RBS-TMA Synchronization via Switch Command Word
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Solution Overview
Problem
In Time Division Duplex (TDD) communication systems, Tower Mounted Amplifiers (TMAs) face protection issues due to leakage in circulators, leading to potential damage of Low Noise Amplifiers (LNAs), and existing solutions like limiters or switches require additional cables and modify the RBS platform, increasing costs and operational expenditures.
Innovation Solution
A method for synchronizing a Radio Base Station (RBS) part with a TMA part using a switch signal with a switch command word, where the RBS modem generates and sends a switch signal to the TMA modem, which demodulates and compares it with stored command words to control a switch for synchronization, protecting the LNA and reducing hardware costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a switch or limiter is placed between the circulator and LNA to protect the LNA from leakage, then the LNA is protected from damage, but additional hardware components and synchronization cables are required, increasing system complexity and cost
Solution Approach 1:
The TMA modem autonomously synchronizes with the RBS modem by independently processing switch signals and generating control signals for the switch, without requiring external synchronization cables or manual configuration. The system serves itself by using the existing communication interface to achieve synchronization.
Solution Approach 2:
The existing communication interface between RBS and TMA modems is made multi-functional by using it not only for data communication but also for transmitting switch signals and achieving synchronization. This eliminates the need for separate synchronization cables.
2Reliability
If additional signal cables are used to synchronize the switch with the RBS, then synchronization is achieved, but the cost and operating expenditures increase
Solution Approach 1:
The existing communication interface is made multi-functional to carry both data traffic and synchronization signals (switch commands), eliminating the need for separate synchronization cables and reducing installation costs.
Solution Approach 2:
The synchronization function is merged with the existing communication interface between modems. The same physical interface and protocol stack are used for both data communication and switch signal transmission, consolidating functions.
3Reliability
If the current RBS platform is modified to achieve synchronization, then synchronization capability is obtained, but the modification cost and platform complexity increase
Solution Approach 1:
The TMA modem autonomously achieves synchronization by independently processing switch signals received through the existing interface and generating appropriate control signals, without requiring modifications to the RBS platform hardware or software.
Solution Approach 2:
The switch signal acts as an intermediary carrier that conveys synchronization information from the RBS modem to the TMA modem through the existing communication interface, enabling synchronization without direct platform modification.
4Reliability
If a limiter is used to protect the LNA, then the LNA is protected from high leakage, but the loop gain increases the output inband ripple
Solution Approach 1:
The switch dynamically changes state based on the TDD frame structure, being closed during uplink reception to protect the LNA and open during downlink transmission. This dynamic control prevents the LNA from being exposed to high-power leakage while avoiding the continuous signal path that would cause inband ripple with a limiter.
Solution Approach 2:
The potentially harmful high-power leakage during downlink transmission is converted into a useful control signal that triggers the switch to change state, protecting the LNA during uplink reception without degrading signal quality through limiting.
Data Source
AI summary
A base station subsystem (1000), a TMA part (100) and a RBS part (150) of a communication system employing TDD; and respective methods are provided for synchronizing the RBS part of the base station subsystem (1000) with the TMA part (100) The RBS part (150) comprises an RBS modem (160) adapted to generate a switch signal comprising a switch command word, and to further send the switch signal to a TMA modem (110). The TMA modem (110) is adapted to demodulate the switch signal and to compare the switch command word with switch command words stored in a register. When any of the switch command words in the register (111) matches the switch command word of the demodulated switch signal, the TMA modem (110) is configured to generate a control signal for controlling a switch of the TMA part for synchronizing the RBS part (150) with the TMA part.