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Base Station Frequency Bands

At the time of this survey, mobile phone base stations in Australia were able to transmit in four frequency bands reserved for this purpose.

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

Example spectra: 850 MHz Band, 900 MHz Band, 1800 MHz Band, 2100 MHz Band

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 850 MHz Band spectrum

The 850 MHz 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 narrowband Code Division Multiple Access CDMA services. Telstra and Vodafone Hutchison Australia (VHA) now use this band for their Wideband Code Division Multiple Access WCDMA (or UMTS) services.

Example 850 MHz Band spectrum

The example spectrum shown contains two Telstra and one VHA WCDMA (or UMTS) services. 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 (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]
870.68 - 874.52 VHA WCDMA (UMTS) Chan 4363 1.71 0.002 <0.001
880.48 - 884.32 Telstra WCDMA (UMTS) Chan 4412 563.22 0.563 0.001
885.280 - 889.120 Telstra WCDMA (UMTS) Chan 4436 500.73 0.501 0.001
870.000 - 880.000 All Vodafone Hutchinson Australia 1.847 0.002 <0.001
880.000 - 890.000 All Telstra 1104 1.104 0.001
870.000 - 890.000 All 850 MHz Band 1106 1.106 0.001

 

WCDMA stands for Wideband Code Division Multiple Access. This is a modulation scheme that spreads the transmitted signals across a range of frequencies (3.84 MHz) within the 5 MHz channel. All phone calls transmitted from the WCDMA base station in a single channel 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. In typical conditions up to 80 phone calls can be handled simultaneously in a single WCDMA channel. Network operators may therefore operate more than one channel at particularly busy sites.

For each channel being used by a WCDMA 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.

Example 900 MHz Band spectrum

The 900 MHz 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.

Example GSM900 spectrum

 

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 1800 MHz Band spectrum

The 1800 MHz frequency band used by mobile phone base station antennas in Australia runs from 1805 to 1880 MHz. The allocation of the 1800 MHz frequency band varies across Australia. Sections of this spectrum are also used by the some of the Australian states’ railway authorities. Several network operators use this band for GSM1800 services.  Telstra also uses part of this spectrum for its 4G or Long-Term Evolution (LTE1800) services.

Example1800 MHz Band spectrum

 

In the example spectrum shown Telstra signals have been highlighted. The wideband signal at the lower end of the spectrum is a 10 MHz LTE channel, while the narrow signals higher in the band are GSM channels The GSM control channel signals are indicated by arrows. In this spectrum, the GSM signal strength is up to two hundred thousand times higher than the background noise level while the LTE signal strength is around one 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 LTE channel, Telstra’s band 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]
1825.1 - 1825.3 Telstra GSM1800 BCCH 612 0.567 0.001 <0.001
1827.7 - 1827.9 Telstra GSM1800 BCCH 625 687 0.687 0.001
1828.9 - 1829.1 Telstra GSM1800 BCCH 631 13.906 0.014 <0.001
1825.0 - 1830.0 Telstra GSM1800 738 0.738 0.001
1805.0 - 1815.0 Telstra LTE1800 33.249 0.033 <0.001
1805.0 - 1815.0
1825.0 - 1830.0
All Telstra GSM1800 and LTE1800 771 0.771 0.001
1815.0 - 1825.5
1830.5 - 1880.0
All Other Services in1800 MHz Band 300 0.300 <0.001
1805.0- 1880.0 All 1800 MHz Band 1072 1.072 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.

The width of each LTE channel is chosen by the network operator within the constraints of the available spectrum. The LTE specification permits channel bandwidths of 1.4, 3, 5, 10, 15 and 20 MHz. At the time of this survey, Telstra was using a 10 MHz channel width in Melbourne and Sydney and a 15 MHz channel width in Adelaide, Brisbane and Perth.

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. At particularly busy sites, network operators may use multiple 5 MHz channels within their spectrum allocation. This band is used by 3GIS, Optus, Telstra and Vodafone for their third-generation mobile networks.

Example UMTS2100 spectrum

 

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


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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