PPDU Signal Field Fixed Bandwidth WLAN Transmission
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Solution Overview
Problem
In wireless local area networks (WLANs) supporting TV white space bands, there is a challenge in managing transmission channel bandwidth and power to prevent interference with licensed devices while ensuring reliable communication, particularly due to the hidden node problem and scalability issues with existing IEEE 802.11 protocols.
Innovation Solution
A method and apparatus for transmitting a physical layer convergence procedure (PLCP) protocol data unit (PPDU) with a fixed transmission bandwidth for the signal field and a variable bandwidth for the data field, where the transmission power for the signal field is greater than that for the data field, including a transition gap and specific fields for indicating bandwidth and guard intervals, to maximize synchronization and demodulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If transmission power is lowered to decrease interference with licensed devices, then interference with licensed devices is reduced, but transmission coverage becomes narrower and hidden node problem occurs
Solution Approach 1:
The patent divides the PPDU into two distinct fields with different transmission parameters: a signal field transmitted at higher power for reliable reception, and a data field transmitted at lower power to minimize interference with licensed devices. This segmentation allows each field to be optimized independently for its specific function.
Solution Approach 2:
Different transmission powers are applied to different parts of the transmission: the signal field uses higher transmission power to ensure reliable reception at the receiver end, while the data field uses lower transmission power to reduce interference with licensed devices. This local differentiation of transmission quality resolves the contradiction between coverage and interference.
2Productivity
If transmission bandwidth is increased to improve data rate, then transmission rate is improved, but interference with licensed devices increases
Solution Approach 1:
The patent segments the transmission into a signal field and a data field, where the data field can utilize variable bandwidth for high-rate transmission while the signal field maintains fixed bandwidth parameters to control interference. This allows the system to achieve high data rates without causing excessive interference to licensed devices.
3Ease of operation
If DCF and EDCA protocols are applied to TV WS environment, then channel access is enabled, but scalability problem grows worse
Solution Approach 1:
The patent introduces variable transmission bandwidth as a new parameter that can be dynamically adjusted based on the number of active STAs and interference conditions. This parameter change enables the system to scale effectively in TV WS environments by adapting the data field bandwidth according to actual network conditions, thereby improving scalability while maintaining ease of operation.
Data Source
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AI summary
A method for transmitting a physical protocol data unit (PPDU) in a wireless local area network (WLAN) is provide. The method includes generating a PPDU frame comprising a signal field and a data field and transmitting the PPDU frame, in which a transmission bandwidth for transmitting the signal field is fixed, buta transmission bandwidth for transmitting the data field is variable.