BER Estimation for WCDMA Channel Quality Detection
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Solution Overview
Problem
In WCDMA systems, the existing methods fail to correctly estimate Bit Error Rate (BER) when TPC symbols are invalid, particularly when the channel condition is poor, affecting in-sync/out-of-sync decisions and outer-loop power control.
Innovation Solution
A method and system that judges the validity of TPC symbols, counts valid and invalid symbols, and estimates BER based on the number of symbols with opposite polarities to accurately detect channel quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the prior art formula (1) is used to estimate BER based on statistical probabilities P1 and P2, then the BER estimation works under normal channel conditions, but the estimation becomes incorrect when the channel condition is poor and TPC symbols have no path (all RAKE receiver outputs are 0)
Solution Approach 1:
The patent changes the estimation parameters from statistical probabilities P1 and P2 (which become 0 when all TPC symbols are invalid) to a direct counting method that tracks the number of invalid symbols Nu and valid symbols Nv. This parameter transformation allows the system to distinguish between different channel conditions and provide meaningful BER estimates even when P1=0, thereby resolving the contradiction between measurement precision and reliability under poor channel conditions
Solution Approach 2:
The patent performs preliminary classification of TPC symbols into valid and invalid categories before BER estimation. By pre-identifying invalid symbols (where I and Q components are both 0) and separating them from valid symbols, the system prepares the data in advance for accurate BER calculation. This preliminary action ensures that invalid symbols don't incorrectly contribute to the BER estimate, maintaining reliability under poor channel conditions while preserving measurement precision
Data Source
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AI summary
A method, a device and a system for detecting channel quality are provided. The method includes: judging whether a Transmit Power Control (TPC) symbol output by a receiver is an invalid symbol; when the TPC symbol is a valid symbol, judging whether polarities of in-phase/quadrature (I/Q)components of the valid symbol are opposite to each other; counting the number of invalid symbols, the number of valid symbols, and the number of valid symbols with opposite polarities; and estimating a Bit Error Rate (BER) according to the number of the invalid symbols, the number of the valid symbols, and the number of the valid symbols with the opposite polarities, and detecting the channel quality through the BER. The corresponding device includes a first judging module, a second judging module, a counting module, and an estimation module. A system for detecting channel quality is further provided. Through the method, the device and the system, the defect that the BER cannot be correctly estimated in the case of an invalid TPC symbol in the prior art is overcome.