Beam Sweep Pattern Adaptation for SFN Broadcast Interference

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Solution Overview

Problem

Wireless communications systems using single frequency networks (SFNs) face interference issues due to shorter delay spread and narrowband fading, leading to improper reception of broadcast messages by user equipment (UEs), resulting in increased errors and the need for retransmissions.

Innovation Solution

Implementing beam sweeping patterns, where a base station transmits a message using a first beam sweep pattern and identifies a second, different beam sweep pattern for retransmissions, to reduce interference and improve communication quality, by adjusting the order, frequency, or timing of transmission beams based on feedback and coordination messages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If beamformed transmissions are used to transmit broadcast communications over SFN channel, then transmission directionality and signal focus are improved, but interference at UE receiving from multiple sources increases due to shorter delay spread and narrowband fading

Engineering Contradiction:

Improvesignal focusVSAvoidinterference

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent applies dynamics by making the beam sweep pattern adjustable and changeable over time. The base station can switch between different beam sweep patterns (first pattern for initial transmission, second pattern for retransmission) based on feedback from UEs. This dynamic adaptation allows the system to respond to changing channel conditions and interference scenarios, resolving the contradiction between signal focus and interference by optimizing beam patterns according to actual reception quality.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameters of the beam sweep pattern itself - specifically the order, frequency, or timing of transmission beams. By modifying these parameters when switching from the first beam sweep pattern to the second beam sweep pattern, the system alters the transmission characteristics to reduce interference while maintaining signal focus. This parameter adjustment directly addresses the technical contradiction by transforming the transmission approach based on observed interference levels.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If the same beam sweep pattern is used for initial transmission and retransmission, then system complexity is reduced, but communication reliability deteriorates due to persistent interference causing NACK feedback and requiring retransmissions

Engineering Contradiction:

Improvesystem complexityVSAvoidcommunication reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements feedback mechanisms where UEs provide HARQ feedback (ACK/NACK) to the base station regarding the quality of received broadcast transmissions. When NACK feedback indicates improper reception due to interference, the base station uses this feedback information to select a different beam sweep pattern for retransmission. This feedback loop enables the system to adapt to interference conditions and improve reliability without requiring overly complex predetermined strategies.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent prepares multiple beam sweep patterns in advance (first pattern and second pattern) before transmission occurs. When a retransmission is needed, the system has already have alternative patterns ready to deploy, avoiding the need for complex real-time pattern generation. This preliminary preparation of multiple patterns balances complexity management with reliability improvement, as the complexity is fixed in advance rather than dynamically generated.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If beam sweeping with multiple patterns is implemented for retransmissions, then interference reduction and reception quality are improved, but transmission timing and coordination complexity increase

Engineering Contradiction:

Improvereception qualityVSAvoidtransmission timing

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent employs periodic beam sweeping where beams are transmitted in structured sequences or patterns over time. The first beam sweep pattern and second beam sweep pattern both follow periodic structures, making it easier to coordinate timing even when switching between patterns. This periodic approach maintains temporal organization and reduces timing complexity compared to arbitrary beam transmission sequences, while still enabling interference reduction through pattern variation.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS11546038B2Beam sweeping patterns for single frequency network broadcast channel

Publication Date: 2023.01.03 QUALCOMM INC

AI summary

Methods, systems, and devices for wireless communications are described. The method includes a method for wireless communications at a base station. The method includes transmitting a message to a number of user equipments (UEs) over a single frequency network channel using a first beam sweep pattern. The method also includes identifying a second beam sweep pattern from a plurality of beam sweep patterns that is different from the first beam sweep pattern for retransmissions of the message. The method further includes transmitting a retransmission of the message to the plurality of UEs over the single frequency network channel using the second beam sweep pattern.