Midamble Measurement Signals for Channel Estimation Under LBT Timing
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Solution Overview
Problem
Channel estimation based on measurement signals is cumbersome for transmitters operating in listen-before-talk procedures due to unpredictable transmission times, making it difficult to perform channel estimation at specific points in time.
Innovation Solution
A method for a transmitter to provide physical layer packets with measurement signals for channel estimation by adjusting the transmission time of midambles to coincide with specific times, using techniques such as data padding or puncturing to ensure accurate channel estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transmitter operates in listen-before-talk procedure with unpredictable transmission times, then the transmitter can access the channel dynamically, but it becomes difficult to provide measurement signals at pre-specified points in time for channel estimation
Solution Approach 1:
The transmitter inserts multiple midambles containing measurement signals at predetermined time positions before the actual data transmission. This preliminary placement of measurement signals ensures that channel estimation can be performed at specific points in time even though the overall transmission timing is determined dynamically by LBT procedure.
Solution Approach 2:
The system dynamically adjusts the timing and number of midambles inserted into the physical layer packet based on the actual transmission opportunity obtained through LBT. The transmitter can flexibly position measurement signals within the packet structure to match the specific transmission timing while maintaining channel estimation capability.
2Measurement precision
If multiple midambles are inserted to enable channel estimation at specific times, then channel estimation accuracy improves, but the complexity of packet structure increases
Solution Approach 1:
The midambles serve multiple functions: they contain measurement signals for channel estimation, maintain the OFDM signal structure, and can be positioned to satisfy both channel estimation requirements and transmission timing constraints. This multi-functionality reduces the need for separate dedicated measurement signal structures.
Solution Approach 2:
The system changes parameters such as the number of midambles, their positions within the packet, and their timing relationships based on the specific transmission scenario and channel estimation requirements. This flexibility allows optimization of channel estimation accuracy while managing packet structure complexity.
Data Source
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AI summary
A method is disclosed of a transmitter configured to transmit a physical layer packet in accordance with a listen-before-talk procedure. The method comprises acquiring an indication of a specific time for channel estimation, providing the physical layer packet with at least one measurement signal for channel estimation based on the specific time, and transmitting the physical layer packet. In some embodiments, the physical layer packet is provided with a plurality of midambles, wherein each midamble comprises one or more measurement signals for channel estimation. In some embodiments, the physical layer packet is provided with a floating midamble which comprises one or more measurement signals for channel estimation. A method is also disclosed of a receiver configured to receive a physical layer packet transmitted in accordance with a listen-before-talk procedure. The method comprises acquiring an indication of a specific time for channel estimation, receiving the physical layer packet, provided with at least one measurement signal for channel estimation based on the specific time, and performing channel estimation for the specific time based on the at least one measurement signal. Corresponding apparatuses, devices and computer program product are also disclosed.