Evaluation of Two Fully Rugged Laptop Computers for the Forest Service, Page18

Evaluation of Two Fully Rugged Laptop Computers for the Forest Service

Appendix K—Cellular Connectivity Tests

Purpose

The WWAN tests determined the expected throughput of the WWAN devices of each laptop and compared the signal strength with the two laptops side by side.

The two WWAN EVDO (Evolution, Data Only) cards were different. The card installed in the XR-1 laptop was the latest model from Verizon Wireless, while the card installed in the CF-30 laptop was an older model.

Equipment

See appendix J for information on Ixia IxChariot software and on the five scripts that were used to test cellular connectivity.

Procedure

Three laptops were used for the WWAN throughput tests, two XR-1 laptops and a CF-30 laptop. All three were connected to a secure WWAN with an internal EVDO aircard. IxChariot software was loaded on one XR-1 laptop and the CF-30 laptop and each was configured as endpoint 1. The other XR-1 laptop was configured as endpoint 2. Endpoint 2 was located at MTDC at the best signal strength possible (-70dB). The other two laptops (one XR-1 and the CF-30) were moved together to different locations to run IxChariot throughput tests at three different signal strengths (-100dB, -70 dB, and -50 dB). Each ran the five throughput scripts independently.

Results

Figures K–1 through K–3 show the results from the WWAN EVDO throughput tests.

Graph fo the IxChariot Throughput Tests-EVDO Express Cards (-50dB) for the CF-30 and XR-1. The tests were done with the FTPGet, FTPPut, HTTPGif, HTTPText, and Throuput measured in Millions bits per second.
Figure K–1—This graph shows the results from the IxChariot
throughput tests using the WWAN EVDO aircard at -50 dB signal strength.
The five tests represent typical Internet usage in a field situation.

Graph fo the IxChariot Throughput Tests-EVDO Express Cards (-75dB) for the CF-30 and XR-1. The tests were done with the FTPGet, FTPPut, HTTPGif, HTTPText, and Throuput measured in Millions bits per second.
Figure K–2—This graph shows the results from the IxChariot
throughput tests using the WWAN EVDO aircard at -75 dB signal strength.
The five tests represent typical Internet usage in a field situation.

Graph fo the IxChariot Throughput Tests-EVDO Express Cards (-100dB) for the CF-30 and XR-1. The tests were done with the FTPGet, FTPPut, HTTPGif, HTTPText, and Throuput measured in Millions bits per second.
Figure K–3—This graph shows the results from the IxChariot
throughput tests using the WWAN EVDO aircard at -100 dB signal strength.
The five tests represent typical Internet usage in a field situation.

Conclusions

The WWAN EVDO card in the XR-1 laptop had much higher throughput for nearly all the tests. The throughput was much higher when the signal was stronger (lower dB levels) for the newer Verizon Wireless Aircard in the XR-1 laptop than for the older Verizon Wireless Aircard in the CF-30 laptop.