* Vectoring in VDSL2 :
* Vectoring is a technology used to mitigate crosstalk (interference between adjacent copper lines) in VDSL2 systems, improving data rates and stability.
* Crosstalk occurs when signals from one line interfere with signals on another line, especially in bundled copper cables.
* Pre-coder Technology :
* Pre-coding is a key technique used in vectoring for downstream transmission.
* It works by pre-distorting the transmitted signal at the DSLAM (Digital Subscriber Line Access Multiplexer) to cancel out the expected crosstalk at the receiver (CPE).
* This ensures that the received signal at each CPE is free from interference caused by other lines.
* Other Options :
* fdps : Not a recognized term in the context of vectoring or VDSL2.
* Canceller : While cancellation is part of vectoring, the specific term "Canceller" is not used in this context.
* Postponed : This is unrelated to vectoring or crosstalk mitigation.
* Why C?
* Pre-coding is the correct technology used in vectoring to cancel downstream crosstalk in VDSL2.
Thus, the correct answer is C .
References:
* HCIA Huawei ACCESS Official Documentation , Chapter: VDSL2 Vectoring.
* ITU-T G.993.5 Standards for Vectoring in VDSL2 .