Low-Latency Relaying for Future Wireless Networks

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Future wireless communication systems are expected to support the reliable transfer of ultra high data rates exceeding tens of  Gigabits per second with low latency of less than one millisecond. Meeting these requirements simultaneously comprises a major challenge that form the focal point of many research groups around the globe.  Among the most efficient and cost-effective techniques to enable the goals of future wireless networks to be achieved is the deployment of intermediate communication-assisting nodes known as wireless relays. Relays can be categorized based on their relaying technique. These techniques include  amplify-and-forward (AF),  decode-and-forward (DF) and compress-and-forward (CF). Relays can be also categorized based on their operational modes, e.g., half-duplex or full-duplex, and/or their underlying communication protocols, e.g., one-way or two-way. To make effective use of relays, their configuration must take into consideration the communication scenario. For instance, when the transmitter-relay channel is significantly stronger than the relay-receiver channel, the  DF relaying strategy is optimal. However, when the transmitter-relay channel does not satisfy this condition, DF relaying may be superseded by other relaying techniques. In a complementary fashion, full-duplex and two-way relays are generally more effective than their respective half-duplex and one-way relays, yet they invoke higher computational complexities and implementation challenges. The performance advantages that relaying nodes can offer to a network depend primarily on the network topology, the propagation environment and the operational signal-to-noise ratios. The focus in this research program is to explore the enhancement and utility of relaying techniques to meet the stringent constraints imposed by future wireless delay and security sensitive applications, e.g., autonomous vehicles and Internet-of-Things (IoT). This research program will consider the following directions:  Direction I: Studying the efficacy of AF, DF and CF relaying techniques under conventional wireless channel conditions but with practical delay constraints.  Direction II: Exploring the utility of relaying techniques, e.g., AF, DF and CF,  and operational modes, full and half duplex, when the wireless channel exhibits temporal and spatial correlation. Both one-way and two-way relay networks will be considered.  Direction III: Exploring optimal relaying in fast vehicular communications wherein the channel is unknown to the receiver and optimal relaying under stringent delay constraints has yet to be developed. These directions will contribute important innovative elements to the global effort to reduce latency of wireless networks while enhancing their reliability and throughput. These directions will also serve as a platform for training highly qualified personnel who are ready to assume leadership roles in the wireless communications arena.