IP & Legacy TDM

In Aviation and other Industries, there's a technology change moving from Legacy Communications to Internet Packets (IP). This is Analogue/Time Division Multiplexing (TDM - timeslot) to packet based Asynchronous operation. Telecom Service Providers are phasing out TDM leased lines and replacing TDM with IP Networks. In the UK, BT's Kilostream (64Kb/s) Megastream (2048Kb/s) TDM services were withdrawn, 31Mar2020.

FTI has solutions for TDM Systems to enable migration of these proven Legacy Comms Systems to IP Networks. Aviation organisations such as Eurocontrol and the Federal Aviation Administration are mandating interoperability requirements, to meet the forecast growth in air travel. Systems based on IP Networks are seen as having greater resilience than TDM, because of the distributed network intelligence, greater functionality and flexibility. Security, performance, configuration, access, monitoring, optimisation, verification of IP Networks for critical infrastructure are the main goals.

Time-division multiplexing (TDM) was designed in early 50-s to carry voice calls. This technology reserves dedicated portion of network capacity for each voice connection, achieving constant delay during conversation. It is important, because humans are sensitive to delays during conversation. Unfortunately, reserved capacity cannot be used for other applications, if there is no voice traffic. That is one of the biggest TDM limitations, and technology of 50-s was not able to overcome it.

Ethernet network in turn does not ensure constant propagation delay, because latter is not required by most data applications. Thus, Ethernet and other packet-based networks make better utilization of available network capacity, as no part of total capacity is constantly reserved for voice calls. Many operators still nowadays rely upon TDM networks as their transmission backbones, because these networks have reliably served over the years delivering voice, telemetry and data traffic. However, the future of communication networks is no doubt IP/MPLS, because TDM networks cannot support steadily increasing capacity demand by new applications.

Therefore, most network operators and utility providers running TDM networks have migrated their communication infrastructure to IP/MPLS or will be implementing upgrades in the next few years.