Access to unlicensed spectrum has thus far been based on simplistic rules, such as a transmission power limitation, requirement for tolerance of interference, and a relaxed out-of-band transmission mask. Such rules originate from the rudimentary applications originally envisaged for such spectrum, which don't consider the current technical capabilities of radio devices. This paper introduces the concept of "ISMAdvanced", which incorporates Cognitive Radio capabilities into the rules for unlicensed spectrum access in ISM bands. It is argued and shown that the introduction of such capabilities can significantly improve the efficiency of spectrum usage, as well as the quality of service that is experienced by spectrum users. Moreover, constraints such as on transmission power can be relaxed under the proposed scheme, and the stability in performance of unlicensed spectrum can be improved. Among many other benefits, these characteristics facilitate use of unlicensed spectrum by quality-of-service-conscious telecommunication service entities such as cellular (LTE) operators, likely in aggregation with and supplementing their licensed spectrum.In view of the increased use and allocations being seen of unlicensed spectrum, it is suggested that the policies and technical rules that govern dynamic spectrum access in ISM bands be reviewed bringing them up to a level matching technical capabilities of modern radio equipment using Cognitive Radio technology.

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We introduce the concept of 'pluralistic licensing', which we describe as the award of licenses under the assumption that opportunistic secondary spectrum access will be allowed, and that interference may be caused to the primary with parameters and rules that are known to the primary at the point of obtaining the license. A key aspect of the concept is that the primary will choose from a range of offered 'pluralistic licenses' each with associated fees, and each specifying alternative opportunistic access rules and associated interference characteristics. Our proposal is a novel means to take forward spectrum licensing which is fair to both primary and secondary users and takes into account the requirements of both parties. The objective is to incentivize the primary to obtain this type of license through means such as a reduced license fee, whereby the opportunistic secondary spectrum access will use 'cognitive radio' mechanisms to avoid causing interference to the primary or to otherwise keep interference within known parameters. © 2012 IEEE

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The authors verify the benefits of directivity for a 4 × 4 multiple‐input multiple‐output (MIMO) system in a non‐line‐of‐sight indoor propagation environment. A novel prototype with four directive antennas has been designed to have full aggregate azimuth coverage, which is conveniently achieved without the need for electronic or mechanical beam‐steering. In this way, it captures similar multipath content to that of an equivalent omnidirectional device as confirmed by the field measurements. This coupled with the inherently larger gain of directive antennas renders the prototype a better choice for multi‐antenna receivers. The prototype design makes it possible to use a simple but effective power‐based antenna selection algorithm. Importantly, this algorithm achieves close to the theoretical maximum channel capacity when only two radio frequency chains are available at the receiver. For the first time, these results show that in an MIMO indoor environment directive receive antennas are a viable option.

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