As the commercialization of LTE-TDD and LTE-A accelerates, there is a growing need for time synchronization on base stations. Traditionally, the GNSS (GPS/GLONASS/Beidou) and PTP solutions were used on base stations to implement time synchronization.
The GNSS solution requires GNSS antenna to be deployed on each base station, leading to high TCO. The PTP solution requires 1588v2 support on network-wide devices, resulting in huge costs on network reconstruction for network carriers.
Furthermore, GNSS antenna can properly receive data from GNSS satellites only when they are placed outdoor and meet installation angle requirements. When it comes to indoor deployment, long feeders are in place to penetrate walls, and site selection requires heavy consideration due to high-demanding lightning protection. These disadvantages lead to high TCO and make GNSS antenna deployment challenging on indoor devices. Another weakness is that most indoor equipment rooms are leased, which places strict requirements for coaxial cables penetrating walls and complex application procedure. For example, taking security factors into consideration, the laws and regulations in Japan specify that radio frequency (RF) cables are not allowed to be deployed in rooms by penetrating walls.
To address the preceding challenges, the Atom GNSS timing system is introduced to NetEngine 8000 Fs. Specifically, an Atom GNSS module which is comparable to a lightweight BITS device is inserted to an NetEngine 8000 F to provide GNSS access to the bearer network. Upon receipt of GNSS clock signals, the Atom GNSS module converts them into SyncE signals and then sends the SyncE signals to NetEngine 8000 Fs. Upon receipt of GNSS time signals, the Atom GNSS module converts them into 1588v2 signals and then sends the 1588v2 signals to base stations. This mechanism greatly reduces the TCO for carriers.
An Atom GNSS module supports only GE optical interfaces and the 1000M full duplex mode. It does not support the adaptive mode.
The PTP device type supported by an Atom GNSS module can be boundary clock (BC) or telecom boundary clock(T-BC). A BC or T-BC has multiple clock interfaces. On a BC/T-BC, one interface is used to implement time synchronization with upstream devices, and other interfaces (passive interfaces excluded) are used to transmit time information to downstream devices.
By default, an Atom GNSS module supports the delay request-response mechanism, which is the PTP link delay measurement mechanism. Configuring this mechanism is not supported.