This document summarizes a project presentation on analyzing the performance of CSMA/CA and TDMA MAC protocols in wireless mesh networks. It first provides background on wireless mesh networks and describes their architecture and characteristics. It then discusses CSMA/CA and TDMA protocols and how they work. The project involved simulating a wireless mesh network topology using NS-2 and evaluating the performance of the two protocols based on metrics like throughput, delay, and packet loss under varying conditions like number of hops and link distance. The results showed that TDMA performance was better than CSMA/CA. The conclusion recommends further analysis using directional antennas.

1. B.Tech (IT) Minor Project Presentation,2014
Performance analysis of CSMA/CA and TDMA MAC
protocols in Wireless Mesh Networks
SAGAR GUPTA(BT/IT/1154)
PRANJAL DAS(BT/IT/1146)
DHRUBA JYOTI SAIKIA(BT/IT/1114)
DARIHUNLANG SUCHIANG(BT/IT/1205(L))
Under the supervision of
Md. Iftekhar Hussain
Department Of Information Technology
North-Eastern Hill University
SHILLONG-22

2. CONTENTS
 WIRELESS MESH NETWORKS
• WMN vs MANET
• WMN Architecture
• WMN Characteristics
• Application Scenarios
 MAC PROTOCOLS FOR WMN
• Background
• CSMA/CA
• TDMA
 Performance Evaluation of CSMA/CA and TDMA in WMN
• Performance Metric
• Experimental Setup
• Experimental Results
 Conclusion And Future works
 References

3. WIRELESS MESH NETWORKS
• WMNs offer multiple redundant communications paths
throughout the network. Whenever a link fails, the network
automatically routes messages through alternate paths.
• Even in adverse conditions devices in WMNs co-operate with
each other in transmitting packets through the network.
• WMNs are believed to be self-configuring and self-healing
networks.
• Dramatic increase in link quality just by shortening the
distance between the nodes

5. Types of Nodes in WMN
 Wireless Mesh Router
• contains additional routing functions to support mesh networking.
• usually equipped with multiple wireless interfaces built on either the same
or different wireless access technologies.
• improves the flexibility of mesh networking.
 Mesh Clients
• can also work as routers since they also have necessary functions for mesh
networking.
• gateway and bridge functions do not exist in these nodes.
• usually have only one wireless interface as in Laptop/desktop PC, pocket
PC etc.

6. WMN vs MANET
There are various factors which can differentiate wireless mesh network from
Ad-hoc Network. The major differences between these two types of network
are the network topology and mobility of node
• Network topology: Ad- hoc network are called as the infrastructure less
network with a highly dynamic topology where as WMN have a relatively
static network topology
• Mobility of relay nodes: In Ad-hoc network the relay nodes have a higher
degree of mobility i.e. relay nodes aren't fixed whereas in WMN's the
degree of mobility of relay node is much lower than in Ad-hoc networks.
• Infrastructure requirement: Ad-hoc network is infrastructure less whereas
WMN has partial or fully fixed infrastructure.
• Energy constraints: In Ad-hoc network energy constraints is high whereas
it is low in the WMNs.

7. WMN Architecture
• Based on the functionality of the nodes the
architecture of WMNs can be classified into:
• Infrastructure mesh Architecture
• Client mesh Architecture
• Hybrid mesh architecture

8. Infrastructure Mesh
In infrastructure mesh architecture, the mesh routers
collectively provide a wireless backbone infrastructure.
Client node is passive in mesh infrastructure.

9. Client Mesh [1]
Client meshing provides peer-to-peer networks among
client devices. Here no such mesh router is required. Client will
act like a mesh router by relaying the packets.

10. Hybrid Mesh
• Mesh router provide the backbone of such network.
• With the help of network functionalities such as routing and
forwarding of data packets, clients can actively participate in
the creation of the mesh.

11. WMN Characteristics
• Dynamic self-configuration and self-organization
• Adaptation
• Fault tolerance and robustness
• Low-Cost
• Integration and interoperability

12. Application Scenarios
• Broadband Home Networking
• Community and neighborhood networking
• Enterprise Networking
• Building automation
• Security Surveillance systems

13. Mac Protocols for WMN
• Objectives
o Maximize channel utilization.
o Minimize channel access delay.
• CSMA/CA : [4],[6],[8]
o It is a Random Access Protocol.
o It continuously senses the channel.
o Collision avoidance technique –
- Request to send/clear to send(RTS/CTS)
- Transmission

14. Working of CSMA/CA
CSMA/CA was invented for Wireless Networks . In Wireless
Networks collisions are need to be avoided because they cannot
be detected. Collisions are avoided by three strategies:
• The Interframe space
• The Contention Window
• Acknowledgements

15. Working of CSMA/CA (contd.)

16. MAC protocols in WMN(cntd.)
TDMA: [3],[4],[7],[10]
• It is a channelization protocol.
• Each channel is allocated with a unique time slot.
• Three kinds of time slots-o
Control slots
o Contention slots
o Data slots

17. TDMA frame structure

18. Working of TDMA
• In TDMA, a single channel can support multiple transmission,
if each transmission is divided into relatively short fragments
then are assigned a time slot to be transmitted .

19. Performance evaluation of
CSMA/CA and TDMA
Performance metric
• Throughput
• Delay
• Packet loss

20. Assumed topology

21. Experimental Setup
• Performance of the assumed network topology has been
evaluated in terms of simulation in NS-2[5].
• The experiments were conducted to analyze the performance
of the CSMA/CA and TDMA MAC protocol.
• Table 1 specifies the various parameters considered along with
their values during the simulation.

22. Table 1: Simulation
Parameters
Parameter Name Values
• Traffic Types
• Packet Size
• Routing Protocol
• Radio Propagation Model
• Bandwidth
• Antenna Type
• Distance per hop
• No. of Nodes
• Simulation Time
• CBR and FTP
• 1000 bytes
• AODV
• Two Ray Ground Reflection
Model
• 11 Mbps
• Omni Antenna
• 20 Km
• 11
• 50 Secs

23. Experimental Results
• With different number of Hops in TDMA MAC protocol

24. Experimental Results (cntd)
• With different number of Hops in CSMA/CA.

25. Throughput in CBR Traffic

26. Throughput in FTP Traffic

27. Delay in CBR traffic

28. Delay in FTP Traffic

29. Packet loss in CBR traffic

30. Packet loss in FTP Traffic

31. With varying link distance in
CBR

32. With varying link distance in
CBR

33. With varying link distance in
CBR

34. Conclusion and Future works
• In this Project we have studied and analysed the performance
of CSMA/CA and TDMA MAC protocols in Wireless Mesh
Network.
• CSMA/CA is having different problems like hidden node,
exposed node, information asymmetry.
• TDMA provide good solutions to traffic correlation, heavy
collision.
• Comparingly in our performance analysis, we found that the
performance of TDMA is far better than that of CSMA/CA.
• Since CSMA/CA performance is not good using omni-directional
antenna. So, in future we can work on these two
protocols using directional antenna.

35. REFERENCES
[1] Akyildiz, Ian F., XudongWang, and WeilinWang. "Wireless mesh networks: a survey." Computer networks
47.4 (2005): 445-487.
[2] Ian F. Akyildiz and Xudong Wang ,”Wireless Mesh Networks”:JohnWiley and Sons ,Ltd Publication
[3] Mihail L. Sichitiu,”Wireless Mesh Networks: Opportunities and Challenges”
[4] IEEE Standard for Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications,
Nov. 1997,P802.11.
[5] “Network Simulator- ns2.” http://www.isi.edu/nsnam/ns.
[6] Manshaei, H., et al. "Performance analysis of the IEEE 802.11 MAC and physical layer protocol." World of
Wireless Mobile and Multimedia Networks, 2005. WoWMoM 2005. Sixth IEEE International Symposium on a.
IEEE, 2005.
[7] Akyildiz, Ian F., et al. "Medium access control protocols for multimedia traffic in wireless
networks." Network, IEEE 13.4 (1999): 39-47.
[8] Bianchi, Giuseppe, Luigi Fratta, and Matteo Oliveri. "Performance evaluation and enhancement of the
CSMA/CA MAC protocol for 802.11 wireless LANs."Personal, Indoor and Mobile Radio Communications,
1996. PIMRC'96., Seventh IEEE International Symposium on. Vol. 2. IEEE, 1996.
[9] Perkins, Charles E. Ad hoc networking. Addison-Wesley Professional, 2008.
[10] Sen, Sayandeep, and Bhaskaran Raman. "Long distance wireless mesh network planning: problem
formulation and solution." Proceedings of the 16th international conference on World Wide Web. ACM, 2007.

36. THANK YOU!!!!!