PUSCH Transmission Scheduling in LAA Uplink
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Solution Overview
Problem
Current wireless communication systems face limitations in improving communication capacity, speed, flexibility, and efficiency, particularly in uplink Licensed-Assisted Access (LAA) data transmission, where the detailed design of the uplink transmission procedure for LAA carriers has not been fully defined, affecting the scheduling and channel access mechanisms.
Innovation Solution
The implementation of systems and methods that include a physical downlink control channel (PDCCH) receiver and transmitter in user equipment (UE) and evolved NodeBs (eNBs) to manage multiple physical uplink shared channels (PUSCHs) with advanced channel access procedures, such as listen before talk (LBT) and clear channel assessment (CCA), to optimize PUSCH scheduling and transmission in LAA operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple PUSCHs are scheduled in consecutive subframes for LAA uplink transmission, then communication capacity and efficiency are improved, but channel access complexity and scheduling difficulty increase due to LBT requirements
Solution Approach 1:
The base station performs preliminary scheduling of multiple PUSCHs in consecutive subframes and provides advance LBT parameter information to the UE through DCI formats. The UE prepares channel access procedures in advance based on received scheduling assignments, including setting counters, selecting random backoff values, and determining transmission parameters before actual channel access attempts, thereby managing complexity through advance planning
Solution Approach 2:
The system implements dynamic channel access procedures where LBT parameters such as contention window sizes, backoff counters, and transmission powers are adjusted based on channel conditions and scheduling requirements. The UE dynamically selects transmission opportunities among multiple scheduled PUSCHs based on successful LBT outcomes, and the base station dynamically adapts scheduling decisions based on channel access success feedback
2Reliability
If channel access procedures like LBT and CCA are implemented before PUSCH transmission, then transmission reliability is improved, but transmission delay and time loss increase
Solution Approach 1:
Channel access procedures including LBT and CCA are performed in advance before PUSCH transmission opportunities. The UE executes clear channel assessment and listen-before-talk protocols during designated sensing periods before scheduled transmission subframes, ensuring channel viability is determined preliminarily to avoid transmission failures and retransmission delays
Solution Approach 2:
The system maintains continuous channel monitoring and access attempts across multiple consecutive subframes where PUSCHs are scheduled. Instead of interrupting the transmission sequence, the UE continuously performs channel access procedures and maintains transmission readiness, ensuring that useful communication action continues as long as channel conditions permit, minimizing idle time between access attempts
3Adaptability or versatility
If the starting position of PUSCH is set later than the initial boundary of the subframe, then channel access flexibility is improved, but transmission efficiency and time utilization deteriorate
Solution Approach 1:
The PUSCH starting position within subframe n is made dynamic rather than fixed at the initial boundary. The actual start position is determined by channel access success timing, LBT outcomes, and scheduling adjustments, allowing the transmission to begin at the earliest feasible moment after successful channel access while still within the scheduled subframe, thereby balancing flexibility with efficiency
Solution Approach 2:
The base station preliminarily assigns PUSCH resources and provides flexible starting position indications through DCI formats, allowing the UE to adjust the actual transmission start time based on channel access outcomes. The scheduling assignment includes information fields that indicate permitted starting positions, enabling advance planning while maintaining adaptability to channel conditions
Data Source
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AI summary
A user equipment (UE) is described that includes a PDCCH receiver configured to receive a PDCCH with a DCI format, the PDCCH scheduling a first physical uplink shared channel (PUSCH) in subframe n and a second PUSCH in subframe n+1, the DCI format including an information field for indicating that a starting position of the first PUSCH is later than an initial boundary of an initial symbol of the subframe n. The UE also includes a channel sensor configured to perform a first channel access before the first PUSCH. The UE further includes a PUSCH transmitter configured to transmit the first PUSCH and the second PUSCH, in a case when the first channel access is successful. The channel sensor is further configured to, in a case when the first channel access is not successful, perform a second channel access before the second PUSCH.