Unlicensed Cell Backoff Control for LAA Interference Management
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Solution Overview
Problem
In wireless communication systems, there is a need to efficiently restrict transmission and reception on unlicensed spectrum to avoid interference and comply with regulatory requirements, especially when coexisting with other technologies like Wi-Fi, while leveraging existing LTE investments through licensed-assisted access (LAA).
Innovation Solution
A method and apparatus for delaying transmission and/or reception on an unlicensed cell by receiving a backoff time or access probability factor from a licensed cell, allowing the user equipment to determine whether to perform downlink or uplink operations on an unlicensed cell, thereby controlling data transmission/reception on the unlicensed spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transmission and reception are performed on unlicensed spectrum, then spectral efficiency is improved, but interference with other technologies increases
Solution Approach 1:
The patent implements listen-before-talk (LBT) mechanism where the user equipment performs clear channel assessment before transmitting on unlicensed spectrum. This preliminary action detects whether the channel is occupied by other technologies (e.g., Wi-Fi) and prevents transmission that would cause interference, thus resolving the contradiction between utilizing unlicensed spectrum for improved spectral efficiency and avoiding interference with existing systems
2Object-affected harmful factors
If transmission and reception are restricted on unlicensed spectrum, then interference is reduced, but service availability decreases
Solution Approach 1:
The patent implements dynamic transmission control where the user equipment adjusts its transmission behavior on unlicensed spectrum based on real-time channel conditions detected through LBT. When the channel is clear, transmission is permitted to maintain service availability; when the channel is occupied, transmission is restricted to reduce interference. This dynamic adaptation resolves the contradiction by making the restriction conditional rather than absolute
3Object-affected harmful factors
If backoff time is implemented for unlicensed cell, then interference is minimized, but transmission delay increases
Solution Approach 1:
The patent implements periodic clear channel assessment where the user equipment repeatedly checks the unlicensed channel at defined intervals. Instead of implementing a fixed backoff time that always delays transmission, the system performs periodic LBT checks and transmits whenever the channel becomes available. This periodic action minimizes interference by respecting channel occupancy while reducing transmission delay by transmitting as soon as the channel is clear, rather than waiting for a predetermined backoff period
Data Source
AI summary
A method and apparatus for delaying transmission or reception on an unlicensed cell in a wireless communication system is provided. A user equipment (UE) performs downlink (DL) reception or uplink (UL) transmission on a second cell. The second cell is a second serving cell on an unlicensed carrier. The UE receives a backoff time for the second cell from a first cell when there is overload in the unlicensed carrier. The first cell is a first serving cell on a licensed carrier. The UE suspends ongoing DL reception or UL transmission on the second cell during the backoff time.