surement of the EDGE TCP transfer (bps) on "probe" side (sending) for Time/Div. from 100 ms to 5 us. Service Delivery Platforms 12.1.3.1.2 EDGE DL Access on UDP The same scenario of Figure 12.2a was used. Similar charts were plotted (see Figure 12.10) for the same benchmarks like in the previous DL case (Section 12.1.3.1.1). The following interpretation of results is pointing also the main differences from TCP DL. No effect of the buffering is visible at the probe (server) side, because UDP is a connectionless protocol. Buffering has visible effects on the receiving (cli- ent) side. Because of the initial buffering and because there is no TCP windowing mechanism, the available bandwidth is slightly decreasing. Interpretation of Figure 12.10: As emphasized previously, buffering is not visi- ble on the probe (server) side because of the connectionless nature of the UDP protocol SO the bit rate is not influenced by the retransmission or loss of packets. Buffering is visible on the receiving (client) side, although not as much as for TCP (no retransmission implemented in the UDP). When the bit rate approaches the available bandwidth the number of lost packets is increasing, making the transmis- sion unreliable. The jitter is slightly increasing during the transmission because the packets are stored in the buffers where they spend more and more time. 12.1.3.2 EDGE UL Access 12.1.3.2.1 EDGE UL Access on TCP It used the scenario of Figure 12.2b. First the bandwidth was investigated using Jperf/Iperf and Ethereal/WireShark, both at probe and client side. In case the probe and the client are both mobile, the UL limitations apply in both cases. This means a series of delays, which actually limit the transfer rate by UL access. The UL bandwidth is very similar to the DL bandwidth but proportionally lower (due to the reduced number of GPRS/EDGE channels available for UL)-this observation is valid for all the performance measurements related to the TCP UL transfer. 10,000 bps 5000 bps 100 s 150 s 200 S 250 S Figure 12.10 Ethe