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 TechnologyNorth-Eastern Hill University

SHILLONG-22

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

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

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.

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.

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

Infrastructure Mesh

In infrastructure mesh architecture, the mesh routers

collectively provide a wireless backbone infrastructure.

Client node is passive in mesh infrastructure.

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.

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.

WMN Characteristics

• Dynamic self-configuration and self-organization

• Adaptation

• Fault tolerance and robustness

• Low-Cost

• Integration and interoperability

Application Scenarios

• Broadband Home Networking

• Community and neighborhood networking

• Enterprise Networking

• Building automation

• Security Surveillance systems

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

Working of CSMA/CACSMA/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

Working of CSMA/CA (contd.)

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

TDMA frame structure

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 .

Performance evaluation of

CSMA/CA and TDMA

Performance metric

• Throughput

• Delay

• Packet loss

Assumed topology

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.

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

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

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

Throughput in CBR Traffic

Throughput in FTP Traffic

Delay in CBR traffic

Delay in FTP Traffic

Packet loss in CBR traffic

Packet loss in FTP Traffic

With varying link distance in

CBR

With varying link distance in

CBR

With varying link distance in

CBR

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.

REFERENCES[1] Akyildiz, Ian F., Xudong Wang, and Weilin Wang. "Wireless mesh networks: a survey." Computer networks

47.4 (2005): 445-487.

[2] Ian F. Akyildiz and Xudong Wang ,”Wireless Mesh Networks”:John Wiley 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.

THANK YOU!!!!!