Asynchronous Channel Reservation with Dynamic Cyclic Prefix

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Solution Overview

Problem

Wireless communication networks face interference and congestion due to increased demand for mobile broadband access, particularly in shared spectrum environments where network nodes may operate asynchronously, leading to challenges in channel reservation and synchronization across different network operators.

Innovation Solution

Implementing a listen before talk (LBT) procedure with a dynamic length cyclic prefix and channel reservation message transmission, allowing for asynchronous preamble transmission followed by synchronous channel reservation message transmission at OFDM symbol boundaries, to facilitate efficient channel reservation in asynchronous network operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If asynchronous preamble transmission is used to enable early channel occupation, then channel reservation efficiency is improved, but synchronization complexity increases due to partial symbol alignment

Engineering Contradiction:

Improvechannel reservation efficiencyVSAvoidsynchronization complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent applies dynamics by making the cyclic prefix length adjustable rather than fixed. The cyclic prefix length is dynamically configured based on the timing offset detected from the asynchronous preamble, allowing the system to adapt to different synchronization scenarios while maintaining efficient channel reservation

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of cyclic prefix length from a fixed value to a configurable parameter that varies according to the detected timing offset. This parameter change enables the system to handle asynchronous transmissions with partial symbol alignment while maintaining proper synchronization for subsequent channel reservation messages

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If dynamic length cyclic prefix is used to accommodate partial symbol alignment, then adaptability to asynchronous operations is improved, but transmission overhead increases

Engineering Contradiction:

Improveadaptability to asynchronous operationsVSAvoidtransmission overhead

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent applies partial action by only extending the cyclic prefix length when needed to accommodate the detected timing offset, rather than using a consistently long cyclic prefix. The extension is precisely matched to the required alignment, avoiding excessive overhead while maintaining adaptability to asynchronous operations

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The cyclic prefix length is dynamically adjusted based on the specific timing offset detected in each transmission scenario, allowing the system to use the minimum necessary overhead while maintaining adaptability to various asynchronous operating conditions

Inventive Principle:

Principle #15Dynamics

3Reliability

If channel reservation message is transmitted at OFDM symbol boundaries to ensure synchronous transmission, then signal decoding reliability is improved, but channel occupation latency increases

Engineering Contradiction:

Improvesignal decoding reliabilityVSAvoidchannel occupation latency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by having the transmitting node detect the timing offset and configure the cyclic prefix length before transmitting the channel reservation message. This preliminary configuration ensures that the message is properly aligned at OFDM symbol boundaries, maintaining decoding reliability while minimizing the time delay through efficient timing setup

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent replaces the mechanical approach of waiting for fixed symbol boundaries with a detection and configuration mechanism that measures the actual timing offset and adjusts the cyclic prefix accordingly. This substitution allows the system to achieve proper alignment with minimal latency rather than waiting for predetermined boundaries

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP3643103B1Asynchronous channel reservation design with partial symbol alignment

Publication Date: 2022.03.30 QUALCOMM INC

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AI summary

An asynchronous channel reservation design is disclosed having a partial symbol alignment. The transmitting node performs a listen before talk (LBT) procedure on a transmission channel shared by one or more transmission/reception points (TRPs). Upon detecting passing the LBT, a preamble is transmitted followed by a dynamic length cyclic prefix that includes the normal cyclic prefix plus an additional variable period. The transmitter then transmits the channel reservation message after the dynamic length cyclic prefix. On the detector side, once the preamble is detected, the detecting node assumes a normal cyclic prefix before attempting to detect and decode the channel reservation information in the message. Using a demodulation reference signal (DMRS) in the channel reservation message, the detecting node may detect the channel reservation message information from the shifted version of the detected message.