Global Cyclic Shift Delays for Distributed Wireless Transmissions
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Solution Overview
Problem
Wireless communication devices operating in PSD-limited channels, such as the 6 GHz band, face reduced wireless communication range and impaired packet detection and channel estimation due to power constraints.
Innovation Solution
The implementation of global cyclic shift delays (CSDs) for distributed transmissions, where data is modulated on noncontiguous tones across a wireless channel, allowing for increased transmit power without exceeding PSD limits, and the use of existing STF tone plans with minor modifications for AGC support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If transmit power is increased to extend wireless communication range, then communication range is improved, but power spectral density (PSD) limits are exceeded in the 6 GHz band
Solution Approach 1:
The patent segments the frequency spectrum by distributing data tones across noncontiguous subcarriers throughout the channel bandwidth rather than using contiguous subcarriers. This distribution allows the total transmit power to be spread across multiple frequency segments, increasing the overall communication range while maintaining compliance with per-MHz PSD limits in the 6 GHz band.
2Length of moving object
If data is modulated on noncontiguous tones across the channel, then transmit power is enhanced and communication range is extended, but packet detection and channel estimation capabilities are impaired due to PSD limits
Solution Approach 1:
The patent segments the channel into distributed resource units (dRUs) with noncontiguous subcarrier allocations. This segmentation enables the system to overcome PSD limits by distributing power across multiple frequency segments while maintaining reliable packet detection and channel estimation through coordinated resource allocation and signaling mechanisms.
Solution Approach 2:
The patent introduces trigger frames as intermediary signaling elements that coordinate distributed transmissions. These trigger frames carry resource allocation information and enable multiple stations to transmit on noncontiguous tones without interference, thereby maintaining packet detection and channel estimation capabilities while extending communication range under PSD limits.
3Productivity
If multiple devices transmit simultaneously on the same channel, then channel utilization is improved, but unintentional beamforming occurs due to aligned STF transmissions
Solution Approach 1:
The patent applies periodic cyclic shifts to short training field (STF) sequences transmitted by different stations. By introducing periodic time-domain shifts to STF transmissions from multiple devices, the system enables simultaneous channel access and maintains high channel utilization while preventing unintentional beamforming through deliberate phase misalignment of training sequences.
Data Source
AI summary
This disclosure provides methods, devices and systems for increasing the transmit power of wireless communication devices operating on power spectral density (PSD)-limited wireless channels. Some implementations more specifically relate to short training field (STF) designs and signaling that support distributed transmissions. A transmitting device that transmits data on a distributed resource unit (dRU) may transmit an STF sequence over a spreading bandwidth of the dRU according to an existing STF tone plan. Each STA allocated a dRU for transmission in a trigger-based (TB) physical layer convergence protocol (PLCP) protocol data unit (PPDU) maps its STF sequence to one or more spatial streams and may apply one or more global cyclic shift delays (CSDs) to the STF sequence mapped to the one or more spatial streams, respectively. As such, different global CSDs may be assigned to different STAs so that each STA transmits its STF sequence with different amounts of delay.