# Multiservice-Based Traffic Scheduling for 5G Access Traffic Steering, Switching and Splitting
## 1 Introduction
### Related Work  
Multipath management, traffic scheduling, and congestion control are the main topics being studied by the 3 GPP SA2 working group. There are also technical difficulties in implementing the ATSSS feature currently under research. Fortunately, traffic scheduling methods in LWA and multipath transmission control protocol (MPTCP) have received significant research attention over the years. Owing to the similarity between LWA and ATSSS, traffic scheduling strategies for the former can be used as a reference for the development of new ones for the latter. In [17], a novel radio access technology (RAT) selection method was proposed that can maximize the total throughput by simultaneously selecting optimal RATs for a group of UEs. In [18], it was proved essential that the network should intelligently switch a data radio bearer (DRB) to utilize either LTE or Wi-Fi. The authors of [18] proposed two types of switched LWA policies: guaranteed bandwidth and equal sharing. Their study indicated that switched LWA can effectively reduce the blocking probability of the DRBs. Both [17; 18] provided efficient and high-capacity mode selection methods and solutions to the handover problem between different access technologies that do not support the simultaneous operation of multiple access technologies. The traffic load balancing and resource-allocation scheme proposed in [19] is set to play a crucial role in leveraging the dense and increasingly heterogeneous deployment of multi-radio wireless networks. A scenario is considered in [19], where the traffic for each user may be split across macro-cells or small Wi-Fi cells, connected by non-ideal backhaul links. The fraction of the user's traffic sent over macro-cells is proportional to the ratio between the peak capacity of that macro-cell and the throughput of the small cell. Reference [20] focuses on the MPTCP scheduler, with the goal of providing a good user experience for latency-sensitive applications when interface quality is asymmetric. Two novel scheduling techniques are presented in [20], which reduce web object transmission times and provide faster communication for interactive applications, compared to MPTCP's default scheduler. However, Refs. [19; 20] only focus on the performance with one user, and neither considers fairness between all users, nor achieves an optimal system. In a previous study [21], linear programming techniques were used to optimize the bandwidth of a licensed spectrum, using the bandwidth of an unlicensed spectrum to maximize the overall network throughput. In study [22], the convex optimization theory was applied to the power of a licensed spectrum, and the duration of an unlicensed one was used to maximize the total utility for users. In [23], delay-tolerance service was proposed for the first time for LWA, and a cross-system learning method was also proposed to optimize power, cell-range extension bias, sub-band selection, and service scheduling. In study [24], a semi-Markov model, based on a distributed coordinated function channel-access mechanism, was proposed to establish a Wi-Fi network between closely related network resources capable of meeting the QoS requirements. [PERSON] et al. [25] proposed a rate-efficient power allocation strategy for delay outage limited applications with constraints on energy-per-bit consumption of the system. [PERSON] et al. [26] proposed computationally efficient algorithms based on threshold structures for the association and offloading of users in LWA HetNet. Although traditional radio resources include user-transmit power, bandwidth, time, and spectrum, since the development of 5G, the focus of traffic scheduling has shifted to resource blocks and transmit power. In the traditional traffic scheduling algorithm, the optimal allocation of network resources is mostly achieved by maximizing the total network throughput.