System and method of determining standby time for a mobile station
View Patent ↗A method and system for determining standby time for a mobile station uses a battery simulator, a base station emulator, a computer to control the test equipment and MSUT for testing a mobile station. The computer includes a module for determining a radio off battery voltage, a module for deriving a battery capacity in dependence upon the radio off battery voltage, a module for measuring battery capacity usage in a predetermined time while the mobile station is in standby mode and a module for determining a standby time for the mobile station in dependence upon the battery capacity and the battery capacity usage, where the predetermined time is less than the standby time.
1. A method of determining standby time for a mobile station, the method comprising:
measuring an average current consumption while the mobile station is in a standby mode, the standby mode including a transmit mode and a receive mode, the average current consumption being measured in both the transmit mode and the receive mode;
determining an available battery capacity of a battery in the mobile station;
determining a standby time for the mobile station in dependence upon the available battery capacity and the average current consumption; and
determining a radio off battery voltage, the available battery capacity determined upon the radio off battery voltage, wherein the determining a radio off battery voltage comprises:
providing a simulated battery voltage at a first voltage value to the mobile station;
determining if a mobile station radio is on;
if the mobile station radio is on, decrementing the first voltage value to a next voltage value by a predetermined amount, and repeating the determining if a mobile station radio is on step; and
if the mobile station radio is off, recording the radio off battery voltage.
2. The method as claimed in claim 1 , wherein the measuring the average current consumption comprises measuring a first plurality of current measurement data points in the transmit mode, and measuring a second plurality of current measurement data points in the receive mode.
3. The method as claimed in claim 2 , wherein the first plurality of current measurement data points are measured over at least one complete transmit event.
4. The method as claimed in claim 3 , further comprising calculating the capacity used of each transmit event.
5. The method as claimed in claim 4 , wherein the measuring average current consumption is repeated to record a plurality of transmit measurements.
6. The method as claimed in claim 5 , further comprising calculating an average capacity usage in each transmit event (C tx ) as:
C
tx
=
(
∑
j
=
1
N
(
C
j
)
)
/
N
,
where N is the total number of transmit events measured; and
calculating the average transmit current (i tx ) as:
i tx =C tx /T tx
where T tx is a registration interval.
7. The method as claimed in claim 2 , wherein the measuring average current consumption further comprises triggering the simulator to start collecting current measurement data points when a transmit activity is detected and wherein triggering comprises setting a threshold for current level exceeding the current consumption level for receiver only operation.
8. The method as claimed in claim 2 , wherein the second plurality of current measurement data points are measured in a plurality of measurement intervals.
9. The method as claimed in claim 1 , wherein the available battery capacity determined upon a radio off battery voltage.
10. The method as claimed in claim 1 , wherein the determining a radio off battery voltage is repeated a plurality of times and the resulting voltage value is averaged to determine the radio off battery voltage.
11. The method as claimed in claim 10 , further comprising simulating an equivalent series resistance effect of the battery while determining the radio off battery voltage.
12. The method as claimed in claim 1 , further comprising determining receive capacity usage the determining receive capacity usage comprising:
configuring the base station emulator to disable timer based registration and all other types registrations except the power up registration; and
measuring the receive current array of the mobile station segment by segment using a sampling interval small enough to capture all current activities.
13. The method as claimed in claim 12 , wherein the determining receive capacity usage further comprises:
Recording a plurality of receive current segments;
for each of the plurality of receive current segments:
post processing a current measurement data array; and
calculating the mean current value of each of the plurality of receive current segments;
calculating the mean (i rx ) over all the segments measured; and
determining the capacity used while in receive mode for 1 hour of operation of the mobile station.
14. The method as claimed in claim 13 , wherein the capacity used for 1 hour by receive mode (C rx — in — 1hr ) is calculated by:
C
rx_in
_
1
hr
=
(
i
rx
*
(
1
-
t
tx_in
_
1
hr
)
)
where
t
tx_in
_
1
hr
=
(
∑
j
=
1
N
(
t
j
)
)
*
(
M
/
N
)
;
t
j
=
m
*
Δ
t
;
m is the last point of transmit activity; and
Δt is the sampling interval;
the total capacity used by the mobile station in one hour is:
C 1hr =C rx — in — 1hr +C tx — in —1hr ;
and the standby time in hours is calculated to be:
T standby =( C new −C cutoff )/( C 1hr )
where C new −C cutoff is the capacity difference between a fully charged battery and the capacity at a cutoff voltage.
15. The method as claimed in claim 13 , wherein the capacity used for 1 hour by receive mode (C rx — in — 1hr ) is calculated by:
C rx — in — 1hr =( i rx *1 hr).
16. The method as claimed in claim 1 , further comprising determining average receive current, the determining average receive current comprising:
configuring the base station emulator to disable timer based registration and all other types registrations except the power up registration; and
measuring the receive current array of the mobile station segment by segment using a sampling interval small enough to capture all current activities.
17. The method as claimed in claim 16 , wherein the determining average receive current further comprises:
Recording a plurality of receive current segments;
for each of the plurality of receive current segments:
post processing the current measurement data array; and
calculating the mean current value of each of the plurality of receive current segments; and
calculating the mean (i rx ) over all the segments measured.
18. The method as claimed in claim 17 , wherein the standby time in hours is calculated to be:
T standby =( C new −C cutoff )/( i tx +i rx )
where C new −C cutoff is the capacity difference between a fully charged battery and the capacity at the cutoff voltage, and i tx +i rx is the total of the average transmit current and the average receive current.