Honeywell International Inc. WLUWIFIM010 Manuale Utente
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HIF-1472R6(1)
6.
SYSTEM DESCRIPTION AND OPERATION
6.1. General
This document covers the system description and installation for the Terminal Wireless LAN Unit (TWLU),
Crew Wireless LAN Unit (CWLU), and the derived Wireless LAN Unit (WLU). The WLU is a Honeywell
developed common hardware platform that can be configured to provide either Terminal Wireless LAN Unit
(TWLU) or Crew Wireless LAN Unit (CWLU) functions. Figure 6-1 shows an exploded view of the WLU.
Figure 6-1 Wireless LAN Unit
There will be three CWLUs covering the cabin/flight deck, two CWLUs covering eebays/baggage areas, and
one CWLU for external coverage. A single TWLU will provide a connection between the aircraft network and
airport network at an airport terminal. CWLU and TWLU communications are based on the IEEE 802.11
wireless standard. It is intended that aircraft shall be able to connect through TWLU systems and then access
their airline networks, as they move to different airports. Passenger devices are not permitted to send or
receive data directly through the WLU.
The WLU provides NAT routing between an Ethernet based aircraft network and a ground-based network
through the wireless interface. The Wi-Fi wireless interface along with separate internally and externally
mounted aircraft antenna will act as 802.11 client stations and operate in IEEE 802.11b/g modes.
The Ethernet will support a 10/100 Mbps interface (IEEE 802.3) and be capable of supporting up to 4 Ethernet
clients. The Wi-Fi primary mode of operation will be IEEE 802.11 infrastructure mode but may also participate
in ad-hoc sessions.
The WLU was designed with the intent to support future changes in security, which were under development
within the wireless network industry when this document was written. The WLU application software is field
upgradeable via its Ethernet port. A diagram of the TWLU and CWLU typical communication links is shown in
Figure 6-2.