Low-Latency Relaying for Future Wireless Networks

未来的无线通信系统有望以不到1毫秒的低延迟支持超过数十千兆比特每秒的超高数据速率的可靠传输。同时满足这些要求构成了一个重大挑战，构成了全球许多研究小组的焦点。 能够实现未来无线网络目标的最有效和最具成本效益的技术之一是部署称为无线中继器的中间通信辅助节点。继电器可以根据其继电保护技术进行分类。这些技术包括放大转发(AF)、解码转发(DF)和压缩转发(CF)。还可以基于其操作模式(例如，半双工或全双工)和/或其底层通信协议(例如，单向或双向)对中继器进行分类。为了有效利用继电器，其配置必须考虑到通信场景。例如，当发射机-中继器信道明显强于中继器-接收器信道时，DF中继策略是最优的。然而，当发射机-中继器信道不满足这一条件时，DF中继器可以被其他中继器技术所取代。在互补的方式中，全双工和双向中继通常比它们各自的半双工和单向中继更有效，但它们带来了更高的计算复杂性和实现挑战。中继节点能够为网络提供的性能优势主要取决于网络拓扑、传播环境和操作信噪比。 该研究计划的重点是探索中继技术的增强和实用，以满足未来无线延迟和安全敏感应用(例如自动驾驶汽车和物联网)施加的严格限制。本研究计划将考虑以下方向： 方向I：研究在传统无线信道条件下但具有实际延迟约束的AF、DF和CF中继技术的有效性。 方向II：当无线信道表现出时间和空间相关性时，探索中继技术的效用，例如，AF、DF和CF，以及全双工和半双工工作模式。单向和双向中继网都将被考虑。 方向三：探索在快速车载通信中的最优中继，其中接收器未知信道，并且严格延迟约束下的最优中继尚未开发。 这些方向将为减少无线网络延迟，同时提高其可靠性和吞吐量的全球努力贡献重要的创新要素。这些方向还将成为培训准备在无线通信领域担任领导角色的高素质人员的平台。

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 However, when the transmitter-relay channel does not satisfy this condition, DF relaying may be superseded by other relaying techniques.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.