Transmission Scheme for TD-SCDMA Baseband Signals
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Solution Overview
Problem
Current fiber capacity limitations in TD-SCDMA radio systems, such as 2.5 Gbps fibers, cannot support the required number of antenna-carriers as demanded by China Mobile Communication Corporation, leading to inadequate data transfer performance, especially with the use of Automatic Gain Control which has limited effects and increased costs with high-speed fibers.
Innovation Solution
Transmitting digital signals over fiber before spreading and combining, with power and weight factors sent separately, allowing the receiving RRU to sum these signals, reducing data volume and handling complexity through Field-Programmable Gate Array (FPGA) processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If 2.5 Gbps fiber is used for data transmission, then the system cost is low, but the fiber capacity is insufficient to support required number of antenna-carriers
Solution Approach 1:
The patent segments the transmission data into two parts: digital baseband signals (before spreading and combining) and power/weight factors. By transmitting only the digital baseband signals over the fiber and handling the power and weight factors at the receiving end through FPGA processing, the data volume is significantly reduced, enabling 2.5 Gbps fiber to support more antenna-carriers
Solution Approach 2:
The patent extracts and removes the power and weight factor information from the fiber transmission data, keeping only the essential digital baseband signals. This extraction reduces the transmitted data volume while maintaining the ability to reconstruct the full signal at the receiving end through local processing
2Adaptability or versatility
If high speed fiber (3.7 G or 5 G) is used, then the fiber capacity is sufficient to support more antenna-carriers, but the system cost increases significantly
Solution Approach 1:
The patent changes the parameter of data representation by transmitting digital baseband signals before spreading and combining rather than the final modulated signals. This parameter change in data format reduces the required transmission bandwidth, allowing existing 2.5 Gbps fiber infrastructure to support higher carrier configurations without upgrading to expensive high-speed fiber
3Quantity of substance
If Automatic Gain Control is used to reduce IQ bit-length from 16 to 10, then the data volume is reduced, but the uplink performance is not significantly improved and downlink performance is affected
Solution Approach 1:
The patent performs preliminary processing by transmitting the digital baseband signals before spreading and combining operations. This allows the receiving end to perform spreading and combining with full precision using FPGA, avoiding the performance degradation that would result from premature quantization or gain control operations
Data Source
AI summary
In a transmission scheme for transmitting data over a connection connecting a transmitting Main Unit and a receiving Radio Unit of a cellular radio system, where the transmitted data corresponds to user-plane data in the form of digital baseband data for different antenna-carriers, the digital signal is transmitted over the connection, e.g. a fiber, before spreading and combining is provided. The power and weight factor is transmitted separately with a few additional bits. Hereby, the Digital signal before spreading and combining is transmitted in the fiber instead of the combined multi-code signal.