4G LTE includes:
What is LTE LTE OFDMA / SCFDMA MIMO LTE Duplex LTE frame & subframe LTE data channels LTE frequency bands LTE EARFCN UE categories / classes LTE-M (Machine to Machine) LTE-LAA / LTE-U VoLTE SRVCC
LTE Advanced topics: LTE Advanced introduction Carrier aggregation Coordinated multipoint LTE relay Device to device, D2D
There are very many different LTE frequency bands which have been allocated around the globe.
As different countries have different areas of available spectrum it has not been possible to have a high level of coordination from one country to the next and this has issues with roaming and the number of bans needed for handsets.
Each frequency band is allocated a number so it can be defined easily and its limits known.
The LTE radio channels are also allocated numbers - these can be calculated from a simple defined formula. By having defined radio channels, they can be coordinated globally to facilitate roaming.
LTE bands for FDD & TDD
The spectrum requirements and hence the frequency band allocations for LTE are different for FDD and TDD.
- FDD LTE bands: FDD spectrum requires pair bands, one of the uplink and one for the downlink. It is also important that there is sufficient spacing between the top of the lower band and the bottom of the upper band to allow sufficient filtering. Also the uplink to downlink channel spacing must be sufficient to allow sufficient filtering to prevent the transmitted signal from entering he receiver and desensitising it.
- TDD LTE bands : TDD transmissions only require a single band and in this way paired spectrum is not needed.
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.
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|
|32||DL CA Only||1452 - 1496||44||N/A||N/A|
|65||1920 - 2100||2120 - 2200||90||190||20|
|66||1710 - 1780||2110 - 2200||90||400||330|
|67||DL CA Only||738 - 758||20||N/A||N/A|
|68||698 - 728||753 - 783||30||55||25|
|69||DL CA Only||2570 - 2620||50||N/A||N/A|
|70||1695 - 1710||1995 - 2020||25||295||285|
|71||663 - 698||617 - 652||35||-46||11|
|252||DL CA Only||5150 - 5250||100||N/A||N/A|
|255||DL CA Only||5725 - 5850||125||N/A||N/A|
bands 15 and 16 are now obsolete
DL CA Only refers to bands that are used for downlink carrier aggregation only
Bands 252 and 255 use the unlicensed spectrum and used with LTE-LAA / LTE-U.
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|
|45||1447 - 1467||20|
|46||5150 - 5925||775|
|47||5855 - 5925||70|
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. . . . . . . . .
LTE radio channel bandwidths
LTE supports different channel bandwidths and as a result a different number of resource blocks can be supported.
For all the channel bandwidths except 1.4 MHz, the resource blocks in the transmission bandwidth fill up 90% of the channel bandwidth.
|Radio Channel Bandwidths Specified in LTE|
|Channel Bandwidth||Number of Resource Blocks|
The LTE bands have proliferated around the globe. This has resulted from the very fragmented amounts of spectrum that have been available. This has made the design of handsets for roaming more difficult as filters need to ensure that out of band products are sufficiently reduced, but having banks of filters to accommodate the huge variety of bands is difficult.
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