Frequency bands are the most fundamental part of the radio network for any cellular technology. When second-generation (2G) GSM networks started, they were initially limited to the 900 MHz frequency band, but they have expanded and can operate in various frequency bands.
GSM networks use multiple frequency bands, including 900 MHz, 1800 MHz, 850 MHz and 1900 MHz. The 900 MHz/1800 MHz combination is primarily used in Europe, Asia, Africa, the Middle East and Australia, whereas the 850 MHz/1900 MHz combination is used mainly in North and South America.
The frequency spectrum is one of the most crucial resources for a mobile network operator. It is the means for allowing mobile operators to transmit and receive signals in any geographical location so that their customers can get access to cellular services.
The spectrum defines the frequency bands allocated to mobile network operators (MNO) within a country, which they can use to create frequency channels. These frequency channels allow our mobile phones to send and receive communication to and from the nearest base stations at specified radio frequencies.
GSM frequency bands for different parts of the world
GSM mobile networks are one of the most widely deployed second-generation cellular technology standards around the globe. GSM can operate in multiple frequency bands, including but not limited to the 900 MHz, 1800 MHz, 850 MHz and 1900 MHz bands. The 900 MHz band ranges from 880 to 960 MHz, and the 1800 MHz band ranges from 1710 to 1880 MHz. The 850 MHz band ranges from 824 to 894 MHz, and the 1900 MHz band ranges from 1850 to 1990 MHz.
The 900 MHz and 1800 MHz, GSM frequency bands, are primarily used in Europe, the Middle East, Africa, Asia and Australia, including GSM 900 Primary (P-GSM) and GSM 900 Extended (E-GSM) bands; the 850 MHz and 1900 MHz GSM frequency bands are used mainly in North America and South America.
| GSM Standard | Regions | Frequency Range |
|---|---|---|
| GSM 900 Primary (P-GSM) | Europe, Asia, Africa, the Middle East, and Australia | 890 MHz to 960 MHz |
| GSM 900 Extended (E-GSM) | Europe, Asia, Africa, the Middle East, and Australia | 880 MHz to 960 MHz |
| GSM 1800 | Europe, Asia, Africa, the Middle East, and Australia | 1710 MHz to 1880 MHz |
| GSM 850 | North America and South America | 824 MHz to 894 MHz |
| GSM 1900 | North America and South America | 1850 MHz to 1990 MHz |
GSM uses separate frequency bands for uplink and downlink
GSM networks use the Frequency Division Duplex or FDD duplex scheme, requiring separate frequency bands for the uplink and downlink transmissions. The opposite of FDD is Time Division Duplex or TDD, where time slots separate the uplink and downlink transmissions within the same frequency band.
Mobile networks rely on various multiple-access technologies for the air interface to allow the base station to facilitate multiple calls or sessions simultaneously. In GSM networks, the uplink and downlink frequency bands use a combination of Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA) for enabling multiple access.
That way, the frequency band is utilised much more efficiently by first dividing the available frequency band into frequency channels (ARFCNs) and then splitting the channels further into time slots. GSM networks are digital and have a higher bandwidth than the earlier first-generation (1G) network technologies. The higher bandwidth makes it easier for GSM networks to facilitate more services than the first-generation mobile networks.
GSM networks use frequency channels called ARFCN
An ARFCN in GSM is a pair of frequency channels used for uplink and downlink transmissions. Each channel (ARFCN) is assigned an identification number (e.g. ARFCN # 1) and represents one frequency range for the uplink (phone to network) and one frequency range for the downlink (network to phone).
The uplink and downlink frequency bands in 2G GSM networks are divided into frequency channels of 200 kHz bandwidth. The frequency channels in GSM are called Absolute Radio Frequency Channel Number (ARFCN). Each frequency range (uplink & downlink) within each ARFCN has eight timeslots representing the physical channels for two-way communication. The signalling protocols and voice traffic are sent and received through these timeslots.
GSM frequency bands: 900 MHz and 1800 MHz
The GSM networks primarily employ the 900 MHz and 1800 MHz bands in various parts of Europe, Asia, Africa, the Middle East, and Australia.
The original frequency band for GSM 900 was from 890 MHz to 960 MHz, where 890-915 MHz was for uplink and 935-960 MHz for the downlink. There is a 20 MHz guard band between the uplink and downlink (i.e. 915 MHz to 935 MHz). This frequency band is now referred to as the Primary GSM frequency band or P-GSM. In P-GSM, there are 124 ARFCNs.
The extended version of the original GSM frequency band is called E-GSM, ranging from 880 MHz to 960 MHz. The extended band added a further 10 MHz to the uplink and the downlink. The uplink frequency range in E-GSM is 880 MHz to 915 MHz, and the downlink range is 925 MHz to 960 MHz. The ARFCNs in E-GSM start from 0 to 124 and 975 to 1023. Finally, the 1800 MHz frequency band ranges from 1710 MHz to 1880 MHz.
| GSM 900 Primary (P-GSM) | GSM 900 Extended (E-GSM) | |
|---|---|---|
| ARFCN | 1 to 124 | 0 to 124 AND 975 to 1023 |
| Uplink Frequency Range | 890 MHz to 915 MHz | 880 MHz to 915 MHz |
| Downlink Frequency Range | 935 MHz to 960 MHz | 925 MHz to 960 MHz |
The uplink frequency range for GSM 1800 is from 1710 MHz to 1785 MHz, and the downlink range is from 1805 MHz to 1880 MHz. The ARFCNs in GSM 1800 range from 512 to 885.
| GSM 1800 | |
|---|---|
| ARFCN | 512 to 885 |
| Uplink Frequency Range | 1710 MHz to 1785 MHz |
| Downlink Frequency Range | 1805 MHz to 1880 MHz |
GSM frequency bands: 850 MHz and 1900 MHz
The 850 MHz and 1900 MHz frequency bands are primarily used in North America and South America, including countries like the US, Canada, Mexico and other South American countries. The frequency range for GSM 850 is from 824 MHz to 894 MHz, where 824 MHz to 849 MHz is reserved for the uplink and 869 MHz to 894 MHz for the downlink.
In GSM-1900, the frequency ranges from 1850 MHz to 1990 MHz, i.e. 1850 MHz to 1910 MHz is for the uplink and 1930 MHz to 1990 MHz for the downlink.
| GSM 850 | GSM 1900 | |
|---|---|---|
| ARFCN | 128 to 251 | 512 to 810 |
| Uplink Frequency Range | 824 MHz to 849 MHz | 1850 MHz to 1910 MHz |
| Downlink Frequency Range | 869 MHz to 894 MHz | 1930 MHz to 1990 MHz |
Here are some helpful downloads
Thank you for reading this post. I hope it helped you in developing a better understanding of cellular networks. Sometimes, we need extra support, especially when preparing for a new job, studying a new topic, or buying a new phone. Whatever you are trying to do, here are some downloads that can help you:
Students & fresh graduates: If you are just starting, the complexity of the cellular industry can be a bit overwhelming. But don’t worry, I have created this FREE ebook so you can familiarise yourself with the basics like 3G, 4G etc. As a next step, check out the latest edition of the same ebook with more details on 4G & 5G networks with diagrams. You can then read Mobile Networks Made Easy, which explains the network nodes, e.g., BTS, MSC, GGSN etc.
Professionals: If you are an experienced professional but new to mobile communications, it may seem hard to compete with someone who has a decade of experience in the cellular industry. But not everyone who works in this industry is always up to date on the bigger picture and the challenges considering how quickly the industry evolves. The bigger picture comes from experience, which is why I’ve carefully put together a few slides to get you started in no time. So if you work in sales, marketing, product, project or any other area of business where you need a high-level view, Introduction to Mobile Communications can give you a quick start. Also, here are some templates to help you prepare your own slides on the product overview and product roadmap.
