# Lower-Latency Screen Updates over QUIC with Forward Error Correction
## 6 Empirical Results on Emulab
### Streaming Updates
**Partial order+FEC reduced the message-blocking time and inter-delivery time with the baseline setting (Figure 9):** In Figure 9a, we show the **CDF of the message-blocking time**, in which using partial+FEC with both a 5% redundancy rate (i.e., red, n/k = 1.05) and 10% (i.e., black, n/k = 1.1) yielded a 99-percentile time of 0.4 ms. However, the 80-percentile of total (i.e., blue) was already 101.08 ms, and the 99-percentile was 230 ms. Also, in Figure 9b, the total and partial delivery methods had higher **message inter-delivery times** compared to partial+FEC because they needed to wait for at least an RTT to receive the retransmissions. The 99.95-percentile of the message inter-delivery time was 135 ms for blue, 102 ms for gold, 6 ms for red, and 9 ms for black. 2. **Partial order+FEC improvements increased as the packet-loss rate and RTT grew (Figures 9-13):** Increasing **packet-loss** from 0.1% shown in Figure 10 to 0.5% shown in Figure 9 to 1% shown in Figure 11 show that partial+FEC can result in close to zero message-blocking and message inter-delivery time results even for a 1% packet-loss rate while the latency results became worse for total and partial delivery (i.e., blue and gold). For example, the 70-percentile of the message-blocking time for total shown in Figure 11 was 99.14 ms. Also, as we increased RTT from 50 ms shown in Figure 12 to 100 ms shown in Figure 9 to 200 ms shown in Figure 13, partial+FEC could keep the latency numbers close to zero independent of the RTT, while the message-blocking and message inter-delivery times of total and partial grew as a function of the RTT. For example, the 70-percentile of the message-blocking time for total shown in Figure 13 was 191.88 ms.
3. **Partial order+FEC improvements remained across different bandwidth values (Figures 9, 14 and 15):**  
Figure 16: **Partial+FEC reduced message-blocking and message inter-delivery time for CUBIC CCA. ** Streaming updates, **CUBIC** (0.5% loss, 100 ms RTT, 100 Mbps): **(a)** CDF of message-blocking time. **(b)** Message inter-delivery time in which the number of points above 100 ms is 70 for blue, 40 for gold, 2 for red, and 3 for black. Blue completed at 66.98 s, gold at 68.12 s, red at 71.92 s, and black at 75.08 s.  
Partial+FEC could help reduce both the message-blocking and message inter-delivery times for all three different values of the **bandwidth** in our experiments, from 10 Mbps shown in Figure 14, to 100 Mbps shown in Figure 9, to 1 Gbps shown in Figure 15. For example, the number of messages with an inter-delivery time higher than 100 ms was 71, 59, and 46 for total v.s. 1 or less for partial+FEC with 10 Mbps shown in Figure 14b, 100 Mbps shown in Figure 9b, and 1 Gbps shown in Figure 15b, respectively. 4. **Partial order+FEC reduced latency with both BBR and CUBIC CCA (Figures 9 and 16):** Figure 16 shows the message-blocking and message inter-delivery times for **CUBIC** CCA. Considering the results with BBR and the same other network parameters (i.e., loss, RTT, and bandwidth) shown in Figure 9, we can see the increase in the message inter-delivery time of partial+FEC shown in Figure 16, but these are still better results compared to total and partial delivery. The reason is that we had a smaller congestion window with CUBIC compared to BBR in the case of the packet-loss rate (i.e., 0.5%), so we needed more time to receive the redundant packets at the end of each update to be able to recover lost packets [8]. 5. **The results for the packet-loss rate to set the redundancy rate of partial order+FEC (Figure 17):** The amount of redundancy rate depends on the packet-loss rate. We evaluated three values for redundancy rate in our experiments: 1.05 and 1.1 for all of the results except for the 0.1% packet-loss rate shown in Figure 10, with n/k = 1.03 and n/k = 1.05 rates (where n/k = 1.03 is different from the other experiments).