T he A verage end-to-end Delay

The Average end-to-end Delay of FAAC-Multipath, FAAC-MM, CACP and MACMAN protocols are shown in Figure 5-8. The average end-to-end delay o f the session increases with the increase in the data rate due to higher collision and increase in PLR. CACP and MACMAN protocol pauses the data sessions frequently, which eventually increases the end- to-end delay. The protocols drop the session if the average end-to-end delay is longer than the bounded end-to-end delay of the consecutive three data packets. Therefore, CACP and MACMAN protocols drop the sessions and then admits more new sessions, which increases the overhead in the network by finding and testing the capacity of the routes. The FAAC- MM protocol maintains the average end-to-end delay below 20ms. The figure confirms that FAAC-MM protocol always maintain the bounded end-to-end delay o f the data sessions. All other studied protocols other than FAAC-MM, do not care about the delay of the sessions and results in sessions drop. The SCR in Figure 5-6 confirms the trend of average end-to-end delay the protocols. The FAAC-MM protocol admits and then takes care o f the data sessions according to the throughput and delay requirements o f the data session. It switches the data flow to avoid congestion and collision form primary to secondary route on the basis of throughput and average end-to-end delay while all other protocols only consider throughput explicitly. FAAC-Multipath protocol also maintains lower average end-to-end delay due to thorough admission control and fast re-routing.

5.3.1.5 T he A ggregate T h ro u g h p u t

Figure 5-9 shows the aggregate throughput o f CACP, MACMAN, FAAC-Multipath and FAAC-MM protocols. The increase in data rate also increases the collision, PLR and as a result data sessions drop more frequently. CACP protocol achieves lowest aggregate throughput due to higher PLR, longer average end-to-end delays and lower SCR. CACP protocol drops a higher ratio of the admitted data sessions in the middle due to not upholding the requirements o f the data sessions. The higher ratio of sessions drop affects the aggregate throughput severely because each new data session will add overhead to the network for finding the route for new data sessions. When a protocol admits the data session, it means that it has already found the route and now is the time to reimburse the overheads by delivering more and more data packets.

MACMAN protocol achieves higher aggregate throughput than CACP protocol but lower than FAAC-Multipath and FAAC-MM protocols. FAAC-MM protocol achieve highest aggregate throughput among the studied protocol because it suffers from less collision and maintains lowest PLR and delay. The switching mechanism and controlled admission of data sessions into the network helps the protocol to avoid congestion which leads to collision and route failures. 700 600 -9 500 400 300 fAAWAM--- FAAC-Multipath CACP--- - MACMAN 200 ÿ 100 0 100 125 150 25 50 75 D ate Rate (kbps) FAAC-Multipath MACMAN FAAC-MM CACP 250 50 75 100 Data R ate (kbps) 150

Figure 5-9 Aggregate Throughput Figure 5-10 Useful Aggregate Throughput

5.3.1.6 U seful A ggregate T h ro u g h p u t

Figure 5-10 shows the useful aggregate throughput o f FAAC-Multipath, FAAC-MM, CACP and MACMAN protocols. The aggregate throughput consists of the throughput of the completed as well as dropped sessions. Therefore, the aggregate throughput does not fully explain the achievement of the protocols. The aggregate throughput of the drop sessions may not be useful to the application users. Therefore, to show the fully achievements of the protocols in terms of aggregate throughput, we use useful aggregate throughput metric. Useful aggregate throughput shows the aggregate throughput of only those sessions that has

Multi-Metrics QoS Provisioning with Multi-path Admission control Protocol 111

been successfully completed. The sessions may be dropped not only due to throughput degradation but also due to not upholding the bounded end-to-end delay. FAAC-MM protocol attains highest useful aggregate throughput due to its highest aggregate throughput and also highest SCR.

5.3.2 Session Arrival Rate

The main function o f an AC protocol is to manage the offered load, and therefore this study highlights one o f the most important aspects of FAAC-MM protocol performance. This study shows how the protocol manages the increasing load in form of increasing number of sessions per source. Each session has throughput and bounded end-to-end delay requirements and these requirements does not change with the number o f sessions per source. The increase in number of sessions per source means increase in data traffic in the network. Ideally, the protocol should maintain its guaranteed throughput and bounded end- to-end delay irrespective of increase in number of requesting sessions, but the requesting sessions impose overheads in the network although if it is rejected. The requesting data session must be rejected on the basis of available capacity of the network and end-to-end delay and the network capacity must be checked for each requesting data session, which is a source o f overheads in the network. So instead of careful admission control, still protocol will face some degradation in QoS assurance.

5.3.2.1 Session A dm ission R atio

Figure 5-11 shows the Session Admission Ratio of FAAC-Multipath, FAAC-MM, CACP and MACMAN protocols. The SAR o f all the above stated protocol decreases as number of sessions per source increases means traffic load. The capacity and end-to-end delay requirements o f all the sessions remain constant and same irrespective o f increasing number o f total session. All other protocols except FAAC-MM admit the sessions only on the basis o f capacity’s requirements o f the session. Figure 5-11 shows that the SAR of the FAAC-MM protocol as less as compared to all other protocols. FAAC-MM protocol make sure before admitting the new sessions that it has the route that can satisfy both the requirement o f the session. Because the completion of session is more important than the admission o f the session and the protocol has to make sure that the capacity is neither under-utilized nor over­ utilized.

5.3.2.2 Session C om pletion R atio

The Session Completion Ratio shows the ability of the protocols to complete the sessions. The protocols that admit the data session only on the basis of throughput requirement may

drop due to not upholding the end-to-end delay of the data session. The SCR of the protocols decreases as the number of session per source increases. On the other hand, we saw before that as the number of session per source increases, the SAR of each protocol also decreases.

FAAC-MM protocol achieves highest SCR among all the studied protocols. Other protocols have also discussed in earlier chapter 3 and 4; therefore, here we mainly concentrate on the behaviour of FAAC-MM protocol. The FAAC-MM protocol achieves highest SCR mainly due to its awareness of the data session requirement o f throughput as well as end-to-end delay before admission of the session into the network. The protocol also using its switching mechanism on the basis of throughput and bounded end-to-end delay, so it avoids congestion and route failure.

FAAC-Multipath MACMAN FAAC-MM CACP 0.9 _{-♦— FAAC-MM} # — -FAAG-M#ttpath CACP o 0.7 | o , 6 1 0.5 -|o .4 gO .3 MACMAhT § 07 % 0.6 Q. 0.5 i 0.4 e 0.3 0.2 0.1 0.1

Session s per source Sessions per source

Figure 5-11 Session Admission Ratio

5.3.2.3 P ack et Loss R atio

Figure 5-12 Session Completion Ratio

Data packets drop either due to buffer overflow or collision and these two factors mainly depend on the congestion level of the network. When the number of session increases in the network, it increases the data traffic and as a result chances of congestion also increase. The route failure that occurs either due to node mobility or collision at MAC layer also leads to data packet loss. FAAC-MM protocol has less PLR among the studied protocol because of mainly its careful data admission and switching of data traffic between multiple routes. The multiple routes increase the overhead but it compensates the protocol in terms of less packet loss. FAAC-MM protocol also does not pause the session which increases the end-to-end delay and then as a result PLR increases.