Uplink Control Channel Pilot Symbol Patterns for False Detection Prevention
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Solution Overview
Problem
In the EUTRA mobile communication system, there is a risk of false detection of ACK/NACK information by the base station when a user equipment (UE) transmits only CQI information, leading to potential communication failures due to misinterpretation of channel coding and interference with downlink scheduling.
Innovation Solution
The implementation of distinct RS symbol patterns for cases where the UE transmits only CQI information and cases where both CQI and ACK/NACK information are transmitted, ensuring accurate channel estimation and preventing false alarms by maintaining orthogonality between different transmission scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the base station uses a unified channel estimation method for both CQI-only and CQI+ACK/NACK transmissions, then the system complexity is reduced, but the false detection rate of ACK/NACK information increases
Solution Approach 1:
The patent segments the channel estimation process into two distinct paths: one for CQI-only transmission and another for CQI+ACK/NACK transmission. The base station determines which path to use based on the transmission type, applying different demapping and channel estimation methods accordingly. This segmentation resolves the contradiction by maintaining low complexity through structured decision-making while improving reliability through scenario-specific optimization.
Solution Approach 2:
The patent changes the channel estimation parameters based on the transmission scenario. For CQI-only transmission, a specific demapping method is applied, while for CQI+ACK/NACK transmission, a different demapping method is used. This parameter adaptation allows the system to maintain optimal performance for each scenario without requiring a completely separate system for each case.
2Reliability
If the base station applies aggressive channel coding for CQI information to improve reception reliability, then the CQI reception quality improves, but the probability of false ACK/NACK detection increases due to misinterpretation of coded bits
Solution Approach 1:
The patent introduces an intermediary decision-making process at the base station that determines whether the received signal contains only CQI or both CQI and ACK/NACK. This intermediary step prevents the misinterpretation of channel-coded CQI bits as ACK/NACK information by selecting the appropriate demapping method based on the transmission type, thus resolving the contradiction between reception quality and false detection probability.
Solution Approach 2:
The patent applies preliminary action by performing channel decoding and determination of transmission type before final ACK/NACK detection. The base station first decodes the CQI information, then determines whether ACK/NACK was transmitted based on the decoding results and signal characteristics. This preliminary processing prevents false detection by establishing the correct interpretation context before extracting ACK/NACK bits.
Data Source
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AI summary
A method and apparatus for transmitting/receiving pilot symbols for demodulation of control channel information in the uplink of a wireless communication system are provided. When an Evolved Node B (ENB) expects to receive both the Channel Quality Information (CQI) and the Acknowledgement (ACK)/Negative ACK (NACK) from a User Equipment (UE) in a certain subframe, if the UE transmits only the CQI channel, the ENB is prevented to detect the nonexistent ACK/NACK information from the CQI channel, thereby avoiding false alarm.