Dynamic Spectrum Access (DSA) Systems are one of the most promising technologies available to increase the range and efficiency of spectrum dependent services. DSA systems locate unused spectrum, and organize their users to operate within the spectrum they have identified. DSA systems ensure no interference to other users by scanning and sensing the environment, as the Defense Advanced Research Projects Agency (DARPA) NeXt Generation spectrum sharing field tests have established, or through pre-existing knowledge, such as the geolocation database proposed for unlicensed access to TV band white space, or a combination of both. Reported experimental results to date have shown that the promises from DSA technology are realistic and achievable.
Additionally, recent research has shown that DSA has significant benefits, for both licensed and unlicensed users, even if a service has more than sufficient spectrum. These advantages derive from improvements in network scaling, increased density and, potentially, actual reductions in the cost of equipment, compared to equivalent performing, non-DSA systems. Even with relatively unlimited spectrum, there are strong advantages to using DSA; therefore advocacy for DSA need not be constrained to only those who seek additional spectrum access. For example, there are strong reasons to believe that DSA technology can address the intractable problems of co-site interference, such as those driving the NEXTEL spectrum relocation. Denser, more crowded spectrum will likely make these situations more common.
In summary, DSA affords two benefits:
- It provides for increased density, better system management, and inherent in-channel and co-site interference resolution; and,
- It enables opportunistic access to the spectrum for uncoordinated sharing of spectrum on a non-interference basis.
A number of communities are advocating for DSA in order to leverage the technology to introduce a variety of new services or products in what appears to be underutilized and potentially shareable spectrum. Not surprisingly, incumbent spectrum users have been generally hostile to the introduction of shared devices within spectrum they are dependent on for services, operations, or revenue. Therefore, they have been hostile to regulatory acceptance of DSA.
There have been several preconceptions about DSA that appear to have become a “conventional wisdom” and which run through the dialog regarding how to best achieve acceptance and deployment of DSA Systems. Belief in these preconceptions may cause advocates of DSA to overlook potential partners in advocating for the technology. In particular, while there is tension between the advocates and military authorities in considering sharing spectrum within the United States, there may be mutual interest in obtaining access for DSA devices internationally. Similarly, while public safety interests might fear the introduction of DSA devices within “their” spectrum, demonstration that DSA offers increased performance, responsiveness, and density to public safety networks may make DSA a desirable technology to these communities.
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