In this work, we have proposed link adaptation based joint spectrum and power allocation algorithms for uplink cellular vehicle-to-everything (C-V2X) communication for OFDMA based 5G systems. In C-V2X, vehicle-to-vehicle (V2V) users share radio resources with vehicle-to-infrastructure (V2I) users. Existing works primarily focus on the optimal pairing of V2V and V2I users under the assumption that each V2I user needs a single resource block (RB); minimizing any interference through power allocation. In contrast, in this work, we have considered that the number of RBs needed by the users is a function of their channel condition and Quality of Service (QoS) - a method called link adaptation. It is effective in compensating for the incessant channel quality fluctuations at the high frequencies of operation of 5G. The first proposed resource allocation scheme of this work greedily allocates RBs to V2I users using link adaptation and then uses Hungarian algorithm to pair V2V with V2I users, while minimizing interference through power allocation. To reduce the complexity, the second scheme groups RBs into resource chunks (RCs); then uses Hungarian algorithm twice - first to allocate RCs to V2I users, and then to pair V2I users with V2V users. Extensive simulations reveal that link adaptation increases the number of satisfied V2I users as well as their sum-rate, while also improving QoS of individual users, thereby making it indispensable for C-V2X system. We have also considered the presence of best-effort users, and the diverse QoS has been provided through the multi-numerology frame structure of 5G.

翻译：本文针对基于OFDMA的5G系统，提出了一种面向蜂窝车联网（C-V2X）上行通信的链路自适应联合频谱与功率分配算法。在C-V2X中，车辆与车辆（V2V）用户与车辆与基础设施（V2I）用户共享无线资源。现有研究主要聚焦于V2V与V2I用户的最优配对，其假设每个V2I用户仅需单个资源块（RB），并通过功率分配最小化干扰。与此不同，本文考虑用户所需RB数量取决于其信道条件与服务质量（QoS）——即链路自适应方法。该方法能有效补偿5G高频段运行中持续的信道质量波动。本文提出的第一种资源分配方案，首先利用链路自适应贪婪地为V2I用户分配RB，随后采用匈牙利算法实现V2V与V2I用户配对，并通过功率分配抑制干扰。为降低复杂度，第二种方案将RB分组为资源块组（RC），并两次运用匈牙利算法：首次为V2I用户分配RC，第二次实现V2I与V2V用户配对。大量仿真表明，链路自适应不仅提升了满意V2I用户数量及其总速率，还优化了单个用户QoS，使其成为C-V2X系统的关键支撑技术。本文同时考虑了尽力而为型用户，并借助5G多参数集帧结构实现了差异化QoS保障。