UDP

We measure the UDP throughput of our scheme on NCTUns2.0, so we can evaluate our scheme without the affection of TCP congestion control. We used a CBR UDP packet stream in each experiment suit of this section.

6.2.2.2.1 Single Hop Count

In those experiments below, every RN is just one hop away from DN, so data packets can be sent to DN directly from each RN in MANET (Figure 6.2.2.1.1-1).

In the first experiment suite, no RN provides additional GPRS channel bandwidth to help the DN download its requested file. Thus, the packets carrying the file’s content are transmitted on the DN’s own GRPS channel. We pumped a CBR UDP packet stream about 3.75 KB/sec on PS.

Figure 6.2.2.2.1-1 shows that the average throughput without applying out scheme is about 3.74 KB/sec.

GPRS Udp t hroughput

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GPRS UDP Throughput +stddev -stddev

Figure 6.2.2.2.1-1: GPRS UDP throughput

In the second experiment suite, one RN is used and its channel and the DN’s channel are used to download the file in parallel. We pumped a CBR UDP packet stream about 7.5 KB/sec on PS. Figure 6.2.2.2.1-2 shows that the average throughput is about 7.45 KB/sec. The throughput speedup is 1.99 (7.45 / 3.74).

One Rel ay Node -One Hop

Figure 6.2.2.2.1-2: GPRS UDP throughput – One Relay

In the third experiment suite, two RNs are used and in total three GPRS channels are used to download the file in parallel. We pumped a CBR UDP packet stream about 11.25 KB/sec. Figure 6.2.2.2.1-3 shows that the average throughput is about 11.21 KB/sec. The throughput speedup is 2.99 (11.21/3.74).

Two Rel ay Nodes - One Hop

UDP Throughput +stddev -stddev

Figure 6.2.2.2.1-3: GPRS UDP throughput – Two Relay

In the fourth experiment suite, three RNs are used and in total four GPRS

channels are used to download the file in parallel. We pumped a CBR UDP packet stream about 15 KB/sec on PS. Figure 6.2.2.2.1-4 shows that the average throughput is about 14.08 KB/sec. The throughput speedup is 3.76 (14.08/3.74).

Three Rel ay Nodes - One Hop

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Figure 6.2.2.2.1-4: GPRS UDP throughput –Three Relay

In the fifth experiment suite, four RNs are used and in total five GPRS channels are used to download the file in parallel. We use a traffic generator program to generate a CBR UDP packet stream, the sending rate of which is about 18.75 KB/sec on a PS. Figure 6.2.2.2.1-5 shows that the average throughput is about 18.4 KB/sec.

The throughput speedup is 4.91 (18.4/3.74).

Four Rel ay Nodes - One Hop

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Figure 6.2.2.2.1-5: GPRS UDP throughput – Four Relay

In Figure 6.2.2.2.1-6, there are two CBR UDP traffic flows belonged to two different experiments of the fifth experiment suit. The throughput of TCP swings between 20 Kbytes/sec to 16 K.

UDP Traf f i c Fl ow - Four Rel ay

Figure 6.2.2.2.1-6: UDP Traffic Flow – Four Relay

In the sixth experiment suite, five RNs are used and in total six GPRS channels are used to download the file in parallel. We pumped a CBR UDP packet stream about

22.5 KB/sec on PS. The performance when using five RNs is even worse than the performance when using four RNs when the download file size exceeds 200 KB.

In Figure 6.2.2.2.1-8, there are two CBR UDP traffic flows belonged to two different experiments of the sixth experiment suit. The UDP throughput of this experiment suit drops to zero and rises up again several times. This is also because there are some packet losses in GPRS network, so a DN would enqueue data packets until all data packet in its reordering queue are in order. In our data transfer protocol, a DN would reorder data packets by the sequence number that is given by our scheme.

Fi ve Rel ay Nodes - One Hop

Figure 6.2.2.2.1-7: GPRS UDP throughput – Five Relay

UDP Tr af f i c Fl ow - Fi ve Rel ay

Figure 6.2.2.2.1-8: UDP Traffic Flow – Five Relay

In the seventh experiment suite, six RNs are used and in total seven GPRS channels are used to download the file in parallel. We pumped a CBR UDP packet stream about 26.25 KB/sec on PS.

Si x Rel ay Nodes - One Hop

Figure 6.2.2.2.1-9: GPRS UDP throughput – Six Relay

In Figure 6.2.2.2.1-10, there are two CBR UDP traffic flows belonged to two different experiments of the seventh experiment suit.

UDP Tr af f i c Fl ow - Si x Rel ay

Figure 6.2.2.2.1-10: UDP Traffic Flow – Six Relay

In Figure 6.2.2.2.1-11, we conclude the experiment results in section 6.2.2.2.1.

When the GPRS FIFO queue mentioned in section 6.2.1 is overflow, the throughput of our scheme would decrease as showed in sixth and seventh experiment suits.

UDP Throughput - One Hop

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Figure 6.2.2.2.1-11: UDP throughput – One Hop

6.2.2.2.2 Multiple Hop Counts

In those experiments below, some RNs are multiple hops away from DN, so data packets would be forwarded by other RNs in the MANET (Figure 6.2.2.1.2-1).

Figure 6.2.2.2.2-1 presents the experiment results of section 6.2.2.2.2.

The experiment results in Figure 6.2.2.2.2-1 are similar to those results in Figure 6.2.2.2.1-11.

UDP Throughput - Mul t i pl e Hops

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No RN One RN Two RNs Three RNs Four RNs Five RNs Six RNs

Figure 6.2.2.2.2-1: UDP throughput – Multiple Hops

6.2.3 Evaluation Experiments with an Advanced Wireless Physical Layer