Wireless Base Station SRS Timing for Path Estimation
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Solution Overview
Problem
Existing wireless communication systems, such as those using the LTE scheme, face challenges in determining the optimal timing for transmitting Sounding Reference Signals (SRS) relative to downlink user data, which affects the accuracy of transmission path estimation and antenna directivity setting.
Innovation Solution
A wireless base station is configured with a user data resource determination unit, a sounding resource determination unit, a transmission path state estimation unit, and a transmission unit to determine suitable subframes for SRS transmission, ensuring timely and accurate estimation of the transmission path state and subsequent antenna directivity formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If timing to transmit downlink user data and timing to receive an SRS are distant from each other, then the wireless base station has more time to estimate transmission path state and form antenna directivity, but the state of transmission path changes over time which degrades estimation accuracy
Solution Approach 1:
The patent applies preliminary action by having the wireless terminal transmit the SRS in advance (in the uplink part of a subframe) before the downlink user data transmission. The wireless base station receives and processes the SRS beforehand, allowing transmission path estimation and antenna directivity formation to be completed prior to the actual downlink transmission, thus resolving the contradiction between having sufficient processing time and maintaining path state stability.
2Measurement precision
If timing to transmit downlink user data and timing to receive an SRS are too close to each other, then the transmission path state remains relatively stable, but time for estimating transmission path state and forming antenna directivity cannot be secured
Solution Approach 1:
The patent structures the communication timeline so that the SRS is transmitted in the uplink part of a subframe, allowing the wireless base station to perform transmission path estimation and antenna directivity formation in advance before the downlink user data transmission begins. This preliminary processing action ensures that sufficient time is available for accurate estimation while maintaining temporal proximity between SRS reception and downlink transmission.
3Adaptability or versatility
If SRS transmission timing is not properly defined, then the system has flexibility in scheduling, but antenna directivity cannot be appropriately set
Solution Approach 1:
The patent defines a specific timing relationship where the SRS is transmitted in the uplink part of a subframe preceding the downlink user data transmission. This predetermined timing arrangement provides scheduling flexibility while ensuring that the wireless base station has adequate time to process the SRS and set up antenna directivity before downlink transmission, thus resolving the contradiction between scheduling flexibility and antenna directivity accuracy.
Data Source
AI summary
A user data resource determination unit determines any sub carriers in any downlink subframe as a first resource from which downlink user data is transmitted to a wireless terminal. A sounding resource determination unit determines a part of an uplink part in a closest switch subframe preceding the determined downlink subframe as a second resource from which a wireless terminal transmits a sounding reference signal, and notifies the wireless terminal of the determined second resource. A transmission path state estimation unit estimates a state of a transmission path to the wireless terminal based on the sounding reference signal from the wireless terminal. A transmission unit forms directivity of a plurality of antennas based on the estimated state of the transmission path and transmits downlink user data.