N121-062 TITLE: Spectrally Compliant Waveforms for Navy Communication Systems

TECHNOLOGY AREAS: Information Systems

ACQUISITION PROGRAM: PMW 160, Tactical Networks

RESTRICTION ON PERFORMANCE BY FOREIGN CITIZENS (i.e., those holding non-U.S. Passports): This topic is "ITAR Restricted". The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120 - 130, which control the export of defense-related material and services, including the export of sensitive technical data. Foreign Citizens may perform work under an award resulting from this topic only if they hold the "Permanent Resident Card", or are designated as "Protected Individuals" as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign citizen who is not in one of the above two categories, the proposal will be rejected.

OBJECTIVE: Develop spectrally compliant communication signals that are capable of making coherent use of fragmented spectral bands to maximize data rate with minimal compromise in transmission efficiency.

DESCRIPTION: Evolving Navy applications require continually increasing communications data rates which, in turn, require corresponding increases in communications spectral bandwidths. Growing spectral crowding caused by expanding commercial and military radio frequency (RF) usage, however, makes it necessary to share the available designated spectral bandwidths with other systems. Increased spectral bandwidth generally exacerbates the degree of conflict with other systems due to spectral crowding. To co-exist with expanding commercial and other military RF systems, it is necessary to identify the sub-bands occupied by these other systems and confine the communication signals to sub-bands that are free of such conflict. Beside the need for sufficient isolation among the sub-bands used for communications and neighboring sub-bands used by competing systems, the challenge also exists to maximize the data rate by operating coherently through a fragmented spectrum, and by maximizing the transmission efficiency and the corresponding signal-to-noise ratio by optimizing the peak-to-average-power-ratio (PAPR), thereby helping to minimize the error rate. Communication systems that attempt to increase the data rate by generating parallel independent transmissions in different sub-bands, suffer unacceptable PAPR. In extreme cases this PAPR can be so high that the transmitted signal through the broad band fragmented spectrum cannot even match the throughput of un-fragmented narrower band channels. To maximize efficiency this topic seeks innovative techniques that utilize the fragmented spectrum in a coherent fashion as a single transmit channel and generate corresponding high data rate signals of constant amplitude. The techniques developed are also required to adjust the communication signals in near-real-time so as to effect timely adjustments to changes in application radio frequency (RF) environments.

PHASE I: Define and develop one or more alternate concepts for communication waveforms capable of utilizing fragmented spectra as a single, coherent, constant amplitude, or near-constant amplitude channel. Analyze the performance of each developed technique in terms of data rate, error rates, transmitter efficiency and channel isolation. Compare the techniques against existing techniques and quantify the performance differences. Analyze the implementation issues and determine the theoretical feasibility of each technique in steady and varying RF environments. Develop a Phase II plan with tasks and milestones to demonstrate the concept(s) of Phase I.

PHASE II: Produce prototype hardware based on Phase I communication system analysis in the Phase II plan. Mechanize the waveform generation scheme and demonstrate its performance in a controlled environment. Generate a number of alternative sets of such waveforms across several different notional fragmented spectra. Validate the selected technique, or techniques, by implementing the selected waveforms in the communication system prototype, together with a more conventional technique, and demonstrating its advantages. The work in this Phase may require access to classified information.

PHASE III: Should a Phase III contract be awarded, the company will build upon the results of the Phase II effort, further refine the validated communication technique, automate it, and prepare it for insertion into a candidate communication system. Insert the technology into suitable candidate communication system identified by the Navy and effect transition of the new communication technique into that system.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Commercial applications include communication systems utilized by all branches of the DOD, FAA, Homeland Security, etc.

REFERENCES:
1. IEEE Standard 802.16d-2004

2. IEEE Standard 802.16e-2005

3. Gulliver, T. and Felstead. E., "Anti-jam by Fast FH NCFSK-Myths and Realities', IEEE Milcom'93, Oct. 1993, 187-191

KEYWORDS: Communications; Waveforms; Spectral-Compliance; Fragmented Spectra; Spectral Crowding; Sub bands

** TOPIC AUTHOR (TPOC) **

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