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5. Multi-hop
In the conventional HD-PLC, two PLC terminals were to communicate directly. On the other hand,
the multi-hop technology of the HD-PLC can expand the range of the communication area by
having a relay function among the nodes. As shown below, even when communication cannot be
directly performed, by using multi-hopping, communication can be performed by relaying other
terminals.
Master
Even when communication
cannot be made directly,
communication can be
performed by relaying via
other terminals.
In order to realize multi-hop communication, we use the routing protocol CMSR (Centralized
Metrics based Source Routing).
It is a routing protocol that always selects the optimal route by periodically exchanging "HELLO
message" between nodes.
This protocol has the following features.
1. The amount of traffic is overwhelmingly smaller than general proactive routing.
2. Message length can be greatly reduced. In other methods, there is a possibility that the
bandwidth will be exceeded only by the routing traffic, so it is difficult to handle multiple units.
3. Since there is sufficient communication bandwidth, it can be shared with various
communications.
4. It is an international standard as ITU-T G.9905. (Approved in August 2013)
5. Scalable protocol for large scale systems supporting 1,024 units.
6. Stable route generation taking account of multiple metrics such as received signal strength and
time fluctuation as well as the number of hops can be ensured, and transmission condition
change followability can be secured.
7. Since the route is selected with bidirectional link quality, stable communication is possible in
various environments.
Terminal
Terminal
(Hopping)
Direct communication not possible
48
DA-PU100 Series Administrator's Manual
One Master can take 1: N: N
form.
Terminal
Terminal
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