Joint Tactical Radio System (JTRS) Ground Mobile Radios (GMR)

By Barry Rosenberg-Macaulay

 The JTRS Ground Mobile Radios (GMR) program is working at an accelerated pace to stay in lock-step with the Army’s PEO Integration, which is targeting 2011 to deliver Increment 1 capability to nine Infantry Brigade Combat Teams.

A key part of those capabilities is the GMR four-channel National Security Agency (NSA) Type 1 and Type 2 certifiable software defined radio. The GMR operates over the Wideband Networking Waveform (WNW) and the Soldier Radio Waveform (SRW), as well as legacy waveforms that include: Single Channel Ground and Airborne Radio System (SINCGARS); Enhanced Position Location Reporting System (EPLRS); Ultra High Frequency Satellite Communication (UHF SATCOM); and High Frequency (HF).

The heart of GMR is the WNW waveform, which can re-route and re-transmit communications in non-line-of-sight situations to maintain situational awareness on the ground. It does this via mobile ad-hoc networking (MANET) capabilities that work in urban areas or terrain-constrained environments like that found in Iraq or Afghanistan.

“WNW is the primary application for GMR because it provides the network that everything else will communicate over,” said Army COL Gregory Fields, program manager for JTRS GMR. “That is particularly important in an area where our forces have knocked out all the communications before we go into a tactical area for operations, or our communication networks might not be established because the country lacks the infrastructure. So in those cases, one of things that GMR brings with it to the battlefield is its own mobile ad-hoc network.”

GMR Hardware/Waveforms
JTRS GMR is one of the five major programs within the JPEO JTRS Enterprise. GMR Increment 1 provides the ability to interoperate with legacy radios, in addition to providing higher capacity, highly networked communications that are integrated with the Global Information Grid.

Through software reconfiguration, JTRS GMR can emulate current force radios and operate new Internet Protocol-based networking waveforms offering increased data throughput utilizing self-forming, self-healing, and managed communication networks. The GMR route and retransmit functionality links various waveforms in different frequency bands to form one inter-network. GMR can scale from one to four channels supporting multiple security levels and effectively use the frequency spectrum within the 2-megahertz to 2-gigahertz frequency range.

JTRS GMR provides dual/simultaneous secure (secret) and non-secure communications on selected channels, or single-mode dedicated Top Secret only communications for all four channels. Although still evolving, the following military vehicle platforms are being targeted for use by the GMR system: Abrams battle tank, Bradley Fighting Vehicle, Stryker, Armored Personnel Carrier (M113), M1068, High Mobility Multi-Purpose Wheeled Vehicle, FMTV, MULE and ARV.

Ground Mobile Radio: 4-channel; SCA Compliant; 2 MHz to 2 GHz; Supports: WNW, SRW, SINCGARS, EPLRS, UHF & HF SATCOM

The major test of WNW over GMR took place this past summer and fall during a scheduled Systems Integration Test (SIT) at the Electronic Proving Grounds at Fort Huachuca in Arizona. The SIT was the first real test to be controlled by the federal government (specifically the Army Test and Evaluation Command (ATEC)), as opposed to the contractor. Up to this point, the contractor was in charge of all testing, according to Fields.

The test had two parts. The first focused on developmental testing to make sure the waveforms and the systems do what they were supposed to do from a design standpoint. The second part was the operational aspect, where Soldiers and Marines went through operational vignettes with the radio, conducting different tactical operation scenarios to shake out the functionality of the system.

The test at Fort Huachuca gave the GMR program the opportunity to discover new things about the program that did not arise during testing in the laboratory.

“I’ll be honest, we’ve been going through a test-fix-test scenario, said Fields. “One of the things you find out in the field is how the environment and terrain affect the operation of the waveforms. But given the complexity of the system, there is no other radio communications system out there that can do what this radio does, given the complexity of the crypto subsystem, the software, the operating system and the layers of other software applications that all have to work in conjunction with one another, as well as with the waveforms.”

Near-Term Roadmap
The next step for the JTRS GMR program is the Limited User Test (LUT) in 2011 at White Sands Missile Range in New Mexico. For the LUT, the radio will be installed on 35 platforms, primarily Humvees. During the LUT, Soldiers and Marines will communicate over all the new and legacy waveforms.

The GMR program wants to ensure it checks off a number of boxes coming out of the LUT. One is conducting information assurance testing to make sure the system is not vulnerable to a network attack. The LUT will also prove the GMR radios ability to conduct simultaneous communication.

“It is a four-channel radio that can operate with various configurations using a combination of those six waveforms, and I want to make sure that the system can actually perform and communicate simultaneously,” said Fields. “It is a complicated system so we also want to make sure that Soldiers and Marines can appropriately operate the system.”

Given a successful LUT, the GMR program will work toward a Milestone C decision also in 2011 so Low Rate Initial Production can begin for the initial systems earmarked for the Infantry Brigade Combat Teams. Longer term, the program will undergo Multi-Service Operational Test & Evaluation (MOT&E) to include Soldiers and Marines in late 2012. More than 100 GMR radios are scheduled to participate in MOT&E. After that, assuming the program receives a good report and rating, it will receive a full rate production decision from the Office of the Secretary of Defense.