LTE–U/LAA and Spectrum Sharing - Coexistence Principles in the Unlicensed Spectrum Bands

Abstract

The FCC issued a Public Notice on May 5th, 2015 asking for comments on current trends in LTE-Unlicensed (LTE-U) and License Assisted Access (LAA) technology. LTE-U/LAA is a method for cell carriers to pair unlicensed spectrum with licensed spectrum to complement and improve signal strength for wireless commercial service. The emergence of LTE-U/LAA as a method for licensed wireless carriers to utilize unlicensed spectrum is a symptom of the emerging convergence and integration of previously separate licensed and unlicensed spectrum user regimes. Delivery of internet services to the consumer has been increasingly enabled by a hybridization of network deployment mechanisms -- traditional wireline companies are utilizing spectrum, while wireless companies are purchasing wired backhaul capacity to deliver an increasingly similar set of service to consumers. This paper applies an interdisciplinary analytical framework to discuss the key spectrum management issues and questions raised by this controversy. The analysis outlines the arguments presented by comments submitted to the FCC docket, and reviews the academic and theoretical literature guiding the criteria for FCC’s decision-making regarding the extent of its involvement in encouraging the development of new technologies or protecting existing investment and innovation in the unlicensed space. The framework organizes the issues raised in this debate into technical, economic, and policy categories to identify key spectrum coexistence principles raised by the introduction of new technology into already congested unlicensed spectrum bands. Overall, the inquiry comments generally show that advocates of LTE-U/LAA, such as wireless carriers, wireless equipment manufacturers, and wireless industry trade groups, believe this technology creates new opportunities to improve efficient spectrum utilization in the unlicensed space. Wireline companies, the cable industry, consumer advocacy groups and unlicensed band equipment manufacturers, on the other hand, present concerns that LTE-U/LAA compromises and degrades existing uses of unlicensed spectrum. Proponents advocate for the FCC to take a laissez-faire, technologically-neutral approach, while existing unlicensed band “incumbents” propose that the FCC actively oversee the introduction of this technology by establishing ongoing working group meetings of commission staff and engineers from involved parties, requiring monthly reports from relevant standards bodies regarding new spectrum coordination mechanisms, and ensuring that LTE-U is not allowed to launch until all the requirements have been met to a satisfactory standard. Considering the increasing demand for internet services and the diminishing availability of exclusively-licensed spectrum, the future of data service delivery is moving toward spectrum-sharing and coexistence mechanisms. Unlicensed spectrum is a common good -- it is available to all wishing to take advantage of it, but it can be exhausted due to interference and congestion, risking a tragedy of the commons. Ultimately, the role of the FCC and its criteria for decision-making regarding licensed carrier presence in the unlicensed spectrum space will be dependent on the general principles of commons management, its willingness to exercise positive and negative punishment and reinforcement, and rational decisions on the best and highest use of that spectrum frequency. Building on top of this qualitative analysis, future work will be to add a risk analysis of the controversy in an attempt to estimate and perform a quantitative assessment of the different options that can be pursued in the introduction of LTE-U/LAA technology to the unlicensed bands.