Wireless Device Feedback Encoding for Channel Quality Correlation
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Solution Overview
Problem
In wireless communication systems, especially in LTE, channel conditions change faster than the feedback system can communicate, leading to sub-optimal modulation and coding choices, resulting in lower performance due to inaccurate feedback, particularly in MU-MIMO scenarios where user pairing and modulation/coding selection are critical.
Innovation Solution
A method in a wireless device that measures channel quality, correlates it with the received transmission parameter, and encodes this information with Hybrid Automatic-Repeat-Request (HARQ) feedback using channel selection over predefined resource indices, allowing for improved interference estimation and modulation/coding scheme selection directly associated with data transmission, enhancing spectral efficiency and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If channel selection is used for transmitting feedback information, then feedback can be transmitted using existing uplink resources, but the feedback accuracy is insufficient due to delayed channel condition reporting
Solution Approach 1:
The patent applies preliminary action by having the wireless device determine and report the recommended modulation and coding scheme (RMCS) in advance, before the actual data transmission occurs. This allows the network node to prepare optimal transmission parameters based on current channel conditions, reducing the delay between channel condition changes and their reflection in transmitted data. The RMCS is calculated based on measured channel quality indicators and reported proactively rather than reactively.
Solution Approach 2:
The patent implements a feedback mechanism where the wireless device continuously monitors channel quality indicators (CQI) and provides feedback to the network node about the recommended modulation and coding scheme. This feedback loop enables the network node to adapt transmission parameters dynamically based on real-time channel conditions, improving both feedback accuracy and timeliness compared to traditional periodic reporting methods.
2Reliability
If link adaptation is based on reference signals, then feedback can be obtained regularly, but the modulation and coding choices do not accurately reflect actual data transmission channel conditions
Solution Approach 1:
The patent applies local quality by shifting the measurement focus from general reference signals to specific data transmission channels. Instead of using uniform reference signal measurements for all link adaptation decisions, the system measures channel quality indicators specifically on the downlink shared channel where actual data is transmitted. This localized measurement approach ensures that the recommended modulation and coding scheme accurately reflects the actual channel conditions experienced during data transmission.
Solution Approach 2:
The patent implements parameter changes by transitioning from fixed reference signal-based measurements to dynamic data channel-based measurements. The system continuously updates channel quality indicators based on actual data transmission conditions, allowing the recommended modulation and coding scheme to adapt to changing channel parameters such as signal-to-interference-plus-noise ratio (SINR) and channel fading characteristics in real-time.
3Device complexity
If sub-optimal modulation and coding are chosen due to delayed feedback, then system complexity is reduced, but spectral efficiency and throughput decrease
Solution Approach 1:
The patent applies partial action by implementing selective feedback reporting rather than continuous full-parameter reporting. The wireless device calculates the recommended modulation and coding scheme and only reports changes or critical updates to the network node, rather than continuously reporting all channel state information. This reduces feedback overhead and system complexity while maintaining sufficient accuracy to achieve near-optimal spectral efficiency.
Data Source
AI summary
The disclosure relates to a method 10 in a wireless device 3 for providing feedback information. The wireless device 3 is adapted for wireless communication in a communication system 1 comprising a network node 2. The method 10 comprises: receiving 11, from the network node 2, a downlink transmission, the downlink transmission comprising a transmission parameter used for the downlink transmission; measuring 12 channel quality of the received downlink transmission; determining 13, based on the measured channel quality, a transmission parameter, that the wireless device 3 is able to support; correlating 14 the transmission parameter used for the downlink transmission with the determined transmission parameter, giving a correlated transmission parameter; and encoding 15 the correlated transmission parameter together with Hybrid Automatic-Repeat-Request feedback information. Methods in a base station node, a base station node, computer programs and computer program products are also presented.