Trials and Results

 

The milestones of the demonstrator development

w        10th-15th November 2003: WAEA meeting in Hamburg

The first important demonstration of the Wireless Cabin project took place in Hamburg at the Airbus facility in Finkenwerder. The World Airline Entertainment Association was having its “Wireless Onboard” conference and was hosted by Airbus. As one of the leading projects in the field, Wireless Cabin was represented at this event. And a demonstration of a preliminary version of the system was an important side-show to the presentations and discussions.

At this point of time the system was able to demonstrate a call from a GSM mobile to a fixed terrestrial telephone via a satellite link and possibly use the rest of the bandwidth for e-mails and web browsing via Wireless LAN. A representation of the architecture of the system as it was presented at the WAEA meeting in Hamburg, is depicted in the figure below.

 

 

Figure 1 WirelessCabin demonstrator architecture in November 2003

 

w        May 2004: ILA air show in Berlin

After this first event on WAEA, the major work was put on enhancing the demonstrator in terms of stability and functionality.

Therefore in January and March 2004, two Implementation Meetings of the WirelessCabin demonstrator team took place at DLR in Oberpfaffenhofen. During these two weeks, the different parts of the software and hardware from the various consortium partners were integrated into the system. The final layout of the network was decided then and implemented.

The improved and extended version of the set-up was then demonstrated on the ILA air show in Berlin. For WirelessCabin, it was the chance to demonstrate the future capabilities on board commercial aircrafts to a broad range of public and professional visitors. There was also an interview and demonstration on one of the main scientific magazines on the German television as well as a few articles in national newspapers. The demonstrator displayed to the public for the first time a call from a mobile phone to a terrestrial telephone via a satellite link, along with many additional services for the crew (traffic control and monitoring, emergency calls to the ground, quality of service management, billing, etc…) and passengers (internet browsing, e-mails, voice over IP, GSM calls). This was the main full scale demonstration of the system before the preparation of the test flights.

 

w        September 2004: Test Flight at Airbus (Toulouse)

As highlight of the demonstrator development and integration, a test flight was carried out with the complete WirelessCabin demonstrator set-up. The test flight lasted about 2,5 hours and was conducted from Toulouse some way above the Mediterranean and then back to Toulouse.

The trial was quite successful, and the only major problem was the satellite connection which was lost for a short period of time. But after all, during the given time all major scenarios described in Deliverables D15 and detailed in D19 could be successfully conducted: GSM phone calls to and from ground, calls with H.323 clients to and from ground, streaming audio content from onboard and from ground and streaming onboard video content to notebooks and PDAs, Telemedicine demonstration, etc.

Figure 2 Airbus A340-600 test flight team

 

w        November 2004: Additional Ground Test at DLR

In addition to the previously conducted tests (laboratory pre-tests, ground test, flight test) some further tests are planned with the demonstrator on ground in laboratory environment. These tests will complement and refine the already available results. For this test, it is planned to simulate also the aircraft background noise using a previously recorded realistic noise sample from inside the aircraft cabin, which is important for evaluation of the voice quality during the phone calls.

GSM measurements during test flight

As representative results of the big amount of data which was collected during the trials and which are still being analysed, we describe and present in this section the measurement results of the GSM tests, performed during the test flight with a mobile scanning device and an Ericsson P-900 mobile phone. The target of these tests was to use real mobile phones to determine their behaviour during all phases of flight.

Set up

Two mobile phones were installed one on each side in the front of the AC (see photo below). Therefore a free line of sight was achieved. This position will present the worst case for a mobile on board, when it will be used from passenger.  The two mobiles and two laptops were independent from each other.

The mobile was connected over an adapter box to a laptop to store all received data from the mobile. The mobile will send a number of information between the different layers (mainly Layer3). The installed log-tool on the laptop will save this information.

 

            

Figure 3 GSM Phone Set Up and Installation

 

Measurement Data

 

A Matlab program was used to filter the imported information and to process the collected data.

 

The following measurement data sets have been collected during various trials:

·         TCPdump on the ground SI and Cabin SI

·         Power Control

·         Voice recording during GSM/VoIP calls

·         Sound recording during audio streaming

·         In-Cabin Spectrum

·         Telephone Logs files-2

·         Billing data

·         Other Log files (log of Nocat gateway, Apache server, etc)

At the time of writing of this report, result analysis is still on-going and the following parameters will be derived:

a)   Voice data:

 

          PSD plots

          Periodogram (an improved version of PSD plots)

          Spectrogram (Spectral analysis w.r.t. both time domain and frequency domain)

          SNR 

          Cross-correlation analysis of the signals

 

b)   IP data:

 

           Elapsed time between first and last packets arrival in seconds

           Total Number of Packets

           Average Packet/sec

           Total Bytes

           Average packet size

           Average bytes/sec

           Throughput in  kb/sec

 

The graphs shown in the following are the results of the measurements with the Ericsson P-900 mobiles.