Uplink Interference Management in Heterogeneous Cellular Networks

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In heterogeneous networks, low power nodes face significant uplink interference due to UEs with higher signal to interference noise ratios connecting to macro base stations, leading to inefficient use of battery power and challenges in interference cancellation and scheduling, especially with non-trivial communication delays in the X2 interface.

Innovation Solution

A two-step uplink scheduling approach is implemented, where the macro eNB allocates uplink resources and scheduling information to pico eNBs, allowing them to manage uplink scheduling and synchronize interfering UEs, reducing interference and optimizing power usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If UEs connect to macro base station based on received signal power, then downlink coverage is improved, but uplink interference increases at low powered nodes

Engineering Contradiction:

Improvedownlink coverage areaVSAvoiduplink interference

Core Design Contradiction:

Area of stationary objectVSObject-generated harmful factors

Solution Approach 1:

The patent divides the base station functionality into separate macro eNB and pico eNB entities, each handling specific functions. The macro eNB provides downlink coverage while the pico eNB handles uplink reception for nearby UEs, segmenting the interference-prone uplink function from the downlink coverage function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary mechanism where the macro eNB forwards uplink scheduling information to pico eNBs, which then manage uplink receptions. This intermediary arrangement allows UEs to be served by the appropriate node for uplink without changing their downlink serving cell, thus reducing interference while maintaining coverage.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If UEs use higher uplink transmit power to overcome path loss, then uplink connectivity is improved, but battery consumption increases

Engineering Contradiction:

Improveuplink connectivityVSAvoidbattery power consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the parameter of uplink receiving node by allowing pico eNBs to receive uplink signals from UEs that are geographically closer to them, even though these UEs are downlink-connected to macro eNBs. This parameter change reduces the path loss for uplink transmissions, thereby reducing required transmit power and battery consumption.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If interference cancellation is performed in frequency domain after Rx FFT, then interference mitigation is achieved, but scheduling complexity increases due to resource block spillover

Engineering Contradiction:

Improveinterference mitigationVSAvoidscheduling complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent extracts the uplink scheduling function from the macro eNB and relocates it to the pico eNB for UEs in the vicinity. This extraction allows the pico eNB to independently manage uplink resource allocation and timing, eliminating the complexity of coordinating interference cancellation across multiple resource blocks at the macro eNB.

Inventive Principle:

Principle #2Taking out (Extraction)

4Reliability

If X2 interface is used for interference management communication, then coordination between eNBs is achieved, but communication delay increases

Engineering Contradiction:

Improveinterference coordinationVSAvoidcommunication delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent merges the downlink serving function (macro eNB) and uplink serving function (pico eNB) for the same UE through the dual-connectivity framework. This merging allows the UE to be scheduled by the pico eNB for uplink transmissions, eliminating the need for delayed X2 interface communication for scheduling decisions and enabling real-time uplink resource management.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentEP2721858B1Method and system for uplink interference management in heterogeneous cellular networks

Publication Date: 2017.10.18 BLACKBERRY LTD

AI summary

A method, at a first network access device of a heterogeneous network, the method sending a report to a second network access device indicating a user equipment (UE) in the vicinity of the second network access device to be handled in the uplink by the second network access device; receiving an uplink timing control report from the second network access device; transmitting uplink timing control adjustments to the UE; allocating uplink resources for the second network access device to forward uplink information; allocating physical downlink control channel ('PDCCH') resources belonging to the first network access device for transmitting uplink scheduling information provided by the second network access device to the UE; receiving uplink information including uplink scheduling information from the second network access device at the first network access device; and sending the uplink scheduling information to the UE.