Sharing Spectrum Through Spectrum Policy Reform and Cognitive Radio

Abstract

| Traditionally, interference protection is guaranteed through a policy of spectrum licensing, whereby wireless systems get exclusive access to spectrum. This is an effective way to prevent interference, but it leads to highly inefficient use of spectrum. Cognitive radio along with software radio, spectrum sensors, mesh networks, and other emerging technologies can facilitate new forms of spectrum sharing that greatly improve spectral efficiency and alleviate scarcity, if policies are in place that support these forms of sharing. On the other hand, new technology that is inconsistent with spectrum policy will have little impact. This paper discusses policies that can enable or facilitate use of many spectrum-sharing arrangements, where the arrangements are categorized as being based on coexistence or cooperation and as sharing among equals or primary-secondary sharing. A shared spectrum band may be managed directly by the regulator, or this responsibility may be delegated in large part to a license-holder. The type of sharing arrangement and the entity that manages it have a great impact on which technical approaches are viable and effective. The most efficient and cost-effective form of spectrum sharing will depend on the type of systems involved, where systems under current consideration are as diverse as television broadcasters, cellular carriers, public safety systems, point-to-point links, and personal and local-area networks. In addition, while cognitive radio offers policy-makers the opportunity to improve spectral efficiency, cognitive radio also provides new challenges for policy enforcement. A responsible regulator will not allow a device into the marketplace that might harm other systems. Thus, designers must seek innovative ways to assure regulators that new devices will comply with policy requirements and will not cause harmful interference.

Detecting Selfish Behavior in a Cooperative Commons

“…If it proves to be viable, the cooperative commons could provide a valuable and radically different approach to the deployment of wireless infrastructure and the management of spectrum [1][2][3]. A block of spectrum could be allocated for shared use by any and all wireless devices.…”

“…First, a regulator or license-holder may allocate a spectrum band in which a device can only be deployed if it cooperates as part of a cooperative commons [1,2]. Second, a cooperative commons may form in today's unlicensed bands, if enough people choose to participate, although with this approach, the cooperative commons must contend with some unlicensed devices that are not part of the commons.…”

“…A number of commercial companies, such as Meraki in San Francisco [10] and non-profit organizations, such as NetEquality Equal Access Community Internet [5], and the Champaign-Urbana Community Wireless Network [6], have pursued this approach [7]. Third, devices in a cooperative commons may share spectrum with the existing licensed primary spectrum user, and operate as secondary devices [1,2]; secondary devices may cooperate both to avoid harmful interference to the primary, and to carry each other's traffic. Many researchers have suggested this approach using cognitive radio system (e.g.…”

“…Moreover, this can lead to far greater spectral efficiency [3,11], perhaps alleviating the shortage of available spectrum [3]. However, there are serious security challenges associated with the cooperative commons [1,2], some of which are addressed in this paper.…”

“…First, because any device is allowed to join the cooperative commons, devices must cooperate with and carry traffic for other devices, even though these devices do not serve the same administrative domain [1,2]. This leads to many challenges.…”