Staggered UL/DL Waveform Design for Low Latency Wireless
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Solution Overview
Problem
Wireless communication systems face increased latency due to rigid timing configurations in uplink and downlink symbol durations, which can lead to higher hybrid automatic repeat request (HARQ) and scheduling request latency, especially when using hybrid automatic repeat request (HARQ) and scheduling request (SR) processes.
Innovation Solution
Implementing a staggered uplink/downlink (UL/DL) format where symbol periods are offset, allowing for shorter decoding times and reduced round trip times by staggering the UL/DL symbol periods and using thin control channels to expedite responses and retransmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If rigid timing configurations are used for uplink and downlink symbol durations, then system stability is maintained, but latency increases due to longer HARQ and scheduling request round trip times
Solution Approach 1:
The patent applies dynamics by making the timing configuration flexible rather than rigid. Specifically, it introduces a staggered UL/DL format where the start of uplink symbols is offset from the start of downlink symbols by a configurable time offset. This allows the system to dynamically adjust timing relationships to optimize for low latency while maintaining stability through controlled configuration parameters.
Solution Approach 2:
The patent changes the timing parameters by introducing a time offset between uplink and downlink symbol starts. This parameter adjustment allows the system to reduce HARQ round trip time by enabling earlier uplink transmissions relative to downlink receptions, thereby reducing latency without compromising system stability through proper parameter management.
2Loss of time
If shorter decoding time periods are used, then latency is reduced, but the complexity of synchronization and timing management increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the staggered timing offset between uplink and downlink symbols. This allows the system to prepare timing relationships in advance, enabling shorter decoding periods while managing complexity through predefined configurations rather than dynamic adjustments during operation.
3Loss of time
If staggered UL/DL symbol periods are implemented, then round trip time is reduced, but the complexity of timing alignment and coordination increases
Solution Approach 1:
The patent manages timing coordination complexity by introducing a single configurable time offset parameter that defines the staggered relationship between uplink and downlink symbol starts. This parameterized approach simplifies coordination compared to complex multi-parameter timing schemes, enabling reduced round trip time while keeping implementation complexity manageable.
Data Source
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AI summary
Methods, systems, and devices for wireless communication are described. In some examples, a wireless system may use a staggered uplink/downlink (UL/DL) format in which the symbol periods of the downlink are offset from the symbol periods of the uplink. Thus, if a user equipment (UE) receives a transmission in a first symbol period, it may decode the transmission and transmit a response in a staggered symbol period (e.g., in a UL control channel symbol period beginning one half of a symbol period after the first symbol period). A base station may then receive the response and, if it is a negative acknowledgement (NACK), retransmit during the third symbol period following the first symbol period. In another example, thin control channels may be used to reduce the round trip time between receiving a transmission and a retransmission.