The Evolution of Untethered Communications (1997) / Chapter Skim
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4 CONCLUSIONS AND RECOMMENDATIONS
4 CONCLUSIONS AND RECOMMENDATIONS
Pages 149-166
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From page 149... ...
4.1 HISTORY AND CHALLENGES OF WIRELESS COMMUNICATIONS Voracious consumer demand is stimulating many advances in commercial wireless communications technology, particularly cellular and cordless telephones. The portfolio of wireless services now available in the commercial marketplace includes a wide range of telephony, paging, and data applications delivered over a variety of service offerings ranging from land mobile radio to cellular to satellite communications.
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From page 150... ...
In the Gulf War, DOD used commercial wireless equipment such as GPS receivers and found that the performance was comparable to that of equipment designed explicitly to meet military needs. Yet current commercial technologies and practices cannot meet all military needs.
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From page 151... ...
Another objective is to advance the state of the art for software radios as a means of fostering economies of scale in R&D and manufacturing in a world of diverse and changing technical standards. By using multiple types of operating software, such radios can serve as single hardware platforms capable of transmitting and receiving signals that conform to a variety of standards.
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From page 152... ...
The first three focus on organizational changes, or meta-issues, that need to be addressed by DOD to help align military requirements with commercial products and services and provide an environment conducive to the absorption of state-of-the-art technologies. The other nine recommendations identify R&D projects that should be carried out by DARPA to advance the synergy between military and commercial systems while also meeting specialized military needs that will exceed anticipated commercial developments.
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From page 153... ...
Military planners need to maintain a continuing awareness of the difference between what is possible technically and what is available in the market to meet military needs. Because military requirements often exceed those of the commercial market, opportunities for the DOD to use commercial products depend on equipment details, which are reflected in standards.
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From page 154... ...
The Army is not building its own ATM switches, which are widely available in the private sector, but instead is developing high-speed encryptors and decrypters that are compatible with commercial switches. Military planners need to understand the thrust of commercial developments and identify critical technologies that are unlikely to emergesoon enough or ever from the commercial sector.
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From page 155... ...
As part of this process the DOD needs to develop the expertise necessary to translate its operational needs into requirements for commercially available equipment. Once the DOD identifies how best to use commercial technologies, cost-efficient acquisition strategies need to be pursued.
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From page 156... ...
4.5 MODELING AND SIMULATION 4. DARPA should build on current research in modeling and simulation to incorporate the communications traffic, mobility of network elements, and radio propagation encountered in mobile military information networks.
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From page 157... ...
This program includes a wireless component that could be enhanced to simulate the traffic, mobility, and radio propagation conditions of military communications. DARPA could also establish libraries of code representing communications waveforms, protocols, source coding techniques, and network interfaces.
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From page 158... ...
4.6 NETWORK ARCHITECTURE 5. DARPA should initiate research to produce network architectures that incorporate commercial products in a manner that meets military requirements.
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From page 159... ...
This is a complex task. As an example of the complex interdependence of algorithms and architecture, the design of effective routing techniques needs to aim for the following objectives: · Routing to maximize data rate, with minimum transport delay and minimum delay variance; · LPD/AT routing around vulnerable spots; · Routing for priority assignment and allocation of resources; · Routing for battery power conservation; · Routing for congestion avoidance; · Routing for access to servers for specific real-time applications; and · Routing to avoid anticipated propagation anomalies.
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From page 160... ...
However, current end-to-end encryption algorithms require considerable network overhead to establish the cryptographic synchronization. DARPA could seek improved methods of end-to-end cryptographic synchronization through multiple networks with lower overhead than is currently possible.
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From page 161... ...
This R&D would be timely because the full deployment of software radios operating in broad frequency ranges will depend on the development of techniques to overcome co-site interference and high-power inband interference. When serving several subscribers in the same band and mode at the same time, SINCGARS radios would experience significant interference.
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From page 162... ...
The multiple roles that can be played by software radios could have an impact on DOD's organizational structure, as services provided by individual organizations and procurements are combined in one system. Commercial software radios are likely to have more limited capabilities (e.g., changing signals and bandwidth on a single frequency)
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From page 163... ...
New DARPA research should be aimed at uniting the theory of adaptive modulation and coding with the emerging technologies of advanced software radios (Section 4.9) , which promise a practical means of implementing adaptive schemes.
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From page 164... ...
Both software radios and high-density platforms require advanced filters. Filters currently constitute 25 percent of the volume of a typical software radio and are used in receive preselectors, power amplifier output filters, local oscillators, and mixers.
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From page 165... ...
4.13 NOVEL COMPONENTS 12. DARPA should develop novel components to enhance the flexibility of software radios.
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From page 166... ...
Research on how to implement wide-dynamic-range analog circuitry monolithically with digital circuitry would provide the basis for implementing an entire software radio on a single component. Such an effort needs to encompass the monolithic implementation of high-performance filters that are tunable over large frequency ranges.
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