MU-MIMO PAPR Reduction via Opportunistic Special Symbol Padding
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Solution Overview
Problem
Conventional MU-MIMO wireless communication systems face challenges in reducing peak-to-average power ratio (PAPR), leading to inefficiencies in power consumption and signal transmission due to peak power amplification and non-linearity, especially when transmitting spatial streams with varying payload lengths.
Innovation Solution
The method involves padding time slots with special symbols, such as CAZAC waveforms or error correction checksums, to identify the end of a payload and reduce PAPR, allowing for joint MAC/PHY layer signaling and improved power management, thereby enhancing system performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If zero padding is used at the MAC layer to fill time slots with unused payload data, then the transmission time is standardized and synchronized, but the peak-to-average power ratio increases and energy consumption increases
Solution Approach 1:
The patent extracts and removes the zero padding data from the transmission stream. Instead of transmitting unnecessary padded bits, the system identifies and eliminates these redundant transmissions, thereby reducing energy consumption while maintaining synchronized transmission time through alternative signaling methods.
Solution Approach 2:
The patent changes the transmission parameter by switching from transmitting zero-padded data to transmitting shortened payload data with appropriate end-of-packet signaling. This parameter change reduces the energy consumption associated with transmitting unnecessary data while maintaining transmission synchronization through modified signaling protocols.
2Loss of time
If zero padding is used to fill time slots, then transmission synchronization is maintained, but the PAPR increases causing non-linearity in power amplifiers
Solution Approach 1:
The patent removes the zero padding elements that cause PAPR issues. By extracting and eliminating the padded data segments, the system reduces the peak power variations that lead to non-linearity in power amplifiers, while maintaining transmission synchronization through alternative mechanisms.
Solution Approach 2:
The patent converts the potential harm of incomplete payload transmission into a benefit by using the shortened transmission opportunity to reduce PAPR. The system leverages the presence of varying payload lengths, which would normally be problematic, to create opportunities for lower peak power transmission by eliminating the need to pad to a fixed length.
3Duration of action of moving object
If padded data is transmitted, then the transmission time is extended to match the longest packet, but the energy consumption increases without additional information content
Solution Approach 1:
The patent extracts and removes the energy-wasting zero padding transmissions. By eliminating these redundant padded bits, the system reduces energy consumption while maintaining appropriate transmission duration through efficient signaling that indicates the actual end of useful data without requiring extension to match the longest packet.
Solution Approach 2:
The patent enables the transmission system to self-regulate its duration and energy usage by using end-of-packet signaling that allows receivers to identify when useful data has ended. This self-service mechanism eliminates the need for fixed-duration padding, allowing each transmission to consume only the energy necessary for its actual information content.
Data Source
AI summary
Methods and apparatuses pertaining to opportunistic peak-to-average power ratio reduction in multi-user multi-input and multi-output (MU-MIMO) wireless communication are described. A method may involve determining whether a length of a payload of each spatial stream of a plurality of spatial streams is less than a predetermined length for transmission of each spatial stream of the plurality of spatial streams. The method may also involve padding one or more time slots associated with a first spatial stream of the plurality of spatial streams with one or more special symbols other than zero in response to a determination that the length of a first payload of the first spatial stream is less than the predetermined length. The method may further involve transmitting the first spatial stream which includes the first payload and the one or more special symbols.