## 2 Optimization Model of Massive MIMO System
### User Scheduling  
As shown in Figure 1, in a downlink single-cell massive MIMO system, it includes a base station (BS) located in the center of the cell and N uniformly distributed single-antenna users. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Work** & **Whether to Consider** & & & \\ \cline{3-5}
**[**6**]** & **Traffic Priority** & **Channel State** & **Resource** & **User Minimum** \\  & & **Information** & **Periodicity** & **Request** \\ \hline
[6] & Yes & No & No & Yes \\ \hline
[7] & Yes & No & No & Yes \\ \hline
[8] & No & Yes & No & Yes \\ \hline
[9] & No & Yes & No & Yes \\ \hline
[10] & Yes & Yes & No & Yes \\ \hline
[16] & Yes & Yes & No & Yes \\ \hline
[17] & Yes & Yes & No & No \\ \hline
[18] & Yes & Yes & No & No \\ \hline
[19] & Yes &
\begin{tabular}{c} Yes, but ignore transfer \\ rate \\ \end{tabular} & Yes & Yes \\ \hline Algorithm in this article & Yes & Yes & Yes & Yes \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison between relevant literature and the algorithm in this article. In practical applications, due to the burstiness of user traffic, the number of users accessing the system will be greater than the limited number of antennas on the base station side. Therefore, bandwidth allocation first requires user scheduling. According to the service priority of the user, channel state information, and the amount of bandwidth resources allocated by the user terminal in the previous scheduling period, the dynamic priority of the user is obtained, and user scheduling is performed according to the obtained priority. Literature [22] divides users into groups according to the types of services used. On this basis, this paper discusses four main types of services, namely conversational services (voice, videophone, etc. ), stream services (video streams, audio streams, etc. ), interactive services (web browsing, online games, etc. ), and background services (E-mail reception, SMS, FTP, etc.). Conversational services strictly limit the transmission delay. Severe delay jitter will cause the conversation to fail normally, but certain voice pauses and picture blurring can be allowed. In order to ensure the delay index of conversational services, this service is set as the highest priority; streaming services also requires real-time performance, but because of the one-way transmission characteristics, the requirements for transmission delay are not as strict as session services, and a certain packet loss rate is allowed; interactive services have low requirements on transmission delay but strict restrictions on packet loss rate; background services have no restrictions on transmission delay and delay jitter but generally require zero packet loss rate. Therefore, this paper regards transmission delay and delay jitter as the key indicators for evaluating service priority and summarizes the requirements of the four types of services for each QoS parameter in Table 2.  
Simply taking the service priority as the user's dynamic priority does not meet the actual needs, and the priority scheduling of users with high service priority but poor channel status may reduce the system throughput. Therefore, channel state information and the number of unsatisfied user request time slots in the previous scheduling cycle are introduced on the basis of service priority to improve user scheduling efficiency while ensuring user fairness as much as possible. Drawing in the form of the correction function