Grant-Free Uplink Interference Mitigation via Dynamic Power Control
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Solution Overview
Problem
In conventional wireless communication networks, the coexistence of grant-based and grant-free uplink transmissions is challenging due to interference issues, particularly when grant-free transmissions are sporadic and unpredictable, leading to inefficient resource utilization and potential collisions with grant-based transmissions.
Innovation Solution
A method is introduced to mitigate interference by detecting grant-free uplink transmissions and adjusting the transmission parameters of grant-based uplink transmissions, such as reducing power levels or shifting transmissions, to accommodate retransmissions of grant-free data, using orthogonal frequency division multiplexed (OFDM) symbols and downlink control signals to instruct user equipment (UE) adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resources are allocated exclusively for grant-free access, then grant-free transmission reliability is improved, but resource utilization efficiency deteriorates when grant-free traffic is sporadic
Solution Approach 1:
The patent makes uplink resources universal by allowing them to serve both grant-free and grant-based access purposes. The base station dynamically controls whether resources are used for grant-free transmissions (when traffic is present) or grant-based transmissions (when resources are not needed for grant-free), thereby achieving multi-functionality of the same physical resources.
Solution Approach 2:
The patent introduces dynamic resource allocation where the base station sends control signals to UEs to adjust transmission parameters (such as muting or power reduction) based on real-time detection of grant-free transmission needs. This dynamic adjustment allows the system to adapt resource usage between grant-free and grant-based modes according to actual traffic conditions.
2Productivity
If resources are shared between grant-based and grant-free access, then resource utilization efficiency is improved, but interference between the two access types increases
Solution Approach 1:
The patent applies preliminary anti-action by having the base station detect grant-free transmission intentions in advance and send control signals to grant-based UEs to mute or reduce power before the actual interference occurs. This preemptive measure prevents interference from happening in the first place, rather than trying to mitigate it after the fact.
Solution Approach 2:
The base station acts as an intermediary that coordinates between grant-free and grant-based UEs. It receives transmissions from both types, detects potential conflicts, and sends control signals to adjust grant-based transmissions accordingly, thereby mediating the interaction between the two access types to prevent harmful interference.
3Loss of time
If grant-free transmissions are allowed without scheduling, then access latency is reduced, but collision with grant-based transmissions occurs
Solution Approach 1:
The patent implements a feedback mechanism where the base station monitors uplink resources for grant-free transmissions and sends control signals back to grant-based UEs when conflicts are detected. This feedback loop allows the system to maintain the low-latency benefit of grant-free access while using real-time information to prevent collisions with scheduled grant-based transmissions.
Data Source
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AI summary
Aspects of this disclosure mitigate interference in a time division duplexed frame by altering a transmission parameter of grant-based uplink transmissions upon determining that a portion of the grant-based transmission will coincide with the retransmission of a detected grant-free uplink transmission. In particular, a base station may determine that a grant-free retransmission is to occur over resources scheduled to carry a grant-based transmission, and then send a signal instructing a UE to delay, or puncture a portion, of the grant-based transmission. This may mitigate interference between the grant-based transmission and the grant-free transmission.