N101-099 TITLE: Spectrum Agile Network Distributed Subcarrier Allocation

TECHNOLOGY AREAS: Information Systems

ACQUISITION PROGRAM: JPEO JTRS _ network Enterprise Domain - ACAT I

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: Define candidate space-time-frequency distributed algorithms and protocols for the physical, MAC, and network layers in a network for manipulating the spectra of OFDM wireless networks nodes in response to degradations observed geographically within the network and within its spectrum. The result will be agile subcarrier allocation strategies for improving mobile military wireless mobile ad-hoc OFDM performance in response to local time-varying spectrum disturbances.

DESCRIPTION: Military wireless networks such as WNW-OFDM need to be able to respond and appropriately adapt to a dynamic electromagnetic environment. The OFDM Mode offers the potential to modify subcarrier allocations in response to environmental challenges given the proper protocols for distributing the responses, which lets the network adapt in a stable fashion. Commercial wireless OFDM cellular networks with fixed infrastructure base stations, towers, cell size, frequency, etc., have an advantage over military networks without fixed infrastructure of a strong central control and the potential to distribute any desired spectrum changes, but do not generally offer this possibility since it would result in changes and degradations to the user interface. Indeed commercial OFDM standards such as IEEE 802.16 cover a wide variety of anticipated commercial users from low data rate voice users to high rate data and video users with vastly differing assigned bandwidths and some preliminary work has addressed mobility and non-contiguous OFDM. IEEE standards continues to develop and incorporate new protocols addressing cognitive radio standards, non-contiguous subcarrier usage, increasing ground mobility and less infra-structure.(e.g., 802.22). However the problem of distributed network control specifically for decentralized geographically dispersed (military) networks continues to be an area that is not well known with known papers only looking at non-applicable solutions such as using GSM (2).

When perfected, spectrum sensing and dynamic spectrum access technologies (see for example references 3, 4, 5, and 6) are expected to be significant enablers of commercial and military wireless networks. The research requested here is intended to look at how subcarrier arrangement strategies can solve electromagnetic problems, and then look at how that strategy/algorithm can be shared and distributed in a non-centralized network.

PHASE I:
1) Establish a state-of-art baseline in subcarrier allocation and net control technology, referring to the 802.22, 802.16xx standards as a minimum.
2) Synthesize candidate dynamic subcarrier allocation strategies and algorithms for OFDM based wireless WNW networks experiencing a variety of possible link conditions including geographically localized narrowband/partial band interference, time varying channels with frequency selective fading, strong neighbor interference and shadowing. The solutions should consist of cross layer subcarrier allocation in the SiS, MDL, MI, & Network layers as well as communicating with neighboring nodes and maintaining network stability.
3) Test/evaluate and rank the candidates in terms of performance benefit, ease of implementation and compatibility with WNW-OFDM architecture.
4) Generate a technology insertion plan for insertion of the winner candidates into WNW.

PHASE II: Develop, demonstrate and validate Phase I selected candidate algorithms and protocols. Revisit the Technology Insertion Plan from Phase I and update it to reflect the current version of WNW. Build a test environment to demonstrate the recommended solutions including their network behavior for stressing environments appropriate to exercise the solutions. Update the net convergence and stability properties of the algorithms based on testing if necessary.

PHASE III: Transition the implementation to the JTRS software environment, inset into WNW, and perform development tests. The software generated in this project is subject to NSA approval prior to incorporation into a JTRS radio, which will have national security requirements and impacts to the vendor. Phase III will include the necessary Information Assurance features for this approval. Phase III will also incorporate JTRS APIs as an application software package for JTRS sets. In addition, the software generated in this project is planned to be incorporated into the JTRS Enterprise Business model, which allows JTRS vendors to utilize common software.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: OFDM and its variants (OFDMA, SOFDMA, etc) is used by both military and commercial wireless systems. The techniques developed as part of this SBIR will be directly applicable to improving the performance and affordability of commercial mobile networks.

REFERENCES:
1. IEEE Standard 802.16e-2005

2. Implementation of a Low Cost Wireless Distributed Control System using GSM Network
Ganegedara, K.M.T.N.; Jayalath, J.A.R.C.; Kumara, K.M.K.; Pandithage, D.N.U.; Samaranayake, B.G.L.T.; Ekanayake, E.M.N.; Alahakoon, A.M.U.S.K.; Industrial and Information Systems, 2008. ICIIS 2008. IEEE Region 10 and the Third international Conference on 8-10 Dec. 2008 Page(s):1 - 6

3. Ekram Hossain and Vuay Bhargava, "Cognitive Wireless Communication Networks", Springer Verlag, 2007

4. Rakesh Rajbanshi, Wyglinski, A.M, Minden, G.J.,Subcarrier Power Adjustment Technique for Peak to Average Power Ratio Reduction of OFDM Systems, MILCOM 2006, 23-25 Oct, pp 1-6.

5. A channel estimation method for NC-OFDM systems in cognitive radio context Shichang hang; Jun Wang; Shaoqian Li; Communication Systems, 2008. ICCS 2008. 11th IEEE Singapore International Conference on 19-21 Nov. 2008 Page(s):208 - 212 6

6. Robust End-to-End QoS Maintenance in Non-Contiguous OFDM Based Cognitive Radios
Mwangoka, J.W.; Ben Letaief, K.; Zhigang Cao; Communications, 2008. ICC '08. IEEE International Conference on 19-23 May 2008 Page(s):2905 - 2909

KEYWORDS: OFDM, wireless, distributed, JTRS-WNW, MANET, dynamic subcarrier allocation, cognitive radio

** TOPIC AUTHOR (TPOC) **

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