Beam Training and Initial Access in New Radio Systems
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Solution Overview
Problem
New Radio (NR) systems face challenges in achieving reliable initial access and beam training, particularly at high frequency bands above 6 GHz, due to significant attenuation and unfavorable scattering environments, which require multiple narrow beams for coverage, but existing technologies struggle to efficiently manage beam pairing and power adjustments for optimal signal transmission.
Innovation Solution
The implementation of an apparatus with a processor capable of executing instructions for beam link pairing, downlink measurements, and uplink transmit power adjustments, including transmitting PRACH preambles, monitoring PDCCH for RAR, calculating path losses, and adjusting initial uplink transmit power based on beam pair link gain differences, to establish and refine beam pairs between user equipment (UE) and gNB for effective NR communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple narrow beams are used for HF-NR coverage, then coverage reliability is improved, but beam pairing complexity and initial access difficulty increase
Solution Approach 1:
The patent applies preliminary action by performing downlink beam sweeping and beam pairing before uplink transmission. The gNB transmits downlink reference signals through multiple narrow beams, and the UE performs measurements and reports the best beam ID before actual data transmission. This preliminary beam pairing simplifies subsequent uplink communication by establishing the optimal beam pair in advance, resolving the complexity of real-time beam pairing while maintaining coverage reliability.
Solution Approach 2:
The patent implements feedback mechanisms where the UE measures downlink reference signals from multiple narrow beams, identifies the best beam, and feeds back the beam ID to the gNB. The gNB then uses this feedback to determine the optimal uplink receive beam corresponding to the selected downlink transmit beam. This feedback loop enables reliable beam pairing in HF-NR systems by systematically identifying optimal beam combinations without exhaustive searching during data transmission.
2Reliability
If uplink transmit power is increased to overcome attenuation, then signal reliability is improved, but power consumption and interference increase
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting uplink transmit power based on downlink path loss measurements. Instead of using fixed high power, the UE calculates path loss from the received downlink reference signal and adjusts its uplink transmit power accordingly. This adaptive power control ensures sufficient signal reliability to overcome HF-NR attenuation while minimizing unnecessary power consumption and interference by using only the required power level.
Solution Approach 2:
The patent performs preliminary downlink path loss measurement and uplink power calculation before actual uplink transmission. The gNB provides downlink reference signals, the UE measures path loss, and calculates the required uplink transmit power in advance. This preliminary power adjustment ensures that the UE transmits with optimal power levels from the start, avoiding both power deficiency that would compromise reliability and excessive power that would increase consumption and interference.
3Loss of time
If beam training procedures are simplified for faster access, then initial access speed is improved, but beam pairing accuracy decreases
Solution Approach 1:
The patent segments the beam training process into distinct phases: downlink beam sweeping, uplink beam sweeping, and beam pairing. Each phase focuses on a specific aspect of beam establishment. The downlink phase uses reference signals for path loss measurement, the uplink phase uses random access preambles for beam identification, and the pairing phase correlates downlink and uplink beam results. This segmentation enables efficient initial access by parallelizing measurements while maintaining accuracy through dedicated measurement procedures for each beam direction.
Data Source
AI summary
The present application is at least directed to an apparatus including a non-transitory memory with stored instructions for beam link pairing the apparatus to a gNB in a new radio. A processor of the apparatus, operably coupled to the non-transitory memory, executes an instruction of detecting synchronization signal blocks (SS). Another executed instruction includes receiving PRACH resource information in a master information block on a PBCH or system information block (SIB) on the secondary PBCH. Another executed instruction includes transmitting PRACH preambles through a set of uplink transmission beams in a subframe including the group of SS blocks. The PRACH preambles may be obtained from the PRACH resource information. Even another executed instruction including determining the apparatus is in a radio resource control (RRC) connected state. A further executed instruction includes measuring, while in the RRC connected state, a multiple set of channel state information reference signals (CSI-RSs) configured by the gNB. Yet a further executed instruction includes transmitting, to the gNB, a single report based on the multiple set of CSI-RSs.