Question

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How do I select specific bands on my Sierra Wireless module?

Solution

The AT command AT!BAND can be used to select what specific GSM and LTE bands that you want to be active on your module.



If you are experiencing poor DL or UL speeds, one solution may be to only select the bands that you know are available, which can increase the transfer speeds.



(Please note that the following examples are when using a Sierra Wireless EM7421)



First, see that you get an “OK” with command:

AT

Then, to make sure you can see what command has been sent, type:

ATE1



Since what we are about to do is password protected, we need to type:

AT!ENTERCND="A710"



When entering AT!BAND? it will return a reply looking like (for example):

AT!BAND?

Index, Name, GW Band Mask L Band Mask 1 TDS Band Mask L Band Mask 2 L Band Mask 3 L Band Mask 4

00, All Bands 000200000C400000 000007A0880800C5 0000000000000000 0000000000000000 0000000000000000 0000000000000000

OK





The "00" is referring to the selected preset, "All Bands" to the preset name, "000200000C400000" to GSM bands and "000007A0880800C5" to selected LTE bands in hexadecimal.



To get information on all available bands, we need to type:

AT!BAND=?



Starting at the GSM band (at chapter "AT!BAND - Select/return frequency band set" in the AT command reference manual) we can see that 000200000C400000 corresponds to “0002000000000000 - B8 (900) + 0000000008000000 - B6 (800) + 0000000004000000 - B5 (850) + 0000000000400000 - B1 (2100) = 000200000C400000 (All GSM Bands)”



Now for LTE, which is probably what is a little tricky to understand. Let’s start the Windows Calculator and change it to Programmer mode. If you copy the "000007A0880800C5" into the calculator window it should convert it to binary.

HEX: 0000 07A0 8808 00C5

BIN: 0111 1010 0000 1000 1000 0000 1000 0000 0000 1100 0101



If you look at the line of BIN above you can see what bands are active (1) and which are not (0). Looking from right to left, the first bit corresponds to B1, second bit to B2, third bit B3, and so on…



HEX: 0000 07A0 8808 00C5

BIN: 0111 1010 0000 1000 1000 0000 1000 0000 0000 1100 0101

Selected bands: B1+B3+B7+B8+B20+B28+B32+B38+B40+B41+B42+B43



So if I, for example, only want the GSM bands "GSM 900MHz + GSM 850MHz", and LTE bands "B3, B4, B7, B28" we enter the following:

AT!BAND= 11,"Custom User Preset",0002000004000000,000000000800004C



Now we have created a new preset slot “11”, a name for the preset “Custom User Preset” and selected bands for GSM “GSM 900MHz + GSM 850MHz” and also selected bands for LTE "B3, B4, B7, B28", see explanation below:



Bands: B3, B4, B7, B28

Binary: 1000 0000 0000 0000 0000 0100 1100

Hexadecimal: 800 004C



Now we want to make sure our newly created preset is selected, so we type:

AT!BAND=11



And finally to check that we have selected the preset we again type AT!BAND? and should get the following response:

Index, Name, GW Band Mask L Band Mask 1 TDS Band Mask L Band Mask 2 L Band Mask 3 L Band Mask 4

11, Custom User Preset 0002000004000000 000000000800004C 0000000000000000 0000000000000000 0000000000000000 000000000000000

OK



For further information please take a look at the AT command user guide available on the product's specific page under "technical documentation", which is available for download once logged in.