News and Notes for Our Industrial Partners
April, 2008
FEATURE STORY
EFJOHNSON IS NEW AFFILIATE
We are happy to announce that EFJohnson has joined W@VT as our newest affiliate. EFJohnson provides two way radios and trunked/conventional communication systems for law enforcement, fire fighters, EMS, and the military. The company was one of the first developers of wireless communications products to be fully compliant with Project 25 interoperability standards. EFJohnson offers a comprehensive portfolio of solutions to assist in effectively and affordably managing the transition to digital P25 compliant systems.
NEW VERSION OF OSSIE NOW AVAILABLE
OSSIE Version 0.6.2 Available for Free Download
Wireless@Virginia Tech (http://wireless.vt.edu) is pleased to announce that OSSIE version 0.6.2 is available for free download at http://ossie.wireless.vt.edu.
OSSIE is an open source Software Defined Radio (SDR) development effort based at Virginia Tech. OSSIE is primarily intended to enable research and education in SDR and wireless communications. The software package includes an SDR core framework based on the JTRS Software Communications Architecture (SCA), tools for rapid development of SDR components and waveforms (applications), and an evolving library of pre-built components and waveforms. In addition, free laboratory exercises for SDR education and training are being developed in cooperation with the Naval Postgraduate School and are used in graduate SDR courses at both institutions.
Features of OSSIE 0.6.2
OSSIE 0.6.2 has been installed on PCs running Fedora Core 7 or 8 Linux, but can be ported to other Linux or Unix based operating systems. Wireless@Virginia Tech plans to release a version of OSSIE with enhanced support for embedded as well as PC based applications in the fall of 2008 featuring:
- Simplified installation
- ALF, a new waveform visualization and debugging tool, donated by SAIC, that includes capability to display components that make up a waveform, and their ports and connections
- Plugin tools for applying signals and monitoring response of components or waveforms
- Capability to run individual components as stand-alone waveforms
- Capability to connect a port on a component in one waveform to a port on a component in another waveform
- Ability to monitor throughput of components developed with support for this feature
- An updated version of the OSSIE Waveform Developer (OWD) that includes support for developing Python components and for developing components with timing support for use with ALF
- The ability to save and reuse node configurations for multiple waveforms
Components for OSSIE 0.6.2
OSSIE 0.6.2 is supplied with a demonstration waveform that simulates a simple QPSK system. The components that make up the waveform can be used as a model for modifying existing OSSIE 0.6.1 components to work with OSSIE 0.6.2. A Component Update Guide is also available. Laboratory/tutorial exercises for OSSIE, developed in cooperation with the Naval Postgraduate School, are available, along with additional components, devices, and node configurations.
Where to download OSSIE 0.6.2
OSSIE 0.6.2 is can be downloaded as follows:
VMware image: http://ossie.wireless.vt.edu/download/vmware (after decompressing file, see README file for user id and passwords). This image can be run using the free Vmware player (www.vmware.com/download/player) and is a quick way to try out OSSIE. Source code: http://ossie.wireless.vt.edu/download/tarballs (README contains installation instructions for Fedora Core 7 and Core 8 operating systems. Instructions are also found in User Guide.) User guide and Component Update Guide: http://ossie.wireless.vt.edu/download/user_guides
Questions?
Feedback or questions can be addressed to ossie-discuss@listserv.vt.edu .
Acknowledgments
Thanks to the OSSIE team for all their work on the release, and to our sponsors for their continued support. OSSIE is supported in part by the National Science Foundation under Grant No. 0520418. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. Additional sponsors of OSSIE related projects include ETRI, the Laboratory for Telecommunications Sciences, the Office of Naval Research, SAIC, Tektronix, Texas Instruments, and the U.S. ARMY CERDEC.
RECENT EVENTS
MANETs in the Wild: The MANIAC Challenge 2007
Armed only with laptops, intrepid student explorers hunted this past November in what was possibly the world’s most uncooperative ad hoc network — and still managed to bag an elusive, six-hop route.
Undergraduate and graduate student teams gathered from seven universities to generate a first-of-its-kind mobile ad hoc network (MANET) and to compete for glory in its uncharted territory. The Mobile Ad Hoc Networking Interoperability and Cooperation Challenge (MANIAC) was organized by Wireless@Virginia Tech’s Luiz DaSilva and Allen MacKenzie and held in conjunction with the IEEE Globecom 2007 conference in Washington, D.C. It was the first of at least two such competitions, funded with a three-year grant from the National Science Foundation (NSF).
Teams competed from Auburn University, Bucknell University, The George Washington University, the Technical University of Kosice in the Slovak Republic, the University of North Carolina at Charlotte (UNCC), The University of Puerto Rico at Mayaguez, and Virginia Tech.
Seeking a natural habitat
The competition’s goal was to generate interest in the field among students, while also providing one-of-a-kind opportunities to study actual, uncontrolled, ad hoc networks, where users make their own decisions regarding tradeoffs between self-interest and common network goals.
Although the technology is imminent, MANETs do not currently exist outside of tightly controlled laboratory environment and military deployments, according to MacKenzie. “Questions linger about how well MANETs will work in the wild. Are simulation results reported in the literature too optimistic about performance that can be achieved in these networks?” he said.
The MANIAC Challenge was the first large, multi-hop MANET that was spontaneously formed in a natural habitat, according to DaSilva. “We have a need in this field for data from an ad hoc network that is not controlled by any single research group. We want to see what happens when we don’t control every node and the different nodes may have different, and probably conflicting, interests,” he said.
The November competition focused on cooperation in routing and packet forwarding.
Cooperation is one of the biggest issues surrounding MANETs, DaSilva said. For a stable MANET to exist, all nodes must cooperate, but still retain some selfish behavior in order to achieve their own goals. “Will users of wireless ad hoc networks trade off bandwidth, signal strength, or speed to ensure system effectiveness? If so, how? What incentives will get users to provide services — such as forwarding and routing — to other nodes?”
Strategic selfishness
Each team controlled two laptop nodes on the network. MANETs are based on the premise of users sporting different hardware and software, so the only requirements were that the laptops have 802.11 capabilities and run the MANIAC API and OLSR as the routing protocol.
Strategy played a large role in the competition and teams were evaluated on the creativity of the strategy employed. As a group, the participants wanted to create a robust MANET and hoped to spot elaborate, multi-hop routes. However, each individual team wanted to acquire the highest number of intended packets.
To encourage both cooperative and selfish behavior, MANIAC teams were awarded 10 points for every packet they received that was intended for them, but every packet they forwarded to another team cost them a point. Source nodes for each team were not part of the cooperative network, but issued packets and sniffed the network to capture its topology.
The strategies were predominantly selfish and ranged from extremely simple to very sophisticated. Most teams tried to drop packets that would give other teams points, but maintain their reputation so that other nodes would still send them packets. “This was probably the unfriendliest ad hoc network in the world,” commented DaSilva at the conclusion of the contest.
“We were evil,” admitted a member of the Auburn team. “We dropped every packet with a final destination for the next node.” Dropping next-node packets was a popular strategy with the other teams as well.
Part of the George Washington team strategy involved being unfriendly to nodes that were not in their direct path — not matter how cooperative that unrelated node was. Part of their strategy also included physically positioning their nodes close to sources.
The UNCC team strategy involved a simple, randomized forwarding strategy they called “Keep it Sweet and Simple.” The Bucknell team based their strategy entirely on probablilities. Among other tactics, the team also limited how many packets it would send to each node, not allowing any node to take more than half their time.
As the host school, Virginia Tech’s team was not eligible to win, but offered the most cooperative strategy, which they called “the generous tit for tat strategy.” Based on basic game theoretic strategy – like Bittorrent does – the strategy was to cooperate with nodes who cooperated with them and to avoid blacklisting any particular node. “Those who were dropping any packets with one hop were not going to be successful with us. Only if they forward one of ours to us can they be noted as friendly,” explained Ryan Irwin.
“Live and let live” wins for creativity
The team from Kosice won first place in creativity for their “live and let live” strategy; “Their strategy was ingenious,” commented MacKenzie. The Kosice strategy included manipulating the routing protocol itself to prevent traffic for other teams from being directed towards their devices.
“We were hoping to see the teams come up with fairly simple strategies that when you put it all together would lead to reasonably efficient outcomes for the whole” MacKenzie said. “They didn’t do the things we expected, but that was part of the fun of it,” he added.
“Everybody decided to be a bad guy,” DaSilva said. “This confirms the prisoner’s dilemma.” The prisoner’s dilemma is a classical game theory situation in which two players who may cooperate for gain, or betray the other to go free, typically choose to betray each other, even though this result is inefficient for both parties.
But did it work?
During the competition runs, teams roamed throughout the lower two floors of the Washington Hilton, while the non-network source nodes remained stationary. Many of the teams roamed, looking to be near certain sources or just for better placement in the network.
The network had the common stresses of any wireless network with interference and non-users trying to gain access. In spite of the hostility of the nodes, a complex topology appeared, with the greatest hops measured at 6, which is extremely rare.
“I’m surprised it worked,” DaSilva said. “So many things can go wrong — these networks are pretty fragile. This was less fragile than I expected. This doesn’t mean they are robust networks, however.”
The UNCC team was almost always the multipoint routing node and took first place in the performance runs. The Bucknell team — the only team of undergraduates — came in second.
“The most fun was to see people actually enjoying participating in an experiment of this type,” said DaSilva. “Getting students and faculty excited about something like this is an intangible, but it’s very important in moving the research forward.”
He cited evidence of growing enthusiasm among the participants. “We had undergraduates here and their advisors report there is now a higher probability they will continue in the field and perhaps get a higher degree.” Also, the Kosice team has written a conference paper on their strategy and participation.
DaSilva and MacKenzie are preparing for MANIAC Challenge II, which will focus on power control and spectrum usage.