Uplink Downlink Collision Handling in Wireless Spectrum
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Solution Overview
Problem
Wireless communication systems face challenges in handling collisions between uplink and downlink transmissions, particularly in scenarios where a base station schedules a downlink transmission in the same subframe as a UE's intended uplink transmission, leading to interference and difficulties in compliance with standards like 3GPP TS 36.213 for low-cost devices.
Innovation Solution
The proposed solution involves techniques at both the UE and base station levels to mitigate or avoid collisions by allowing the UE to drop or partially transmit scheduled uplink transmissions when collisions occur, and for the base station to adjust scheduling to avoid such collisions, using methods such as dropping PDSCH with repetitions, prioritizing PUCCH format 2 transmissions, and puncturing PDSCH subframes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the base station schedules downlink transmissions in the same subframe as UE's uplink transmissions, then spectrum utilization is improved, but transmission collisions occur causing interference
Solution Approach 1:
The patent segments the subframe into different parts: a first portion for downlink transmission and a second portion for uplink transmission. This segmentation allows the base station to schedule downlink transmissions in the same subframe as UE uplink transmissions without causing collisions, as each transmission type is confined to its designated time portion. The segmentation resolves the contradiction by enabling high spectrum utilization while maintaining transmission reliability through temporal separation.
Solution Approach 2:
The patent applies preliminary action by having the UE transmit reference signals in advance of the actual uplink transmission. The base station uses these reference signals to determine the exact timing and duration of the uplink transmission, allowing it to schedule downlink transmissions in the same subframe while avoiding collisions. This preliminary timing information enables the base station to allocate the first and second portions of the subframe accurately, resolving the contradiction between spectrum utilization and transmission reliability.
2Productivity
If the UE transmits uplink transmissions in allocated subframes, then communication efficiency is improved, but collisions with downlink transmissions occur
Solution Approach 1:
The patent segments the subframe temporally into a first portion for downlink and a second portion for uplink transmissions. This segmentation allows the UE to maintain communication efficiency by transmitting in its allocated subframe while avoiding harmful interference from downlink transmissions, as the downlink transmissions are confined to the first portion and uplink transmissions to the second portion.
Solution Approach 2:
The patent employs feedback mechanisms where the UE transmits reference signals and the base station uses these signals to determine timing information. This feedback loop enables the base station to dynamically adjust the scheduling of downlink and uplink transmissions, ensuring that the UE can transmit efficiently without experiencing harmful interference from downlink transmissions in the same subframe.
3Productivity
If the base station schedules both uplink and downlink transmissions for a UE, then resource utilization is improved, but collision handling complexity increases
Solution Approach 1:
The patent segments the subframe into distinct first and second portions for downlink and uplink transmissions respectively. This segmentation simplifies collision handling by providing clear temporal boundaries, allowing the base station to schedule both uplink and downlink transmissions efficiently without complex collision resolution mechanisms. The segmentation makes the collision handling straightforward by preventing overlaps in the first place.
Solution Approach 2:
The patent applies preliminary action by having the UE transmit reference signals before the actual uplink transmission. This allows the base station to determine the exact timing and duration of uplink transmissions in advance, simplifying the scheduling of both uplink and downlink transmissions. The preliminary timing information enables the base station to allocate subframe portions accurately, reducing the complexity of collision handling while maintaining high resource utilization.
Data Source
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AI summary
Techniques are described for handling collisions between uplink transmissions and downlink transmissions over a wireless spectrum. Some of the techniques allow a UE to perform a collision management procedure after identifying a transmission collision (e.g., a collision between a downlink transmission with repetition and an uplink transmission, or a collision between a downlink transmission with repetition and a guard frame for an uplink transmission). The collision management procedure allows the UE to refrain from transmitting at least part of an uplink transmission, refrain from decoding at least part of a downlink transmission, or a combination thereof. Other techniques allow a base station to mitigate transmission collisions by scheduling downlink transmissions based on received, inferred, or determined parameters of uplink transmissions.