Conclusion and Future work 

Conclusion 

Packet loss across the network is the main problem to be considered across any type of network like wired or wireless networks. In general across the wireless networks like wireless LAN and MANETs the nodes across the network will develop the tendency to lose the packets and due to this the overall performance of the network is degraded and this behavior is due to the mobile nature of the nodes across the network. If there is an ample amount of packet loss on the network it indicates that the nodes are losing the important data and communication information and due to this the overall network will be dropped in the performance levels and thus always an important solution is required in this context.

If the packet loss is more many communication attributes are affected with this and also the network will lose the important information with respect to this packet losses and to understand the impact of the packet losses on the network a simple OPNET modeler simulation is considered in this process. A mobile ad hoc network is considered against the wireless LAN server and wireless LAN mobile workstations and almost 20 nodes are considered in this simulation. An Email application is used for the simulation process and this email will generate the required FTP traffic on the network and the performance of three routing protocols like AODV, DSR and OLSR are considered at three scenarios level and few performance metrics of Email and wireless LAN are estimated using these scenarios. The simulation is run for one hours to obtain the graphs and from the analysis the key findings are given as below 

When the email download response time is considered it is observed that the overall download response time is more with the AODV is used as the routing protocol when compared to the other scenarios. It is observed that the minimum email download response time is incurred with the OLSR routing protocol and it was initially high and later it was reduced and a minimum download response time is incurred. When the download response time is less it indicates that there is no packet losses across the network and due to the less packet loss the email contents are downloaded at a speeder rate and when the case with DSR is considered the download response time in this case is also less when compared to AODV and more than the OLSR routing protocol. From the overall analysis it is clear that when there is more packet loss across the network the overall download response time has increased a lot and in this context OLSR is the best routing protocol to prevent the packet losses on the network and AODV has shown more packet loss on the network.

When the traffic received in bytes per second is considered it is clear that when the traffic received in bytes per second is more the overall packet loss is more due to the fact that when the traffic is more the scope to lose the traffic in terms of packets is more. In this context the traffic received is more with the OLSR routing protocol as it has the tendency to lose more packets when compared to the other ad hoc routing protocols and even the value is not constant throughout the simulation time.

AODV has a constant traffic received across the network when compared to the other two routing protocols and thus the overall packet loss is less as the traffic received is less and due to this the congestions will be less and thus the packet loss will be less when compared to other routing protocols. When the case with the DSR routing protocol is considered the overall traffic received is more and also the corresponding packet loss is also more and even the traffic received is not constant and this indicates that the packet loss is more due to the expected congestion levels on the network.

From the overall analysis it is clear that AODV can be considered as the best performing routing protocol in terms of traffic received and minimum packet loss across the wireless LAN server. It is observed that the traffic received in packets per second is more with the OLSR routing protocol and it has received more number of packets in the form of traffic flooding and due to this the chances of losing the packets are increased a lot. When the case with AODV routing protocol is considered it has shown a minimal value and thus the traffic received in packets per second has reduced a lot. Due to this process the overall congestion is decreased and also the chances for packet flooding are reduced and the overall packet loss will be less when compared to the other scenarios.

DSR has shown an optimal performance in terms of packet loosing and the losing ration is more when compared to AODV and less when compared to OLSR thus this indicates that AODV can be considered as the best routing protocol to minimize the packet looses in the network. When the traffic received in packets per second has reduced across the network the chances for packet flooding are minimized and in this context AODV has reduced the packet flooding chances and the nodes along with the wireless LAN server now can lose a minimum level of packets on the network. 

When the traffic sent in bytes per second is compared it is clear that the overall traffic sent is more with the OLSR routing protocol and even this value is not constant across the network. AODV routing protocol has shown an optimal performance levels in terms of the traffic sent in bytes per second this value is constant throughout the simulation time and this indicates that the chances of losing the packets at the node and wireless LAN server are reduced and thus the overall performance of the network in terms of packet loss is optimized on the network.

When the case with the DSR routing protocol is considered the packet loss is more on the network due to the fact the dynamic routing forming sequences are more on the network and in the process of updating the routes dynamically the packets are lost and thus from the overall analysis it is clear that the overall performance of the network has increased in terms of the packet loss due to the implementation of the AODV routing protocol. Thus even in this case the performance of the network is on the top standards at the AODV routing protocol levels. It is observed the overall traffic sent is more with the OLSR routing protocol as the OLSR has more tendency to make the mobile nodes on the network to send more traffic at a constant rate to the server and due to this all the nodes will sent continuous requests to the server.

With this the server will become busy in processing the requests of the nodes and the chances of losing the packets will be more with the OLSR routing protocol. When the case with AODV is considered it is clear that a low rate of traffic is sent and also the AODV will make the nodes to sent the routing requests to the neighboring nodes at a constant rate and this will reduce the burden on the server and thus the server can process the requests from the nodes at a constant rate and thus the overall congestion on the network is reduced a lot.

When the case with the DSR is considered the overall traffic sent is more when compared to AODV and this is due to the reason that the dynamic nature of the nodes will make the server to process all the requests at a time and the tendency to lose the packets has increased. So from the overall analysis it is clear that that AODV has shown an optimal performance in terms of packet looses against the traffic sent in packets per second. It is clear that the upload response time is more with the AODV routing protocol and this is due to the fact that the static nature of the routing protocol will consume more time to upload the content and in this process the chances to lose the packets are increased when compared to the other routing protocols like OLSR and DSR. When the case with the OLSR routing protocol is considered it has shown a minimum download response time and thus it indicates that the overall packet loss in terms of upload response time is very less when compared to the AODV and DSR routing protocol and DSR has shown an optimal performance with respect to the upload response time.

Thus from the overall analysis it is clear that when the packet loss is more on the network the upload response time has increased and in this context OLSR is proved to the best routing protocol to minimize the packet loss on the network in terms of upload response time. Thus when the Email performance metrics are considered apart from the download response time and upload response time the overall performance of the AODV is considered to be at the maximum level in terms of packet loss and with the implementation of the AODV routing protocol on the network the overall performance of the network has increased a lot. 

It is observed that the overall data drop is more with the DSR routing protocol when compared to the other routing protocols and due to the dynamic nature of the nodes and the server they will improve the tendency to lose the packets and thus the overall packet loss will more with the DSR routing protocol. When the case with the OLSR is considered it is observed that it has shown an optimal performance and the data dropped is less when compared to the DSR routing protocol and AODV has shown an optimal performance in terms of the data dropped. When the data drop on the network is less then automatically the packet loss would be low and this indicates that the AODV is the best routing protocol to reduce the packet loss on the network and the overall performance of the network can be improved a lot.

DSR has shown maximum data drop on the network and also the packet loss is more and thus few refinements should be done in this context to improve the performance of the network. It is also observed that all the routing protocols has shown a constant data drop across the network and this is due to the random mobility model chosen and AODV is the best across this simulation to optimize the packet losses. From the resultant graph of the wireless LAN delay it is observed that the overall delay on the wireless LAN server is more due to the DSR routing protocol and if the delay is more on the network it indicates that the server has loose the packets at a constant rate and due to this the corresponding delay is incurred on the network. A minimum delay is observed with the OLSR routing protocol and even AODV has shown an optimal performance in terms of delay on then network.

OLSR is proved to be the best routing protocol in this context and has imposed a very less delay on the network and due to this packet loss is also reduced a lot on the network and when the case with the AODV is considered the overall packet loss is at constant rate and at the end of the simulation it is reduced to zero and this indicates that even AODV is better to be considered when packet loss reduction is considered. Thus from the overall analysis it is clear that AODV and OLSR are proved to be the best routing protocols to be considered to reduce the delay and also the packet loss on the wireless LAN server. When the load on the network is considered it is observed that the overall load on the network is more due to the OLSR routing protocol and due to the heavy load on the network the tendency to lose the packets is increased and thus in terms of load OLSR has shown a poor performance and thus it should be optimized.

When the case with AODV is considered initially the load on the network is more and then it is reduced a lot due to the routing performance of the protocol and DSR has shown a minimum load on the network when compared to other routing protocols. This indicates that when the load on the wireless LAN server is considered the optimal packet loss is observed with the DSR routing protocol due to its dynamic nature and thus in this context DSR can be considered as the best routing protocol to reduce the load and also packet loss on the network and even the performance of AODV is also better in terms of reducing the network load and the corresponding packet loss on the network. When all the three routing protocols are considered AODV can be considered as the best one as a constant load on the network is incurred due to this routing protocol. 

When the medium access delay is considered it is clear that the overall delay is more with the DSR routing protocol and this delay is more due to the impact of the dynamic nodes on the network. In general when the nodes feel a particular route across the network to reach the destination Email server is not working then automatically they will make the medium busy to built a new route to reach the destination and due to this the medium will lose the important packets on the network and thus the packet loss is more with the DSR routing protocol. When the OLSR routing protocol is considered it is observed that there is a very minimum medium access delay on the network and due to this the packet loss is also reduced a lot and even the value is constant across the communication process. AODV has shown an optimal performance and due to this the packet losses are reduced a lot when compared to the DSR routing protocol and thus from the overall analysis it is clear that the performance of the network can be optimized against the packet looses with the implementation of OLSR and AODV routing protocols.

When the network load is considered it is clear that the load on the network is more when the nodes and the server are using the OLSR routing protocol and a minimum load is imposed by the DSR routing protocol. As the nodes and the server using the DSR routing protocol will behave in a dynamic in nature the network load is reduced a lot and thus even the packet loss is also reduced a lot with this routing protocol. When the case with the AODV routing protocol is considered even this routing protocol has shown an optimal performance in this context of network load and due to this minimum network load the packet loosing conditions are reduced and also the overall performance of the network is optimized again.

A constant network load is imposed due to the AODV routing protocol and again in this context AODV is proved to be the best performing routing protocol to reduce the network load and also optimize the packet loosing conditions where the packet loss is reduce a lot with both the AODV and DSR routing protocol. When the number of retransmission attempts is considered it is observed that a maximum retransmission attempts is shown with the DSR routing protocol and this is due to the fact that when the nodes are dynamic in nature due to the DSR routing protocol they develop the required tendency to lose the packets and thus they keep on sending the retransmission attempts to the network. When the case with the OLSR routing protocol is considered a minimum number of retransmission attempts is made and this indicates that the OLSR routing protocol is the best routing protocol to be considered to eliminate the retransmission attempts and also to reduce the packet loss on the network.

AODV has shown an optimal performance in this context and also has reduced the tendency to lose the packets at the wireless LAN server side and thus the performance of the network has improved a lot due to this routing protocol. Thus when the overall performance of the routing protocol is analyzed in the context of retransmission attempts and packet losses OLSR and AODV has shown an optimal performance all the time and this indicates that when the routing protocols are static in nature the overall packet loss on the network is reduced a lot.

From the throughput analysis it is clear that a maximum throughput is incurred with the OLSR routing protocol when compared with the AODV and DSR routing protocols. Even the throughput is constant throughout the simulation time and this indicates that the packet loss is very less at the wireless LAN server side due to the OLSR routing protocol and when the case with AODV is considered it has shown a better throughput when compared with the DSR routing protocols and also there are some variations in the curve and this indicates that the overall packet loss is optimized at the end of the simulation due to the implementation of AODV routing protocol.

When the case with DSR routing protocol is considered it is clear that the throughput is very less and this indicates that the overall packet loss is very high due the DSR routing protocol. Thus when all the performance metrics of the wireless LAN are considered it is clear that OLSR routing protocol can be considered as the best routing protocol to optimize and reduce the packet losses on the network and the next place is occupied by the AODV routing protocol. When the overall Email and Wireless LAN metrics are considered the average packet loss is reduce with the implementation of AODV routing protocol. 

Future work 

There is some scope to improve the simulation to estimate the packet loss across the network and the key future work need to be done is as given below 

  • Proactive and reactive routing protocols can be considered in future to estimate the packet loss situations and also understand the best range of protocols
  • Different applications can be compared in future to understand the application level analysis against the packet loss conditions.