PRACH Preamble Format for Cell Coverage Beyond 52.6 GHz
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Solution Overview
Problem
Existing wireless communication systems face challenges in enhancing cell coverage and efficient PRACH transmission beyond 52.6 GHz due to limitations in PRACH sequence lengths, subcarrier spacing, and system coverage, leading to potential losses in frequency resource utilization and reduced transmit power.
Innovation Solution
Implementing a new PRACH preamble format based on a short sequence with enhanced subcarrier spacing and repetition mechanisms to extend cell coverage, including a new B5 format that doubles the guard period and cyclic prefix duration, and allowing for longer sequence lengths and consecutive RO allocation linked to synchronization signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If longer PRACH sequence lengths (L=571, L=1151) are used to achieve higher transmit power and extended cell coverage, then cell coverage is improved, but frequency resource utilization deteriorates due to more selective channels and wasted bandwidth
Solution Approach 1:
The patent implements dynamic PRACH sequence length selection where the UE and gNB can adaptively choose between different sequence lengths (L=139, L=571, L=1151) based on current channel conditions, coverage requirements, and frequency resource availability. This dynamic adaptation resolves the contradiction by allowing longer sequences only when necessary for coverage extension while using shorter sequences for efficient resource utilization in good channel conditions.
Solution Approach 2:
The patent changes the parameter of PRACH sequence length from fixed to variable, enabling the system to select appropriate sequence lengths based on operating conditions. By introducing configurable sequence length parameters that can be adjusted according to channel quality, coverage requirements, and resource availability, the system optimizes both coverage area and resource efficiency without being constrained by fixed sequence length limitations.
2Loss of energy
If larger subcarrier spacing (480 kHz, 960 kHz) is used for PRACH transmission, then frequency resource utilization is improved, but system coverage deteriorates due to reduced transmit power capability
Solution Approach 1:
The patent implements dynamic subcarrier spacing selection where the system can adaptively choose between different SCS values (60 kHz, 120 kHz, 480 kHz, 960 kHz) based on channel conditions, coverage requirements, and resource availability. This dynamic approach allows the system to use larger SCS for resource efficiency when coverage is sufficient, while switching to smaller SCS when extended coverage is needed, resolving the contradiction between resource utilization and coverage area.
Solution Approach 2:
The patent introduces configurable subcarrier spacing parameters that can be dynamically adjusted based on operating conditions. By making SCS a variable parameter rather than a fixed value, the system can optimize the trade-off between frequency resource utilization efficiency and system coverage area, selecting appropriate SCS values according to channel quality, power availability, and resource constraints.
3Reliability
If non-consecutive RACH occasions are configured to aid Listen-Before-Talk (LBT) processes, then LBT compliance is improved, but transmission time increases due to gaps between occasions
Solution Approach 1:
The patent implements dynamic RACH occasion configuration where the timing and spacing of RACH occasions can be adaptively adjusted based on LBT requirements, channel conditions, and traffic patterns. This dynamic configuration allows the system to optimize the balance between LBT compliance and transmission time by adjusting occasion spacing according to regulatory requirements and operational needs, rather than using fixed non-consecutive timing.
Data Source
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AI summary
Disclosed are methods and apparatus to enhance RACH transmission for beyond 52.6 GHz communications. A Physical Random Access Channel (PRACH) configuration information including an indication of a PRACH preamble format for a predefined subcarrier spacing (SCS) to enhance cell coverage may be received. The PRACH configuration information may include a new PRACH preamble format in a time-domain based on a short sequence PRACH preamble format. Additionally, the PRACH preamble may be transmitted using the PRACH preamble format over a PRACH to a base station (BS). The short sequence PRACH preamble format may be repeated over two consecutive time-domain RACH occasions (ROs).