4G Spectrum Frequencies and Bands

Today's post was inspired by a friend's troubles after buying an expensive phone in the USA. The phone was on sale on Amazon at around $500+, shipping inclusive.

After six days the phone arrived, almost everything worked great till it was time to hook up with the internet. He only got 3G reception. But the phone was listed as a 4G phone! Yes, the cellphone was a 4G LTE enabled device. He made one little mistake; he did not check the band of the particular 4G LTE network he wanted to use! He is pissed off for this oversight and is now making a deal with the seller for a return that will cost him about $40 or more in courier cost.

What is a frequency band?

In telecommunication, a band or frequency band is a range or group of frequencies with sometimes an upper or lower limit.

The cellular phone has antennas and amplifiers that are frequency specific, so if you are looking for a new phone, you must ensure that its antenna has support from the frequency of the carrier (cellular phone provider) in the locality that you want to make use of the cell phone.

Let's discuss a little on the different 4G LTE frequency bands and their various spectrum and channels.

The LTE frequency bands allocated across the world are numerous. Even in the same country, the carriers operate on different frequency bands.

To make it easier for identification, each frequency band has a number designated to it which covers the frequency range or group that the particular number represents.

Transmission Techniques

To have a better understanding of the two duplex system that is employed in the LTE 4G system, it will be nice to understand the following transmission technique.

1. Simplex: This is a simple one-directional method of transmission. One device transmits, the other receives. The communication here is one way, and the channel (frequency) is one. A great example of the traditional radio communication and non-interactive television

2. Half Duplex: One party can transmit and receive but not simultaneously or at the same time. This is a two-way transmission method using one frequency (channel). A great example is the two-way walkie-talkie transceiver (push to talk); at any particular time only one user can transmit or receive but never both at the same time.

3. Full Duplex: Here, both communicating party can simultaneously transmit and receive at the same time. The communication is two-way, and two frequencies are employed. A good example is a telephone. Both parties can talk at the same time as well as hear what the other is saying.

In 4G LTE technology, there are two types of LTE standards which depend on the method of duplex configuration scheme or mode.

To share this limited scarce spectrum resource, the following full duplex communication system is applied.

The 4G LTE TDD Spetrum

This is the Time Division Duplexing (TDD) which involves the use of one frequency for both transmitting and receiving. Looking at the above technology, it would appear that the TDD is using a full duplex system on a half-duplex channel.

The 4G LTE FDD Spetrum

The Frequency Division Duplexing (FDD) is the communication system whereby two frequencies are used for simultaneous transmitting (uplink frequency between the device and tower) and receiving (downlink frequency between the communication tower and device) of signals.

The two frequencies are allowed a sufficient separation, i.e. the uplink and downlink frequency spectrum have a gap to avoid the impairment or class of the two frequencies. The spacing of these two frequencies is called the band gap which is shown for different bands in the table below.

This band gap must be sufficient to reduce the incidence of received signal getting "blocked" or impaired.

The 4G networks are designed to support both the unpaired spectrum for time division duplexing (TDD) and the paired spectrum of the Frequency Division Duplex (FDD) .

LTE FDD

Band	Uplink	Downlink	Width of Band	Duplex Spacing	Band Gap
-	(MHz)	(MHz)	(MHz)	(MHz)	(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

DL CA is the band used for DownLink Carrier Aggregation.

Band 15 and 16 are no longer in use.

On the other side of the band allocation is the time division duplex where there is the same frequency for both uplink and downlink. The only separation between the two is time.

Below is a table listing the different band and its LTE band number

LTE TDD

Band No	Allocation(MHz)	Bandwidth(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

Below are the 4G frequency bands of the primary telecommunication operators in Nigeria

4G LTE Frequencies in Nigeria

MTN
Band 7(2600MHz)
Glo
Band 28 (700MHz)
Airtel
Band 3 (1800MHz)
9Mobile
Band 3 (1800MHz)
NTel
Band 3 (1800MHz) and 8 (900MHz)
Swift
Band 40 (2300MHz)
Spectranet
Band 40 (2300MHz)
Smile
Band 20 (800MHz)

The problem was the phone my friend bought supports 4G LTE signals but not all the bands. It supports LTE band 1(2100MHz), 3(1800MHz), 7(2600MHz), 38(2600MHz), 39(1900MHz), 40(2300MHz), and 41(2500MHz). Unfortunately, he wanted to use it on Glo's 4G LTE network which unfortunately was Band 28(700MHz) as you could see above.

It is essential you check the compatibility of a phone to a carrier before making a purchase. The phone's full specification and network compatibility can also be viewed on the manufacturer's site or this website here.

This 700MHz spectrum overlaps the former digital TV signal known as the UHF (300MHz to 3GHz). It was licenced to be used for mobile telephony in 2014.

Even though most cell phones do not support Band 28 700 MHz frequency, why do some carrier like Glo opt for it?

The 700Mhz band has a high penetrating power which is why if you are using a Glo 4G network you will get good coverage in elevators, inside building and other indoor location because of its low frequency.

The received power or amount of transmitted power an antenna gets decreases proportionally to the inverse of frequency. In other words, low-frequency signals like say 700 MHz will propagate better than a 2100 MHz signal under the same condition.

This outcome will mean less number of BTS antennas deployed, more wider coverage area by one antenna.

^References

• ^{ITU,Spectrum Management for 4G-LTE}
• ^{LTE Spectrum Bands and Allocations}
• ^{700 MHz LTE Band}
• ^{700 MHz- Why is it so valuable}

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^{Image References}

• ^{[Wikipedia]4G Sign by Wadzifox}
• ^{[Pixabay]Cell Phone Tower}

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