LTE CSI Report Distribution via UE-Specific Timing Patterns

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Solution Overview

Problem

In LTE wireless communication systems, the reduced frequency of cell-specific reference signals for CSI measurements leads to uplink congestion as multiple UEs send CSI reports in the same subframe, causing resource block congestion in the PUCCH.

Innovation Solution

Distributing CSI reports among UEs by determining a transmission pattern or parameter indicative of when each UE should send reports, based on the interval of cell-specific reference signals, to avoid collisions and optimize resource usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If cell specific reference signals are transmitted less frequently to reduce overhead, then reference signal overhead is reduced, but uplink congestion occurs because multiple UEs send CSI reports in the same subframe

Engineering Contradiction:

Improvereference signal overheadVSAvoiduplink congestion

Core Design Contradiction:

Loss of substanceVSObject-generated harmful factors

Solution Approach 1:

The invention segments the uplink CSI report transmissions by introducing a UE-specific parameter that divides UEs into different transmission groups. Each UE transmits CSI reports in different subframes based on its group assignment, thereby segmenting the concentrated uplink traffic into distributed time slots and eliminating uplink congestion while maintaining reduced reference signal overhead.

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If multiple UEs send CSI reports in the same subframe to maintain measurement accuracy, then measurement precision is maintained, but resource block congestion occurs in PUCCH

Engineering Contradiction:

ImproveCSI measurement precisionVSAvoidresource block congestion

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The invention resolves the resource block congestion by adding a time dimension to the CSI report transmission. Instead of all UEs transmitting simultaneously in the same subframe (same time dimension), UEs are distributed across different subframes using the UE-specific parameter. This dimensional distribution maintains measurement precision while reducing the quantity of simultaneous transmissions and eliminating PUCCH resource block congestion.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If dedicated resource blocks are allocated for PUCCH to handle CSI reports, then reliability of CSI transmission is improved, but resources available for PUSCH are reduced

Engineering Contradiction:

ImproveCSI transmission reliabilityVSAvoidresources available for PUSCH

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The invention implements periodic action by distributing CSI report transmissions across different subframes based on the UE-specific parameter and reference signal interval. This periodic distribution spreads the CSI transmission load over time, maintaining reliable CSI transmission without requiring dedicated resource blocks, thereby preserving resources for PUSCH while ensuring CSI reliability through structured time-division multiplexing.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS8929235B2Controlling CSI reporting in a LTE cellular communication network

Publication Date: 2015.01.06 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

The object of the present invention is to distribute the transmission of the CSI (Channel state information) reports among the different UEs, wherein the CSI reports are based on measurements on cell specific reference signals from the base station. This is achieved in a LTE cellular communication network by controlling the transmission of CSI reports from the UEs.