Figure 4-13 represents average end to end delay of FAAC, FAAC-Multipath, CACP and MACMAN protocols. It consists of queuing delay, re-transmission, and propagation delay. It mainly depends on transmission opportunity of a node and PLR. The transmission opportunity of a node decreases with the increasing number of requesting data sessions to the network. The heavy traffic load in the network causes the collision and PLR, which results in longer average end-to-end delays.
CACP suffers from longer delays as compare to other studied protocols due to frequent route failure and unavailability of backup routes. MACMAN protocol has higher delay than FAAC and FAAC-Multipath protocol. The session pausing, slow re-routing and more overheads in finding totally disjoint routes results in longer delay. FAAC-Multipath protocol takes advantages of thorough admission control, efficient use of cache information, local route repair and fast re-routing to control the average end-to-end delay.
4.3.2.S T he A ggregate th ro u g h p u t
The aggregate throughput represents the received data at application layer in unit time. It is usually measured in bits per second. Figure 4-14 shows the aggregate throughput of FAAC, FAAC-Multipath, CACP and MACMAN protocols. The aggregate throughput represents the receive data of each session irrespective of either session has been completed or dropped. An average end-to-end delay and packet loss affects the achieved aggregate throughput of the protocols. The SCR of the protocol also predict its aggregate throughput. The aggregate throughput of each protocol increases when data sessions increases from 5 to 25 sessions per source. FAAC-Multipath protocol achieves highest aggregate throughput among the studied protocols. Shorter end-to-end delay and lower PLR contribute to highest aggregate throughput of the protocol. MACMAN protocol performs better than CACP due to backup route availability.
700 600
B 200
t
100Sessions per source
FAAC-Multipath MACMAN FAAC CACP & g 250 10 15 20 25 30 Sessions p er source 35 40
Figure 4-14 Aggregate Throughput Figure 4-15 Aggregate Useful Throughput
4.3.2.6 U seful A ggregate th ro u g h p u t
The useful aggregate throughput parameter explains the actual place of the protocols as shown in figure 4-16. This metric is the same as the aggregate throughput, except that it is multiplied by the Session Completion Ratio. This indicates what fraction of the throughput is useful in terms of allowing an application data session to be completed while upholding its throughput requirements. It shows almost the same trend as that of aggregate throughput and session completion ratio.
4.3.2.7 N orm alized R outing L oad
The Normalized Routing Load represents actual data transmission at a cost of control or routing overheads. The NRL of all the studied protocols decrease as the session per source increases up to 20, because all protocol achieves higher aggregate throughput at that session rate. CACP suffers from higher PLR and has longer end-to-end delays, which results in lower aggregate throughput. The route discovery and capacity testing is also very complex in
QoS Assurance in MANETs through Multi-path Admission control Protocol 89
CACP and introduces overheads into the network. Therefore, CACP has highest NRL. MACMAN tries to maintain fully disjoint multiple routes for each data session, which is very difficult to achieve in such frequently changing topology. The MACMAN capacity testing mechanism also over-estimate or under-estimate the capacity, which is also a source of high NRL.
NRL of FAAC is lower than CACP and MACMAN due to its higher aggregate throughput, although it is higher than NRL of FAAC-Multipath. FAAC-Multipath introduces overheads in start of session admission because it maintains partially disjoint multiple routes for each session, but higher aggregate throughput of FAAC-Multipath compensates these overheads and as a result has low NRL.
1.2 fAAC--- FAAC-Multipath ■6A6P--- MACMAN 1 0.8 0.6 0.4 0.2 0 5 10 15 20 25 30 35 40 Sessions p er source
Figure 4-16 Normalized Routing Load
4.3.3 Packet Size
We analyse the behaviour of the protocols with different packet size. As different applications have different packet size, so we will investigate the protocol how they react or behave with different size data packet. Data traffic will be generated by the application with different packet size. The data rate will be same i.e. 25kbps for all different types o f packet size.
4.3.3.1 Session A dm ission R atio
Figure 4-17 shows Session Admission Ratio of FAAC, FAAC-Multipath, CACP and MACMAN. This figure represents the effect of different size data packets on the session admission into the network. As the data rate remains constant i.e. 25kbps for this set of simulation irrespective of data packet size, so large number of smaller packets will be transmitted to achieve this data rate as compared to bigger size data packets. Smaller size data packets means more overhead will be introduced in the network. The SAR o f the
protocols increases as the packet size increases because higher size data packets introduced less overheads and more capacity is available for data sessions.
The SAR of CACP is highest among the studied protocols, because CACP does not search for multiple routes or in other words it only tests a single route capacity for the session admission. It admits more sessions but then it fails to assure the guaranteed throughput to the sessions. SAR of FAAC is higher than FAAC-Multipath and MACMAN due to unavailability of multiple paths.
SAR o f MACMAN and FAAC-Multipath protocols are lower due to resource checking of multiple paths. MACMAN tries to find fully disjoint multiple routes between source and destination, which reduces the session admission into the network. Moreover, MACMAN is using perceptive method to test the resources which also causes the over-estimation of free capacity and as a result collision increases and drops the sessions.
0.9 § 0.5 E 0.4 < 0.3
I
0.2^
0.1 — FAAC h—FAA€-M tittipath r= C A C P_________ MACMAN 1024 256 64 P acket Size (B) FAAC-Multipath MACMAN FAAC CACP 256 P acket Size (B) 1024Figure 4-17 Session Admission Ratio Figure 4-18 Session Completion Ratio