148 1. La representación del pasado y presente en redes sociales: el caso de Twitter
7. Conclusiones
1.36.1 LBFD-00300501 Clock Source Switching Manually or Automatically
Availability
This feature is available from eRAN1.0.
Summary
This feature enables manual or automatic switching between clock sources.
Benefits
If unexpected events occur in the current clock sources, the system will not be affected.
Description
The eNodeB can work in multiple clock synchronization modes. The system clock source can be chosen in a convenient and flexible manner. When one clock source fails, the system clock can be manually or automatically switched to another available one.
The eNodeB clock sources that can be selected are as follows:
Synchronization with Ethernet(ITU-T G.8261)
Synchronization with the clock over IP (IEEE1588V2)
Synchronization with the clock over IP (Huawei proprietary solution)
Synchronization with GPS
Synchronization with the BITS
Synchronization with E1/T1 interface
Synchronization with 1PPS
In addition to the previous clock sources, the eNodeB can work with the local oscillator.
Enhancement
None
Dependency
None
1.36.2 LBFD-00300502 Free-running Mode
Availability
This feature is available from eRAN1.0.
Summary
The free-running mode is an alternative mode to the clock sources if all clocks fail.
Benefits
When all clock sources are lost, this feature can keep the eNodeB in normal service for up to 90 days.
Description
When all clock sources are lost, the eNodeB internal clock can work in the free-running mode to keep the eNodeB free-running.
The enhanced stratum 3 Oven Controlled Crystal Oscillator (OCXO) with a high accuracy works as the master clock of the eNodeB. The OCXO can keep the eNodeB in normal service for up to 90 days.
Enhancement
None
Dependency
None
1.36.3 LBFD-00300503 Synchronization with GPS
Availability
This feature is available from eRAN1.0.
Summary
The eNodeB can work in multiple clock synchronization modes to suit different clock topologies. Global Positioning System (GPS) can be one of the
synchronization sources.
Benefits
This feature provides GPS as one of the synchronization sources. The eNodeB internal clock can be synchronized with the transport network and no auxiliary clock equipment is needed, in order to reduce the cost. The synchronized clock is of the required accuracy to meet both radio frequency and transmission network requirements.
Description
In compliance with 3GPP, the eNodeB clock must have a higher clock precision.
The frequency stability of the 10-MHz master clock of the eNodeB should be lower than ±0.05 ppm.
It is required if a GPS clock should be used as the clock source.
The clock signals are processed and synchronized as follows:
The GPS antenna and feeder system receives GPS signals at 1575.42 MHz, and transmits the signals to the GPS card. The system can simultaneously trace up to eight (normally three or four) satellites. The GPS card processes the signals and transmits them to the main clock module.
Enhancement
None
Dependency
GPS antenna and feeder system
Optional USCU (Universal satellite Card and Clock Unit) card.
1.36.4 LBFD-00300504 Synchronization with BITS
Availability
This feature is available from eRAN2.0.
Summary
The eNodeB can work in multiple clock synchronization modes to suit different clock topologies. Building Integrated Timing Supply System (BITS) can be one of the synchronization sources.
Benefits
This feature provides BITS as one of the synchronization sources. The eNodeB internal clock can be synchronized with the transport network and no auxiliary clock equipment is needed, in order to reduce the cost. The synchronized clock is of the required accuracy to meet both radio frequency and transmission network requirements.
Description
In compliance with 3GPP, the eNodeB clock must have a higher clock precision.
The frequency stability of the 10-MHz master clock of the eNodeB should be lower than ±0.05 ppm.
The eNodeB can synchronize its clocks with the 2-MHz clock signal from an external reference clock. The reference clock can be a BITS or a 2-MHz clock from the transmission equipment. Through phase locking and frequency dividing, the main clock module converts the clock signals into various clock signals required by the eNodeB.
Enhancement
None
Dependency
Optional USCU (Universal satellite Card and Clock Unit) card.
1.36.5 LBFD-00300505 Synchronization with 1PPS
Availability
This feature is available from eRAN2.0.
Summary
The eNodeB can work in multiple clock synchronization modes to suit different clock topologies. 1PPS can be one of the synchronization sources.
Benefits
This feature provides 1PPS as one of the synchronization sources. The eNodeB internal clock can be synchronized with the transport network and no auxiliary clock equipment is needed, in order to reduce the cost. The synchronized clock is of the required accuracy to meet both radio frequency and transmission network requirements.
Description
In compliance with 3GPP, the eNodeB clock must have a higher clock precision.
The frequency stability of the 10-MHz master clock of the eNodeB should be lower than ±0.05 ppm.
This feature provides 1PPS as one of the synchronization sources.
Enhancement
None
Dependency
Optional USCU (Universal satellite Card and Clock Unit) card
1.36.6 LBFD-00300506 Synchronization with E1/T1
Availability
This feature is available from eRAN2.0.
Summary
The eNodeB can work in multiple clock synchronization modes to suit different clock topologies. Synchronization with E1/T1 is one option.
Benefits
This feature provides synchronization with E1/T1 option. The eNodeB internal clock can be synchronized with the transport network and no auxiliary clock equipment is needed, in order to reduce the cost. The synchronized clock is of the required accuracy to meet both radio frequency and transmission network requirements.
Description
In compliance with 3GPP, the eNodeB clock must have a higher clock precision.
The frequency stability of the 10-MHz master clock of the eNodeB should be lower than ±0.05 ppm.
The clock source of the eNodeB can be synchronized with the E1/T1 line clock sources. When the S1 interface is over E1/T1, the eNodeB can be synchronized with the E1/T1 line clock.
Enhancement
None
Dependency
Optional UTRP(Universal Transmission Processing unit) card