Coded Caching and Interference Management for Future Wireless Networks

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Transforming physical world data into digital content and services, Internet of Things (IOT) will connect together all things that can be connected evolving into the Internet of Everything. There are far more cars, traffic lights, parking meters, drones, game consoles, appliances, sensors etc. than people. While the “exponential” growth of human-centric networks is bound to saturate at a level proportional to the world population, i.e., several billions the number of nodes in 5G networks will grow beyond trillions. The number of IOT devices has already exceeded world population and will reach 20 times earth's population in early 2020's. This dizzying growth comes with considerable challenges and opportunities. While the increase in objects' density causes huge interference, the availability of many devices in a small area allows resource sharing through cooperative communications.***Given the rapid growth of storage capacity of smart devices, cooperative caching can provide high quality data transmission without undue demand on the backhaul capacity or mobile device's power. Smart devices can share stored popular contents using Device to Device (D2D) communications without routing through the infra-structure. The objects will be divided into Content Helpers (CH) and Content Requesters (CR) whose relationship can be viewed as a bi-partite matching problem and solved using matching theory. Being mobile and having different priorities, a CH may not be always ready to help a given CR. Content loss due to CH unavailability may be avoided using erasure correcting codes.***In cooperative caching the main constraints are: rate, storage and complexity. We will find the best trade-off between the three and develop rate-memory trade-offs for various computational constraints. We will also develop novel robust caching schemes using rateless codes for efficient content placement and recovery.***The rapid growth of the D2D traffic will saturate the spectrum necessitating the use of non-orthogonal multiple access (NOMA). We will develop novel multiple access, coding and interference cancellation schemes for code domain NOMA.***Most smart devices are equipped with multiple antennas that can be used for forming a multitude of beams. This allows the use of Interference Alignment (IA) for increasing the capacity of D2D communication in 5G. Using a game theoretic approach, we will develop novel IA schemes for D2D applications.***Use of Ultra Dense Networks (UDNs) in 5G will result in drastic inter-cell interference and complex interference cancellation techniques will be needed. To reduce device complexity, Cloud Radio Access Network (C-RAN) can be used where complex functions are performed at Baseband Units (BBUs) connected to the cloud. Content caching at BBUs can reduce the back-haul-front-haul traffic.***Our research will include: Cooperative coded caching for D2D Communications, Cooperative NOMA for 5G Networks, IA for D2D communications, and content caching for C-RAN.**