Cellular frequencies
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All cellular phone networks worldwide utilize a portion of the radio frequency spectrum designated as Ultra High Frequency, or "UHF", for the transmission and reception of their signals. The UHF band is also shared with Television, Wi-Fi and Bluetooth transmission. The cellular frequencies are the sets of frequency ranges within the UHF band that have been allocated for cellular phone use.
Due to historical reasons, radio frequencies used for cellular networks differ in the Americas, Europe, and Asia. The first commercial standard for mobile connection in the United States was AMPS, which was in the 800 MHz frequency band. In Nordic countries of Europe, the first widespread automatic mobile network was based on the NMT-450 standard, which was in the 450 MHz band. As mobile phones became more popular and affordable, mobile providers encountered a problem because they couldn't provide service to the increasing number of customers. They had to develop their existing networks and eventually introduce new standards, often based on other frequencies. Some European countries (and Japan) adopted TACS operating in 900 MHz. The GSM standard, which appeared in Europe to replace NMT-450 and other standards, initially used the 900 MHz band too. As demand grew, carriers acquired licenses in the 1800 MHz band. (Generally speaking, lower frequencies allow carriers to provide less coverage for a larger area, while higher frequencies allow carriers to provide service to more customers in a smaller area.)
In the U.S., the analog AMPS standard that used the Cellular band (800 MHz) was replaced by a number of digital systems. Initially, systems based upon the AMPS mobile phone model were popular, including IS-95 (often known as "CDMA", the air interface technology it uses) and IS-136 (often known as D-AMPS, Digital AMPS, or "TDMA", the air interface technology it uses.) Eventually, IS-136 on these frequencies was replaced by most operators with GSM. GSM had already been running for some time on US PCS (1900 MHz) frequencies.
And, some NMT-450 analog networks have been replaced with digital networks utilizing the same frequency. In Russia and some other countries, local carriers received licenses for 450 MHz frequency to provide CDMA mobile coverage.
Many GSM phones support three bands (900/1800/1900 MHz or 850/1800/1900 MHz) or four bands (850/900/1800/1900 MHz), and are usually referred to as tri band and quad band phones, or world phones; with such a phone one can travel internationally and use the same handset. This portability is not as extensive with IS-95 phones, however, as IS-95 networks do not exist in most of Europe.
Mobile networks based on different standards may use the same frequency range; for example, AMPS, D-AMPS, N-AMPS and IS-95 all use the 800 MHz frequency band. Moreover, one can find both AMPS and IS-95 networks in use on the same frequency in the same area that do not interfere with each other. This is achieved by the use of different channels to carry data. The actual frequency used by a particular phone can vary from place to place, depending on the settings of the carrier's base station.
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[edit] Frequency bands recommended by ITU
ITU-R approved in June 2003 the following bands to the terrestrial Mobile telecommunication IMT-2000: 806-960 MHz, 1710-2025 MHz, 2110-2200 MHz and 2500-2690 MHz.
[edit] Frequency bands used in the United States
| Current / Planned Technologies | Band | Frequency (MHz) |
|---|---|---|
| SMR iDEN | 800 | 806-824 and 851-869 |
| AMPS, GSM, IS-95 (CDMA), IS-136 (D-AMPS), 3G | Cellular | 824-849, 869-894, 896-901, 935-940 |
| GSM, IS-95 (CDMA), IS-136 (D-AMPS), 3G | PCS | 1850-1910 and 1930-1990 |
| 3G, 4G, MediaFlo, DVB-H | 700 MHz | 698-806 |
| Unknown | 1.4 GHz | 1392-1395 and 1432-1435 |
| 3G, 4G | AWS | 1710-1755 and 2110-2170 |
| 4G | BRS/EBS | 2500-2690 |
The usage of frequencies within the United States is regulated by the Federal Communications Commission (FCC). The US is then divided geographically into a number of Trading Areas. A mobile operator (or other interested parties) must bid on each trading area individually. A bidder can use the frequency spectrum for whatever purpose he wants. Go to Wireless Advisor for a listing of the network operators for a given ZIP-code.
The Cellular band (869-894 MHz) is divided into 2 frequency blocks (A and B). There are 306 Metropolitan Service Areas and 428 rural service areas. Each trading area consists of one or more counties.
The PCS band (1850-1990 MHz) is divided into six frequency blocks (A through F). Each block is between 10 MHz and 30 MHz bandwidth. License (A or B) is granted for a Major Trading Areas (MTAs). License (C to F) is granted for a Basic Trading Areas (BTAs). There are 51 MTAs and 493 BTAs in the United States.
The AWS bands, auctioned in the summer of 2006, were for 1710-1755 MHz, and 2110-2155 MHz. The spectrum was divided into blocks: A blocks were for Cellular Market Areas, based on existing cellular (1G) licenses, and were 2x10 MHz. B and C blocks (2x10 MHz and 2x5 MHz respectively) were for Basic Economic Areas, larger than CMAs, usually comprising of large portions of single states. D, E, and F blocks covered huge areas of the country, typically several states at a time, and covered 2x5 MHz for D and E blocks, 2x10 MHz for F.[1]
The 700 MHz band was auctioned in early 2008, with Verizon Wireless and AT&T Mobility winning the majority of available spectrum. Qualcomm and Echostar were winners of a significant amount of broadcast-oriented spectrum. The winners have not yet announced what technology they intend to deploy on this spectrum, but it is expected to host a range of 3G, 4G, and broadcast technologies such as MediaFlo and DVB-H.
More bands are under consideration for auction by the FCC. These are currently used by DoD, NASA, and other government agencies.
Cellular and PCS bands are also used in other countries in the Americas.
[edit] Most widely used channelization and frequencies
The following chart presents graphically the forward link (base station to mobile) frequencies and channelization most prevalently used in today's cellular communication systems.
[edit] Frequency bands used by GSM
| System | Band | Uplink | Downlink | Channel Number |
|---|---|---|---|---|
| GSM 400 | 450 | 450.4 - 457.6 | 460.4 - 467.6 | 259 - 293 |
| GSM 400 | 480 | 478.8 - 486.0 | 488.8 - 496.0 | 306 - 340 |
| GSM 850 | 850 | 824.0 - 849.0 | 869.0 - 894.0 | 128 - 251 |
| GSM 900 (P-GSM) | 900 | 890.0 - 915.0 | 935.0 - 960.0 | 1 - 124 |
| GSM 900 (E-GSM) | 900 | 880.0 - 915.0 | 925.0 - 960.0 | 0 - 124, 975 - 1023 |
| GSM-R (R-GSM) | 900 | 876.0 - 880.0 | 921.0 - 925.0 | 955 - 973 |
| DCS 1800 | 1800 | 1710.0 - 1785.0 | 1805.0 - 1880.0 | 512 - 885 |
| PCS 1900 | 1900 | 1850.0 - 1910.0 | 1930.0 - 1990.0 | 512 - 810 |
GSM Frequency band usage is defined in ETS 05.05.
[edit] Other Regions
| System | Country | Uplink | Downlink |
|---|---|---|---|
| CDMA | China | 2300-2400 | |
| CDMA | Japan | 830-840 | 875-885 |
| CDMA | S. Korea | 1750-1780 | 1840-1870 |
| CDMA-450 | Sweden | 452.5-457.5 | 462.5-467.5 |
[edit] See also
- 3GPP
- Dual band
- GSM frequency bands
- Quad band
- Roaming
- Tri band
- UMTS frequency bands
- 700 MHz wireless spectrum auction
[edit] References
[edit] External links
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