ZyXEL VES1724-56B2 User Guide - Page 101

Chapter 9 VDSL Setup reduces crosstalk interference that leads to service interruption. When there is a burst of CRC errors, the receiver initiates a simple OLR (On-line reconfiguration) request for switching to a predetermined adjustment transmission reference to the transmitter over an ROC (Robust Overhead Channel), then the transmitter sends a synchronous signal (SyncFlag). The receiver and transmitter synchronizes switching without exchanging the bit/gain table during SOS to avoid failure and new noise. G.INP G.998.4 is also known as G.INP, which defines how data is retransmitted in an ADSL(+) or VDSL2 system to correct errors when impulse noise occurs. G.INP is similar to PhyR, Broadcom's proprietary physical layer retransmission scheme to improve impulse noise protection. In G.INP, the smallest amount of data that may be retransmitted is called DTU (Data Transfer Unit). The differences between G.INP and PhyR includes: • DTU is a set of an integer number of ATM cells or PTM 65B codewords. • The overhead (indicator bit (IB), embedded operations channel (EOC)) information is carried on a separate latency path. • A time stamp is appended to each DTU to provide better jitter control if necessary. RFI (Radio Frequency Interference) RFI is induced noise on the lines by surrounding radio frequency electromagnetic radiation from sources such as AM and HAM radio stations. Since VDSL uses a much larger frequency range that overlaps with other radio frequency systems, signals from VDSL lines and other radio systems interfere with each other. To avoid performance degradation due to RFI, set the switch to not transmit VDSL signals in the RFI band. VDSL Profiles A profile is a table that contains a list of pre-configured VDSL line settings or VDSL alarm threshold settings. Each VDSL port has one (and only one) line and alarm profile assigned to it at any given time. Profiles allow you to configure VDSL ports efficiently. You can configure all of the VDSL ports with the same profile, thus removing the need to configure the VDSL ports one-by-one. You can also change an individual VDSL port by assigning it a different profile. For example, you could set up different profiles for different kinds of accounts (for example, economy, standard and premium). Assign the appropriate profile to a VDSL port and it takes care of a large part of the port's configuration. 9.1.1 VDSL Profile Example This example shows you the configuration relationships between VDSL templates, VDSL line profiles, VDSL line channel profiles, and subscriber ports. Since each VDSL line may have different loop conditions, you need to configure several VDSL line profiles and channel profiles in the VDSL Setup > VDSL Profile > VDSL Line Profile and VDSL Channel Profile screens. For example, you have 3 VDSL line profiles (LinProfile-1, LinProfile-2 and LinProfile-3) and 3 channel profiles (ChanProfile-1, ChanProfile-2 and ChanProfile-3). VES1724-56 User's Guide 101