As the commercialization of LTE-TDD and LTE-A accelerates, there is a growing need for time synchronization on base stations. Traditionally, the GPS and PTP solutions were used on base stations to implement time synchronization.
The GPS solution requires GPS 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, GPS antenna can properly receive data from GPS 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 GPS 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 GPS timing system is introduced to NetEngine 8000 Fs. Specifically, an Atom GPS module which is comparable to a lightweight BITS device is inserted to an NetEngine 8000 F to provide GPS access to the bearer network. Upon receipt of GPS clock signals, the Atom GPS module converts them into SyncE signals and then sends the SyncE signals to NetEngine 8000 Fs. Upon receipt of GPS time signals, the Atom GPS module converts them into 1588v2 signals and then sends the 1588v2 signals to base stations. This mechanism greatly reduces the TCO for carriers.
The PTP device type supported by an Atom GPS 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 GPS module supports the delay request-response mechanism, which is the PTP link delay measurement mechanism. Configuring this mechanism is not supported.