Base Station Unlicensed Sub-band Selection for D2D Interference
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Solution Overview
Problem
In Device-to-Device (D2D) communications using unlicensed frequencies, there is a risk of interference due to the potential use of sub-bands by other communications, leading to reduced reception quality and increased power consumption from carrier sensing across all unlicensed sub-bands.
Innovation Solution
A method where a base station and user equipment perform carrier sensing to identify idle or high-probability idle sub-bands on both transmission and reception sides, using these as candidates for data transmission, and reserve them to avoid interference, simplifying the scheduling process and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carrier sensing is performed across all unlicensed sub-bands to identify idle frequencies for D2D communication, then the reliability of frequency selection is improved, but the power consumption and time required for sensing increases
Solution Approach 1:
The unlicensed band is divided into multiple sub-bands, and carrier sensing is performed selectively on specific sub-bands rather than all sub-bands. The base station identifies candidate sub-bands and instructs terminals to perform sensing only on those candidates, reducing overall sensing overhead while maintaining reliable frequency selection.
Solution Approach 2:
The base station performs preliminary identification of candidate unlicensed sub-bands before instructing terminals to perform carrier sensing. This preliminary action narrows down the sensing scope to only those sub-bands that are likely to be available, reducing the total sensing time and power consumption while ensuring reliable frequency selection.
2Reliability
If carrier sensing is performed across all unlicensed sub-bands to identify idle frequencies, then the reliability of frequency selection is improved, but the scheduling complexity increases
Solution Approach 1:
The scheduling process is segmented into distinct phases: base station identifies candidate sub-bands, instructs terminals on sensing scope, terminals perform selective sensing, and results are reported back. This segmentation simplifies the overall scheduling complexity by breaking down the complex task of unlicensed band management into manageable steps.
Solution Approach 2:
The base station acts as an intermediary that coordinates the carrier sensing process between multiple terminals and the unlicensed spectrum. It identifies candidate sub-bands, instructs terminals on which sub-bands to sense, and consolidates sensing results, thereby simplifying the scheduling complexity that would arise from distributed sensing across all sub-bands.
3Device complexity
If transmission side terminal determines idle sub-bands independently, then the device complexity is reduced, but interference with reception side terminal occurs
Solution Approach 1:
The reception side terminal performs carrier sensing and reports the results back to the base station. The base station uses this feedback information to identify candidate unlicensed sub-bands that are actually idle, and then instructs the transmission side terminal to use only those specific sub-bands. This feedback mechanism ensures that interference is avoided while keeping terminal complexity manageable.
Solution Approach 2:
The base station serves as an intermediary that coordinates frequency selection between transmission and reception side terminals. It collects carrier sensing results from the reception side, identifies suitable candidate sub-bands, and instructs the transmission side to use only those sub-bands, thereby preventing interference while maintaining reasonable terminal complexity.
Data Source
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AI summary
Abase station (1) comprising: acontroller (11) configured to extract at least one or more sub-bands of an unlicensed frequency being a frequency of which a use is not licensed for data transmission and being determined that are in an idle status or have a high possibility to be in the idle status by at least one terminal in a result of carrier sensing as candidates for sub-bands of the unlicensed frequency that a transmission terminal among the at least one terminal uses in data transmission with the device-to-device communications; and a transmitter (115A, 115B) configured to transmit an allocation result of radio resources using licensed frequencies of which a use for the data transmission is licensed and candidates for the unlicensed frequency to a terminal when device-to-device communications using the licensed frequencies is performed in addition to the device-to-device communications using the sub-bands in the unlicensed frequency.