Spectrum for Mobile Communication
• Radio Spectrum is a limited resource• For mobile communication we are using following ranges:
VHF 30 MHz - 300 MHz
UHF 300 MHz - 3 GHz
SHF 3 GHz - 30 GHz
The whole radio spectrum is divided for convenience into bands such as VHF, UHF and so
on. The range of the spectrum used by GSM is in the UHF band.
Frequency Allocation
• Authority to use a frequency is given under certain conditions
such as:
• Location• Power levels
• Modulation types
• Bandwidth
• Regulatory bodies deal with this allocation in different parts of
the world:
• International Telecommunications Union (ITU)
• European Telecommunications Standards Institute (ETSI)
• Radiocommunications Agency (RA) in the UK
• European Telecommunications Standards Institute (ETSI)
• Radiocommunications Agency (RA) in the UK
A major initial financial outlay for network operators is to acquire a licence to use a particular
bandwidth of radio spectrum. The method of allocation differs from country to country, but
may be by auction or direct choice of operators by the government organisation responsible.
bandwidth of radio spectrum. The method of allocation differs from country to country, but
may be by auction or direct choice of operators by the government organisation responsible.
4.2.1 PRIMARY GSM SPECTRUM
GSM uses Frequency Division Duplexing (FDD) where the uplink and downlink of each
channel operates on a different frequency. Therefore, two frequency bands were allocated to
GSM, 20 MHz apart.
The following frequency bands were initially allocated to GSM (now known as Primary
GSM):
Uplink sub band: 890 MHz to 915 MHz
Downlink sub band: 935 MHz to 960 MHz
Each band is divided into a number of carriers, with each carrier having a 200kHz Bandwidth.
Therefore 124 carriers were available within each of the up and down link bands (allowing for
guard bands).
The channel pair allocation has been arranged such that the two frequencies comprising a
channel pair are 45Mhz apart
Each frequency pair is identified by an ‘Absolute Radio Frequency Carrier Number ‘
(ARFCN)’.
channel operates on a different frequency. Therefore, two frequency bands were allocated to
GSM, 20 MHz apart.
The following frequency bands were initially allocated to GSM (now known as Primary
GSM):
Uplink sub band: 890 MHz to 915 MHz
Downlink sub band: 935 MHz to 960 MHz
Each band is divided into a number of carriers, with each carrier having a 200kHz Bandwidth.
Therefore 124 carriers were available within each of the up and down link bands (allowing for
guard bands).
The channel pair allocation has been arranged such that the two frequencies comprising a
channel pair are 45Mhz apart
Each frequency pair is identified by an ‘Absolute Radio Frequency Carrier Number ‘
(ARFCN)’.
Up and downlink channel frequencies can be calculated as follows:
Uplink frequencies: Fu(n) = 890 + 0.2 n (1 <= n <= 124)
Downlink frequencies: Fd(n) = Fu(n) + 45
Uplink frequencies: Fu(n) = 890 + 0.2 n (1 <= n <= 124)
Downlink frequencies: Fd(n) = Fu(n) + 45
4.2.2 EXTENDED PRIMARY GSM (E-GSM) SPECTRUM
E-GSM allocated an additional 10MHz of bandwidth at the bottom end of each of the up and
down link frequency bands. The new frequency bands are:
Uplink sub band: 880 MHz to 915 MHz
Downlink sub band: 925 MHz to 960 MHz
This resulted in the following:
· An extra 50 carrier pairs (10MHz / 200kHz channels)
· A reduction in bandwidth isolation between up and down link frequency bands from
20MHz to 10MHz
· An increase in size of up and down link frequency bands from 25Mhz to 35MHz
· Assignment of new ARFCN in the range 975-1023
· The P-GSM ARFCN 0 now reverts from a guard band to a valid ARFCN
E-GSM up and downlink channel frequencies can be calculated as follows:
Uplink frequencies: Fu(n) = 890 + 0.2 n (0 <= n <= 124)
Fu(n) = 890 + 0.2 (n – 1024) (975 <= n <= 1023)
Downlink frequencies: Fd(n) = Fu(n) + 45
down link frequency bands. The new frequency bands are:
Uplink sub band: 880 MHz to 915 MHz
Downlink sub band: 925 MHz to 960 MHz
This resulted in the following:
· An extra 50 carrier pairs (10MHz / 200kHz channels)
· A reduction in bandwidth isolation between up and down link frequency bands from
20MHz to 10MHz
· An increase in size of up and down link frequency bands from 25Mhz to 35MHz
· Assignment of new ARFCN in the range 975-1023
· The P-GSM ARFCN 0 now reverts from a guard band to a valid ARFCN
E-GSM up and downlink channel frequencies can be calculated as follows:
Uplink frequencies: Fu(n) = 890 + 0.2 n (0 <= n <= 124)
Fu(n) = 890 + 0.2 (n – 1024) (975 <= n <= 1023)
Downlink frequencies: Fd(n) = Fu(n) + 45
4.2.3 DCS-1800 SPECTRUM
Digital Communication System (DCS) – 1800 introduced a further 1800 MHz spectrum range
for GSM. The characteristics of radio frequencies in this range are such that DCS-1800 is
typically used for smaller microcells overlaid over existing GSM-900 macrocells. The up and
down link bands are 75MHz each and have a 20MHz separation in the following ranges:
Uplink sub band: 1710 MHz to 1785 MHz
Downlink sub band: 1805 MHz to 1880 MHz
Each band is divided into 200kHz carriers, as with GSM -900. Therefore 374 carriers are
available within each of the up and down link bands (allowing for guard bands). Channel
numbers are in the range 512-885 (ARFCNs).
The channel pair allocation has been arranged such that the two frequencies comprising a
channel pair are 95Mhz apart.
DCS-1800 up and downlink channel frequencies can be calculated as follows:
Uplink frequencies: Fu(n) = 1710.2 + 0.2 (n – 512) (512 <= n <= 885)
Downlink frequencies: Fd(n) = Fu(n) + 95
for GSM. The characteristics of radio frequencies in this range are such that DCS-1800 is
typically used for smaller microcells overlaid over existing GSM-900 macrocells. The up and
down link bands are 75MHz each and have a 20MHz separation in the following ranges:
Uplink sub band: 1710 MHz to 1785 MHz
Downlink sub band: 1805 MHz to 1880 MHz
Each band is divided into 200kHz carriers, as with GSM -900. Therefore 374 carriers are
available within each of the up and down link bands (allowing for guard bands). Channel
numbers are in the range 512-885 (ARFCNs).
The channel pair allocation has been arranged such that the two frequencies comprising a
channel pair are 95Mhz apart.
DCS-1800 up and downlink channel frequencies can be calculated as follows:
Uplink frequencies: Fu(n) = 1710.2 + 0.2 (n – 512) (512 <= n <= 885)
Downlink frequencies: Fd(n) = Fu(n) + 95
4.2.4 PCS-1900 SPECTRUM
Personal Communication System (PCS) – 1900 MHz is used in USA and Central America to
provide a service similar to GSM. The 1900MHz frequency band was selected due to a
shortage of available 1800 band frequencies in the USA. The up and down link bands are
60MHz each and have a 20MHz separation in the following ranges:
PCS-1900 frequency bands are:
Uplink sub band: 1850 MHz to 1910 MHz
Downlink sub band: 1930 MHz to 1990 MHz
Each band is divided into 200kHz carriers, as with GSM. Therefore 299 carriers are available
within each of the up and down link bands (allowing for guard bands). Channel numbers are
in the range 512-810 (ARFCNs).
The PCs-1900 channel pair allocation has been arranged such that the two frequencies
comprising a channel pair are 80Mhz apart.
PCS-1900 up and downlink channel frequencies can be calculated as follows:
Uplink frequencies: Fu(n) = 1850.2 + 0.2 (n – 512) (512 <= n <= 810)
Downlink frequencies: Fd(n) = Fu(n) + 80
provide a service similar to GSM. The 1900MHz frequency band was selected due to a
shortage of available 1800 band frequencies in the USA. The up and down link bands are
60MHz each and have a 20MHz separation in the following ranges:
PCS-1900 frequency bands are:
Uplink sub band: 1850 MHz to 1910 MHz
Downlink sub band: 1930 MHz to 1990 MHz
Each band is divided into 200kHz carriers, as with GSM. Therefore 299 carriers are available
within each of the up and down link bands (allowing for guard bands). Channel numbers are
in the range 512-810 (ARFCNs).
The PCs-1900 channel pair allocation has been arranged such that the two frequencies
comprising a channel pair are 80Mhz apart.
PCS-1900 up and downlink channel frequencies can be calculated as follows:
Uplink frequencies: Fu(n) = 1850.2 + 0.2 (n – 512) (512 <= n <= 810)
Downlink frequencies: Fd(n) = Fu(n) + 80
4.2.5 GSM-450 SPECTRUM
The GSM-450 standard has grown from a study undertaken to evaluate a digital standard to
replace the widespread analogue NMT-450 systems. The 450MHz band has a number of
advantages over existing GSM bands, not least of which is the increased coverage per cell (up
to 120km) and hence a lower cell count. It can also provide valuable additional capacity
replace the widespread analogue NMT-450 systems. The 450MHz band has a number of
advantages over existing GSM bands, not least of which is the increased coverage per cell (up
to 120km) and hence a lower cell count. It can also provide valuable additional capacity
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