Small-Cell Base Station Timing Synchronization
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Solution Overview
Problem
Conventional communication systems fail to account for transmission delays in cables and propagation delays in radio transmission paths, leading to timing shifts in signal transmission from base stations to communication terminals, which can result in interference that exceeds allowable limits when using eICIC technology.
Innovation Solution
A communication system that includes a small-cell base station with a listening apparatus to measure and adjust the transmission timing of downlink signals, taking into account transmission delays and propagation delays to ensure synchronization within an allowable range, thereby reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transmission timing is synchronized at BBU level without considering cable and propagation delays, then time synchronization between base stations is achieved, but signal arrival timing at terminals shifts beyond allowable range causing interference
Solution Approach 1:
The patent applies preliminary action by measuring and compensating for transmission delays in cable connections and propagation delays in radio transmission paths before signal transmission. The base station measures the time difference between its own signal transmission and received signals from other base stations, then adjusts future transmission timing accordingly to pre-correct for these delays, ensuring signals arrive at terminals within the allowable time range without causing interference
Solution Approach 2:
The patent implements feedback by measuring the actual arrival time difference of signals from multiple base stations at the terminal and using this measurement information to adjust transmission timing. The base station receives feedback about timing deviations and modifies its transmission schedule accordingly to maintain synchronized signal arrival at terminals, thereby preventing interference while preserving time synchronization
2Object-affected harmful factors
If eICIC technology is applied between neighboring base stations, then interference control in time domain is improved, but timing shifts due to transmission and propagation delays cause the technology to fail
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the transmission timing parameter of base station signals based on measured transmission and propagation delays. By changing the transmission timing parameter to compensate for cable delays and radio propagation delays, the system ensures that eICIC technology functions reliably by maintaining proper time alignment of signals arriving at terminals, thereby preventing interference while preserving the reliability of the eICIC interference control mechanism
3Device complexity
If transmission delay and propagation delay are not considered, then system complexity is reduced, but signal arrival timing accuracy deteriorates
Solution Approach 1:
The patent applies self-service by enabling the base station to autonomously measure its own transmission delay through cable connections and the propagation delay of its radio signals, then automatically adjust its transmission timing without external intervention. This self-measurement and self-correction mechanism maintains signal arrival timing accuracy while avoiding the complexity of centralized timing management systems, as each base station independently compensates for its own delays
Data Source
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AI summary
A deviation of time at which downlink signals synchronously transmitted from a macro-cell base station and a small-cell base station respectively reach a communication terminal apparatus can be made within an allowable range, without being affected by transmission delay in transmission cables of base station and propagation delay in radio transmission paths. The small-cell base station is provided with a radio transceiving section connected with antenna, a radio communication control section, a transmission cable connected with the radio transceiving section and the radio communication control section, and a downlink signal receiving section for receiving downlink signals transmitted from the macro-cell base station and the own base station respectively. The small-cell base station measures a reception-timing difference of downlink signals transmitted from the macro-cell base station and the own base station based on a reception result of the downlink signal, adjusts a transmission timing of downlink signal of the own base station based on the reception-timing difference, and transmits a downlink signal at the adjusted transmission timing.