Analysis and Application Scenarios for Telemetry Data Transmission and Synchronisation over Wireless LAN

• Main Authors: Cranley, Nikki, Corry, Diarmuid
• Other Authors: ACRA Control Inc.
• Language: en_US
• Published: International Foundation for Telemetering 2008
• Online Access: http://hdl.handle.net/10150/606181; http://arizona.openrepository.com/arizona/handle/10150/606181

ITC/USA 2008 Conference Proceedings / The Forty-Fourth Annual International Telemetering Conference and Technical Exhibition / October 27-30, 2008 / Town and Country Resort & Convention Center, San Diego, California === The use of IEEE 802.11 Wireless LAN (WLAN) technology offers numerous advantages over wired Ethernet including high bandwidth, device mobility, and the elimination of network wiring within the aircraft. With such benefits, there are certain caveats associated with the ability and performance of WLAN technology to carry time-sensitive and critical telemetry data using current IEEE 802.11 WLAN standards. In this paper, the limitations of WLAN for real-time data transmission are experimentally investigated. In particular, it will be shown how the fundamental wireless access mechanism and contention impact on the WLANs ability to carry real-time data. Although telemetry data is constant, the wireless access mechanism causes the WLAN throughput and per-packet delays to vary over time. Moreover, with the increased popularity of the IEEE 1588 Precision Time Protocol (PTP), the ability of the WLAN to provide time synchronisation is investigated. It is shown that asymmetric data loads on the uplink and downlink introduce synchronization errors. To mitigate some of these issues, this paper will discuss how the Quality of Service (QoS) Enabling WLAN standard, IEEE 802.11e, can be used to provide differentiated services and prioritised transmission for critical data.