Beam Selection Using Delay Spread Thresholds
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Solution Overview
Problem
In wireless communication systems, particularly in the millimeter-wave band, there is a challenge in selecting the most suitable beam for data transmission due to high path loss and frequent changes in channel conditions, which affects the efficiency of beamforming and equalizer performance, leading to increased complexity and power consumption.
Innovation Solution
The method involves determining delay spread values and reference signal received power (RSRP) levels for each beam, allowing user equipment (UE) to identify beams with delay spread less than a threshold value and transmit this information to the base station, which then selects the appropriate beam for downlink transmissions based on these criteria, accounting for the capabilities of the equalizer used by the UE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If beamforming is used to compensate for high path loss in millimeter-wave band, then communication coverage and signal strength are improved, but device complexity and power consumption increase due to frequent beam switching and channel condition changes
Solution Approach 1:
The system performs preliminary beam identification by measuring delay spread values of reference signals before actual data transmission. The UE identifies candidate beams with delay spread below a threshold and provides feedback to the base station, which pre-selects the optimal beam for downlink transmission. This preliminary beam selection process reduces the need for frequent beam switching during data transmission, thereby reducing device complexity and power consumption while maintaining reliable communication coverage.
2Reliability
If more equalizer taps are used to compensate for multipath effects, then channel equalization performance is improved, but device complexity and power consumption increase
Solution Approach 1:
The invention changes the selection criterion for beam identification from traditional RSRP-based metrics to delay spread-based metrics. By measuring the delay spread value of reference signals on each beam and comparing it against a threshold, the system identifies beams with favorable multipath characteristics. This parameter change allows the equalizer to operate with fewer taps because the selected beams inherently have less severe multipath effects, thereby reducing equalizer complexity and power consumption while maintaining channel equalization performance.
3Ease of operation
If traditional beam selection based on RSRP is used, then beam selection process is simple, but it does not account for delay spread which affects equalizer performance and communication efficiency
Solution Approach 1:
The system performs preliminary measurement of delay spread values for reference signals on multiple beams before final beam selection. The UE measures delay spread for each beam, identifies candidate beams with delay spread below a threshold, and provides this information as feedback to the base station. This preliminary action incorporates delay spread consideration into the beam selection process without significantly increasing operational complexity, thereby improving communication efficiency by selecting beams that are more favorable for equalizer performance.
Data Source
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AI summary
This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for selecting a beam to be allocated for transmitting downlink (DL) data to user equipment (UE). In some implementations, a UE receives a reference signal on each of a number of beams associated with a base station, and determines a delay spread value for each beam. The UE identifies each beam for which the determined channel delay spread value is less than a threshold value, and determines a reference signal received power (RSRP) level for each identified beam. The UE transmits an indication of the determined RSRP levels of the identified beams to the base station, and receives, in response to the transmitted indication, a selection of the beam to be allocated for DL transmissions to the UE. In some other implementations, a UE receives a reference signal on each of a number of beams associated with a base station, and determines a signal-to-interference-plus-noise ratio (SINR) value for each beam of the number of beams. The UE transmits an indication of the determined SINR values to the base station, and receives, in response to the transmitted indication, a selection of one beam of the number of beams to be allocated for downlink (DL) transmissions to the UE, wherein the selection of the one beam is based at least in part on the determined SINR values.