Millimeter-Wave Network Entry Using Preferred Beam Random Access
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Solution Overview
Problem
Current cellular systems face challenges in network entry for mobile stations due to the use of directional antennas, making it difficult for mobile stations to detect base stations and establish communications, especially in millimeter-wave mobile broadband systems.
Innovation Solution
A method and apparatus for network entry in millimeter-wave mobile broadband systems using beamforming techniques, where mobile stations acquire downlink control channels, send initial random access signals, and receive feedback to determine preferred uplink and downlink beams for efficient network access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If directional antennas are used in millimeter-wave systems, then data rate and spectrum efficiency are improved, but network entry difficulty increases due to inability to detect base stations
Solution Approach 1:
The patent segments the network entry process into multiple stages: initial cell search using omnidirectional antennas to detect base stations, followed by beam training phases where directional beams are systematically tested. This segmentation allows the system to overcome the detection problem by separating the discovery phase from the high-rate communication phase.
Solution Approach 2:
The patent implements preliminary beam training actions before establishing high-rate directional communication. The mobile station and base station perform preliminary sweeps with different beam directions to identify suitable beams in advance, storing this information for subsequent use. This preliminary action resolves the contradiction by preparing the directional link before actual data transmission begins.
2Reliability
If beamforming is implemented for millimeter-wave communication, then coverage and reliability are improved, but device complexity increases due to multiple antenna elements
Solution Approach 1:
The patent implements dynamic beamforming where the beam directions and widths are adjusted based on channel conditions and mobility state. The system dynamically selects between wide beams for cell search and narrow beams for data transmission, and adapts beam directions during handover and mobility scenarios. This dynamic approach maintains reliability while managing complexity through adaptive control.
Solution Approach 2:
The patent changes key parameters including beam width, beam direction, and antenna element activation based on operational requirements. During initial access, wider beams are used to increase coverage; during data transmission, narrower beams provide higher gain. The system also changes the active antenna subset based on channel conditions, effectively managing the complexity-reliability tradeoff through parameter optimization.
Data Source
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AI summary
A method performed by a base station to support network entry of a mobile station in a communication system, the method comprising: transmitting, to the mobile station, system information comprising random access configuration over each of a plurality of downlink, DL, transmission beams; receiving, from the mobile station, an initial random access signal based on the random access configuration, wherein the initial random access signal indicates a preferred DL beam from among the plurality of DL transmission beams; and transmitting a random access acknowledge signal in response to the initial random access signal based on the indicated preferred DL beam to the mobile station.