TDD Optical Repeater Control Frame Timing
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Solution Overview
Problem
TDD optical repeaters face challenges in accurately distinguishing between downlink and uplink signals due to time delay in optical signal transmission, leading to unstable control of remote nodes in shadowing areas like underground and building environments, where conventional systems lack dedicated channels for switch control and status information.
Innovation Solution
A method where the main donor generates a control frame during non-downlink periods to control the remote node, including sync, remote control, and status information, which is analyzed by the remote to perform control operations and transmit status back during non-uplink periods, eliminating the need for additional optical transceivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If TDD optical repeaters use conventional systems without dedicated control channels, then device complexity is reduced, but control stability of remote nodes deteriorates due to time delay in optical signal transmission
Solution Approach 1:
The patent merges control information transmission with existing downlink and uplink signal transmissions by embedding control frames within the TDD signal structure. The main donor embeds control frames in downlink signals sent to remote nodes, and remote nodes embed status frames in uplink signals sent back to the main donor, eliminating the need for separate dedicated control channels while maintaining control stability despite time delays.
Solution Approach 2:
The patent applies preliminary action by having the main donor generate control frames in advance during non-downlink transmission periods and the remote node generate status frames in advance during non-uplink transmission periods. This timing arrangement ensures that control and status information is prepared and transmitted during appropriate time slots before they are needed, compensating for the optical transmission time delay.
2Speed
If TDD optical repeaters transmit control information during active signal periods, then control responsiveness is improved, but signal interference increases leading to inaccurate signal distinction
Solution Approach 1:
The patent implements periodic action by transmitting control frames and status frames during specific periodic time slots when no downlink or uplink signals are being transmitted. The main donor transmits control frames during non-downlink periods, and remote nodes transmit status frames during non-uplink periods, creating a periodic pattern that avoids interference with active signal transmission while maintaining control responsiveness.
Solution Approach 2:
The patent segments the TDD transmission timeline into distinct periods: downlink transmission periods, uplink transmission periods, non-downlink periods for control frame transmission, and non-uplink periods for status frame transmission. This segmentation allows control and status information to be transmitted in dedicated time slots separate from data transmission, preventing signal interference while maintaining responsiveness.
Data Source
AI summary
A method and apparatus for transmitting data to an Access Point (AP) and a Mobile Station (MS) in a Time Division Duplex (TDD) optical repeater. A main donor generates a control frame for controlling a remote, upon receipt of data from the AP, and transmits the control frame to the remote during a non-downlink transmission period. The remote analyzes the control frame received from the main donor, detects sync information about a downlink signal and an uplink signal, and remote control information from the analyzed control frame, performs a control operation according to the detected remote control information, and generates a status frame for notifying the main donor of the status of the remote upon receipt of data from the MS. The status frame is transmitted from the remote to the main donor during a non-uplink transmission period.