ARPANSA - Australian Radiation Protection and Nuclear Safety Agency

The Australian Communications and Media Authority (ACMA) issue licences for use of the electromagnetic spectrum and regulate transmissions in these bands.

Example spectra: CDMA800, GSM900, GSM1800, UMTS2100

The instrument used to measure the RF levels of base station antennas is a spectrum analyser connected to an antenna. The antenna converts the RF EME into an electrical signal that is proportional to the amplitude of the RF field. The spectrum analyser records the strength of the RF at each frequency over a selected range.

The total power in a channel is obtained by adding up all the contributions from each frequency within the channel (integrating under the peak). It is often unnecessary to subtract the background noise when the signal level is strong, for example integrating a control channel, as the contributions from outside the channel are so small. However, when integrating over an entire frequency band (where many channels contain no signal) it is important to subtract the background noise.

Example CDMA800 spectrum

The CDMA800 frequency band used by mobile phone base station antennas in Australia runs from 870 to 890 MHz. This band has in the past been used by Hutchison and Telstra for their now defunct narrowband CDMA services. Telstra now uses this band for its wideband CDMA (or UMTS) service.

 

The example spectrum shown contains two narrowband CDMA services and one wideband CDMA (UMTS) service. In this spectrum, the signal strength is around ten thousand times higher than the background noise level.

This table shows the RF power in the example spectrum for each of the services, the operators’ bands and the entire band. The values are reported in three different units: microwatts per square metre mW/m², milliwatts per square metre mW/m² and watts per square metre W/m².

Frequency Range [MHz]	Service	RF Power [µW/m2]	RF Power [mW/m2]	RF Power [W/m2]
880.905 - 882.135	Telstra narrowband CDMA Chan 384	181.43	0.181	<0.001
883.425 - 884.655	Telstra narrowband CDMA Chan 468	215.63	0.216	<0.001
885.280 - 889.120	Telstra wideband CDMA(UMTS)	489.22	0.489	<0.001
870.000 - 880.000	All Hutchinson	0.14	<0.001	<0.001
880.000 - 890.000	All Telstra	909.27	0.909	0.001
870.000 - 890.000	All CDMA800	909.41	0.909	0.001

 

CDMA stands for Code Division Multiple Access. This is a modulation scheme that spreads the transmitted signals across a range of frequencies. All phone calls transmitted from the CDMA base station use the same frequency range at the same time. Individual calls are distinguished by a system of codes transmitted along with the call information. Each mobile phone handset only decodes the required part of the transmission and ignores all other calls as background noise.

For each CDMA base station antenna one of these coded signals is transmitted at a constant power, this is the pilot signal. Other codes are used intermittently as required by the demands of traffic on the network. The pilot signal typically uses 10% of the available output power of the base station amplifier.

Two types of CDMA technology have been used in Australia, narrowband and wideband. Each narrowband CDMA channel occupies around 1.25 MHz of the spectrum. A single wideband CDMA channel occupies almost 5 MHz of the spectrum.

Example GSM900 spectrum

The GSM900 frequency band used by mobile phone base station antennas in Australia runs from 935 to 960 MHz. This band is split between three network operators right across Australia: Telstra, Optus and Vodafone.

 

In the example spectrum shown, the base station had both Telstra and Vodafone GSM900 services. The control channel signals are indicated by arrows and channel numbers. All the Optus signals originated from other nearby base stations. In this spectrum, the signal strength is up to one hundred thousand times higher than the background noise level.

This table shows the RF power in the example spectrum for each of the control channels (BCCH), the operators’ bands and the entire band. The values are reported in three different units: microwatts per square metre µW/m², milliwatts per square metre mW/m² and watts per square metre W/m².

Frequency Range [MHz]	Service	RF Power [µW/m2]	RF Power [mW/m2]	RF Power [W/m2]
939.9 - 940.1	Telstra GSM900 BCCH 25	2.77	0.003	<0.001
940.5 - 940.7	Telstra GSM900 BCCH 28	336.37	0.336	<0.001
941.3 - 941.5	Telstra GSM900 BCCH 32	6.50	0.007	<0.001
954.7 - 954.9	Vodafone GSM900 BCCH 99	1.30	0.001	<0.001
955.5 - 955.7	Vodafone GSM900 BCCH 103	118.65	0.119	<0.001
956.7 - 956.9	Vodafone GSM900 BCCH 109	0.08	<0.001	<0.001
935.0 - 943.4	All Telstra GSM900	398.21	0.398	<0.001
943.4 - 951.8	All Optus GSM900	2.32	0.002	<0.001
951.8 - 960.0	All Vodafone GSM900	128.88	0.129	<0.001
935.0 - 960.0	All GSM900	529.41	0.529	0.001

 

Each GSM channel occupies 200 kHz of the spectrum.

Every GSM base station antenna uses a single channel (the control channel or BCCH) at constant full power. Other channels are used intermittently as required by the demands of traffic on the network.

Example GSM1800 spectrum

The GSM1800 frequency band used by mobile phone base station antennas in Australia runs from 1805 to 1880 MHz. The allocation of the GSM1800 frequency band varies across Australia. Sections of this spectrum are also used by the some of the Australian states’ railway authorities.

 

In the example spectrum shown below only Optus and Telstra signals are present. The control channel signals are indicated by arrows. In this spectrum, the signal strength is up to one hundred times higher than the background noise level.

This table shows the RF power in the example spectrum for each of the control channels (BCCH), the operators’ bands and the entire band. The values are reported in three different units: microwatts per square metre µW/m², milliwatts per square metre mW/m² and watts per square metre W/m².

Frequency Range [MHz]	Service	RF Power [µW/m2]	RF Power [mW/m2]	RF Power [W/m2]
1825.5 - 1825.7	Telstra GSM1800 BCCH 614	0.002	<0.001	<0.001
1826.1 - 1826.3	Telstra GSM1800 BCCH 617	0.202	<0.001	<0.001
1827.1 - 1827.3	Telstra GSM1800 BCCH 622	0.003	<0.001	<0.001
1839.1 - 1839.3	Optus GSM1800 BCCH 682	0.835	0.001	<0.001
1841.5 - 1841.7	Optus GSM1800 BCCH 694	0.005	<0.001	<0.001
1805.0 - 1815.0 1825.0 - 1830.0	All Telstra GSM1800	0.742	0.001	<0.001
1820.0 - 1822.5 1837.5 - 1850.0	All Optus GSM1800	1.641	0.002	<0.001
1815.0 - 1820.0 1822.5 - 1825.0 1830.0 - 1837.5 1850.0 - 1880.0	All Other GSM1800	1.456	0.001	<0.001
1805.0- 1880.0	All GSM1800	3,835	0.004	<0.001

 

Each GSM channel occupies 200 kHz of the spectrum.

Every GSM base station antenna uses a single channel (the control channel or BCCH) at constant full power. Other channels are used intermittently as required by the demands of traffic on the network.

Example UMTS2100 spectrum

The UMTS2100 frequency band used by mobile phone base station antennas in Australia runs from 2110 to 2170 MHz. Each network operator uses a single channel of about 5 MHz for their services right across Australia.

 

In the example spectrum shown 3GIS (a collaboration between Hutchison and Telstra), Optus and Vodafone signals are present. The pilot signals are mixed in with the traffic and cannot be distinguished in this plot. In this spectrum, the signal strength is up to one hundred times higher than the background noise level.

This table shows the RF power in the example spectrum for each of the services, the operators’ bands and the entire band. The values are reported in three different units: microwatts per square metre µW/m², milliwatts per square metre mW/m² and watts per square metre W/m².

Frequency Range [MHz]	Service	RF Power [µW/m2]	RF Power [mW/m2]	RF Power [W/m2]
2110.68 - 2114.52	3GIS UMTS Chan 10563	34.490	0.034	<0.001
2145.48 - 2149.32	Optus UMTS Chan 10737	16.352	0.016	<0.001
2160.48 - 2164.32	Vodafone UMTS Chan 10812	18.047	0.018	<0.001
2110.00 - 2120.00	All 3GIS UMTS	36.165	0.036	<0.001
2140.00 - 2150.00	All Optus UMTS	17.018	0.017	<0.001
2160.00 - 2170.00	All Vodafone UMTS	18.771	0.019	<0.001
2110.00 - 2170.00	All UMTS2100	73.766	0.074	<0.001

This band is used by 3GIS, Optus and Vodafone for their third-generation mobile networks.

Mobile phone handsets are able to identify individual base station antennas using a system of codes transmitted with their signals. In this manner all base stations and antennas owned by a company can use the same channel. For each base station antenna one of these coded signals is transmitted at a constant power, this is the pilot signal (or P-CPICH). Other codes are used intermittently as required by the demands of traffic on the network.

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