## 5 Wireless Physical Resources Management  
Based on the aforementioned analysis in Section 2, the two main types of communication services, i.e., the mission-critical service and passenger Internet service can be categorized as the eMBB and uRLLC services. Since these two application cases are supported simultaneously in 5G, the joint physical resource scheduling of eMBB and uRLLC traffic is another challenging issue to the Hyperloop. Thanks to the flexible frame structure of the 5G, a time slot can be divided into several mini-time slots to cope with the uRLLC traffic. The concept of multiplexing is to deal with these two coexisting services by puncturing/superposing parts of PRBs assigned to eMBB traffic for the sporadically arrived uRLLC packets at the next mini-slot boundaries [19]. Currently, much work about multiplexing has been investigated, such as [19; 20; 21], which mainly aim to boost the throughput of the eMBB services subject to the instant puncturing of the uRLLC traffic on the eMBB packet transmission upon arrival. However, the primary issue of these research is that all sporadically arrived uRLLC traffic are treated equally without any discrimination. Consequently, these methods cannot process the multiple types of uRLLC traffic with different KPIs for Hyperloop and that is the issue we try to solve. Figure 8 presents a diagram of the proposed wireless PRB multiplexing of the eMBB and uRLLC traffic. As shown in this figure, each time slot with one millisecond time duration is divided into \(M\) mini-slots equally so as to achieve the stringent latency requirement of uRLLC. Four different colors represent 4 eMBB services users, which are scheduled at the slot boundary periodically. In addition, the proportional fairness algorithm is adopted to guarantee the data rate fairness among different users. Three types of the uRLLC traffic arrive sporadically during the time slot whose PRBs are already allocated to different eMBB users and should be processed before the next time slot due to the strict latency requirements. Given the fact that the 5G supports a flexible frame structure, each type of uRLLC traffic can be allocated to a PRB with specific bandwidth and time duration [18]. Specifically, a traffic with a stringent latency requirement is allocated to a PRB with small time duration but large bandwidth. To cope with the multi-types of uRLLC traffic for Hyperloop, we propose a novel latency-margin-based multiplexing scheme herein. In contrast to the conventional multiplexing scheme, multi-types of uRLLC traffic will be processed not at the next mini-slot directly. Instead, it is  
Figure 8: The diagram of the physical resource multiplexing of the eMBB and uRLLC. within its corresponding latency margin. For instance, two different types of uRLLC traffic arrive at the eighth mini-slot in Figure 8, the system ought to deal with OVCS traffic in no longer than next three mini-slots (latency margin: three mini-slots), whereas it would cope with the TCS and OCS traffic within next mini-slot (latency margin: one mini-slot). Obviously, the latency-margin-based idea enables great puncturing flexibility of PRB when multiplexing. The goal of the proposed latency-margin-based multiplexing scheme is to maximize the throughput of all eMBB traffic and minimize the allocated power of the uRLLC traffic when guaranteeing the latency and BER demands of the sporadically arrived uRLLC traffic. Let \(n_{0}\) denote the channel noise power, \(h_{t,f}\) means the channel gain of the PRB at the \(t\)-th mini-slot and \(f\)-th subcarrier. Several \(M\)-quadrature amplitude modulation (QAM) modes can be chosen based on the BER and data rate requirements as well as the channel gain \(h_{t,f}\). Then, this optimization problem can be expressed as  
\[\min_{t_{q},f_{q},t_{q+i,f_{q}+j}}\{\alpha\tau^{\text{uRLLC}}+\beta P^{\text{ uRLLC}}\}, \tag{10}\]  
\[\text{s.t.