問87
頻出度★★★
IoT エリアネットワークでも用いられ, 電気を供給する電力線に高周波の通信用信号を乗せて伝送させることによって, 電力線を伝送路としても使用する技術はどれか。
令和5年度 ITパスポート試験 問87
テクノロジ系ネットワーク › ネットワーク方式
This question's explanation and your answers so far.
解説
問 87
- ア
正解 The correct answer is “ア (PLC).” PLC stands for Power Line Communication; it is a technology that superimposes high-frequency communication signals onto the power line that supplies electricity, so that the existing power line itself is also used as a transmission path for communication. Because no new communication wiring has to be installed and indoor power lines can be used to communicate, it is, as the question states, also used in IoT area networks (short-range networks that connect devices within a home or building). The question’s wording—carrying high-frequency signals over the power line and also using the power line as a transmission path—matches the definition of PLC exactly, so “ア” is correct.
Incorrectイ
PoE (Power over Ethernet) is a technology that supplies power over a LAN (Ethernet) cable at the same time as communication. Here it is the communication cable that carries the power, the opposite direction from the question (it does not communicate over a power line; it supplies power over a communication line). It is not a technology that uses a power line as a transmission path, so it is wrong.
Incorrectウ
Energy harvesting (ambient power generation) is a power-generation technology that gathers tiny amounts of ambient energy—such as light, heat, vibration, or radio waves—and converts it into electricity. It is a means of powering devices such as sensors, not a technology for communication, and it does not use a power line as a transmission path, so it is wrong.
Incorrectエ
Tethering is a function that lets a PC or tablet connect to the Internet by way of the mobile line of a device such as a smartphone. It is connection sharing over wireless (Wi-Fi/Bluetooth) or USB and has nothing to do with power lines, so it is wrong.
ここがポイント
- Definition of PLC (Power Line Communication): a technology that superimposes high-frequency communication signals onto a power line and also uses the existing power line as a transmission path for communication. It needs no new wiring and is also used in IoT area networks.
- Sorting out the easily confused power-supply and communication terms: PoE supplies power over a communication cable, energy harvesting is ambient power generation, and tethering is connection sharing over a mobile line—all different from PLC, which communicates over a power line.
用語