In-Band Full-Duplex Communication for Applications with Security and Low-Latency Constraints

• Applicants: Professor Dr.-Ing. Gerald Enzner; Professor Dr.-Ing. Aydin Sezgin
• Subject Area: Communication Technology and Networks, High-Frequency Technology and Photonic Systems, Signal Processing and Machine Learning for Information Technology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 449601577

The demands towards wireless networks with higher data throughput, lower latency and better security are steadily increasing.The communication technology will in this context face a number of challenges. While many protocols specify bidirectional communication to support for instance feedback or two-way handshaking, in the past this has required the allocation of distinct time or frequency resources including hardware support for transmission and reception in half-duplex (HD) mode. In the case of time-division radio-frequency (RF) transceivers, the HD mode specifically requires to finish transmission before reception can take place, which obviously introduces delay, which is inconsistent with the demands towards low latency communications. Another important aspect is the security of data messages, especially considering the envisaged use cases of next-generation wireless networks such as remote surgery. Due to broadcast nature of thewireless medium, an eavesdropper can intercept any transmitted message. Specifically, it is still unknown how to design communication networks with varying security levels at the users. In order to deal with these challenges, a promising technology is in-band full-duplex (IBFD) communication. The IBFD technology makes it possible for communication nodes to transmit and receive at the same time on the same frequency band. With the help of IBFD communication the opportunities for (physical-layer) security and low-latency applications are significantly extended. To research these dimensions of IBFD networks, the collaborative project is organized by two layers, the node and the network layer. On the node layer, we deal with the advancement of the IBFD technique on a single node. The biggest challenge here is imposed by the fact that RF chains of transmitter and receiver of the same device are in close proximity and, therefore, huge power is coupled from the transmitter into the receiver as self-interference (SI). Hence, the SI must be cancelled (SIC) or significantly mitigated. To this end, we explore advanced linear and nonlinear, adaptive interference cancellation algorithms.On the network layer, we investigate the optimal information flow of communication messages in two-way networks with partial information access and real-time requirements. This layer serves as the ``top'' layer in which we abstract from the actual realization of the IBFD technique by using certain models. We do, however, seek the interplay of both layers in the proposed project, while most state-of-the-art approaches consider them separately.Hence, the proposed project is collaborative work of two groups on the design of models, algorithms, and performance metrics. Ultimately, the results of the project are tested and verified on a joint IBFD implementation based on software-defined radio devices in order to foster mutual inspiration on both layers.

• DFG Programme: Research Grants