令和2年度 ITパスポート試験問98

This question's explanation and your answers so far.

問98

頻出度★★★

IoT エリアネットワークの構築に当たり, ①～③ の通信規格の使用を検討している。これらの通信規格を有線と無線に分類したとき, 無線ネットワークに分類されるものだけを全て挙げたものはどれか。 ① BLE ② PLC ③ ZigBee

出典　令和2年度 ITパスポート試験問98

解説

問 98

Incorrectア
(1) BLE being wireless is indeed correct, but (2) PLC is wired communication that uses power lines as its transmission path, so it must not be included in the set of wireless standards. This is not a combination of only wireless ones.
Incorrectイ
This treats (1), (2), and (3) all as wireless, but (2) PLC is wired communication. Not all three are wireless, so it is incorrect.
ウ
正解 The ones classified as wireless are (1) BLE and (3) ZigBee, so the option that lists both of them — (1), (3) — is correct. (1) BLE (Bluetooth Low Energy) is a short-range wireless communication standard that uses radio waves, and (3) ZigBee is likewise a low-power short-range wireless communication standard based on IEEE 802.15.4; both connect devices to each other without any wiring. In contrast, (2) PLC (power line communication) is wired communication that uses the power lines inside a building as its communication path, so it is not counted as wireless. Therefore the combination that lists all and only the wireless standards is (1) and (3).
Incorrectエ
It includes (2) PLC (wired) while omitting (1) BLE, which is wireless. The selection of wireless standards is wrong in two ways.

ここがポイント

Distinguishing wired from wireless among the typical communication standards used in an IoT area network: BLE and ZigBee are short-range wireless, while PLC (power line communication) is wired and uses power lines.
As its name (Power Line Communication) indicates with “Line = power line”, PLC is a wired method that makes use of existing wiring; this is the key to identifying it.

用語

解答問98ウ