Integration Manual
SARA-R4/N4 series - System Integration Manual
UBX-16029218 - R13 System description Page 19 of 119
1.5.1.2 VCC current consumption in LTE connected mode
During an LTE connection, the SARA-R4/N4 series modules transmit and receive in half duplex mode.
The current consumption depends on output RF power, which is always regulated by the network (the current base
station) sending power control commands to the module. These power control commands are logically divided into a slot
of 0.5 ms (time length of one Resource Block), thus the rate of power change can reach a maximum rate of 2 kHz.
Figure 4 shows an example of SARA-R4/N4 series modules’ current consumption profile versus time in connected mode:
transmission is enabled for one sub-frame (1 ms) according to LTE Category M1 half-duplex connected mode.
Detailed current consumption values can be found in the SARA-R4/N4 series Data Sheet [1].
Time
[ms]
Current [mA]
0
300
20 0
100
500
400
Current consumpt ion value
depends on TX power and
act ual ant enna load
1 Slot
1 Resour ce Block
(0.5 m s)
1 LTE Radio Fram e
(10 m s)
1 Slot
1 Resour ce Block
(0.5 m s)
1 LTE Radio Fram e
(10 m s)
Figure 4: VCC current consumption profile versus time during LTE Cat M1 half-duplex connection
1.5.1.3 VCC current consumption in 2G connected mode
When a 2G call is established, the VCC consumption is determined by the current consumption profile typical of the 2G
transmitting and receiving bursts.
The current consumption peak during a transmission slot is strictly dependent on the transmitted power, which is
regulated by the network. The transmitted power in the transmit slot is also the more relevant factor for determining the
average current consumption.
If the module is transmitting in 2G single-slot mode in the 850 or 900 MHz bands at the maximum RF power control level
(approximately 2 W or 33 dBm in the Tx slot/burst), then the current consumption can reach a high peak / pulse (see the
SARA-R4/N4 series Data Sheet [1])
for 576.9 µs (width of the transmit slot/burst) with a periodicity of 4.615 ms (width of
1 frame = 8 slots/burst), that is, with a 1/8 duty cycle according to GSM TDMA (Time Division Multiple Access).
If the module is transmitting in 2G single-slot mode in the 1800 or 1900 MHz bands, the current consumption figures are
much lower than during transmission in the low bands, due to the 3GPP transmitter output power specifications.
During a 2G call, current consumption is not significantly high while receiving or in monitor bursts, and it is low in the
bursts unused to transmit / receive.