Airborne Wi-Fi Station Medium Reservation via Control Packets
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Solution Overview
Problem
In Wi-Fi networks, airborne stations face challenges in transmitting data packets to ground-based access points due to interference from multiple active networks, leading to continuous medium busy indications and unsuccessful transmissions.
Innovation Solution
The method involves transmitting a series of control packets with extended duration values to delay other network traffic, allowing for successful acknowledgment packet reception by setting a power save bit and using CTS or RTS packets to reserve the medium for data or management packet transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple ground-based networks transmit simultaneously in the coverage area, then the network capacity and coverage are improved, but the airborne station receives continuous interference causing the medium to be permanently busy and unable to transmit
Solution Approach 1:
The airborne station transmits control packets (RTS/CTS) in advance before actual data transmission to reserve the medium. By setting extended duration values in these control packets, the airborne station proactively creates a protected time window that prevents ground-based networks from transmitting during the critical data exchange period, ensuring reliable communication despite high network density.
Solution Approach 2:
The patent modifies the duration parameter in control packets to extend beyond the normal transmission time required. This parameter change allows the virtual carrier sense mechanism to hold other networks in standby mode for longer periods, creating sufficient time margin for the airborne station to complete its data transmission and acknowledgment exchange without interference.
2Productivity
If the airborne station transmits data packets during high interference periods, then the communication efficiency is improved, but the packets are blocked by simultaneous ground-based transmissions
Solution Approach 1:
The airborne station applies preliminary anti-action by transmitting control packets that actively prevent ground-based networks from transmitting during the critical communication window. The extended duration values in RTS/CTS packets create a preemptive barrier that blocks potential interference before it can occur, allowing data packets to be transmitted without collision despite the presence of multiple active ground-based networks.
3Reliability
If the medium reservation time is extended to cover acknowledgment transmission, then the transmission reliability is improved, but the network throughput is reduced due to longer medium occupation
Solution Approach 1:
The extended medium reservation is applied locally and selectively only to the specific airborne station's communication window, rather than globally affecting all networks. By targeting the reservation to specific RTS/CTS exchanges involving the airborne station, the patent ensures reliable acknowledgment reception for that station while minimizing the impact on other ground-based networks that can continue operating in their own time slots.
Data Source
AI summary
A method and device are disclosed that enable communication between an airborne STA and a ground based AP in the presence of a multitude of other ground based networks that would normally cause such interference that communication would not be possible. A succession of control packets are sent prior to an air to ground communication such that the ground based networks delay their traffic allowing the wanted acknowledgment packet to be received. A succession of control packets are sent followed by a PS poll or data null packet prior to a ground to air communication such that the wanted ground to air packet is sent at a known time and the other ground based networks delay their traffic allowing the wanted ground to air packet to be received.