Antenna-Specific SRS Transmission in Uplink Grants
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In LTE wireless communication networks, users with time-variant channels require more frequent channel estimation updates, but conventional SRS resource allocation is static and unfair, consuming resources from all users, including those who do not need additional SRS transmission, especially with the introduction of MIMO transmissions.
Innovation Solution
User-specific resources allocated for uplink transmissions are used to convey antenna-specific SRSs within granted resources, allowing MIMO UE to transmit additional SRSs instead of uplink data, dynamically configuring SRS transmission based on user needs, and using control signaling within uplink grants to manage these transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resources are reserved for SRS transmission on a cell level in a static or semi-static fashion, then all users in the cell are configured to transmit SRSs using the reserved resources, but this consumes resources from all users including those who do not need additional SRS transmission, making it unfair to users with no need for frequent channel estimation
Solution Approach 1:
The patent segments the cell-level SRS resources into user-specific resources by associating SRS transmission with individual uplink grants. Each user's SRS resources are separated from the common pool, allowing only users who need frequent channel estimation to consume resources, while users with stable channels do not incur additional overhead.
Solution Approach 2:
The patent transitions from static/semi-static resource reservation to dynamic resource allocation. SRS resources are allocated dynamically based on actual user needs detected by the eNodeB, allowing flexible adjustment of which users transmit SRS and when, rather than forcing all users to use reserved resources.
2Adaptability or versatility
If additional SRS resources are added to support MIMO transmissions, then more frequent channel estimation updates are available for users with multiple antennas, but this increases the total resources consumed in the cell, potentially reducing resources for other users
Solution Approach 1:
The patent implements self-service by having users with MIMO capability automatically utilize their granted uplink resources for SRS transmission without requiring separate resource allocation. The UE itself determines when to transmit SRS based on its configuration and needs, using its own scheduled resources rather than consuming additional cell-wide resources.
Solution Approach 2:
The patent makes uplink data transmission resources serve dual purposes: they can carry user data and simultaneously provide resources for antenna-specific SRS transmission when needed. This multi-functionality allows the same resources to serve both data communication and channel estimation purposes.
3Adaptability or versatility
If aperiodic SRS transmission is introduced to provide more frequent channel estimation, then users with time-variant channels receive updates when needed, but this requires additional SRS resources that consume resources from users with no need for further SRS transmission
Solution Approach 1:
The patent employs feedback mechanisms where the eNodeB monitors user channel conditions and transmission needs. Based on this feedback, the eNodeB dynamically decides which users should transmit aperiodic SRS and when, ensuring resources are allocated only to users who actually need frequent channel estimation updates rather than uniformly to all users.
Data Source
AI summary
The present invention uses user-specific resources, as allocated on the uplink, for conveying one or more antenna-specific sounding reference signals (SRSs). This technique advantageously permits, for example, a user equipment (UE) configured for uplink Multiple-Input-Multiple-Output (MIMO) operation to send antenna-specific SRSs within the granted resources allocated to the UE via one or more scheduled uplink grants. That is, within the granted resources allocated by a given uplink grant, a UE uses at least a portion of those resources for sending antenna-specific SRSs, rather than for sending uplink data (user traffic). Thus, in one or more embodiments, the present invention comprises a method at a UE of transmitting antenna-specific SRSs for two or more uplink transmit antennas. The method comprises transmitting an antenna-specific sounding reference signal for at least one of the uplink transmit antennas within a granted resource allocated to the user equipment for a scheduled uplink data transmission.