Description and Rules

1. Introduction
What is the DARPA Spectrum Challenge?
The DARPA Spectrum Challenge is a competition to demonstrate a radio protocol that can best use a given communication channel in the presence of other dynamic users and interfering signals. The Challenge is not focused on developing new radio hardware, but instead is targeted at finding strategies for guaranteeing successful communication in the presence of other radios that may have conflicting co-existence objectives. The Spectrum Challenge will entail head-to-head competitions between your radio protocol and an opponent's in a structured testbed environment. Using a standardized radio hardware platform, the team that finds the best strategies for guaranteeing successful communication in the presence of other competing radios will win.
Why is DARPA interested in spectrum usage?
Radios are used for a wide range of tasks, from the most mundane to the most critical of communications, from garage door openers to military operations. As the use of wireless technology proliferates, radios can often compete with, interfere with, and disrupt the operations of other radios. DARPA seeks innovative approaches that ensure robust communications in such congested and contested environments. Other factors that motivate the need for intelligent use of spectrum include:
  • High priority radios in the military and civilian sectors must be able to operate regardless of the ambient electromagnetic environment, to avoid disruption of communications and potential loss of life.
  • Rapid response operations, such as disaster relief, further motivate the desire for multiple radio networks to effectively and efficiently share the spectrum without direct coordination or spectrum preplanning.
2. Eligibility and Application
The Spectrum Challenge is open to any U.S. academic institution, business, or individual entity. An applicant may be an individual competing alone or a team representing an academic institution, business, or group of individuals. In the latter cases, only one application per team should be submitted. The person identified as the team leader must be a U.S. citizen or permanent resident (green card holder) at time of registration and throughout the competition. Other team members need not be U.S. citizens or permanent residents.
The following requirements apply to Spectrum Challenge applications:
  • Each team must identify the team leader and all team members on the application form.
  • Individuals may be members of only one team.
  • There is no limit on the number of teams an academic institution or business may enter, but a maximum of three teams per entity will be accepted as contestants (please see the Participation section below for more details on becoming a Challenge contestant).
Applications may be withdrawn at any time by emailing the Challenge mailbox at spectrumchallenge@darpa.mil. Questions regarding eligibility and participation should be directed to the Challenge mailbox.
The following groups of individuals are not eligible to participate in this Challenge: 1) employees of the U.S. Government, including spouses and dependents for tax year 2013; 2) DARPA employees and support contractors and their immediate families; 3) employees of Federally Funded Research and Development Centers (FFRDCs); 4) current Rutgers University employees and students; 5) current and former WINLAB employees and students; and 6) current WINLAB industrial affiliates.
3. Participation
All interested Spectrum Challenge contestants must fill out the DARPA Spectrum Challenge Application Form electronically through the Spectrum Challenge website at www.darpa.mil/spectrumchallenge. Validated applications will receive an email be acknowledgment from DARPA. The application period closes at 12:00PM EST January 31, 2013. Shortly after the application period, all valid applicant teams will receive detailed instructions via email for performing a three-step qualification process. This marks the beginning of a 3-week qualification period during which applicants will vie for 1 of approximately 14 contestant slots. Valid applications received after the application period ends will receive the instructions for the qualification process on a first-come, first-served basis. Applications received after the qualification period ends may not be considered if all contestant slots are filled.
During the qualification period, applicants will be required to complete a series of hurdles to demonstrate proficiency in using software-defined radios and GNU radio development tools (see www.gnuradio.org). The top-performing approximately 14 applicants who complete the exercises during the qualification period may move on to become contestants in the Preliminary and Final Challenge events. These contestants may be eligible to receive a radio development kit (RDK) and limited travel funds on a needs basis. All remaining applicants who have completed the qualification hurdles are eligible to compete for a limited number of wildcard slots in the Challenge events. Wildcard teams may participate in the Challenge and develop radios just like the contestant teams; however, shortly before the Preliminary Challenge event, each wildcard team radio will be tested, and the top performing teams will become tournament contestants for the Preliminary and Final Challenge events (See details on wildcard selection process below).
The number of contestants and wildcard positions cited above are tentative. DARPA, at its discretion, may adjust the number of contestants accepted during the qualification period and the number of available wildcard slots, if any, depending on the number of applications received. DARPA anticipates approximately 16 contestants for the Challenge events.
4. Spectrum Challenge Rules
The goal for each team is to design a radio that will transmit the contents of a designated file from one node to another node as quickly as possible. The Spectrum Challenge is a head-to-head competition to demonstrate the radio’s ability to operate in the presence of interfering radio signals, from both other competitors and “house” emitters. Contestants may design their radios using any available resources, but should be cognizant of the hardware and software configuration that will be used for the actual competition (see below).
The Setup
To focus the competition on development of radio waveforms and protocols, all competitions will use identical radio hardware hosted by Rutgers University WINLAB ORBIT radio grid testbed (see http://www.orbit-lab.org). Each contestant will be assigned a pair of radios on the grid, onto which they will load their software for the competition. The hardware and software used by ORBIT will be specifically described in the RDK. Contestants may develop radios using any desired hardware and software; however, the radios used during the competition will be identical to those in the RDK. Details of the RDK and performance criteria will be supplied to all contestants following the qualification period and will include limitations regarding the use of the embedded field programmable gate array (FPGA) and the requirement to include several supplied software modules to serve as hooks for monitoring purposes
The Competition
The Spectrum Challenge competition will consist of Preliminary and Final events, scheduled roughly 6 months apart. Multiple practice sessions will be made available so contestants can test the performance of their algorithms prior to the formal events. All testing will take place via remotely accessing WINLAB’s (Rutgers University) ORBIT radio grid testbed. Details on remotely accessing the testbed will be provided.
During each event, two types of tournaments will be held – a competitive tournament that rewards individual behavior, and a cooperative tournament that rewards group behavior. All teams are expected to compete in both tournaments.
Each team will be given a fixed amount of data to transmit between two communication nodes. Each “match” is played between two or more contestant teams over a fixed time period. All radios are required to operate in the same designated frequency band. In the competitive tournament, contestant teams are scored individually on their ability to successfully transmit all their data from one radio to another faster than the other contestants. In the cooperative tournament, multiple contestants are scored as a group on their ability to efficiently share the designated spectrum with other users. In all matches, other radios or radio frequency emitters may be present in addition to those of the contestants.
Competitive Tournament: : In each match, pairs of teams will utilize the same frequency band to simultaneously attempt to transfer a given data file from one of their radios to the other. The match continues until both teams have successfully transmitted their data or a specified maximum time is reached. While interfering with other contestants’ transmissions is not required, it is an acceptable tactic to prevent them from finishing first.
The team that transfers all data bits without errors in the shortest time is the winner. If no team completes the transfer error-free in the specified time, the winner is the team that successfully transfers the most error-free bits; the shortest transfer time will be used to break ties.
The tournament will be structured as a double elimination bracket with each team guaranteed at least three matches, as depicted below. The team that makes it all the way through the bracket is the tournament winner.
Cooperative Tournament: In each match, the goal is to share the specified spectrum with three other contestant teams whose radio characteristics are not known. Teams will be scored as a group of four players. Each player p, is given an equal amount of data D to transmit between their two radios. The match ends at time t once every player in the group has successfully transmitted all their data or once the maximum time T is reached (where t = T). The group score S(G) is a weighted average of the total time t of the match and the amount of successful data received rp by each player p.
This tournament will be structured as a round robin with an elimination round and a playoff round. In the elimination round, each team will be grouped with combinations of three other teams, such that all teams have a chance to play a match with all other teams (five matches per team). For each match, all teams in the group receive the same group score, but each team accumulates its own total score over the five matches. At the end of the elimination round, the six highest scoring teams advance to the playoff round. A similar process is used in the playoff round, except the six teams play in all combinations of groups of four. Each team accumulates a total score over its 10 matches and the team with the highest total score in the playoff round is the tournament winner.
To illustrate the process, the figure below depicts the tentative tournament schedule. The elimination round has five match mixes (A-E), each consisting of four team groupings (w-z). For each match, all teams within a group receive the same score. For example, for mix A, teams 5, 6, 7 and 8 would receive the score S(A,x). When all mixes have been played, team 5’s score would be S(A,x) + S(B,w) + S(C,x) + S(D,y) + S(E,z). If team 5 is in the top six scores, it advances to the playoff round, and accumulates a new score over ten matches. The winner is the highest total scoring contestant team in the playoff round.

Wildcard Team Selection
If there is a wildcard process, selection of the wildcard teams will take place approximately 4 weeks prior to the Preliminary Challenge tournament. At that time, each wildcard team’s radio pair will be individually loaded onto the ORBIT grid. The radio link will attempt to transfer the contents of a designated file from one node to the other, in the presence of unknown interfering signals. The interference signals will be the same for all wildcard teams. The teams that complete the file transfer the fastest, without errors, will be selected as tournament contestants. If no team completes the transfer error-free in the specified time, then teams will be ranked based on the number of error-free bits successfully transferred and the shortest transfer time will be used to break ties. The number of available wildcard team slots will be determined by DARPA during the initial qualification period.
5. Tournament Location
Preliminary and final tournaments will be held at the DARPA Conference Center in Arlington, Virginia where all contestants are welcome to attend to view the competition as it happens on the ORBIT testbed. The testbed will be instrumented to capture operational characteristics for each radio during a competition. Data will be streamed to video monitors, so contestants can see the performance of their radios in real time.
6. Prizes
The Spectrum Challenge will award cash prizes to the winner of each tournament in the Preliminary and Final events. Winners of the competitive and cooperative tournaments in the Preliminary Challenge event will each receive $25,000, and winners of the competitive and cooperative tournaments in the Final Challenge event will each receive $50,000.
The prize money will be transmitted by electronic funds transfer to the bank account specified by the leader of the team determined by DARPA to be the winner of each tournament. If the winner is a team, it is the responsibility of the team leader, not DARPA, to determine the subsequent division of any prize money.
Tax treatment of prizes will be handled in accordance with U.S. Internal Revenue Service guidelines. The recipient must provide an appropriate U.S. taxpayer identification number (e.g., social security number, employer identification number, etc.). The awardee will be contacted by DARPA at time of award to provide the necessary information. The recipient should consult a tax advisor to ensure that the prize money is handled properly and reported accurately for tax purposes.
If DARPA is unable to contact a winning contestant within 72 hours after the announcement of the winner, DARPA may award the prize to the runner-up.
7. Additional Information
The Challenge is authorized under 10 U.S.C. § 2374a, which authorizes the Secretary of Defense to award prizes in recognition of outstanding achievements in basic, advanced, and applied research, technology development, and prototype development that have the potential for application to the performance of military missions of the Department of Defense. Award of the Spectrum Challenge cash prize is contingent upon Congress renewing 10 U.S.C 2374a.
The rules apply to all contestants in the DARPA Spectrum Challenge and may be changed without prior notice. Contestants should monitor the Challenge website for the latest information.
Registration information collected by DARPA will be used solely for the purpose of administering the event. Registration information will not be distributed to any parties outside of DARPA nor released for any other purpose except as noted in this document.
Applicants’ names and affiliations may be listed on the Spectrum Challenge website to enable the event to be tracked by interested members of the public. The names and photographs of the winners may be posted on the DARPA website and released to the media.
DARPA may contact registered contestants to discuss the algorithms and techniques used by their radio design. Nothing in these rules, including information on the Spectrum Challenge website and communications by DARPA officials, may be interpreted as authorizing the incurrence of any costs or modifying the statement of work or authorizing work outside the terms and conditions of any existing agreements or contracts with DARPA.
DARPA claims no rights to intellectual property developed as a result of participation in the Spectrum Challenge.
DARPA reserves the right to disqualify a contestant whose actions are deemed to violate the spirit of the competition for any reason, including, but not limited to, the violation of laws or regulations in the course of participation in the Challenge. DARPA does not authorize or consent to contestants infringing on any U.S. patent or copyright while participating in the Challenge.
DARPA may cancel or modify the Spectrum Challenge without notice.
The DARPA Director is the final decision authority for all matters concerning the Spectrum Challenge.
By registering and/or participating in the Spectrum Challenge, contestants agree to follow these rules and to hold harmless and release the U.S. Government from any and all liability and costs arising from the contestant’s participation in the Spectrum Challenge.
The appearance and reference to any person, name, place, film, artwork or any other images that are used in connection with the Spectrum Challenge does not constitute or imply endorsement by the U.S. Government, Department of Defense or DARPA.
Questions regarding the rules, privacy policy, or other aspects of the Spectrum Challenge may be directed to spectrumchallenge@darpa.mil.
8. DARPA Spectrum Challenge Qualification Hurdles
After a Challenge application is submitted, applicants will receive detailed instructions for performing a three-hurdle qualification exercise. Upon completion of each step, instructions for the next step will be provided. The hurdles are designed such that each step requires more effort and proficiency. The qualification period will run for approximately 3 weeks. Applicants are to complete the first two hurdles as quickly as possible to provide maximum time on the third hurdle, which must be submitted by the end of the qualification period. Hurdle 3 will require teams to design and implement a radio with certain characteristics, whose performance will be quantitatively assessed on the ORBIT testbed. The top-performing teams will become the Challenge contestants. Teams that are not among the top contestants may be eligible to compete for wildcard spots and, ultimately, compete in the Preliminary and Final Challenge tournaments. The number of top teams and wildcard spots will be determined shortly after the qualification period.
Details of the hurdles will not be revealed to applicants until the end of the application period, at which time all valid applicant teams will receive instructions via email at the same time. Applications received after the application period will receive instructions as soon as the applications are validated.
The following is a general description of the three qualification hurdles:
Hurdle 1
Demonstrate the ability to access ORBIT during a specified time slot, image a node with a given image file and execute a tutorial on the node. Upon completion, instructions for Hurdle 2 will be sent to the team leader.
Hurdle 2
Demonstrate an understanding of the basic principles of wireless communications and familiarity with Universal Software Radio Peripheral and GNU radio software tools by properly configuring and executing a basic transmitter/receiver system on a pair of radios on the ORBIT grid. Upon completion, instructions for Hurdle 3 will be sent to the team leader.
Hurdle 3
Build a radio pair (transmitter and receiver) that can properly perform in the presence of interference. Teams will be provided a baseline transmitter and receiver implementation. Using these transmitter and receiver modules as starting points, teams must write their own transmitter and receiver modules that can transfer the most error-free packets in the presence of a specified interference environment. Teams must submit one final version of their radio pair by the end of the qualification period.