Navy puts satellite broadband platform to the test

Flexible modem technology stands up to rigorous testing during joint exercise

A series of rigorous tests at an event in which all branches of the military participated earlier this year validated certain pivotal technologies designed to deliver and enhance broadband satellite communications.

During the Joint Users Interoperability Communications Exercise (JUICE) held at Fort Monmouth, N.J., and at military installations across the world, the Space and Naval Warfare Systems Command (SPAWAR) put cutting edge military-grade satellite modem technology through its paces. The event brought personnel from all branches of the military together for the purpose of testing the latest communications technology applicable to a Joint Task Force operational environment.

SPAWAR had previously tested a satellite broadband platform provided by iDirect Government Technologies (iGT) in a lab environment with five simulated ships connected over satellite to a single hub platform. In the JUICE 2009 testing, a Digital Video Broadcast – Satellite - Second Generation (DVB-S2) modem was placed aboard the Navy vessel USS Wasp, which connected via satellite back to the hub system in Portsmouth, Va.

“The military environment is unique,” said David Glovier, SPAWAR support contractor and co-owner of Pinnacle Network Systems that supported the testing. “Often, commercial products are adapted for military purposes and don’t work as well as advertised because the military environment includes Type One (I) encryption, Advanced Encryption Standards (AES) 256 coding and other layers not used quite as rigorously in the commercial world,” he said.

“But the testing was very positive,” Glovier added.

SPAWAR tested iGT’s implementation of DVB-S2 over Deterministic Time Division Multiple Access (D-TDMA). Though originally developed for video transmission over satellite, DVB has been adopted in data platforms to simultaneously transfer voice, video and data traffic.

D-TDMA exploits the sporadic nature of Transmission Control Protocol/Internet Protocol traffic by dynamically assigning time slots in a satellite channel between sites sharing the same bandwidth. The D-TDMA system continuously monitors traffic patterns and demands, allocating bandwidth to remote sites based on their needs at a given time.

Navy personnel are often concerned that aircraft carriers or any high consumer of bandwidth could consume the entire channel leaving little room for other vessels to transmit, Glovier said. The iGT platform allows for the configuration of group quality of service policies that ensure each remote is provided with an absolute minimum amount of bandwidth as well as their share of the unused bandwidth, based upon the policy provided by the network owner. The system can also be configured to impose quality of service profiles, allowing for the prioritization of one remote site over another or to provide bandwidth guarantees on an application basis. This allows for applications to be given special treatment, such as guaranteeing the performance of real-time services, such as voice over IP.

The technologies demonstrated at JUICE 2009 present optimum performance capabilities for the Navy or any other branch of the armed forces, according to military and contractor officials. Ships distributed across a broad geographic region can share the same satellite capacity. Ships can connect to the platform at varying transmission rates depending on their local conditions, such as local atmospheric interference, without negatively affecting other ships in the same network. For example, a single ship experiencing rain fade does not bring down the data rate of other sites on the same satellite segment.

The iGT DVB-S2 system performed as well at JUICE on the Wasp as it did previously in lab testing, Glovier said. The testing showed that “traffic surges up to 8 or 9 Mbps per remote vessel are possible over 6.5 Mhz of spectral bandwidth using 16APSK8/9 (amplitude phase-shift keying), versus a typical QPSK 3/4 (quadrature phase-shift keying) normally used in this environment,” Glovier said.

“Ships often see extreme weather conditions,” said Glovier. “Worst case, a ship can drop back to QPSK 1/2,” reducing its transmission rate in response to local conditions, he said. Ships in the same network but in other geographic areas with more favorable atmospheric conditions need not drop their receive rates.

In related tests conducted at JUICE, soldiers in a communications-on-the-move vehicle traveling at speeds up to 65 mph were able to conduct a live videoconference with Fort Monmouth and a Joint Task Force Forward Operating Base without interruption in transmission.

Another scenario was a simulated disaster that rendered the Fort Monmouth network unavailable. The iGT Global Network Management System switched the network connection from the failed site to the backup hub in Portsmouth, Va., automatically and seamlessly.

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