Sounding Reference Signal Transmission in Unlicensed Bands
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Solution Overview
Problem
In wireless communication systems using unlicensed bands, the opportunistic discontinuous channel characteristics make it challenging to guarantee resources for transmitting sounding reference signals (SRS), which is different from the continuous resource allocation in licensed bands.
Innovation Solution
A method for transmitting SRS in unlicensed bands involves receiving a grant for uplink multiple subframes from a base station, determining a first subframe for SRS transmission based on SRS transmission position information, and transmitting the SRS in that subframe. This method also includes configuring and allocating resources for SRS transmission, such as using specific time domain symbols and considering clear channel assessment for unlicensed band channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous resource allocation is used for SRS transmission as in licensed bands, then SRS transmission reliability is improved, but it cannot be applied to unlicensed bands due to opportunistic discontinuous channel characteristics
Solution Approach 1:
The patent applies dynamics by making the SRS transmission resource allocation adaptive rather than static. The base station dynamically grants uplink multiple subframes based on channel conditions and traffic requirements, and the terminal dynamically determines which specific subframe to use for SRS transmission based on received position information. This dynamic allocation mechanism allows the system to adapt to the opportunistic discontinuous characteristics of unlicensed bands while maintaining reliable SRS transmission.
Solution Approach 2:
The patent changes the parameter of resource allocation from continuous (licensed band) to opportunistic discontinuous (unlicensed band). By introducing flexible subframe selection mechanisms and allowing the terminal to determine SRS transmission timing based on granted uplink multiple subframes and position information, the system transforms the rigid continuous allocation into a flexible discontinuous allocation that matches unlicensed band characteristics.
2Productivity
If opportunistic discontinuous channel access is used in unlicensed bands, then spectrum utilization is improved, but SRS resource guarantee becomes difficult
Solution Approach 1:
The patent applies preliminary action by having the base station pre-grant uplink multiple subframes to the terminal before SRS transmission is needed. The base station provides SRS transmission position information in advance, allowing the terminal to prepare and transmit SRS at the appropriate time. This preliminary resource allocation ensures that SRS resources are guaranteed even in the opportunistic discontinuous unlicensed band environment.
Solution Approach 2:
The patent introduces SRS transmission position information as an intermediary mechanism between the base station's resource grant and the terminal's SRS transmission. This intermediary parameter allows the base station to control exactly when SRS should be transmitted within the granted uplink multiple subframes, ensuring resource guarantee while maintaining flexibility for opportunistic channel access.
3Adaptability or versatility
If SRS transmission position information is provided for multiple subframes, then transmission flexibility is improved, but determining the specific transmission subframe becomes more complex
Solution Approach 1:
The patent applies partial action by providing SRS transmission position information that indicates only the necessary subset of subframes for SRS transmission, rather than requiring the terminal to evaluate all possible subframes. The position information selectively identifies specific subframes within the granted uplink multiple subframes, reducing the determination complexity while maintaining transmission flexibility.
Data Source
AI summary
Disclosed herein is a method for transmitting, by a terminal, a sounding reference signal (SRS). The terminal receives a grant for uplink multiple subframes from a base station. The terminal determines a first subframe for an SRS transmission of the terminal among the uplink multiple subframes on the basis of SRS transmission position information received from the base station. Further, the terminal transmits the SRS in the first subframe.