Multi-Mode Index Modulation for Partial Transmit Sequence PAPR Reduction
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Solution Overview
Problem
Current wireless communication systems lack a framework to effectively combine partial transmit sequence (PTS) techniques with multi-mode index modulation (IM) for improved spectral efficiency and reduced peak-to-average-power ratio (PAPR) in OFDM transmissions.
Innovation Solution
A wireless communication method that partitions information bits into index bits and constellation bits, where the constellation bits are modulated using multi-mode IM, and phase rotations are applied to the outputs of inverse Fast Fourier Transforms (IFFTs) to obtain candidate PTSs with a low PAPR, ensuring each group of bits has the same size for transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-mode index modulation is used to improve spectral efficiency, then data transmission capacity increases, but peak-to-average-power ratio increases
Solution Approach 1:
The information bits are segmented into two distinct sets: index bits (first set) that indicate which constellation bits (second set) to transmit, and constellation bits that carry the actual data. This segmentation enables implicit conveying of index information through resource allocation, improving spectral efficiency while allowing separate optimization of PAPR for the constellation bits.
Solution Approach 2:
The patent applies phase rotations as a parameter transformation to the OFDM signal. By rotating the phase of subcarriers in a controlled manner, the signal's peak-to-average-power ratio is reduced while maintaining the spectral efficiency benefits of multi-mode index modulation. This parameter change allows simultaneous optimization of both contradictory properties.
2Measurement precision
If index bits are explicitly transmitted to indicate constellation bit indices, then decoding accuracy improves, but spectral efficiency decreases
Solution Approach 1:
The index information is extracted from the data stream and used to control resource allocation independently. Instead of transmitting index bits as part of the data payload, the system uses the index to select and activate specific constellation bits for transmission on allocated subcarriers. This extraction allows the index to be conveyed implicitly through resource allocation patterns, maintaining decoding accuracy while improving spectral efficiency.
Solution Approach 2:
Resource allocation acts as an intermediary mechanism that carries dual information: both the index (which constellation bits to use) and the data (constellation bit values). By using resource allocation as the mediator, the system eliminates the need for separate explicit index transmission, achieving both spectral efficiency improvement and maintained decoding accuracy through the implicit indexing scheme.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. A transmitting wireless device may identify different sets of bits that are included in information bits of a signal to be transmitted. For example, a first set of bits may be used as an index for a second set of bits, and the second set of bits may include multiple groups of bits, where each group may have a same size (e.g., a same quantity of bits). Based on the groups of bits having the same size, the transmitting wireless device may obtain candidate partial transmit sequences (PTSs) based on applying phase rotations to respective inverse Fast Fourier Transform (IFFT) outputs associated with each group of bits. The transmitting wireless device may select a PTS from the candidate PTSs and may transmit the signal including the information bits to a receiving wireless device using the selected PTS.