With the global introduction of 5G, even though end to end phase synchronization requirements are still 1.5 microseconds, this is good for operators as it enables them to roll out services much faster. However, when it comes to the development of coordinated multi-point and intercellular carrier aggregation, things become a little more challenging. There are two reasons for this.
First, there are new requirements for front-hall phase synchronization of 130 nanoseconds between the distribution unit and the remote radio head. Even though this sounds difficult to overcome, it should not delay operators, if they choose highly accurate timing solutions that can meet evolving standards.
Secondly, the biggest obstacle will be the migration from CPRI (Common Public Radio Interface) to e-CPRI, especially if it’s done over new front-hall packet network and not the same PTP (point-to-point) fiber network that’s used in today's CPRI environment. Furthermore, e-CPRI is a much more distributed model that involves connecting the distribution unit and the remote radio head, and it also delivers phase synchronization through PTP. The number of PTP clients that a PTP grandmaster must support is not the number of broadband base units anymore. It is the number of remote radio heads that count as the PTP is terminated here and not at the broadband base units. As such, PTP grandmasters require far more scalability. There are two approaches to support these challenges.
The distributor approach uses a small grandmaster or integrated grandmaster. The operator deploys this in the distribution unit and then only needs this device to support the number of connected remote radio units, each as a PTP client, and this should only be in volumes of 10.
The centralized approach uses a much larger grandmaster as it clusters together many remote radio heads and distribution units, as such there are ultimately more PTP clients that need to be supported. This approach often uses a 10G interface. Both approaches have their benefits and there is no one size fits all.
Dynamic Engineers offers high performance TCXOs such as TCXO911BTLG_series and TCXO914BTLG_series which are designed for synchronization within a 5G environment. For additional information regarding 5G synchronization or other RF / microwave topics, please contact your local Dynamic Engineers sales representative or Inquiry@DynamicEngineers.com