PDSCH Resource Element Mapping for CoMP Interference

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Solution Overview

Problem

In LTE systems, PDSCH resource elements often collide with cell-specific reference signals (CRS) in adjacent cells, causing interference that reduces throughput and signal quality for user equipment at cell edges, especially in coordinated multipoint transmission scenarios.

Innovation Solution

The PDSCH resource element mapping method employs three schemes to mitigate interference: transmitting one PDSCH symbol over three consecutive CRS-collided resource elements, transmitting two PDSCH symbols over three consecutive CRS-collided resource elements, and selectively modifying modulation order for affected resource elements, allowing for interference cancellation and improved data decoding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If PDSCH resource elements are transmitted in the same resource block locations as adjacent cell CRS, then resource utilization is improved, but interference increases and signal quality deteriorates

Engineering Contradiction:

Improveresource utilizationVSAvoidinterference

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by performing interference cancellation before data decoding. The UE first estimates the CRS signal from adjacent cells using known CRS patterns, then subtracts this estimated interference from the received signal before attempting to decode the PDSCH data, enabling successful reception despite resource element collisions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the harmful interference from adjacent cell CRS into a beneficial process by using the known CRS structure and patterns to estimate and cancel the interference. The harmful overlapping signals are transformed into a systematic cancellation process that recovers the desired PDSCH data

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Object-affected harmful factors

If PDSCH resource elements are muted to avoid CRS collision, then interference is reduced, but throughput decreases due to lost resource elements

Engineering Contradiction:

ImproveinterferenceVSAvoidthroughput

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

Instead of muting the PDSCH resource elements, the patent converts the harmful interference situation into a beneficial cancellation process. By using the known CRS patterns to estimate and subtract the interfering signal, the system recovers the PDSCH data from the same resource elements that would otherwise be muted, thereby maintaining throughput while reducing interference

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If three cells transmit jointly using the same resource blocks, then spectral efficiency is improved, but resource element collision with CRS increases

Engineering Contradiction:

Improvespectral efficiencyVSAvoidsignal quality

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by having the UE perform CRS interference estimation and cancellation before PDSCH decoding in three-cell joint transmission scenarios. This preliminary processing step enables reliable signal recovery despite the increased complexity of coordinating three cells' transmissions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies local quality by treating different resource elements differently - resource elements that collide with CRS undergo interference cancellation processing, while non-collided resource elements are decoded normally. This localized approach maintains spectral efficiency while ensuring reliable reception in critical collision regions

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS9236982B2PDSCH resource element mapping for three-cell joint transmission

Publication Date: 2016.01.12 GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP LTD

AI summary

A PDSCH resource element mapping method is used for joint transmissions. The method solves a problem of colliding resource elements in joint transmissions, due to interference caused when PDSCH resource elements are transmitted in the resource block of one cell and cell-specific reference signals (CRSs) are transmitted in the same location of the resource block of an adjacent cell. The method is particularly beneficial for coordinated multipoint (CoMP) transmissions. The PDSCH resource element mapping method employs one of three schemes for transmitting the collided resource elements, with minimal interference. In the first scheme, one PDSCH symbol is transmitted over three consecutive CRS-collided PDSCH resource elements. In the second scheme, two PDSCH symbols are transmitted over three consecutive CRS-collided PDSCH resource elements. In a third scheme, CRS-collided resource elements are transmitted using a lower modulation order than is specified by the modulation and coding scheme.