# Evaluation of VoIP QoS Performance in Wireless Mesh Networks
## 5 Conclusions  
This research work considered various scenarios in which WMNs could be implemented, specifically the scenarios where VoIP applications are mostly preferred. Emergency relief efforts in case of earthquake, flooding, cyclones, fires, etc. have been discussed and identified as the scenarios where WMNs and VoIP applications could be used to save lives and help affected people.  
From those many cases of VoIP implementation in WMNs, we selected five scenarios for our experimental research, namely first responder with waypoint mobility, first responders with random waypoint mobility, flooded village, isolated village, and a platoon deployment with waypoint mobility. Each scenario has been tested under six sub-scenarios with the integration of IEEE 802.11g, 802.11n, 802.11s, 802.11e, AODV, and HWMP routing protocols, G.711 and G.729 codecs. Call duration was 180 s and the simulation time was 500 s.  
Figure 21: Average MOS by routing and mobility.  
The analysis of the results shows that integration of IEEE 802.11g, 802.11s standard with G.711 and G.729 codecs using HWMP routing protocol decreases the VoIP quality as compared to scenarios without the IEEE 802.11s integration using AODV routing protocol. Moreover, using G.711 and G.729 codecs with the IEEE 802.11n standard using AODV routing protocol in WMNs installations where the distances between the nodes are greater can result in decreased VoIP performance as compared to scenarios with IEEE 802.11g using the same codecs and same routing protocol. In general, scenarios with IEEE 802.11g standard without integration of IEEE 802.11s result in better VoIP quality followed by the scenarios with IEEE 802.11s integration, while IEEE 802.11n showed decreased performance in all scenarios.  
This research's scope involved IEEE 802.11g/n/e/s standards using HWMP hybrid path selection protocol and AODV reactive routing protocol, along with high bit rate (G.711) and low bit rate (G.729) voice codecs on selected WMN scenarios. Our future efforts will focus on the inclusion of at least one proactive routing protocol, a medium bit rate codec, and scenarios with no-mobility, partial mobility and full mobility. Additionally, we will also propose approaches that can lead to improvement of VoIP QoS in WMN scenarios. Focused research efforts on IEEE 802.11n/ac standards integration with 802.11s, codecs of variable bit rates, different type of WMN routing protocols could be considered valuable contributions in this domain.  
The main author of the paper is the academic employee of Computer Science Faculty of Kabul University. His study at Tallinn University in the School of Digital Technologies has been supported by the Estonian Ministry of Foreign Affairs within the framework of development cooperation. This project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No. 668995--Horizon 2020 ERA-chair Grant \"Cognitive Electronics COEL\" H2020-WIDESPREAD-2014-2 (TTU project code VFP15051).  
This research has been designed and conducted through the collective efforts of all authors. [PERSON] is the lead author of the paper and has prepared it based on the guidance and feedback of the other authors.  
The authors declare no conflict of interest. The funding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.