# QoS Management and Flexible Traffic Detection Architecture for 5G Mobile Networks
## 5 Quantitative and Qualitative Analysis
### QoS Traffic Detection Strategies' Comparison  
Next, a qualitative comparison of different strategies used to detect traffic with QoS requirement in mobile networks is done. The first two use the strategies of the current EPS architecture; the third one is based on NFV, a VNF concept where the logical mobile element is implemented in data centers in a centralized way; and the last one is implemented using the proposed QoS traffic detection logic.  
* Mechanism based on the AF detection technique: This refers to the mechanism of the 4G networks that use detection devices called AF, which are put in strategic points of the network. These strategic location points are chosen such that the traffic to be inspected must pass through the AF in its normal way. When the QoS requirements are found, they are sent to the central device (PCRF) responsible for QoS policy implementation. The AF devices are usually placed within or before application servers and are specialized in the detection of different types of traffic. This alternative decrements the flexibility and programmability possibilities due to other types of traffic being able to be routed using different paths. On the other hand, the AF element can be placed in a distributed way, while low addition time is added in the QoS detection process.
* Mechanism based on an element as TDF: This occurs when the detection element is put in the centralized data plane element as PGW in the current EPS architecture. As all traffic goes through the PGW, this method could analyze all types of traffic, but a deep packet inspection could compromise the PGW performance. In this alternative, the large amount of traffic to be processed and the centralized nature of the solution significantly impact the scalability and robustness of the solution.
* Mechanism in centralized data center inspections: Several works proposed [13] the implementation of the data and control plane of mobile elements as VNF over VM using commodity hardware put in data centers. In this alternative, all traffic is sent to a data center, and it is processed to find the QoS requirements. This alternative generates additional delay due to routing of traffic to the  
Figure 8: Prototype: Example 2, EPS-Bearer with QoS between UEs.  
data center and requires significant traffic inspection processing. On the other hand, the cloud computing design increments the robustness even if it is implemented in a centralized data center, due to it being an elastic environment able to adapt to the traffic requirement variations.
* Proposed detection mechanism: This alternative is able to send the QoS packet immediately as traffic without QoS requirement, and at the same time, it sends a QoS packet copy to the centralized SDD element to detect the QoS requirement (waiting time is not added). This option increments the robustness due to the QoS traffic continuing to be routed even without the Controller response or without SDD detection (as traffic without QoS requirement). The scalability in this solution is incremented due to the traffic detection functionality is distributed in all OF-NB and all SDD implemented (if only an SDD is implemented can it be considered a Centralized architecture as well, but this could not be an optimal decision). Additionally, this alternative increments the QoS detection possibilities, due to it combining the OF-NB detection and the SDD devices, which are programmable elements able to detect all types of traffic. Finally, this solution could be considered more generic than the previous one. The traffic detection table associated with UE can be changed in the OF-NB at any time, and the new associated detection table can be created to route all the traffic to the SDD element or to a data center (as in the previous alternative).