On the scalability of cognitive radio: assessing the commercial viability of secondary spectrum access

We report results from the recently finished QUASAR project, which has studied overall system aspects of cognitive radio technologies and has paid attention particularly to the economic viability of different use cases. We find that successful secondary sharing goes far beyond the detection of spectrum holes. Large-scale commercial success requires that secondary systems are scalable so that a large number of users can be served in an economically viable fashion. Our key finding is that secondary spectrum use is not an attractive method for most of the commercially interesting scenarios, from neither a business nor technical perspective. Perhaps somewhat surprisingly, the likely commercial “sweet spot” for secondary sharing in the lower frequency bands is short-range indoor communications. We also find that regulation does not currently present a significant barrier in Europe or the United States.

Introduction

Wireless communications has become a ubiquitous part of our society, and the ever increasing number of services and applications rely on availability of robust and cost-efficient wireless access. The commercial success of mobile and wireless access to the Internet has been monumental. At the same time, customer-installed non-mobile networks such as WiFi are becoming gradually more congested due to increased interference and demand. Wireless access technology has practically become viral - so that this rapid development will continue also in the foreseeable future. Recent studies predict at least 25-to 30-fold increase in global mobile data traffic in five years. Furthermore, various machine-to-machine (M2M) applications and services have begun to gain footholds.