Wireless Medium Reservation for Low Latency Audio Streaming
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Solution Overview
Problem
Conventional WLAN protocols fail to ensure tight latency constraints necessary for real-time audio synchronization in audio-visual systems, leading to variable back-off times that prevent guaranteed data transmission latency and fail to meet requirements for real-time data transmission.
Innovation Solution
A wireless network system where a transmitting device reserves a medium for a predetermined transmission duration, accounting for interframe spacings and acknowledgments, to ensure a burst of data frames is transmitted within a fixed duration, using techniques such as Network Allocation Vectors (NAV) and sequential wake times for receiving devices, allowing for controlled data bursts with consistent latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional WLAN protocols are used for audio streaming, then the system can operate with standard protocols, but the latency cannot be tightly constrained within tens of milliseconds
Solution Approach 1:
The access point performs preliminary actions by sending RTS frames with NAV values before actual data transmission, reserving the medium in advance to eliminate variable back-off times and ensure predictable latency for audio data delivery to multiple stations
Solution Approach 2:
The system dynamically adjusts transmission parameters including NAV values in RTS frames, transmission power levels, and data frame sequencing to maintain consistent latency across varying network conditions while ensuring audio synchronization
2Ease of operation
If variable back-off times are used before each data transmission, then medium contention is handled according to standard protocols, but guaranteed latency for real-time data cannot be achieved
Solution Approach 1:
The access point sends RTS frames with NAV values set to cover the entire data transmission sequence in advance, reserving the medium before actual data delivery and eliminating variable back-off times that would otherwise prevent guaranteed latency
Solution Approach 2:
The data transmission is segmented into multiple frames sent in sequence, with each frame preceded by RTS/CTS handshaking, allowing the medium to be reserved for the entire sequence while maintaining protocol compliance
3Productivity
If multiple stations receive audio data simultaneously over wireless medium, then real-time streaming to multiple receivers is enabled, but medium contention increases latency variability
Solution Approach 1:
Audio data for multiple stations is segmented into separate frames transmitted in sequence, with each frame addressed to a specific station, allowing controlled delivery while maintaining consistent latency through pre-reserved medium access
Solution Approach 2:
Multiple data frames for different stations are merged into a single continuous transmission sequence under one reserved medium access period, eliminating repeated back-off times and ensuring predictable latency across all receivers
Data Source
AI summary
Embodiments can include a method in which a transmission duration for data frames to a plurality of different receiving devices is determined by a transmitting device. The transmission duration can include at least interframe spacings that separate the data frames from one another. The transmitting device can transmit a control message over a medium to reserve the medium for the transmission duration. The data frames can then be sequentially transmitted by the transmitting device to the plurality of receiving devices during the transmission duration. The transmitting device can operate according to a contention based protocol. Related devices and systems are also disclosed.