Telstra CDMA Marine Trial

"Peak Alone" Base Station, NSW South Coast

Overview

This report outlines the results of a number of tests that were conducted on the south coast of NSW during April and May 1999.

The objectives of the tests were twofold:

1. Verify the functionality and performance of the CDMA Extended Cell feature that will be used in the Telstra CDMA network. Normally, CDMA range is limited to no more than 62 km by mobile and base station hardware and software. The Nortel Networks extended cell ("Boomer Cell") removes this artificial limitation on range.
2. Test the absolute coverage of CDMA in a marine environment, as measured by call quality and call dropout.

Peak Alone

The Peak Alone analogue base station is approximately 1000 metres above sea level and located 25 km inland from Narooma on the NSW south coast. Coverage from Peak Alone extends up and down the coast from Narooma, as well as east out to sea. At this height above sea level, the predicted radio horizon is around 130 km for a mobile at sea level.

The Peak Alone analogue base station is configured with high power 50 Watt transmitters, with Omni directional antennas. This type of analogue configuration is common in many locations around Australia.

The CDMA installation is co-located and shares the same tower structure with analogue, is equipped with the Nortel "Boomer Cell", and configured as follows:

• Omni directional antennas (similar to analogue).
• High power transmitter amplifiers
• Extended cell capability (remove artificial distance limit)
• High performance tower mounted Low Noise Amplifiers (LNAs) (boosted receiver performance)

Test Methodology

Testing was conducted in chartered boats and due to the logistical difficulties of operating long distances offshore, coverage was tested along the coast, starting at Ulladulla harbour some 122 km from Peak Alone.

A number of CDMA handsets were used during the tests, all handsets were standard output power (0.2 Watt handhelds).

Additionally, via the use of car kits, connection was made to an external marine antenna (6dB gain). The antennas used were purchased from a local company and are typical of those used in the marine environment.

Coverage comparisons with analogue could not be made in this marine test from Peak Alone as a result of the additional analogue base stations located around the Ulladulla area.

Tests were made in both handheld mode ie standing on the boat deck, as well as in the car kit connected to the external "high gain" marine antennas.

Call quality at both ends of the call was monitored during all tests.

Results and Observations

The test route commenced at Ulladulla (122 km from Peak Alone base station) and followed the coast south until at 93 km from Peak Alone the boat turned around and calls were established.

The boat then headed North along the coast moving away from the base station and calls were initiated in both handheld mode and from a unit fitted in a car kit (connected to external antenna).

Every 5 km, spot checks were made of speech quality at both ends of the call.

For handheld units, good quality calls could be made whilst standing on the boat deck outside the cabin to a distance of around 110 km from the Peak Alone base station.

These calls were made in a very noisy environment with engine, wind and wave noise present, yet the call quality as reported from the other end was very good, with only moderate noise detectable, further demonstrating the excellent background noise suppression and call quality of CDMA.

Beyond 105 km, call quality began to deteriorate on the handheld phones, but calls could still be reliably held.

The last handheld call was made at around 120 km at which time speech quality became marginal. Beyond this point the call dropped and no further calls on a handheld unit could be made.

For the units fitted into the car kit and connected to the external antenna, speech quality was found to be excellent until around 130 km where some degradation was detected.

At a distance of 132 km, the call was still holding. It had not dropped since the start of the test at 93 km from Peak Alone.

This clearly demonstrated the additional coverage range and reliability delivered through the use of a car kit fitted with an external antenna.

Conclusions

This test has clearly demonstrated that the Telstra CDMA network is not limited by any artificial range constraints and that the Nortel "Boomer Cell" is capable of delivering extended coverage over very long distances.

The marine test has shown that CDMA coverage to sea can be achieved at distances well in excess of 100 km from very high mountain top base stations.

CDMA coverage to around 130 km was achieved from the Peak Alone base station, beyond which the radio path is obstructed by the curvature of the earth.

CDMA call quality in a marine environment was found to be consistently good, with the background noise suppression being particularly useful in noisy environments.

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