Staggered Common Channel Transmission in Unlicensed Spectrum
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Solution Overview
Problem
As wireless communications networks become congested, there is a need to increase capacity by offloading traffic from cellular networks to unlicensed spectrum, but coordinating access to unlicensed spectrum is challenging to ensure coexistence of different operator deployments, and existing methods require clear channel assessment (CCA) to determine availability, which can be time-consuming and inefficient.
Innovation Solution
The method involves identifying a set of carrier frequencies in the unlicensed spectrum for transmitting common information and using a staggering pattern to transmit this information across multiple frequencies without requiring clear channel assessment, allowing for faster access and reduced power usage by transmitting in short bursts that occupy less than a predetermined time period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If clear channel assessment (CCA) is performed to determine availability of unlicensed spectrum, then reliability of transmission is improved, but transmission time increases and productivity decreases
Solution Approach 1:
The system performs preliminary actions by transmitting common information in short bursts without CCA when channel conditions are favorable, and pre-configures multiple carrier frequencies for potential use. This allows the system to skip CCA in many cases while maintaining reliability through the fallback mechanism of having alternative frequencies ready.
Solution Approach 2:
The system dynamically adapts its transmission strategy by monitoring channel conditions and switching between CCA-based and non-CCA-based transmission modes. When interference is detected, it falls back to CCA; when clear, it transmits immediately. This dynamic behavior resolves the contradiction between reliability and speed.
2Productivity
If multiple carrier frequencies are used for transmitting common information, then spectrum utilization is improved, but device complexity increases
Solution Approach 1:
The system segments the common information transmission across multiple carrier frequencies, with each frequency carrying a portion of the information according to a staggering pattern. This segmentation allows efficient use of spectrum while keeping individual transmission instances simple, as each frequency is handled independently.
Solution Approach 2:
Multiple carrier frequencies serve the universal function of transmitting common information (synchronization, broadcast, paging). The system establishes a standardized staggering pattern that can be applied across different frequencies, reducing the complexity of managing multiple carriers by providing a universal transmission framework.
3Productivity
If transmission duration is reduced to avoid CCA, then transmission efficiency is improved, but information completeness may be compromised
Solution Approach 1:
Common information is segmented and distributed across multiple short transmission bursts on different carrier frequencies following a staggering pattern. Each burst contains essential information elements (synchronization, broadcast, or paging), ensuring that complete information is delivered through the combination of multiple brief transmissions rather than requiring each individual transmission to be lengthy.
Solution Approach 2:
The system maintains continuous information delivery by staggering transmissions across multiple frequencies over time. While individual transmissions are short to avoid CCA, the overlapping and continuous nature of transmissions across different frequencies ensures that information is consistently available to receivers without interruption, maintaining both efficiency and completeness.
Data Source
AI summary
Methods, systems, and apparatuses are described for wireless communications, in which transmission of common information to two or more receivers over unlicensed spectrum may be provided. The common information may be transmitted over a number (e.g., a set) of different carrier frequencies of the unlicensed spectrum. A staggering pattern may be employed to transmit all or a part of the common information across each of the carrier frequencies in the set of carrier frequencies. The detection of the information on one of the carrier frequencies may provide information that may be used to derive the staggering pattern. The duration of the common information transmission on each of the carrier frequencies may be selected such that a clear channel assessment (CCA) to determine availability of the unlicensed spectrum is not required.