November 11, 2019
1. The interface is idle.
ONU generally includes a variety of interfaces, such as FE interface, GE interface, POTS interface, WIFI and IPlV interface. In many cases, only part of the interface is used, and the interface is idle while consuming energy.
2. Increased energy consumption caused by chip module design.
In the design of ONU, modules are usually divided according to their functions and integrated on the same chip, which is controlled by an enabler. When power is supplied, the whole module needs to be supplied, and the unnecessary functional blocks are also consuming energy.
3. Processing OLT data.
Because of the broadcasting transmission characteristics of OLT, when OLT sends broadcasting information or sends information to a ONU, other ONUs that do not receive the information also need to process it, resulting in waste of resources.
4. Leisure monitoring.
For TDM-PON, each ONU can only send upstream data in burst mode in the slot authorized by OLT. OLT forwards downstream data in the form of broadcast frames, which makes all ONUs must be in operation at all times. ONU does not know when the user or OLT sends data to itself. The receiving and sending module keeps listening. When a 0NU has no up-link or down-link data for a long time, the normal running state will make it consume more energy.
5. Waiting time.
The structure of PON system decides to share channel capacity between ONUs in the upstream direction. PON system needs to adopt some arbitration mechanism to avoid collision. Each ONU allocates a slot to buffer the frames received from users first, and the slot can only be sent when it arrives.