gth (corresponding to MPEG-2 packet length). On the end-user's side, set-top box decoders typically employ error concealment techniques to minimize the impact of lost or corrupted IPTV video packets. The errors which may appear in a sequence can cause noticeable quality degradation effects ranging from no noticeable audio or video impact from the losses to complete loss of the video and/or audio signal. 6.3 QoE for VolP and IPTV An example calculation for IPTV losses (considering use of MPEG-2 packets) is the follow- MPEG packets per second = 3 Mbit/s/8 bits per byte/188 bytes per MPEG packet = 1994.7 MPEG packets per second IP packets per second = 1994.7/7 MPEG packets per IP packet = 285 IP packets per second Loss of 16 ms corresponds to = 285 IP packets per second X 0.016 seconds = 4.56 IP pack- ets lost (as an average value, while the number of lost IP packets in a concrete case normally is always an integer value). To combat losses, which can occur (due to non-zero loss probability of every trans- mission media, either copper, fiber, or radio), a common configuration for DSL is using interleaver depth (i.e. forward error correction (FEC) block duration) of 8 ms or 16 ms. Hence, the corresponding loss period is targeted to be 8 ms or 16 ms. However, consid- ering different video bitrates (Table 6.3), this will correspond to a different number of lost video IP packets. Recommended minimum transport layer parameters for satisfactory QoE for MPEG-2 and MPEG-4 AVC or VC-1 encoded SDTV services are given in Table 6.3. Also, it assumes MPEG-2 transport stream with seven 188-byte packets per IP packet; however, 7 X 188 bytes + RTP/UDP/IP headers should overall be less than 1500 bytes, which is the maximum Ethernet MA) frame payload (because Ethernet is used as a unified LAN everywhere between the home gateway node and the set-top box). I the case of optical (fiber) access networks (e.g. FTTH), the packet loss rate is much lower than with DSL access (e.g. the optical network loss rate is in the range of 10-8-10-9). T