Cellular communication networks have become one of society's most important and complex technologies. Mobile data usage has been approximately doubling every year since about 2008, which corresponds to a 1,000 times increase over a decade. To meet this insatiable demand, much more bandwidth is required for cellular systems. This requires going to (much) higher frequencies, since there is very little unused spectrum below about 10 GHz, especially at peak times in urban areas. Significant amounts of lightly used spectrum is available in the "millimeter wave" (mmW) spectrum, defined here as being above 25 GHz. There are numerous fundamental technical challenges in mobile data communication above 25 GHz, and the goal of this project is to explore these fundamental challenges and build new tools to overcome them. The research undertaken should considerably impact the telecommunications industry and society as a whole, by enabling an entirely new paradigm for cellular communication networks. In addition to theoretical contributions, the investigators will pursue an aggressive technology transition plan through their numerous government and industry partners.
This project will develop new mathematical and analysis tools that uncover the potential of mmW cellular networks. The research agenda is built on the belief that the wealth of tools developed for lower frequency systems are insufficient to capture key mmW signal propagation features, specifically high directionality and blockage. The research is structured as three inter-related thrusts, each with several proposed research tasks: mmW signal strength, mmW interference, and the mmW network connectivity. The research tasks are unified around several technical themes that cut across all three thrusts: (1) modeling mmW networks in 3D, including the obstacles for which statistical blocking models will be developed and validated with real building data; (2) accounting for signal and interference correlation in performance analysis, which will be significant in mmW due to their main randomizing factors being blocking and beam alignment rather than fading and shadowing; (3) accounting for and addressing the possibly severe effects of mobility on beam alignment and network connectivity.
The developed theories will be used to devise useful models, parametrized by real building data to facilitate fast performance evaluation. Features of practical mmW transceivers like beam adaptation, mobility, and interference cancellation will be included and used to study key design tradeoffs. The new mathematical framework developed in this proposal will allow transparent and comprehensive performance analysis of mmW cellular systems, and enable the development and fair comparison of new communication techniques.
