Users Manual Part 1

greater than the recommended values (4 hours) may mean that the BTS is unable to maintain
synchronization and can result in call failures and erratic network performance. If the GPS reference
is not recovered in this time period, the MTS switches to the non-synchronized mode. If an MTS is
started when no GPS reference is available, it operates in the non-synchronized mode.
Non-synchronized mode will not have optimized hand-over performance. When an MTS operates in
non-synchronized mode, all the adjacent cells will be indicated as non-synchronized with this MTS.
By default the re-synchronization of MTS running non-synchronized is done automatically whenever
there is valid GPS reference signal and the site does not handle traffic. Prolonged operation in non-
synchronized mode will eventually lead to critical alarms and the frequency accuracy of the MTS will
no longer be guaranteed.
To maintain the frequency accuracy, it is necessary that the oscillator within the MTS is periodically
recalibrated. The periodic recalibration happens automatically when a GPS reference is present.
The critical alarms indicate that recalibration is due and should be performed without delay.
• Forced Non-Synchronized Configuration (FNC)
FNC is not recommended for System Release D6.0. In this configuration, the MTS always operates
non-synchronized to GPS. The failure or lack of GPS will not be reported as an alarm. The sets of
events that are reported in ASC and FNC modes are the same, however the events reported in
ASC mode with Minor severity, in FNC mode are reported with lower – Normal severity.
The MTS starts up in non-synchronized mode regardless of the presence of a GPS signal. However
if GPS is present, the site reference is trained accordingly. Prolonged operation in this configuration
without GPS eventually leads to critical alarms and the frequency accuracy of the MTS is no longer
guaranteed. Frequency accuracy is expected to be maintained for 4 to 8 years.
To maintain the frequency accuracy, it is necessary that the oscillator within the MTS is periodically
recalibrated (every 8th year (400 MHz and 260 MHz) or every 4th year (800 MHz and 900 MHz)).
The periodic recalibration happens automatically when a GPS reference is present. If no GPS
reference is present, it is necessary to ship the Site Controller for calibration at a repair center. The
critical alarms indicate that recalibration is due and should be performed without delay.
It is possible to change configuration with BTS Service Software. The new configuration will only be
active after an MTS reset.
• NSC mode
This mode can be configured through TESS for compatibility reasons but will be treated as ASC.
• Non-GPS / Non-Synchronized mode
The Non-GPS / Non-Synchronized mode introduced in System Release D6.1 guarantees frequency
accuracy of the site reference and the introduction of a Network Time Server (NTS) using Network
Time Protocol (NTM) allows the MTS to operate in non-synchronized mode without being
characterized as a malfunction and with accurate frequency and Network time.
When the BTS is GPS non-synchronized and without GPS and if an NTS is available the NTP time
shall be used to maintain and adjust frequency stability, network time for UTC (Coordinated
Universal Time) and timestamps for BTS log.
If GPS is not available and an NTS is configured with IP address, the time derived from NTP shall
be used for UTC and time stamping of BTS logs.
If the selected NTS is of sufficient accuracy and the BTS is configured for “Allow NTS frequency
locking” the NTS is used for frequency locking of the Oven-Controlled Crystal Oscillator (OCXO), a
type of crystal oscillator used to control the frequency of transmitters, base stations, and other
communications equipment. The usability of the NTS is based on NTS alarm condition, Stratum,
Precision, root distance, reference ID, and reference time.
If GPS is not available and NTS is configured and allowed for locking and the BTS cannot establish
the connection to the NTS or the NTS is not usable for a period of more than an
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Chapter 4: Hardware Installation
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