# Dynamic QoS Management for a Flexible 5G/6G Network Core: A Step toward a Higher Programability
## 4 Architecture Design and Methodology
### Dynamic QoS Methodology
#### 4.2.1 Dynamic Queues Management  
The resource reservation is provisioned by effectively creating upload and download queues, thus providing the bandwidth requirements for that group of services. If requirements change and the user cancels the subscription to a specific group of services,  
Figure 2: Service bonding and provider isolation in a multi-slice environment.  
the reservation of resources for those services should be unprovisioned by removing the upload and download queues. Automatically, the other groups of services (slices) can consume the released leftover bandwidth. Due to user mobility, we expect that variations in signal quality and strength between users and base stations will cause variability in total available bandwidth. In addition, the current congestion of a particular base station is a factor that can lead to a decrease in bandwidth per user. Thus, it is imperative to implement a mechanism that dynamically manages the QoS configuration of slices sensitive to packet loss, and we should treat them differently.  
Moreover, by introducing dynamism into the QoS configuration, the following strategy can be applied--some less-critical services (e.g., Internet service) can be temporarily slowed down or even suspended until the link bandwidth capacity improves. In this paper, we did not evaluate the bandwidth capacity of a wireless link. We assume that we could predict available bandwidth from transmission parameters (e.g., signal strength, signal-to-noise ratio).  
We propose a method for dynamic QoS through dynamic queue management that implies the ability to dynamically change queues' parameter configurations according to the requirements specified through the slice orchestration on the application layer. To achieve this goal, we propose using the OVSDB protocol to extend the SDN controller functionality in addition to the features supported by the OpenFlow protocol. Namely, by applying the OVSDB protocol, we perform dynamic queue management (e.g., creating, deleting, and changing queue parameters dynamically).  
We enable the dynamic control of link bandwidth by following the SDN paradigm through a combination of functionalities contained in the OpenFlow (queue flow assignment) and OVSDB protocols. For QoS to be bi-directionally regulated, queues should be set up on both SDN switches at the base station side (for downstream) and the user side (for upstream). Our proposal for dynamic QoS management is shown in the flow diagram in Figure 3.  
The process depicted in Figure 3 begins with a request for a change of QoS policy for a specific service group in the slice orchestration database. This process contains five steps that each slice controller runs independently from other controllers:  
1. The slice controller retrieves the slice QoS policy for the slice it is in charge of, and if there are any changes in comparison with the previous state, it executes these changes;
2. The slice controller sends a command to modify the queue to the base station via the OVSDB protocol;
3. The slice controller creates a proactive flow to assign slice traffic to the appropriate queue on a base station;  
Figure 3: QoS policy change flow diagram.  
* The slice controller sends a command to modify the queue to the UE via the OVSDB protocol;
* The slice controller creates a proactive flow to assign slice traffic to the appropriate queue on a UE.