Dual-band
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It has been suggested that this article or section be merged into GSM frequency bands. (Discuss) |
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It has been suggested that this article or section be merged into UMTS frequency bands. (Discuss) |
In mobile phones, dual band (also known as dual-band or dualband) refers to functionality that allows a cellphone to support two frequency bands. Having more than one frequency in one device is useful to enable roaming between different countries that peg the allowed transmission frequency at different values or to allow a better coverage in the same country.
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[edit] 2G
In Europe two bands (900/1800 MHz) are used in the same country to improve coverage.
In America two bands (850/1900 MHz) are used in the same country to improve coverage.
Dual band phones are also used to enable roaming between different countries. For example, a cellphone with dual band 850/1800 MHz will work in both the United States (850 MHz) and India (1800 MHz).
[edit] 3G
UMTS / HSDPA devices operate in some combination of UMTS frequency bands 800/850/900/1700/1900/2100 MHz:
- 2100 (downlink) / 1900 (uplink) for Europe and Asia (usually referred simply as W-CDMA 2100)
- 850 / 2100 (independently, for both the uplink and downlink) for Australia (e.g. Telstra)
- 1900 / 850 (independently, for both the uplink and downlink) for America (e.g. Cingular Wireless)
- 2100 (downlink) / 1700 (uplink) for America (e.g. T-Mobile)
- 800 for Japan
UMTS / HSDPA / HSUPA is a further evolution.
Note that being UMTS / HSDPA / HSUPA quad band doesn't mean that phone is a GSM / GPRS / EDGE quad band. An HSUPA quad band could not be a GSM at all. However nearly all HSUPA quad band are EDGE quad band too.
A 3G Tri band or Quad band offers more coverage.
[edit] Devices
Some UMTS/HSDPA dual band are available:
850/2100
900/2100:
850/1900:
