RACH Beam Selection for Reliable Inactive-UE Access
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Solution Overview
Problem
Existing 5G networks face challenges in enabling efficient multicast data reception by user equipments (UEs) in inactive states and enhancing mobility and state transitions, particularly in random access channel (RACH) procedures.
Innovation Solution
A method and system for RACH procedures involving a user equipment (UE) that transmits a random preamble, receives control information on multiple physical downlink control channels (PDCCHs) with different beams, determines the PDCCH with the highest received signal power (RSRP), and reports this to the base station, followed by uplink scheduling information, to enhance communication establishment and contention resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple PDCCHs with different beams are transmitted to enhance coverage and reliability for UEs in inactive states, then the reliability of communication establishment is improved, but the device complexity and processing overhead increase
Solution Approach 1:
The base station performs preliminary beam sweeping and transmits multiple PDCCH candidates with different beams before the UE needs to establish communication. The UE measures these pre-transmitted beams and identifies the best beam in advance, reducing real-time decision complexity while ensuring reliable connection establishment.
Solution Approach 2:
The UE provides feedback by reporting the identified best PDCCH beam to the base station through the random access message. This feedback mechanism allows the base station to adapt its transmission strategy based on actual UE measurements, improving reliability while managing complexity through selective beam reporting rather than processing all possible beams.
2Productivity
If the UE measures and reports the best PDCCH beam to optimize connectivity, then the productivity of state transition is improved, but the loss of time for measurement and reporting increases
Solution Approach 1:
The base station transmits multiple PDCCH candidates with different beams in advance during the random access procedure, allowing the UE to perform measurements on pre-available signals rather than requiring extended measurement periods. This preliminary transmission of beam candidates accelerates the overall state transition process.
Solution Approach 2:
The UE measures and reports only the single best PDCCH beam among multiple candidates rather than evaluating all possible beams exhaustively. This partial action approach achieves sufficient optimization for state transition without the time cost of comprehensive beam analysis, balancing productivity improvement with time constraints.
3Area of stationary object
If the base station transmits multiple PDCCH candidates with different beams to enhance coverage, then the area of coverage is expanded, but the use of energy for transmission increases
Solution Approach 1:
The base station divides the coverage area into multiple directional beams, each targeting a specific spatial sector. By segmenting the transmission into targeted directional beams rather than omnidirectional transmission, the system expands effective coverage area while reducing total energy consumption by concentrating power in specific directions where UEs are likely to be located.
Solution Approach 2:
The base station transmits a limited number of PDCCH candidates with different beams rather than exhaustive beam coverage. This partial action approach provides sufficient coverage expansion for typical deployment scenarios while avoiding the excessive energy consumption that would result from transmitting all possible beam configurations, achieving a practical balance between coverage and energy use.
Data Source
AI summary
The invention provides a method of random access channel (RACH) procedure at a user equipment (UE). The method includes transmitting a first message including a random preamble selected from a set of preambles to a base station (BS), receiving a second message including control information required for establishing communication between the UE and the BS in one or more physical downlink control channels (PDCCHs) in a first time duration, determining one PDCCH in the one or more PDCCHs which has the highest received signal power (RSRP), in a third message reporting the one PDCCH with the highest RSRP to the base station and transmitting uplink scheduling information in one or more physical uplink shared channels (PUSCHs) in a second time duration and receiving a fourth message, the fourth message includes a contention resolution process and a report indicating the one PUSCH with the highest RSRP.