Since the introduction first generation telecommunication technology, network operators use radio waves to transmit and receive information. During the evolutions stages of LTE, more frequency bands were utilized to support voice and increased demand of data.
There are more than 80 active frequency bands in sub-6GHz spectrum and lot of new bands yet to be allocated in millimeter wave spectrum. In FDD mode (Frequency Division Duplex), separate frequency range of the bands is used for uplink and downlink.
Here are some of the common terms related to LTE frequency bands:
From the UE (mobile device) perspective, downlink is the signals transmitted by the base station and received at the mobile device. Each network operator will have separate frequency bands or sharing a common band in some cases.
From the UE (mobile device) perspective, uplink is the signal transmitted to the base station from the mobile device.
Latest mobile devices are capable of supporting multiple frequency bands used b y the service providers across the globe.
LTE operated in two modes; FDD and TDD
Frequency Division Duplex (FDD) Mode
In frequency division duplex mode, separate frequency bands are used to transmit and receive. There will be a clear band gap between the two frequency slots known as guard bands.
Using sufficient band gap will help to reduce interference from each band while sending and receiving simultaneously.
Time Division Duplex (TDD) Mode
In time division duplex mode, full spectrum can be used to send and receive information. During transmit (uplink) mode of operation, the receive mode will be inactive/off (UE will not receive any data). Similarly, transmit mode will not be active during receiving (downlink).
Separate time slot will be allocated for both uplink and downlink. In between uplink and downlink, there is a tiny time frame with no uplink or downlink allowed (guard time).
Bandwidth is the usable frequency range within each frequency bands. Higher bandwidth is necessary to support higher date rate.
Example: Band 40
Start frequency (f1): 2300 MHz, Stop frequency (f2): 2400 MHz. Bandwidth = f1 – f2 = 100 MHz
LTE and 5G – NR Frequency Band List
LTE and NR Frequency Band List in Sub-6GHz (FR1)
NR Bands above 6GHz Spectrum (FR2)
In order to accommodate huge number of devices for technologies like IoT, unused frequency bands are required in sub-6GHz range. Millimeter wave spectrum will be used in future 5G networks to meet higher data rate requirements.