HF Radio


Supporting Mobile Unit mobility between HF Networks

Icon-Topo supports Mobile Unit (MU) mobility between HF Networks, enabling application communications over a wider area than can be achieved with a single ground station.


Icon-Topo provides a Web interface that allows the operator to monitor and control the location of MUs, scheduling the movement of MUs. This information is then used to control the configuration of applications and HF components to provide efficient communication. A detailed description of Icon-Topo is provided in the whitepaper [Supporting Mobile Unit mobility over multiple HF Networks using Icon-Topo]



Icon-Topo manages the following types of system:

  1. Mobile Unit (MU).  This is something moving around with HF Communication. An MU is typically a ship or an aircraft.
  2. HF Access Point (HFAP). This is a ground station that is transmitting and receiving HF. This may include broadcast HF.
  3. Fixed Application Routing Entry Point (FAREP). This is a node to which entities that are not aware of MU location send messages to. The FAREP will send messages to the MU through the correct HFAP. Each MU is assigned to a single FAREP.

Configuration and scheduled changes are managed by the Icon-Topo Configuration Server, which provides a Web interface to the operator with appropriate authorization. Icon-Topo information is stored in a directory accessed by LDAP (Lightweight Directory Access Protocol) which is replicated to all systems.

Icon-Topo Update Server runs on each system, and updates the following Isode applications according to the configured schedule:

  • M-Switch (all nodes). Updates routing information to support both Email and MMHS services, including moving MUs between ACP 127 broadcast services.
  • M-Link (all nodes). Updates XMPP routing information.

Operator View


The Icon-Topo operator UI provides a forms interface to configure the managed entities and to schedule movement of MUs. It also provides a flexible Map UI to visualize MU and HFAP location and to facilitate scheduling of MU Movement.


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