問84
頻出度★★★
IoTエリアネットワークでも利用され，IoTデバイスからの無線通信をほかのIoTデバイスが中継することを繰り返し，リレー方式で通信をすることによって，広範囲の通信を実現する技術はどれか。
令和6年度 ITパスポート試験 問84
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 84
Incorrectア
GPS is a global positioning system that determines a receiver’s current position (latitude, longitude, altitude) from radio waves sent by multiple positioning satellites; it is not a technology in which terminals relay signals to one another to extend communication range.
Incorrectイ
MIMO (Multiple Input Multiple Output) uses multiple antennas on both the transmitting and receiving sides to send and receive several signals at once on the same frequency, increasing communication speed and capacity. It is not a mechanism that extends range through relay hopping.
Incorrectウ
Carrier aggregation is a technology that bundles multiple frequency bands (carriers) for simultaneous use, widening the effective bandwidth to achieve higher speeds (used in mobile LTE, etc.). It has nothing to do with relaying by other terminals.
- エ
正解 The correct answer is “エ”, Multi-hop. Multi-hop communication is a method in which, to reach a far-off point that radio waves cannot reach directly, the IoT devices (nodes) along the path relay (hop) the received signal one after another, like a bucket brigade, until it gets there. Even if a single device has a short radio range, repeating this relay across many terminals can build a wide-area communication network. It matches exactly the question’s description of other IoT devices repeatedly relaying the signal to communicate in a relay fashion, and it is also adopted in the low-power, short-range wireless of IoT area networks.
ここがポイント
- Multi-hop communication = nodes along the way relay (hop) the signal one after another to a distant point that radio waves cannot reach directly, achieving wide-area communication in a relay fashion. It is used in IoT area networks and sensor networks.
- Sorting out confusing wireless terms: GPS = satellite positioning, MIMO = speed-up via multiple antennas, carrier aggregation = speed-up by bundling multiple frequency bands. None of them is about extending range through relaying, which is how to tell them apart.
用語