Sounding Reference Signal Transmission Over Unlicensed Spectrum Interlaces
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Solution Overview
Problem
Current LTE/LTE-A standards face challenges in transmitting sounding reference signals (SRS) effectively over unlicensed radio frequency spectrum bands, leading to resource underutilization and potential loss of channel access due to gaps in transmissions and inadequate bandwidth occupation.
Innovation Solution
The method involves receiving an indication of allocated uplink interlaces from a base station and transmitting SRS over these interlaces, using a processor to configure the SRS sequence based on resource block location and UE/cell identifiers, ensuring continuous channel reservation and better resource utilization by occupying a sufficient percentage of the allocated bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SRS transmission is performed over unlicensed spectrum using current LTE/LTE-A standards, then channel access can be obtained through LBT procedure, but transmission gaps occur and channel reservation is lost
Solution Approach 1:
The unlicensed spectrum band is divided into multiple interlaces (first interlace, second interlace, etc.), each containing non-contiguous resource blocks. SRS transmission is segmented across these interlaces, allowing the UE to transmit on one interlace while preparing for or switching to another, thereby eliminating transmission gaps and maintaining continuous channel reservation.
Solution Approach 2:
The patent implements periodic SRS transmission across different interlaces in a structured manner. By configuring multiple interlaces with specific periodicity and time-domain patterns, the system ensures continuous transmission without gaps, maintaining reliable channel access over the unlicensed spectrum.
2Productivity
If SRS transmission uses current LTE/LTE-A standards, then some bandwidth can be utilized, but adequate bandwidth occupation is not achieved leading to resource underutilization
Solution Approach 1:
The available bandwidth is segmented into multiple interlaces that are distributed across the unlicensed spectrum band. Each interlace contains resource blocks that are non-contiguous in frequency. By transmitting SRS across multiple interlaces simultaneously or in rapid succession, the system achieves adequate overall bandwidth occupation (e.g., meeting the 80% requirement) while maintaining efficient resource utilization.
Solution Approach 2:
The patent introduces a new dimensional approach by organizing resource blocks into interlaces that span both frequency and time domains. This multi-dimensional resource allocation allows the system to occupy sufficient bandwidth across multiple dimensions, transforming the resource utilization problem from a single-frequency constraint to a multi-interlace optimization problem.
3Use of energy by moving object
If gaps are introduced in SRS transmission over unlicensed spectrum, then power consumption may be reduced, but channel reservation is lost and access must be re-contended
Solution Approach 1:
Instead of single continuous transmission followed by idle gaps, the transmission is segmented across multiple interlaces. The UE transmits on the first interlace, then quickly switches to the second interlace, maintaining continuous transmission activity. This segmentation eliminates the need for idle gaps while managing power consumption through efficient interlace switching and configuration.
Solution Approach 2:
The patent ensures continuous useful action by configuring SRS transmission across multiple interlaces without interruption. The UE maintains continuous transmission activity by transitioning between interlaces, eliminating idle gaps that would cause channel reservation loss. This continuous transmission maintains reliable channel access while the structured interlace configuration optimizes power consumption through efficient resource utilization.
Data Source
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AI summary
Techniques are described for wireless communication. A first method includes receiving from a base station an indication of a set of one or more uplink interlaces of an unlicensed radio frequency spectrum band allocated for a sounding reference signal, and transmitting the sounding reference signal for a user equipment (UE) over the indicated set of one or more uplink interlaces of the unlicensed radio frequency spectrum band. A second method includes receiving an indication of an interlace of an unlicensed radio frequency spectrum band allocated for a physical uplink control channel (PUCCH) transmission, and transmitting a scheduling request and a buffer status report over the indicated interlace.