Parameter Name |
T200 SDCCH(5ms) |
|---|---|
Description |
This parameter specifies the expiry value of timer T200 used for the SDCCH over the Um interface. T200 prevents the data link layer from deadlock during data transmission. The data link layer transforms the physical link that is vulnerable to errors into a sequential non-error data link. The entities at the two ends of this data link use the acknowledgement retransmission mechanism. Each message must be confirmed by the peer end.In unknown cases, both ends are waiting if a message is lost. At this time, the deadlock of the system occurs.Therefore, the transmit end must establish a timer. When the timer expires, the transmit end regards that the receive end does not receive the message and then the transmit end retransmits the message.The number of retransmissions is determined by N200.T200 and the N200 ensure that the data link layer sequentially transmits data and that the transmission is free from errors. |
GUI Value Range |
[1,255] |
Default Value |
60 |
Unit |
Milliseconds |
Step |
5 ms |
Modification Rules |
None |
Configuration Policy |
If timer T200 is set to a too small value, the transmit end may mistakenly regard that the link is faulty and the data transmission fails before the transmit end receives a response from the peer end. If timer N200 is set to a too small value, the number of data retransmissions is reduced and the success rate of transmission is decreased. If T200 and N200 are set to too great values, the channels are seized all along when the link is faulty. Thus, resources are wasted. |
Recommended Value |
60 |
Parameter Relationship |
Timer N200: N200 of establish, N200 of release, N200 of SACCH, N200 of SDCCH, N200 of FACCH/TCHH, and N200 of FACCH/TCHF |
BSC Feature |
None |
Parameter Class |
Parameters About Radio Resources |
Caution |
None |