The traffic channel parameters are configured using the following call processing subsystem commands.
Operating Considerations
When configuring the base station emulator you must configure the broadcast channel (see
CALL:BCHannel
) and the traffic channel (TCH). There are a number of parameters for the BCH and the TCH that can be configured; however, the test set's default parameters should allow a properly functioning mobile station to successfully camp on the cell and make a call under most circumstances.
When Operating Mode = Active Cell, if a call is connected, changes to the traffic channel number (ARFCN) or traffic channel timeslot, including a change to the value of the parameter's current setting, causes signaling on the downlink FACCH to initiate a channel reassignment, see
How the Test Set Performs a Dualband Handover
. This configures the TCH to use the new parameter. If a call is not connected, changes to the parameter are stored for when the next call is established
When Operating Mode = Test Mode, if Test Mode Downlink Function (see
CALL:FUNCtion:DOWNlink
) = BCH+TCH, changes to the traffic channel number (ARFCN) or traffic channel timeslot will reconfigure the downlink TCH accordingly, but there will be no signaling initiated. The change will be immediate. If a TCH is not being generated, changes to the parameter are stored for when the next call is established
Downlink speech controls what kind of speech data is transmitted on the downlink TCH. A TCH with speech data is generated when call control status is connected (see
Call Processing State Synchronization
), or when in test mode with downlink function set to BCH+TCH.
When an FBER measurement is activated PRBS15 is transmitted on the downlink TCH, over riding the user setting of downlink speech source. Any changes to downlink speech source will be accepted and saved but not applied until FBER become inactive.
There are 6 different settings for the downlink speech source. See
CALL:TCHannel:DOWNlink:SPEech
.
-
None
-
Echo retransmits the uplink speech frames back to the downlink with a non-selectable delay of about 1 second.
-
PRBS15 the 260 speech frame bits (prior to channel coding) are generated using a pseudo random bit sequence.
-
SIN300 the sequence of 260 speech bit frames represent a sine wave at 300 Hz.
-
SIN1000 the sequence of 260 speech bit frames represent a sine wave at 1000 Hz.
-
SIN3000 the sequence of 260 speech bit frames represent a sine wave at 3000 Hz.
Traffic channel loopback type cannot be set to type C if the traffic channel band is PGSM.
The Max Frames Allowed for Assignment parameter, is used to specify the maximum number of TDMA frames the mobile station is allowed to take for a channel assignment. This is only applicable to changes in TCH band, traffic channel, or TCH timeslot. Changes to any other TCH parameter will not cause an error to be generated if, the number of frames taken to perform the change exceeds the setting of the maximum frames allowed for assignment. If the mobile station does not complete the channel assignment within the specified number of frames, the test set will generate an error message, but this will not cause a call to drop. If the mobile DTX state (discontinuous transmission) parameter is on (see
CALL:MS:DTX[:STATe]
), the error is not generated, because when a mobile station is in discontinuous transmission mode, it is not required to transmit on the new channel, at least not until a SACCH, FACCH, or SID frame is ready. In this case, the mobile station may actually have changed channels in the correct time, but had nothing to transmit.
