LTE has been developed to operate on paired spectrum for Frequency Division Duplex (FDD), and unpaired spectrum for Time Division Duplex (TDD).

For an LTE radio system to facilitate bidirectional communication, it is necessary to implement a duplex scheme so that a device may transmit and receive without collision. In order to achieve high data rates, LTE operates full duplex whereby both downlink (DL) and uplink (UL) communication takes place simultaneously by separating DL and UL traffic either by frequency (i.e., FDD), or time periods (i.e., TDD).

While less efficient and more electrically complex to deploy, FDD tends to be more commonly deployed by operators due to refarming of existing 3G spectrum arrangements. By comparison, deploying TDD requires less spectrum as well as eliminating then need for guard bands permitting a more efficient stacking of spectrum. UL/DL capacity can also be dynamically adjusted to match demand simply by devoting more airtime to one over the other. However, transmission timing must be synchronised between base stations, introducing complexity, along with guard periods being required between DL and UL subframes, which reduces capacity.

FDD LTE Frequency Bands

The continuing evolution of carrier aggregation has resulted in several new bands added, including B29, B32, B67, and B69 used for downlink-only carrier aggregation, termed Supplemental DL bands[5]. Supplemental DL bands 252 and 255 have been included as part of the LTE-U expansion into unlicensed 5 GHz bands U-NII-1 and U-NII-3, respectively.

Release 16.0 in April 2019 saw the introduction of European 450 MHz LTE bands for the purposes of emergency services use during disaster relief.

The below table lists the 39 Frequency Division Duplex and Supplemental Downlink LTE bands, compiled from 3GPP 36.101 (Rel. 17.1) [June 2023]

E-UTRA Band Identifier Uplink (MHz) Downlink (MHz) UL EARFCN DL EARFCN Channel Bandwidths (MHz)
B1 (2100 MHz) IMT Core Band 18000 - 18599 0 - 599 0.2, 5, 10, 15, 20
B2 (1900 MHz) PCS 1900 18600 - 19199 600 - 1199 0.2, 1.4, 3, 5, 10, 15, 20
B3 (1800 MHz) 1800 19200 - 19949 1200 - 1949 0.2, 1.4, 3, 5, 10, 15, 20
B4 (1700 MHz) AWS 1700 19950 - 20399 1950 - 2399 0.2, 1.4, 3, 5, 10, 15, 20
B5 (850 MHz) 850 20400 - 20649 2400 - 2649 0.2, 1.4, 3, 5, 10
B7 (2600 MHz) IMT Extension 20750 - 21449 2750 - 3449 0.2, 5, 10, 15, 20
B8 (900 MHz) 900 21450 - 21799 3450 - 3799 0.2, 1.4, 3, 5, 10
B9 (1800 MHz) 1700 (Japan #2) 21800 - 22149 3800 - 4149 5, 10, 15, 20
B10 (1700 MHz) 3G Americas Extended AWS blocks A-I 22150 - 22749 4150 - 4749 5, 10, 15, 20
B11 (1500 MHz) 1500 (Japan #3) 22750 - 22949 4750 - 4949 5, 10
B12 (700 MHz) US 700 Lower A, B, C 23010 - 23179 5010 - 5179 0.2, 1.4, 3, 5
B13 (700 MHz) US 700 Upper C 23180 - 23279 5180 - 5279 0.2, 5, 10
B14 (700 MHz) US 700 Upper D 23280 - 23379 5280 - 5379 5, 10
B17 (700 MHz) US 700 Lower B, C 23730 - 23849 5730 - 5849 5, 10
B18 (850 MHz) 850 (Japan #4) 23850 - 23999 5850 - 5999 0.2, 5, 10, 15
B19 (850 MHz) 850 (Japan #5) 24000 - 24149 6000 - 6149 0.2, 5, 10, 15
B20 (800 MHz) CEPT 800 24150 - 24449 6150 - 6449 0.2, 5, 10, 15, 20
B21 (1500 MHz) 1500 (Japan #6) 24450 - 24599 6450 - 6599 0.2, 5, 10, 15
B22 (3500 MHz) FDD 3500 24600 - 25399 6600 - 7399 5, 10, 15, 20
B24 (1600 MHz) US L-Band 25700 - 26039 7700 - 8039 5, 10
B25 (1900 MHz) PCS 1900 G 26040 - 26689 8040 - 8689 0.2, 1.4, 3, 5, 10, 15, 20
B26 (850 MHz) E850 Upper 26690 - 27039 8690 - 9039 0.2, 1.4, 3, 5, 10, 15
B27 (850 MHz) E850 Lower LTE 27040 - 27209 9040 - 9209 1.4, 3, 5
B28 (700 MHz) APT 700 27210 - 27659 9210 - 9659 0.2, 1.4, 3, 5, 10, 15, 20
B30 (2300 MHz) LTE WCS 27660 - 27710 9770 - 9869 5, 10
B31 (450 MHz) LTE 450 Brazil 27760 - 27785 9870 - 9919 0.2, 1.4, 3, 5
B65 (2100 MHz) 2 GHz LTE 131072 - 131971 65536 - 66435 1.4, 3, 5, 10, 15, 20
B66 (1700 MHz) AWS Extension 131972 - 132671 66436 - 67335 1.4, 3, 5, 10, 15, 20
B68 (700 MHz) LTE 700 Arab Region 132672 - 132971 67536 - 67835 5, 10, 15
B70 (1700 MHz) AWS-3/4 132972 - 133121 68336 - 68585 5, 10, 15, 20
B71 (600 MHz) US 600 133122 - 133471 68586 - 68935 0.2, 5, 10, 15, 20
B72 (450 MHz) 450 EU BB-PPDR 133472 - 133521 68936 - 68985 0.2, 1.4, 3, 5
B73 (450 MHz) 450 LTE APAC 133522 - 133571 68986 - 69035 0.2, 1.4, 3, 5
B74 (1500 MHz) FDD L-band 133572 - 134001 69036 - 69465 0.2, 1.4, 3, 5, 10, 15, 20
B85 (700 MHz) 700 a+ 134002 - 134181 70366 - 70545 5, 10
B87 (450 MHz) PPDR PMR/PMAR in EU 134182 - 134231 70546 - 70595 0.2, 1.4, 3, 5
B88 (450 MHz) PPDR PMR/PMAR in EU 134231 - 134280 70596 - 70645 0.2, 1.4, 3, 5
B103 (700 MHz) NB-IoT 700 134282 - 134291 70646 - 70655 0.2
B106 (900 MHz) 900 FDD 134292 - 134341 70656 - 70705 1.4, 3

TDD LTE Frequency Bands

The increasing asymmetric demand for downlink data has also resulted in the introduction of Band 46, a downlink-only Supplemental DL band operating in the 5 GHz U-NII frequency range.

Band 47 has been introduced for applications such as Vehicle to Everything (V2X) communications, which is positioned in the U-NII-3 5 GHz unlicensed band. Cellular V2X (C-V2X) may require the use of unlicensed bands to solve regulatory issues related to LTE-Direct, where devices broadcast directly to nearby devices[6]. Like all unlicensed band LTE technologies, V2X operates Band 47 only in carrier aggregation with the operator's licensed band.

The below table lists the 20 Time Division Duplex and Supplemental Downlink LTE bands, compiled from 3GPP 36.101 (Rel. 17.1) [June 2023]

E-UTRA Band Identifier Frequency (MHz) EARFCN Channel Bandwidths (MHz)
B33 (2100 MHz) TDD 2000 Lower 36000 - 36199 5, 10, 15, 20
B34 (2100 MHz) TDD 2000 Upper 36200 - 36349 5, 10, 15
B35 (1900 MHz) 1900 36350 - 36949 0.2, 1.4, 3, 5, 10, 15, 20
B36 (1900 MHz) TDD 1900 36950 - 37549 0.2, 1.4, 3, 5, 10, 15, 20
B37 (1900 MHz) PCS Center Gap 37550 - 37749 5, 10, 15, 20
B38 (2600 MHz) IMT Extension Gap 37750 - 38249 5, 10, 15, 20
B39 (1900 MHz) China TDD 1900 38250 - 38649 5, 10, 15, 20
B40 (2300 MHz) TDD 2300 38650 - 39649 5, 10, 15, 20
B41 (2500 MHz) TDD 2500 39650 - 41589 5, 10, 15, 20
B42 (3500 MHz) TDD 3500 41590 - 43589 5, 10, 15, 20
B43 (3700 MHz) TDD 3700 43590 - 45589 5, 10, 15, 20
B44 (700 MHz) APT 700 TDD 45590 - 46589 3, 5, 10, 15, 20
B45 (1500 MHz) China TDD 1400 46590 - 46789 5, 10, 15, 20
B46 (5200 MHz) LAA 5200 46790 - 54539 10, 20
B47 (5800 MHz) V2X 5800 54540 - 55239 10, 20
B48 (3600 MHz) US CBRS 3500 55240 - 56739 5, 10, 15, 20
B50 (1500 MHz) TD 1500+ 58240 - 59089 3, 5, 10, 15, 20
B51 (1500 MHz) TD 1500- 59090 - 59139 5
B53 (2400 MHz) TDD LTE over WiFi 60140 - 60254 1.4, 3, 5, 10
B54 (1600 MHz) TD 1700 60255 - 60304 5

References

[1] 3GPP TSG, "Evolved Universal Terrestrial Radio Access; User Equipment radio transmission and reception (Release 14)", 3GPP, Valbonne, France, 3GPP TS 36.101 V14.1.0, Sept. 2016.

[2] LTE-U Forum, "LTE-U Technical Report Coexistence Study for LTE-U SDL",  LTE-U Forum Companies, V1.0, Feb. 2015.

[3] Radio-Electronics, LTE FDD, TDD, TD-LTE Duplex Schemes, [Online], Available: http://www.radio-electronics.com/info/cellulartelecomms/lte-long-term-evolution/lte-fdd-tdd-duplex.php

[4] Qualcomm, "Making the Best Use of Unlicensed Spectrum for 1000x", Qualcomm Technologies, San Diego, CA, Sept. 2015.

[5] 4G Americas, "LTE Carrier Aggregation Technology Development and Deployment Worldwide", 4G Americas, Oct. 2014.

[6] Qualcomm, "Leading the world to 5G: Cellular Vehicle-to-Everything (C-V2X) technologies", Qualcomm Technologies, San Diego, CA, June 2016.