SARA-R42 - Application note
UBX-20050829 - R02
PSM, eDRX and deep-sleep mode
Page 32 of 58
C1-Public
☞
The 0000 and 0001 are only applicable in LTE Cat M1. If received in NB-IoT they need to be
interpreted as if eDRX has not been granted by the network.
☞
The 0100, 0110, 0111 and 1000 values are only applicable in LTE Cat M1. If received in NB-IoT
they need to be interpreted as the 0010 value.
☞
The 1110 and 1111 values are only applicable in NB-IoT. If received in LTE Cat M1 they need to be
interpreted as the 1101 value.
8.3.1.2
Encoding of timer PTW
The PTW length is encoded as per Table 10.5.5.32/3GPP TS 24.008
LTE Cat-M1
0 0 0 0
1.28 s
0 0 0 1
2.56 s
0 0 1 0
3.84 s
0 0 1 1
5.12 s
0 1 0 0
6.4 s
0 1 0 1
7.68 s
0 1 1 0
8.96 s
0 1 1 1
10.24 s
1 0 0 0
11.52 s
1 0 0 1
12.8 s
1 0 1 0
14.08 s
1 0 1 1
15.36 s
1 1 0 0
16.64 s
1 1 0 1
17.92 s
1 1 1 0
19.20 s
1 1 1 1
20.48 s
NB-IoT
0 0 0 0
2.56 s
0 0 0 1
5.12 s
0 0 1 0
7.68 s
0 0 1 1
10.24 s
0 1 0 0
12.8 s
0 1 0 1
15.36 s
0 1 1 0
17.92 s
0 1 1 1
20.48 s
1 0 0 0
23.04 s
1 0 0 1
25.6 s
1 0 1 0
28.16 s
1 0 1 1
30.72 s
1 1 0 0
33.28 s
1 1 0 1
35.84 s
1 1 1 0
38.4 s
1 1 1 1
40.96 s
8.3.2
eDRX deep-sleep and paging only image
When the eDRX feature is supported by the network, it is possible for the module to further minimize
its power consumptions by entering deep-sleep mode when not listening to paging in the PTW
periods. This feature can be enabled as usual with
AT+CPSMS=1
command, after having configured
eDRX deep-sleep with
AT+UPSMVER=8
command, which forces eDRX to be used standalone, disabling
PSM requests to the network.
When the eDRX deep-sleep feature is used, power consumption can be further minimized by using a
low power module FW called POI (Paging Only Image) loaded during periodic PTW periods. POI loading
is enabled by default and can be disabled with
AT+UPSMVER=8,0
command. When POI is loaded, the
module is unresponsive until it changes status by itself, due to deep-sleep mode exit at periodic TAU,
paging reception or early wake-up (which is effective only once the module has entered the deep-sleep
state after the PTW period). Transitions between eDRX deep-sleep mode and POI can be monitored
via the RXD or DSR UART lines, which become high during POI period, whereas the module status
indication GPIO, V_INT RXD levels do not change with respect to eDRX deep-sleep state. Usage of POI
in eDRX is notified with
+UUPSMR: 1,2
URC when entering eDRX deep-sleep mode from normal
operation.
8.3.3
Functional diagram of eDRX and PSM
For sake of clarity,
illustrates the states transitions and device activity when both PSM and
eDRX are active. Some configurable parameters are highlighted in the figure. In this case the
negotiated eDRX cycle duration is TeDRX=1024 s. During the PTW, the module listens to paging
continuously or discontinuously in case the network uses discontinuous reception. In below example
the network uses discontinuous reception with a discontinuous reception cycle TDRX=2.56 s. It
should be noticed that unlike PSM related timers, eDRX and DRX related ones start instant does not
