1 Wireless Mesh Networks Impact on Voice over Internet Protocol Mohammad Tariq Meeran PhD Student Institute of Informatics, Tallinn University February 2014
2 What is wireless mesh networks? Wireless Mesh Networks (WMNs) are considered dynamic, self-healing, self-optimizing and fault tolerant wireless networks (Ian, 2005). WMNs usually have dynamic and complex topologies. WMNs are built using two types of topologies. mobile mesh nodes as the infrastructural devices mobile mesh nodes as the mesh clients and fixed mesh routers and access points as the mesh infrastructural devices
3 What is wireless mesh networks? Wireless Mesh Nodes Example 1
4 What is wireless mesh networks? Wireless Mesh Nodes Example 2
5 Learn about WMNs Links to video 9E 1Q Rk&list=PLqnjfDAs-OndWOdUalA-m9dBoP- KJMZBJ
6 What is VoIP? Voice over Internet Protocol (VoIP) is the usage of data networks (packet switched networks) to transport voice over the Internet or internal networks. VoIP mainly provides low cost calls compared to the phone system which uses circuit switched technologies VoIP is considered to be sensitive to delay, jitter and packet loss.
7 What is QoS? ITU-T defines Quality of Service (QoS) as "the collective effect of service performance which determine the degree of satisfaction of a user of the service. QoS is the mechanism or the technology, which has the power to prioritize data flows based on the application requirements and user satisfaction
8 What is QoS? Classes of Service tags the packets edcf (enhanced distributed coordination function) uses the tags to prioritize the packets TXOP (transmission opportunity) reserves the first few seconds of transmission time for high priority packets
9 VoIP Factors Delay is defined as the measurement of time between the moment that something is initiated and the moment that its effects begin Jitter in the field of telecommunication is used to describe the time difference and intervals between the pulses that are transmitted successfully Packet loss is defined as the loss of packets (portion of data) during the communication between the stations over a computer network
10 VoIP factors Acceptable delay for VoIP traffic is ms (Jang, 2003) some studies suggest that acceptable delay for VoIP is 200ms (VoIP Foro, 2006). Acceptable jitter for VoIP is less than 100 ms (Poe, 2007). Acceptable packet loss rate for VoIP is considered to be less than 5% of a whole conversation (Anand, et al, 2007).
11 Research Problem VoIP implementation and QoS issues in wired networks (fiber & copper) address by various standards VoIP implementation and QoS issues in wireless networks are address by IEEE e standard VoIP implementation and QoS issues in WMNs is still a problem and requires more research to find a proper solution.
12 Research goals Finding out how the fixed mesh routers addition to the mesh infrastructure considering different mobility scenarios and traffic profiles will affect the VoIP QoS factors of delay, jitter and packet loss Comparing the results with WMN infrastructures where wireless mesh routers didn t exist as part of the mesh infrastructure. Recommending possible solutions in terms of WMN topologies, better routing approaches, nodes mobility scenarios resulting better quality, traffic types affects and ways to improve the QoS factors for VoIP in WMNs.
13 Research questions How do full mobility, partial mobility and no-mobility of wireless mesh nodes affect VoIP QoS factors? What will be the effect of adding fixed wireless mesh routers on VoIP QoS? Which mobility scenario(s) greatly challenge(s) the VoIP implementation in WMNs? Why does QoS factors exceed the maximum allowed limits? Which type of traffic profiles provides better VoIP service quality in WMNs? Which VoIP QoS factors like delay, jitter, and packet loss fall in the acceptable ranges if the nodes move and exchange VoIP and non-voip traffic?
14 Methodology WMN impact on VoIP QoS Conclusion Experimental Design Research Approach Analysis Simulation and Traffic generation Data Collection
15 Methodology(cont.) Simulation Software Selection of the simulation tool will based on the simulation tool features for supporting WMNs and generation of customized traffic to simulate human conversation other traffic types. One of the following simulation software will be used for this research experimental work. NCTUns Qualnet NS2
16 Methodology(cont.) VoIP characteristics VoIP conversation, using the common G.729 codec, the voice coder sends 50 VoIP packets every second while the speaker is talking, but when the speaker is silent, no packet is sent The VoIP payload can vary according to the codec setting, but by default the G.729 sends a payload of 20 bytes (20ms of VoIP conversation) in each IP packet. The payload size can vary between 10, 20, 30, 40 and 50 bytes. Therefore, in 10 seconds of a VoIP conversation, 500 packets must be sent.
17 Methodology(cont.) Mobility Scenarios Scenarios No Mobility Limited Mobility Full Mobility VoIP Traffic Only VoIP and Non-VoIP Traffic VoIP Traffic Only VoIP and Non-VoIP Traffic VoIP Traffic Only VoIP and Non-VoIP Traffic UDP Traffic UDP+TCP Traffic UDP Traffic UDP+TCP Traffic UDP Traffic UDP+TCP Traffic
18 Methodology(cont.) VoIP traffic profile Simulating a human conversation Using a traffic generation tool that can simulate a human VoIP conversation by generating packets with varying sizes, varying inter packet delays and simulating talking periods (ON states) and silence periods (OFF states) To achieve this, STG (Send Traffic Grapher) and RTG (Receive Traffic Grapher) tools can be used. Non-VoIP traffic profile For the generation of TCP traffic the STCP tool will be used.
19 Data Collection Wireless mesh nodes movement speed, location information, routing table information will logged and collected at each simulation scenario from each device that is part of the mesh network. The VoIP traffic will be simulated using the RTP/UDP/IP (Real Time Protocol/ User Datagram Protocol/Internet Protocol) traffic and non-voip traffic will be simulated using TCP traffic.
20 Data Collection (cont.) The data collection process will record the delay time for each packet that is sent from one node to the other, jitter time between the packets arriving at the receiving nodes, amount of packet loss at the receiving nodes. This data will be used for analyzing and comparing each factor with the acceptable ranges for VoIP and conducting comparative analysis.
21 Analysis Mobility scenarios affect on VoIP quality Traffic types affect on VoIP quality VoIP QoS factors analysis and finding out which factors are greatly affected based on R-Factor based on the E-model defined by ITU-T Comparative analysis of results with topologies and WMNs implementations where fixed wireless routers don t exist as part of the network infrastructure.
22 Expected outcomes Discover how the nodes mobility and speed contribute to the VoIP quality if wireless mesh routers are part of the infrastructure. Recommending mobility scenarios which provide better quality. The delay, jitter and packet loss relationship with the node mobility and traffic profiles will be investigated.
23 Expected outcomes(cont.) The results will show which factor is greatly affected by which mobility scenario and which traffic profile. Based on the results there will be recommendations on how these factors could be brought to acceptable and tolerable ranges. Recommending better WMN topologies, designing new routing protocols, reducing the delay time in each node, etc.
24 Group Activity Divide in 4 groups of 4-5 persons List the domains/areas where you can see that wireless mesh networks or VoIP could be implemented to change the way people live, work, study, travel, etc. You will have 10 minutes to work in groups and 5 minutes to present it.