Initialization Scrambling Sequence for 2-Step RACH Payload
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Solution Overview
Problem
In wireless communication systems, particularly during 2-step RACH procedures, the generation of an initialization scrambling sequence for payload transmission is challenging due to the unavailability of parameters like radio network temporary identifier (RNTI) and cell ID, which hinders the scrambling of payloads and distinguishes user equipment (UE) effectively.
Innovation Solution
A 31-bit initialization scrambling sequence is used, comprising a 16-bit RA_RNTI, a 6-bit preamble index, and a 10-bit cell ID, with optional modifications such as removing the most significant bit from the cell ID or combining bits to ensure the sequence can be generated and used for payload scrambling in both 2-step and 4-step RACH procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional scrambling sequences requiring RNTI and cell ID are used, then payload scrambling and user equipment distinction are achieved, but the random access procedure fails when these parameters are unavailable in 2-step RACH
Solution Approach 1:
The patent changes the parameters used for scrambling sequence generation by replacing the conventional RNTI and cell ID with a preamble index. This parameter substitution enables the scrambling sequence to be generated in the 2-step RACH procedure where RNTI is not yet assigned, while maintaining the ability to distinguish between different user equipment through the unique preamble index.
Solution Approach 2:
The patent performs preliminary action by using the preamble index (which is already known at the time of message A transmission) to generate the initialization scrambling sequence before the RNTI is assigned. This allows the payload to be scrambled in advance using available parameters, ensuring the scrambling can be performed without waiting for RNTI assignment.
2Loss of time
If a 31-bit initialization scrambling sequence based on preamble index is used, then latency is reduced and spectral efficiency is improved, but the complexity of generating and managing the scrambling sequence increases
Solution Approach 1:
The patent simplifies the scrambling sequence generation by changing from a complex multi-parameter system (requiring RNTI and cell ID) to a single-parameter system based on the preamble index. This reduces the computational complexity at the UE side while achieving faster scrambling operation, as the preamble index is already available and requires no additional processing.
Solution Approach 2:
The patent extracts the essential function of user equipment distinction from the complex RNTI and cell ID parameters, retaining only the necessary identification capability through the preamble index. This extraction simplifies the scrambling sequence generation while maintaining the ability to distinguish between different UEs in the random access procedure.
Data Source
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AI summary
Methods, systems, and devices related to digital wireless communication, and more specifically, to techniques related to generating a scrambled payload that distinguishes a wireless device using an initialization scrambling sequence. In one exemplary aspect, a method for wireless communication may include generating a scrambled payload, where the scrambled payload is generated using an initialization scrambling sequence that is at least partially based on a preamble index and includes a length of 31 bits. The method also may include transmitting a first message to a communication node during a random access procedure, the first message including the scrambled payload.