LTE Frequency Bands & Spectrum Allocations
There are very many frequency bands used for LTE TDD and FDD versions. The spectrum allocated for LTE varies around the world and as a result there many LTE bands and frequency allocations.
There is a growing number of LTE frequency bands that are being designated as possibilities for use with LTE. Many of the LTE frequency bands are already in use for other cellular systems, whereas other LTE bands are new and being introduced as other users are re-allocated spectrum elsewhere.
FDD and TDD LTE frequency bands
FDD spectrum requires pair bands, one of the uplink and one for the downlink, and TDD requires a single band as uplink and downlink are on the same frequency but time separated. As a result, there are different LTE band allocations for TDD and FDD. In some cases these bands may overlap, and it is therefore feasible, although unlikely that both TDD and FDD transmissions could be present on a particular LTE frequency band.
The greater likelihood is that a single UE or mobile will need to detect whether a TDD or FDD transmission should be made on a given band. UEs that roam may encounter both types on the same band. They will therefore need to detect what type of transmission is being made on that particular LTE band in its current location.
The different LTE frequency allocations or LTE frequency bands are allocated numbers. Currently the LTE bands between 1 & 22 are for paired spectrum, i.e. FDD, and LTE bands between 33 & 41 are for unpaired spectrum, i.e. TDD.
LTE frequency band definitions
FDD LTE frequency band allocations
There is a large number of allocations or radio spectrum that has been reserved for FDD, frequency division duplex, LTE use.
The FDD LTE frequency bands are paired to allow simultaneous transmission on two frequencies. The bands also have a sufficient separation to enable the transmitted signals not to unduly impair the receiver performance. If the signals are too close then the receiver may be "blocked" and the sensitivity impaired. The separation must be sufficient to enable the roll-off of the antenna filtering to give sufficient attenuation of the transmitted signal within the receive band.
|FDD LTE Bands & Frequencies|
|Width of Band (MHz)||Duplex Spacing (MHz)||Band Gap (MHz)|
|1||1920 - 1980||2110 - 2170||60||190||130|
|2||1850 - 1910||1930 - 1990||60||80||20|
|3||1710 - 1785||1805 -1880||75||95||20|
|4||1710 - 1755||2110 - 2155||45||400||355|
|5||824 - 849||869 - 894||25||45||20|
|6||830 - 840||875 - 885||10||35||25|
|7||2500 - 2570||2620 - 2690||70||120||50|
|8||880 - 915||925 - 960||35||45||10|
|9||1749.9 - 1784.9||1844.9 - 1879.9||35||95||60|
|10||1710 - 1770||2110 - 2170||60||400||340|
|11||1427.9 - 1452.9||1475.9 - 1500.9||20||48||28|
|12||698 - 716||728 - 746||18||30||12|
|13||777 - 787||746 - 756||10||-31||41|
|14||788 - 798||758 - 768||10||-30||40|
|15||1900 - 1920||2600 - 2620||20||700||680|
|16||2010 - 2025||2585 - 2600||15||575||560|
|17||704 - 716||734 - 746||12||30||18|
|18||815 - 830||860 - 875||15||45||30|
|19||830 - 845||875 - 890||15||45||30|
|20||832 - 862||791 - 821||30||-41||71|
|21||1447.9 - 1462.9||1495.5 - 1510.9||15||48||33|
|22||3410 - 3500||3510 - 3600||90||100||10|
|23||2000 - 2020||2180 - 2200||20||180||160|
|24||1625.5 - 1660.5||1525 - 1559||34||-101.5||135.5|
|25||1850 - 1915||1930 - 1995||65||80||15|
|26||814 - 849||859 - 894||30 / 40||10|
|27||807 - 824||852 - 869||17||45||28|
|28||703 - 748||758 - 803||45||55||10|
|29||n/a||717 - 728||11|
|30||2305 - 2315||2350 - 2360||10||45||35|
|31||452.5 - 457.5||462.5 - 467.5||5||10||5|
TDD LTE frequency band allocations
With the interest in TDD LTE, there are several unpaired frequency allocations that are being prepared for LTR TDD use. The TDD LTE bands are unpaired because the uplink and downlink share the same frequency, being time multiplexed.
|TDD LTE Bands & Frequencies|
|Allocation (MHz)||Width of Band (MHz)|
|33||1900 - 1920||20|
|34||2010 - 2025||15|
|35||1850 - 1910||60|
|36||1930 - 1990||60|
|37||1910 - 1930||20|
|38||2570 - 2620||50|
|39||1880 - 1920||40|
|40||2300 - 2400||100|
|41||2496 - 2690||194|
|42||3400 - 3600||200|
|43||3600 - 3800||200|
|44||703 - 803||100|
There are regular additions to the LTE frequency bands / LTE spectrum allocations as a result of negotiations at the ITU regulatory meetings. These LTE allocations are resulting in part from the digital dividend, and also from the pressure caused by the ever growing need for mobile communications. Many of the new LTE spectrum allocations are relatively small, often 10 - 20MHz in bandwidth, and this is a cause for concern. With LTE-Advanced needing bandwidths of 100 MHz, channel aggregation over a wide set of frequencies many be needed, and this has been recognised as a significant technological problem. . . . . . . . .
Additional information on later updates can be found on Electronics Notes.
By Ian Poole
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