# Multiservice-Based Traffic Scheduling for 5G Access Traffic Steering, Switching and Splitting
## 3 Multiservice Type-Based Transmission (MSTT)  
Based on the foregoing DQoS guarantee mechanism, we proposed a scheme to optimize resource allocation by maximizing the total effective network capacity of the NR and WLAN links. The algorithm comprises three steps. First, the UE determines the number of data transmission paths to either (a) transmit its two data streams through the NR or (b) send one stream through the NR and the other through the WLAN. Then, a method to select the transmission path based on load balancing is used to plan the data streams transmission path of each service. Finally, a traffic scheduling scheme under the delay service quality constraint is developed to determine user power decomposition and bandwidth allocation. A schematic diagram of the algorithm is shown in Figure 3.  
The steps are described as follows:  
Step 1. Determination of transmission path number. Figure 3: Multiservice traffic scheduling model. The total utility function of all services is expressed as follows:  
\[U_{all}=\sum_{r\in R}\log_{2}(U_{r}), \tag{11}\]  
where \(r\in R(CBR,DS,VBR)\). To maximally satisfy the user QoS requirements and obtain the maximum overall utility, in the MSTT scheme, it is necessary to first ensure that the rate of the CBR service exceeds the basic transmission threshold. Therefore, according to the characteristics of the CBR utility function, all the CBRs are set to adopt a single connection. Additionally, users implement a single connection when the WLAN network is occupied. Thus, the number of upload paths for all the service data streams is expressed as  
\[\left\{ \begin{array}{ll}1&\quad CBR\quad\text{or}\quad\quad WLAN\quad\text{ collision}\\ 2&\quad\quad\{DS,VBR\}\quad\text{and}\quad\quad WLAN\quad\text{idle}\end{array} \right. \tag{12}\]  
Step 2. Selection of dedicated path. In this subsection, a dynamic dedicated path selection scheme, which allows a user to dynamically adjust the dedicated path based on channel-state information and NR BS load, is proposed. The UE estimates the channel quality of the serving BS and the neighboring cells using the reference signal received power (RSRP) report, which is the most common parameter in mobility decisions for heterogeneous networks. The averaged UE measurement, \(M_{u,c}\), of UE \(u\) from BS \(c\) at the \(n^{th}\) time step is calculated as  
\[M_{u,c}=(1-a)\cdot M_{u,c}(n-1)+a\cdot R_{u,c}(n), \tag{13}\]  
where \(R_{u,c}(n)\) represents the RSRP instantaneously measured by UE \(u\) from BS \(c\), and \(a\) is the filter coefficient configured by the network [45; 46]. It should be clarified that the \(M_{u,c}\) of each UE is acquired only once, whereas the location of the UE is updated at every time step. The UE \(u\) first initializes the uplink candidate set according to a preset threshold, then removes the BSs with poor channel quality based on the relative threshold, and finally removes the overloaded BSs. This not only ensures the throughput requirements of UE \(u\) but also achieves load balancing for the entire system. (1) Uplink candidate set initialization: For each \(u\), we assumed that, if \(M_{u,c}\) is greater than the threshold \(M^{th}\), the BS \(c\) can be added to the candidate set of UE \(u\), i.e., \(\min\limits_{c\in A_{u}}(M_{u,c})\geq M^{th}\). Conversely, if \(M_{u,c}\) is less than \(M^{th}\), no connection between UE \(u\) and BS \(c\) can be established. Considering the typical urban scene layout and the sensitivity of the UE receiver, \(M^{th}\) is usually set to \(-109\) dBm. (2) Removing weak BSs: Very weak links may not yield additional benefits but unnecessarily increase complexity. If the difference between \(M_{u,c}\) and the strongest RSRP BS is greater than the removal offset, \(M^{rmw}\), BS \(c\) will be deleted from the candidate set. However, if it can remain in the candidate set, the following condition must be satisfied:  
\[M_{u,c}\geq\max_{c\in A_{u}}(M_{u,c})-M^{rmw}, \tag{14}\]  
where \(A_{u}\) represents the candidate set of UE \(u\).