Extended Random Access Preamble Identifier for 144-Subcarrier NPRACH
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Solution Overview
Problem
The new NPRACH numerology with 144 subcarriers exceeds the 6-bit limit in legacy MAC PDU subheaders, leading to potential misinterpretation and collisions, as the existing RAPID definition can only specify up to 64 unique subcarriers.
Innovation Solution
Extending the RAPID definition to 8 bits by combining bits from the MAC subheader and RAR, allowing unique identification of each subcarrier without altering the basic structure of MAC subheaders and RARs, and maintaining backwards compatibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the new NPRACH numerology with 144 subcarriers is used, then the subcarrier identification capability is improved, but the legacy 6-bit RAPID field can no longer uniquely identify all subcarriers
Solution Approach 1:
The patent transitions from a 6-bit RAPID field (one dimension) to an 8-bit extended RAPID field (expanded dimension), thereby increasing the identification capacity from 64 to 256 unique subcarriers. This dimensional expansion resolves the contradiction by providing sufficient bit width to identify all 144 subcarriers in the new NPRACH numerology while maintaining the fundamental RAPID identification function.
Solution Approach 2:
The patent changes the parameter of RAPID field length from 6 bits to 8 bits, thereby increasing the identification capacity. This parameter change allows the system to accommodate the new NPRACH numerology with 144 subcarriers, as the extended 8-bit field can represent up to 256 unique subcarrier identifiers, resolving the insufficiency of the original 6-bit field.
2Measurement precision
If the RAPID field is extended to 8 bits, then unique subcarrier identification is improved, but the MAC PDU subheader structure is altered
Solution Approach 1:
The patent applies local quality by making the RAPID field length adaptive rather than uniform. Specifically, for legacy NPRACH formats, the RAPID field remains 6 bits, while for the new NPRACH numerology, it is extended to 8 bits. This localized differentiation allows precise subcarrier identification where needed without unnecessarily increasing MAC PDU structure complexity for all cases.
Solution Approach 2:
The patent introduces dynamic RAPID field length based on the NPRACH format being used. The system can switch between 6-bit and 8-bit RAPID fields depending on whether legacy or new numerology is employed. This dynamic adaptation resolves the contradiction by allowing high precision identification when required while maintaining simpler structure for legacy compatibility.
3Reliability
If the new NPRACH numerology is implemented, then NPRACH reliability and range are improved, but compatibility with legacy systems is reduced
Solution Approach 1:
The patent implements universality by designing the MAC PDU structure to accommodate both legacy 6-bit RAPID and new 8-bit extended RAPID formats. The same MAC PDU framework can handle both NPRACH numerologies, allowing the system to maintain compatibility with legacy systems while supporting the new numerology with enhanced reliability and range coverage.
Solution Approach 2:
The patent segments the RAPID field handling into two distinct modes: 6-bit for legacy NPRACH formats and 8-bit for new NPRACH numerology. This segmentation allows each mode to be optimized independently - legacy systems continue to use the simpler 6-bit format while new systems utilize the extended 8-bit format for improved reliability, without forcing a unified approach that would compromise either.
Data Source
AI summary
A method is performed by a network node. The method comprises determining to use an extended random access preamble identifier, RAPID, for a random access procedure with a wireless device. The method further comprises transmitting a medium access control, MAC, protocol data unit, PDU. The MAC PDU comprises a header and one or more random access responses, RARs. Each RAR is associated with a corresponding subheader within the header of the MAC PDU. The random access procedure is associated with a first RAR of the one or more RARs and the extended RAPID for the random access procedure is indicated by a combination of one or more bits in the first RAR and one or more bits in the subheader that corresponds to the first RAR.