mode with multiple random access channels, the calculation separately considers the downlink time slot information and the specific random access channel index. This segmentation allows the system to maintain flexibility in configuring multiple random access channels while keeping the calculation complexity manageable through a structured, modular approach to identifier generation.
Data Source
AI summary
The invention discloses a method for generating a group identifier of the random access response message. The group identifier is determined according to the serial number of the subframe in which the random access time slot of random access preamble message transmitted by the terminal lies and the serial number of the random access channel in which the random access time slot lies. A random access method and a random access response method in a cellular radio communication system are also provided. Using the method of the present invention, the terminal needs not acquire the absolute system time of the cellular system in which the random access time slot lies, and can access the cellular radio communication system rapidly and accurately.