Army Tests WiMax Mobility

Tests have shown military value for the latest version of the wireless
standard, which offers high data throughputs while moving at high speeds.

By Michael Burnett
 

With responsibility for analyzing how to adapt commercial wireless technologies to the Army's tactical environment, engineers at the Commercial Wireless Branch of the Army Communications-Electronics Research, Development, and Engineering Center (CERDEC) have been closely following developments in WiMax wireless technology in recent years.

The branch is actively involved in evaluating and experimenting with emerging wireless technology to see how the Army could best use it to boost its communications capabilities. So CERDEC officials last year arranged a trial of WiMax technology with Samsung, which had become the first company to introduce products using the latest WiMax standard.

WiMax, or Worldwide Interoperability for Microwave Access, provides wireless data over long distances while augmenting the capabilities of previous wireless communications on the 802.x standard established by the Institute of Electrical and Electronics Engineers.

Companies have refined WiMax, developed under the 802.16 standard, to the point where it is capable of delivering broadband connectivity, defined as 802.16E. WiMax now offers capabilities to achieve high data throughputs of up to 10 megabits per second while moving at high speeds.

Samsung became the first company to offer commercial products at the 802.16E standard. As such, the Army has become very interested in the technology's promise to share satellite communications capability in a defined area while moving in a convoy or between other vehicles.

Seth Spoenlein, CERDEC systems engineer, headed up the project for the Samsung field evaluation, which ended last August. The results of the WiMax trials impressed CERDEC a great deal, Spoenlein reported.

"The military tactical environment is very unique. A lot of times, commercial hardware and the like do not meet our unique requirements. We look at how the technology may be placed in our use-case scenarios and how it performs," Spoenlein explained. "We went to Samsung because they were the first vendor to have an 802.16E product line."

The Army has been using WiMax technology for about two years, but that technology is defined by the 802.16D standard, which allows broadband access at fixed locations only. Adding the ability to hand off communications between WiMax terminals moving from location to location is very attractive to the Army, which often must move supplies and personnel across various distances with maximum flexibility.

Satellite Integration

In the WiMax trial, CERDEC took three Samsung bay stations and mounted them into Humvees, and then ran a satellite link to the WiMax hub as the backhaul. Spoenlein believes it was the first time satellite was ever used with WiMax, which posed some integration challenges.

The first of the integration challenges dealt with size, weight and power issues. The equipment was larger than the Army would've liked initially, although it has shrunk in size since its introduction. But the biggest problem came from trying to share the satellite link between the WiMax users.

"Satellite has inherent delays associated with it that are not found in fiber connections. There were some issues with getting that to work," Spoenlein noted.

The challenges of working with satellite were not due to Samsung's technology, but rather the Army's learning curve on configuring the new technology for best implementation in its tactical environment, suggested Sharon Mackey, chief of the Commercial Wireless Branch at the CERDEC Space and Terrestrial Communications Directorate.

"Some of these unique challenges deal with requirements in the tactical environment," Mackey stressed. "We are going to be using satellite, and a number of the systems have security issues. We are going to investigate how we can deal with these issues. Samsung's equipment was not designed to hook right into our network. So we are going to evaluate the pros and cons of these technologies and for those things that are not perfect, we will examine how to mitigate those risks to provide service to the warfighter within the tactical environment."

Still, CERDEC officials are convinced the Army would benefit greatly from widespread use of WiMax. The Army has been moving from circuit-based designs to network-centric capabilities, and WiMax certainly aids in that goal. WiMax gives the Army the capability to decrease the time required to establish communications, reducing setup times and increasing mobility, Mackey explained.

"It will also allow us to mix wireless and wired technology. As wireless shrinks its requirements in weight and power, that reduces the amount of hardware that's required when we deploy. You want to reduce the size, weight and footprint of our operations in the tactical environment," Mackey commented.

"The individually dismounted warfighter lacks the ability to communicate over band communications that promote mobility and physical collaboration. We are evaluating these technologies to see how we can use these wireless applications to do quick setup on location until we have a larger infrastructure in place," she continued.

Commercial WiMax offers a great deal of promise for meeting these goals, because its pending proliferation will ensure a wide selection of products at affordable prices, Spoenlein said.

Open Ecosystem

Samsung was quick to embrace the 802.16E standard-bearer for the future of broadband in recent years, making more submissions to the standards committee than any other contributor, said Rick Svensson, director of WiMax sales at Samsung Telecommunications America.

"We saw this as the direction that industry would be heading-the open network and the low cost of entry to promote a big ecosystem with lots of chipsets and device vendors," Svensson elaborated. "This is a 180-degree turn from things like ITN, which was Motorola proprietary technology, and CDMA from Qualcomm, which was not entirely proprietary but had a high cost of entry, to the GSM world, which became the predominant standard for the cellular industry in the past few years."

Now hundreds of manufacturers will transition to making devices for an open ecosystem under WiMax much as they did for GSM, Svensson declared. That growth sparks interest from governments and militaries worldwide as the cost of adopting the new technology falls with competition and widespread use.

Svensson anticipates wider adoption of mobile WiMax by Samsung when the company introduces its service via Sprint in the spring.

"Interoperability is key. We have done a lot of interoperability testing on our next-generation product. It is the standard that is here. It's like having WiFi everywhere without the pain of WiFi-having to log in everywhere and figuring out where to find the service. This would have robust coverage and have fees similar to the WiFi network," Svensson added.

"The CERDEC guys were impressed they could take Samsung's commercial gear and strap it onto a Humvee and it still worked. It is not always possible to do that. They can't always take commercial gear and treat it the way they do in the tactical environment and have it still work," he said.

Sean Ham, Samsung director of radio frequency engineering, agreed, reporting that WiMax performed "surprisingly well in the tactical environment" for the CERDEC trials.

"The Korean military also has a contract with Samsung for actual implementation. We have a contract and we are working on that tactical environment for systems for the Korean Army," he remarked. "It is being commercialized and deployed in Korea. One of the operators is Korea Telecom. We have a commercial network that is up. We launched it last year and we have served it to the customer."

WiMax promises throughput of 5-10 megabits per second on the downlink for individual users, Ham observed. The CERDEC trials, however, often operated with constrained bandwidth capacity, which contributed to the satellite communications problems.

"One of the things that was a challenge for this environment was the use of satellites. That could result in a limitation in bandwidth. It was throttling down the capability of the system with the bandwidth they had available," Ham recalled. "There also were some latency issues during the trial. We had to change some parameters to accommodate a greater window due to the latency. Those were some of the things they were looking at when they did their trial."

Sameeran Das, a Samsung engineer, acknowledged that satellite latency was a significant problem to emerge from the CERDEC trial. But he noted that the WiMax devices worked well with any bandwidth constraints that existed.

"I would add that our system took a very low overhead. That was a great thing for CERDEC. It helps if the overhead is very low when bandwidth is very low," he said.

Rapid Adoption

Ed Bursk, chief marketing officer for LGS Innovations, also reflected on issues with integrating WiMax into the Army's tactical environment.

"I don't speak for the Army and I can't speak to other vendors' concerns in terms of implementing, but we anticipate no issues there," Bursk commented. "There is no inherent issue in terms of the WiMax equipment and the WiMax standards interfacing with satellite.

"I think that is more an issue of are you used to integrating satellite communications into your other modes of communications-whether it's wireless, fixed line, etc. We have had a lot of experience with that, including international deployments with the U.S. government," he continued. "There should be no issue in the long term with satellite communications. I would categorize any issues as integration teething problems."

LGS Innovations, headquartered in Vienna, Va., is a subsidiary of Alcatel-Lucent. The company is a leading provider of WiMax technologies, offering solutions under the brand name Evolvium.

"Our parent company, Alcatel-Lucent, is rolling out today to commercial carriers. We have carriers standing up as we speak. We have already announced 17 different carrier implementations, and there will be dozens following that," Bursk said. "We feel there is a tremendous amount of promise here because you have high data rates, quality of service, the ability to do voice over IP and high speed data simultaneously, and mobility so you can have his in a military vehicle driving along at 50 miles per hour and have high speed data and broadband that you couldn't have before."

Military forces can set up a satellite dish and pop up a WiMax antenna next to it to form "a bubble of WiMax" around a particular area or a convoy, Bursk said. That sort of configuration should become commonplace as the technology rolls out, expanding the range of military mobile IP communications up to miles away for mobile assets.

Alcatel-Lucent has supplied some WiMax services to international governments and their militaries, Bursk stressed. While the U.S. government is in trials now, a fairly rapid acceleration of adopting the technology should occur in 2008 and 2009. Government trails should wrap up in 2008, and then the United States will likely deploy WiMax into select exercises and then widespread operations.

"A nice thing about mobile WiMax is that our approach is to have an open ecosystem in terms of interoperability testing with the various terminal devices, whether they be PC or PDA cell phone-type devices," Bursk stated. "You have this ability to have this commercial technology that has carrier-grade reliability, which is what Alcatel-Lucent is all about-super high reliability as well as being cost effective.

"We have a dozen partners we are acting with on the terminal side, so you will have a lot of different devices and types of applications that will be supported in this ecosystem. We feel it is a pretty good fit. You are not stuck with specialized terminal devices but you can use commercial off the shelf stuff as well if you like," he added.

Hardened Systems

Fujitsu, meanwhile, plans to release mobile WiMax products and services within the next several months. With the WiMax rollout, Fujitsu will aggressively market services beyond its home country of Japan, with the U.S. Department of Defense as a primary target customer.

"We are focused on the really small high-power highly linear amplifier stuff for the products that we are releasing. This is stuff that would be great for the military. They are hardened outdoor systems that you could throw up on a post in the middle of a battlefield and have it act as a central station," said Jim Orr, Fujitsu principal network architect for network communications. "It's beneficial for the military and rapid-fire deployment of commercial systems as well."

The military does have special needs concerning battlefield security and communications, Orr acknowledged. One reason the 802.16D Fixed WiMAX standard never caught on more at DoD is because of the department's aggressive move toward Internet Protocol version 6 (IPv6), which is not native to the 802.16D specification. The 802.16E specification does have native IPv6, however.

As for security, Orr said Fujitsu has some solutions in mind, but declined to discuss them at press time for reasons of company competitiveness and confidentiality. He explained, however, that a common approach to increasing WiMax security involves the use of external appliances.

"When you deal with external appliances, you have a nasty habit of interfering with the quality of service controls built into WiMax," he elaborated. "So there has to be some level of negotiation between military requirements and commercial costing that has to go on inside of the military. To gain the full benefits of WiMax, you have to let it be a volume commercial system, and you can't put a lot of military requirements on it."

Fujitsu also plans to improve the WiMax low probability of intercept (LPI) profile.

"The LPI is the probability of a hostile force picking up the bitstream and taking it over," Orr said. "In its native form, WiMax is not necessarily built to assume that someone is trying to take it over. A hostile entity with the horsepower to do this can intercept your system. The control channel for WiMax is too predictable in terms of the LPI profile. So there is some work to be done there to make sure that matches the military's expectations as well."

Fujitsu also has tackled the same kind of delays associated with satellite communications that were encountered in the CERDEC trials. In a typical wireless network configuration, a bay station controller talks to dozens or hundreds of bay stations, deciding which users are assigned to which bay stations as the users move about the network. Many bay station controllers are separate from bay stations, but military tactical operations basically require some level of integration between the two devices.

"For WiMax to work over a satellite, its version of the bay station controller must be collocated or integrated with the bay station. That's the sensitive time delay issue there. It's not 'spec'd' to handle satellite lags of three seconds or more. To break that would be detrimental to the rest of the system," Orr said. "They are looking for the bay station controller or parts of it to be collocated with the bay station. That is a known issue. We intend to participate in that part of the market, and we have a solution for it."

WiMax networks have two different network configurations because of these issues. WiMax Profile A involves a network with the highly integrated bay station controller, while WiMax Profile B refers to remote bay station controllers. WiMax Profile B is suitable for base modernization or other efforts that do not involve soldiers, vehicles or other elements moving through a tactical space, but Profile A solutions are appropriate for tactical environments.

Mobile WiMax technology has yet to actually receive certification from the WiMax Forum, of which Fujitsu is a founding member, Orr reported. Testing for certification of products from all companies is scheduled to being in the spring. ♦