**4.2 Performance degradation due to background traffic in access**

Table 6 shows the video conference performance without PC background. When the xDSL bandwidth profile set to 800 Kbps or equal to BR for iPad, the video quality for iPad is maintained below the threshold; the packet loss below 3% and the jitter far below than 40 ms. By giving 20% more bandwidth to 1 Mbps it will give additional space to anticipate other header and load during busy hours and also it will give better performance for real time

Femtocell Performance Over Non-SLA xDSL Access Network 155

40 ms. In this case, when the femto and PC using the same PVC, ones can improve the performance of femtocell by subscribing more xDSL bandwidth about double than the required bandwidth by a FAP. Of course the final bandwidth is sensitive to the amount of

Figure 13 shows the mix traffic from femtocell and PC when BW profile set to 20 Mbps. Even though the average total traffic from both femtocell and PC is about 2.2 Mbps, setting up line speed to 2 Mbps has given acceptable performance to the real time femtocell traffic.

**Background (bps) iPad Mix (bps) Mix+Background**

**max** 2,839,920 1,234,368 3,280,096 **min** 1,093,248 4,240 1,285,244 **average** 1,703,366.8 526,393.8 2,229,760.6 **variance** 158653351055 66753348160 280358769397

In this chapter the xDSL characteristics has been explained including xDSL attainable rate and transmission delay. Based on TELKOM study result, the performance of ADSL2, ADSL2+ and VDSL2 under FTTE, FTTC and FTTB configuration have been discussed. The backhaul quality model for xDSL has been proposed in order to accommodate both technical limitation of xDSL (in example cable length and constaint in xDSL uplink bandwidth) and current penetration rate of bandwidth subscription profiles both in Indonesia and Europe. DSL backhaul quality model is derived in order to address different qualities of backhaul. The model has been used in FREEDOM project in elaboration of cooperative RRM, scheduling and system level

According to the performance measurement result, it can be concluded that the femtocell performance can be affected by internet traffic in the xDSL modem. This case mostly happens when the users instantly plug in the femtocell to their broadband connection without knowing that the traffic from a FAP and PC could compete to each other without any priority or separation. This is also true if the xDSL service provider is a separate company, and there is no service level agreement with the femtocell service provider in

In order to achieve better performance for femtocell, the customer should have additional bandwidth to accommodate both traffic. Alternatively an integrated modem-femtocell

Fig. 13. Aggregate Throughput in xDSL link, BW profile set to 20 Mbps

simulation which need to take into account the backhaul quality.

order to maintain end-to-end QoS.

internet traffic from local area network (PCs).

**5. Conclusion** 


traffic. In this case, it gives less jitter and increase throughput. TELKOM usually adds 20% on top of bandwidth requirement to engineer xDSl line speed, hence 1 Mbps line speed is used. It can be shown from Table 6 that the performance metrics of 1 Mbps line is closed to 20 Mbps.

Table 6. H264 Video Conference Performance without PC background

We use video conference as reference in order to see the effect of background traffic from PC to the femto service performance, in this case video conferencing. It can be seen from Table 7, as


Table 7. H264 Video Conference Performance in the presence of background traffic from PC

soon the background traffic exist, the packet loss of video quality increase from 2.47% to 3.98% and the jitter double from 20.75 ms to 45.52 ms. In order to improve the video performance we increase the xDSL bandwidth profile from 1 Mbps to 1.2 Mbps, 1.5 Mbps and 2 Mbps. When it set to 2 Mbps, the packet loss is below 3%, and the jitter is also below 40 ms. In this case, when the femto and PC using the same PVC, ones can improve the performance of femtocell by subscribing more xDSL bandwidth about double than the required bandwidth by a FAP. Of course the final bandwidth is sensitive to the amount of internet traffic from local area network (PCs).

Figure 13 shows the mix traffic from femtocell and PC when BW profile set to 20 Mbps. Even though the average total traffic from both femtocell and PC is about 2.2 Mbps, setting up line speed to 2 Mbps has given acceptable performance to the real time femtocell traffic.

Fig. 13. Aggregate Throughput in xDSL link, BW profile set to 20 Mbps
