Base Station Ghost Signalling Mitigation in HSUPA

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Solution Overview

Problem

In High Speed Uplink Packet Access (HSUPA) networks, the risk of 'ghost grants' leads to false detection of absolute grants by user entities, causing sudden interference and dropped calls due to misinterpretation of transmission rates, resulting in increased power emissions and interference.

Innovation Solution

A method where the base station transmits an absolute grant signal on a control channel only if scheduled, and if not, either refrains from transmission or sends a previously transmitted grant to a configured UE, ensuring continuous signaling above the noise floor to reduce ghost grant detection, and transmits at a reduced power level to minimize interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the base station refrains from transmitting absolute grant signals when not scheduled (DTX mode), then downlink power consumption is reduced, but user entities may falsely detect ghost grants leading to interference and dropped calls

Engineering Contradiction:

Improvedownlink power consumptionVSAvoidgrant detection accuracy

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent introduces a mediator entity (the base station transmitting dummy grant signals) that prevents the harmful effect (ghost grant detection) without requiring continuous transmission of actual grant signals. The dummy signals act as an intermediary that satisfies the UE's detection requirements while allowing the base station to conserve power when no actual data transmission is scheduled.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the base station continuously transmits absolute grant signals to prevent ghost grant detection, then grant detection accuracy is improved, but downlink power consumption increases

Engineering Contradiction:

Improvegrant detection accuracyVSAvoiddownlink power consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent implements periodic transmission of dummy absolute grant signals only when needed (when the base station determines that ghost grant detection is a risk), rather than continuous transmission. This periodic action maintains reliability when necessary while minimizing power consumption during periods when ghost grants are not a concern.

Inventive Principle:

Principle #19Periodic action

3Reliability

If the base station transmits absolute grant signals at high power level, then ghost grant detection is reduced, but interference to other users increases

Engineering Contradiction:

Improveghost grant detection rateVSAvoidinterference to other users

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by transmitting dummy grant signals at a reduced power level specifically targeted at preventing ghost grant detection, rather than transmitting all grant signals at high power. This localized approach to signal quality prevents interference to other users while still achieving the goal of reducing ghost grant detection.

Inventive Principle:

Principle #3Local quality

4Reliability

If the base station transmits dummy absolute grant signals to prevent ghost grants, then ghost grant detection is reduced, but downlink power consumption increases compared to DTX mode

Engineering Contradiction:

Improveghost grant detection rateVSAvoiddownlink power consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies partial action by transmitting dummy grant signals only partially (only when ghost grant detection is a risk), rather than continuously. This partial transmission provides sufficient protection against ghost grants while minimizing the additional power consumption compared to pure DTX mode.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentEP2862403B1Mitigating ghost signalling effects in radio systems

Publication Date: 2017.10.25 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method in a base station – and a base station, adapted for scheduling and receiving uplink transmissions from user entities, UEs, in a cell and further forwarding data related to such transmissions to a core network. The base station is being adapted for transmitting (506) an absolute grant signal on a control channel (E-AGCH) for a transmission time interval, for allowing a user entity to transmit an up-link transmission at a granted data rate on a corresponding transmission time interval (500). The method comprises the steps, for a transmission time interval on the control channel, of - if an absolute grant is scheduled (502), transmitting (506) the absolute grant; - if an absolute grant is not scheduled (502), investigating (504) whether at least one UE in the cell is configured for receiving on the control channel (E-AGCH), and if this is not the case, refraining (508) from transmitting (DTX); - if an absolute grant is not scheduled (502) and at least one UE in the cell is configured for receiving (504) on the control channel (E-AGCH). Moreover, the method comprises at least one of - the step of -transmitting (510) an absolute grant for a non-configured UE in the cell; and - the steps of -selecting (514) an arbitrary configured UE in the cell; and -transmitting (511) an absolute grant, which was previously transmitted at an earlier transmission time interval, to the selected UE.