User's Manual Part 1

MC75 Hardware Interface Description
Strictly confidential / Draft
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MC75_V00.190a Page 33 of 91 15.02.2005
3.3 Automatic EGPRS/GPRS Multislot Class Change
Temperature control is also effective for operation in EGPRS Multislot Class 10 and GPRS
Multislot Class 12. If the board temperature increases to the limit specified for restricted
operation
1)
while data are transmitted over EGPRS or GPRS, the module automatically
reverts
• from EGPRS Multislot Class 10 (2 Tx slots) to EGPRS Multislot Class 8 (1Tx),
• from GPRS Multislot Class 12 (4 Tx slots) to GPRS Multislot Class 8 (1Tx),
• from GPRS Multislot Class 10 (2 Tx slots) to GPRS Multislot Class 8 (1Tx)
This reduces the power consumption and, consequently, causes the board’s temperature to
decrease. Once the temperature drops to a value of 5 degrees below the limit of restricted
operation, MC75 returns to the higher Multislot Class. If the temperature stays at the critical
level or even continues to rise, MC75 will not switch back to the higher class.
After a transition from EGPRS Multislot Class 10 to EGPRS Multislot Class 8 a possible
switchback to EGPRS Multislot Class 10 is blocked for one minute. The same applies when
a transition occurs from GPRS Multislot Class 12 or 10 to GPRS Multislot Class 8.
Please note that there is not one single cause of switching over to a lower Multislot Class.
Rather it is the result of an interaction of several factors, such as the board temperature that
depends largely on the ambient temperature, the operating mode and the transmit power.
Furthermore, take into account that there is a delay until the network proceeds to a lower or,
accordingly, higher Multislot Class. The delay time is network dependent. In extreme cases,
if it takes too much time for the network and the temperature cannot drop due to this delay,
the module may even switch off as described in Section 3.2.3.1.
1)
See Table 15 for temperature limits known as restricted operation.