Data Frame Transmission Power Segmentation for WLAN Interference Avoidance
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Solution Overview
Problem
In WLAN systems, devices in long range BSSs often fail to sense data frames from devices in short range BSSs due to power attenuation, leading to interference and transmission failures, and increasing the transmit power to avoid interference can suppress concurrent transmissions in non-overlapping BSSs, affecting overall network throughput.
Innovation Solution
A data transmission method where a device in a first BSS receives a data frame with a preamble sequence and a MAC frame, setting a network allocation vector (NAV) value based on the signal field in the preamble sequence, allowing it to determine the transfer time of the MAC frame and adjust its transmission power to avoid interference, by sending the preamble sequence at a higher power and the MAC frame at a lower power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the transmit power of the device in the short range BSS is increased to avoid interference, then the reliability of data transmission is improved, but the productivity of the network is worsened due to suppression of concurrent transmissions in non-overlapping BSSs
Solution Approach 1:
The data frame is segmented into two parts with different transmit powers: the preamble sequence is transmitted at first power (higher) while the MAC frame is transmitted at second power (lower). This segmentation allows the preamble to be detected by devices in overlapping BSSs to set NAV values and avoid interference, while the MAC frame uses lower power to minimize suppression of concurrent transmissions in non-overlapping BSSs, thus resolving the contradiction between transmission reliability and network throughput.
2Productivity
If the transmit power of the device in the short range BSS is kept low to maintain network throughput, then the productivity of the network is improved, but the reliability of data transmission is worsened due to interference from long range BSS devices
Solution Approach 1:
Different parts of the transmitted signal have different power levels: the preamble sequence uses higher power (first power) to ensure detection by devices in overlapping BSSs for interference avoidance, while the MAC frame uses lower power (second power) to reduce interference with concurrent transmissions. This local quality differentiation resolves the contradiction by making the critical interference-avoidance portion high-power while keeping the data portion low-power.
3Area of stationary object
If the device in the long range BSS uses normal transmit power to communicate, then the area of coverage is improved, but the object-generated harmful factors increase due to interference with short range BSS transmissions
Solution Approach 1:
The preamble sequence is transmitted at higher power before the MAC frame to enable devices in overlapping BSSs to detect the transmission in advance and set their NAV values accordingly. This preliminary high-power transmission allows long range BSS devices to communicate at normal power while preventing interference with short range BSS transmissions, as other devices have already been alerted to the ongoing transmission through the high-power preamble.
Data Source
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AI summary
The present invention discloses a data transmission method and device, and pertains to the communications field. The method includes: receiving, by a device in a first BSS, a data frame sent by a device in a second BSS, where the data frame sent by the device in the second BSS includes a Preamble sequence and a MAC frame; transmit power of the Preamble sequence is first power; transmit power of the MAC frame is second power; and the first power is higher than the second power; if the data frame received by the device in the first BSS includes the Preamble sequence but does not include the MAC frame, setting a NAV value according to a SIG field in the Preamble sequence; and transmitting data according to the NAV value. According to the present invention, a device in a long range BSS does not cause interference to data transmission of a device in a short range BSS.