上行-下行联合优化的uRLLC传输

[摘要] 考虑有界信道状态信息（CSI）误差的影响，解决了上下行联合设计的超可靠低时延通信（uRLLC）传输问题，以保障最差情况下物理层空口传输的端到端可靠性。利用有限码长容量公式近似刻画传输速率、时延和可靠性之间的关系，在信道估计误差、最大功率和传输可靠性的约束条件下，最小化上下行所需的传输时延。通过分析目标函数的单调性和凸性，对优化问题进行等价转化，并提出了有效的交替优化算法来求解该问题。仿真结果分析了信道估计误差、发送功率、可靠性对传输时延的影响，清晰地表明了系统参数之间的折中关系。

[关键词] 超可靠低时延通信；鲁棒波束赋形；有限码长编码；资源分配；交替优化

[Abstract] A joint uplink and downlink beamforming design and reliability tradeoff is considered to guarantee the end-to-end performance requirements of ultra-reliable and low-latency communication (uRLLC) traffics. Under the bounded channel state information (CSI) error, the worst-case transmission latency is minimized, subject to the over-the-air reliability of all links. The transmission rate, latency and packet error probability are characterized by the approximation equation based on the finite blocklength coding. The optimal design problem is reformulated by utilizing the monotonicity and the convexity of the end-to-end latency with respect to the reliability, and an efficient algorithm is proposed based on the alternating optimization technique. The simulation results validate the impact of the CSI error, power and reliability requirements on the transmission latency. It also shows the tradeoff between these system parameters.

[Keywords] uRLLC; robust beamforming; finite blocklength coding; resource allocation; alternating optimization