LTE Uplink Rank Indication via Frequency Hopping Flag Bit
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Solution Overview
Problem
Existing methods for modulation scheme and rank indication in LTE uplink communications fall short of achieving higher spectrum efficiency, particularly in UCI-only PUSCH transmissions, leading to increased control overhead and reduced data throughput.
Innovation Solution
The method involves reusing a frequency hopping flag bit in DCI format 0 to indicate rank-1 or rank-2 transmissions, reducing control overhead without increasing payload size, thereby enabling more efficient spectrum utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing modulation scheme and rank indication methods are used in UCI-only PUSCH transmissions, then control overhead is reduced, but spectrum efficiency is insufficient
Solution Approach 1:
The frequency hopping flag bit is made multi-functional by enabling it to serve dual purposes: indicating frequency hopping mode and indicating transmission rank. This allows the system to reduce control overhead while maintaining the ability to trigger rank-2 transmissions for improved spectrum efficiency, directly resolving the contradiction between productivity and device complexity.
2Productivity
If rank-2 transmissions are enabled with existing methods, then spectrum efficiency improves, but control overhead increases
Solution Approach 1:
The patent changes the parameter interpretation of the frequency hopping flag bit from a single-function indicator to a multi-function indicator that can represent both frequency hopping mode and transmission rank. This parameter change enables rank-2 transmissions to be triggered without increasing control overhead, as the same flag bit carries additional meaning based on configuration.
3Device complexity
If frequency hopping flag bit is reused for rank indication, then control overhead is reduced, but interpretation complexity increases
Solution Approach 1:
The system performs preliminary configuration through higher-layer signaling (RRC configuration) to pre-establish the mapping between the frequency hopping flag bit and its dual meanings (frequency hopping mode and transmission rank). This preliminary action eliminates the need for complex real-time interpretation, as the mobile terminal already knows how to interpret the flag bit based on previous configuration messages.
Data Source
AI summary
A method and apparatus are provided for providing improved spectrum efficiency by triggering a ranked transmission. In this regard, a method is provided that includes causing a configuration message to be transmitted to a mobile terminal, wherein the configuration message provides interpretation information for a frequency hopping flag bit. The method also includes determining a rank for a transmission. The method may include setting a rank indication in the frequency hopping flag bit of a downlink control message based on the determined rank of the transmission.