Precoder for Crosstalk Mitigation in Distributed Base Station Systems

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Solution Overview

Problem

Crosstalk between metallic conductors in distributed base station systems reduces signal quality and bandwidth, affecting the performance of wireless communication networks, particularly in residential Radio Dot Systems that reuse existing twisted-pair cable infrastructure.

Innovation Solution

A method that involves detecting error measures of signals received by radio heads, determining precoding coefficients, and applying these coefficients to pre-cancel crosstalk between nearby cables, using a separate precoder in the intermediate radio unit to mitigate interference without altering baseband processing algorithms in the baseband unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If twisted-pair cables are used to connect radio heads to the intermediate radio unit, then installation cost and complexity are reduced, but crosstalk between cables increases significantly

Engineering Contradiction:
Improveinstallation easeVSAvoidcrosstalk
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary anti-action by calculating precoding coefficients that pre-cancel crosstalk interference before signals are transmitted over the twisted-pair cables. The network node computes coefficients based on channel state information and applies them to the downlink signals, so that when signals arrive at the radio heads, the crosstalk has already been compensated for, enabling the use of inexpensive twisted-pair infrastructure without suffering from its inherent crosstalk problems

Inventive Principle:
Principle #9Preliminary anti-action

2Productivity

If crosstalk cancellation is implemented to improve signal quality, then bandwidth and reach are enhanced, but system complexity increases

Engineering Contradiction:
ImprovebandwidthVSAvoidsystem complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the crosstalk cancellation function into a separate network node that is distinct from both the intermediate radio unit and the radio heads. This dedicated node handles the computationally intensive tasks of calculating and distributing precoding coefficients, while the existing radio access network infrastructure remains unchanged, thereby achieving crosstalk mitigation without significantly increasing the complexity of the core radio units

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary network node that acts as a mediator between the core network and the radio access network. This node receives channel state information from the radio heads, calculates the appropriate precoding coefficients, and distributes them to the intermediate radio unit, thereby enabling sophisticated crosstalk cancellation without requiring modifications to the existing radio head or IRU hardware

Inventive Principle:
Principle #24Intermediary (Mediator)

3Length of stationary object

If signal quality is improved through crosstalk mitigation, then the reach of the system extends further, but processing requirements increase

Engineering Contradiction:
ImprovereachVSAvoidprocessing power
Core Design Contradiction:
Length of stationary objectVSPower

Solution Approach 1:

The patent applies preliminary action by performing all computationally intensive processing operations in advance, before signals are transmitted over the cables. The network node calculates precoding coefficients based on channel state information received from radio heads, and these coefficients are then applied to downlink signals before transmission. This advance processing enables extended reach through crosstalk mitigation without requiring continuous high processing power during signal transmission

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3257165B1Methods and nodes of a wireless communication network for mitigating crosstalk in a distributed base station system
Publication Date: 2018.12.12 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP3257165B1 patent drawingFigure 1~2
  • EP3257165B1 patent drawingFigure 3
  • EP3257165B1 patent drawingFigure 4~5

AI summary

Disclosed is a method for mitigating crosstalk performed by a network node of a wireless communication network operable in a base station system (100) of the wireless communication network, the base station system comprising an intermediate radio unit, IRU (10), a baseband unit, BBU (30), connected to the IRU and a plurality of radio heads, RHs, (21-26) connected to the IRU via a plurality of metallic conductors. The method comprises receiving from a first (21) of the plurality of RHs, a measure of an error of one or more symbols of a signal received by the first RH from the IRU over a first of the plurality of metallic conductors, the measure of the error being detected by the first RH, the signal being destined to a user equipment, UE (60), wirelessly connected to the first RH (21). The method further comprises determining precoding coefficients for a precoder according to the received error measure, and triggering applying the determined precoding coefficients when sending further signals to the first RH over the first of the plurality of metallic conductors, the further signals being destined to UEs wirelessly connected to the first RH.