IPA IP 2024 Question 84
A question IPA Japan published in 令和6年度 ITパスポート試験 公開問題 問84, translated into English. ITPEC is based on the same exams.
Which of the following is a technology that is also used in IoT area networks, and that achieves communication over a wide area by communicating in a relay manner, in which wireless communication from an IoT device is repeatedly relayed by other IoT devices?
Explanation
Multi-hop — a device's radio signal is passed on from device to device until it reaches its destination, so the network covers far more than one radio's range.
In a multi-hop network each IoT device can act as a relay: it receives a neighbour's transmission and forwards it to the next device. Low-power devices with a short radio range can reach a distant gateway this way, which is why IoT area networks (for example, sensor networks and smart meters) use it.
Answer (d)
Why not others:
- •(a) GPS — a satellite system that measures a receiver's position; it does not relay communication between devices
- •(b) MIMO — sends and receives with several antennas at once to raise the speed of one radio link, without relaying through other devices
- •(c) Carrier aggregation — bundles several frequency bands (carriers) into one mobile link for higher speed; it widens the link, not the area
Key rule: Multi-hop extends the range by relaying through other devices; MIMO and carrier aggregation raise the speed of a single link.
Networks · AI-written, may contain errors
This question comes from the past questions IPA Japan publishes, translated into English by ITPEC Practice. ITPEC Practice is an independent study tool and is not affiliated with IPA or ITPEC. See the original paper (PDF) or Report an issue.