TDD和FDD LTE频段的划分

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 FDDLTE 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.

LTE Band Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Uplink Downlink Width of Duplex Spacing Band (MHz) (MHz) (MHz) (MHz) 1920 - 1980 2110 - 2170 60 190 1850 - 1910 1930 - 1990 60 80 1710 - 1785 1805 -1880 75 95 1710 - 1755 2110 - 2155 45 400 824 - 849 869 - 894 25 45 830 - 840 875 - 885 10 35 2500 - 2570 2620 - 2690 70 120 880 - 915 925 - 960 35 45 1749.9 - 1784.9 1844.9 - 1879.9 35 95 1710 - 1770 2110 - 2170 60 400 1427.9 - 1452.9 1475.9 - 1500.9 20 48 698 - 716 728 - 746 18 30 777 - 787 746 - 756 10 -31 788 - 798 758 - 768 10 -30 1900 - 1920 2600 - 2620 20 700 2010 - 2025 2585 - 2600 15 575 704 - 716 734 - 746 12 30 815 - 830 860 - 875 15 45 830 - 845 875 - 890 15 45 832 - 862 791 - 821 30 -41 1447.9 - 1462.9 1495.5 - 1510.9 15 48 3410 - 3500 3510 - 3600 90 100 2000 - 2020 2180 - 2200 20 180 1625.5 - 1660.5 1525 - 1559 34 -101.5 1850 - 1915 1930 - 1995 65 80 Band Gap (MHz) 130 20 20 355 20 25 50 10 60 340 28 12 41 40 680 560 18 30 30 71 33 10 160 135.5 15

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 allocations are unpaired because the uplink and downlink share the same frequency, being time multiplexed.

LTE Band Number 33 34 35 36 37 38 39 40 41 42 43

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. . . . . . . . .

Allocation (MHz) 1900 - 1920 2010 - 2025 1850 - 1910 1930 - 1990 1910 - 1930 2570 - 2620 1880 - 1920 2300 - 2400 2496 - 2690 3400 - 3600 Width of Band (MHz) 20 15 60 60 20 50 40 100 194 200 3600 - 3800 200