Packet Microwave
Somewhere between 50-60% of backhaul links globally are microwave links, with the majority of the remainder fibre, and some remaining copper links.
Microwave topologies can vary depending on resources and sites available, in tree, ring, chain/star and meshed formations. Traffic is then loaded onto MPLS trunking rings at aggregation points. Links can be over 1-2km up to long haul links of 100-200km in some circumstances. Ring protection or link protection switching is applied to ensure resiliency in the case of disruption to links.
Packet Microwave Ethernet switches map Ethernet packets onto the radio airframe, sometimes converting T1/E1 input into Ethernet output.
Some Packet Microwave solutions are, as their name suggests, IP only. But where operators still need to support legacy TDM architectures, hybrid microwave solutions add support for native TDM. In the LTE networks, the output from the base station is packets (Ethernet frames) that can be directly fed into an Ethernet port on the packet microwave switch.
The payload is divided into airframes, along with data for link management, management and Forward Error Correction (FEC) that enables the radio to self-correct a certain number of propagation-induced errors. The more FEC bytes added, the more errors corrected, giving a better receiver threshold performance but at the expense of radio throughput (cf Aviat Networks).
In order to achieve higher capacities across links, vendors apply higher modulation to the waves, sometimes adding the ability for systems to increase or decrease modulation dependent on conditions (interference) in the network (cf Ceragon).
