Small Base Station Beam Precoding for Control Signal Detection
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Solution Overview
Problem
Current radio communication systems face challenges in designing schemes suitable for small cells that geographically overlap with macro cells, requiring efficient capacity and coverage while minimizing network costs and user terminal power consumption.
Innovation Solution
A radio communication method where a user terminal communicates with a macro base station using a first carrier and a small base station using a second carrier of a higher frequency band, with beam forming information generated based on position-related information from the macro base station to precode common control and reference signals for transmission by the small base station.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If small cells are arranged to geographically overlap with macro cells to increase capacity, then network capacity is improved, but interference between cells increases and coverage becomes more difficult to maintain
Solution Approach 1:
The patent segments the network into macro cells for coverage and small cells for capacity, with each serving different purposes. The macro base station and small base station operate semi-independently, allowing the system to simultaneously maintain wide coverage while providing high capacity in specific areas through the overlapping small cell deployments.
Solution Approach 2:
The macro base station acts as an intermediary that assists the small base station in acquiring user terminal position information and generating beam forming information. This intermediary role enables the small cell to maintain coverage reliability by leveraging the macro cell's positioning capabilities, thereby resolving the coverage difficulty in overlapping small cell scenarios.
2Loss of time
If beam forming information is generated using position-related information from macro base station, then detection time of control signals is reduced, but dependency on macro base station increases
Solution Approach 1:
The macro base station performs preliminary actions by acquiring user terminal position information and generating beam forming information before the small base station needs to transmit control signals. This preliminary action reduces the detection time for user terminals, as the beam forming information is already prepared and available when needed.
Solution Approach 2:
The system implements a feedback mechanism where the macro base station provides position-related information and beam forming information to the small base station based on user terminal communications. This feedback loop enables the small base station to optimize its signal transmission without requiring complex independent positioning capabilities, thus reducing system dependency while maintaining efficiency.
3Productivity
If small base station uses higher frequency band for communication, then capacity is increased, but coverage range is reduced
Solution Approach 1:
The patent applies local quality by deploying small base stations with higher frequency bands in specific local areas where high capacity is needed, rather than using higher frequencies network-wide. This allows the system to maintain wide coverage using macro cells at lower frequencies while providing high-capacity local service through small cells at higher frequencies, thus resolving the coverage range reduction issue.
Solution Approach 2:
The system transitions from a two-dimensional coverage problem to a three-dimensional solution by adding the frequency dimension. Small base stations operate at higher frequency bands to provide capacity enhancement in specific geographic areas, while macro base stations operate at lower frequency bands for wide coverage. This dimensional approach allows simultaneous optimization of both capacity and coverage without mutual interference.
Data Source
AI summary
The present invention is designed to shorten the time that a user terminal takes to detect the common control/reference signals while coverage of the common control/reference signals transmitted from a small base station is secured. As the radio communication method of the invention, a radio communication method is provided in which beam forming information for forming transmission beams directed from the small base station to the user terminal are generated based on position-related information of the user terminal acquired by communication between the macro base station and the user terminal using a coverage carrier and position-related information of the small base station, and the small base station precodes at least one of a common control signal and a reference signal that are common in a small cell based on the beam forming information and transmits the precoded signal from a plurality of transmitting antennas using a capacity carrier.