---
title: "Multiplexing vs multiple access"
subject: "Data Communication"
chapter: 6
key: "semester_5/data_communication:mux-vs-multiple-access"
source: https://www.bctengineer.com/q/semester_5/data_communication/mux-vs-multiple-access
site: BCT Engineering
---

# Multiplexing vs multiple access

Data Communication · Chapter 6: Multiplexing and Spreading

- Asked in: 2071 Shrawan, 3 marks
- Video: [Multiplexing vs Multiple Access Explained | SDMA FDMA TDMA CDMA | Mobile Computing](https://www.youtube.com/watch?v=rOjiEvgpyaI) — MKG Online Study
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/data_communication/mux-vs-multiple-access
- Whole chapter: https://www.bctengineer.com/md/semester_5/data_communication/chapter-6

## Question

What are the differences between multiplexing and multiple access?

## Short answer

Multiplexing combines signals from one location into a single link using a central multiplexer, with static allocation (e.g., FDM, TDM). Multiple access lets geographically distributed stations share a medium via a protocol (FDMA, TDMA, CDMA), with dynamic channel allocation. Multiplexing is physical layer; multiple access is MAC sublayer.

## Answer

Both allow many users to share a medium, but they work at different places and for different purposes.

**Multiplexing** combines several signals at one location (a MUX device) into one link; the sharing is fixed and the signals all come from one point, e.g. a telephone exchange multiplexer.

**Multiple access** lets many separate, geographically distributed stations share a common channel, each transmitting independently; a protocol decides who may use the channel, e.g. mobile phones sharing a cell.

| Point | Multiplexing | Multiple access |
|---|---|---|
| Location of users | Same place, at one MUX | Distributed in different places |
| Control | Central, fixed by the multiplexer | Distributed protocol / base station |
| Channel allocation | Static | Static or dynamic (on demand) |
| Aim | Efficient use of a link | Sharing of a medium |
| Layer | Physical layer | MAC sublayer / physical |
| Examples | FDM, TDM, WDM | FDMA, TDMA, CDMA, CSMA, ALOHA |

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which describes multiplexing?
   A. Signals combined at one location by a MUX device
   B. Stations spread over many places share a channel
   C. A protocol decides who transmits
   D. Users transmit independently
   Answer: A. Multiplexing combines signals from one point; multiple access serves distributed stations. (Key point: Location of users)

2. How is the channel shared in multiple access?
   A. By a fixed multiplexer only
   B. By a distributed protocol or base station
   C. By guard bands only
   D. By a single MUX device
   Answer: B. Multiple access uses a protocol or base station to decide who may use the channel. (Key point: Control)

3. Which list contains only multiple access methods?
   A. FDM, TDM, WDM
   B. FDM, CDMA, WDM
   C. FDMA, TDMA, CDMA, CSMA, ALOHA
   D. TDM, ALOHA, WDM
   Answer: C. FDMA, TDMA, CDMA, CSMA and ALOHA are multiple access; FDM, TDM and WDM are multiplexing. (Key point: Examples)

## Related in Data Communication

- [Multiplexing; synchronous vs asynchronous TDM](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Amux-compare-sync-async-tdm) — Data Communication, chapter 6, asked 6×
- [Short note: Analog vs digital mux hierarchy](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Aanalog-vs-digital-mux-hierarchy) — Data Communication, chapter 6
- [Datagram vs virtual circuit switching](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Adatagram-vs-virtual-circuit) — Data Communication, chapter 7, asked 3×

## Related in other subjects

- [CDMA vs TDMA; FHSS multiple access](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Acdma-advantages-fhss-types) — Wireless Communication, chapter 7
- [Spread spectrum multiple access; FDMA vs CDMA](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Aspread-spectrum-ma-fdma-cdma) — Wireless Communication, chapter 7
- [Multiple access; FDMA vs CDMA](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Amultiple-access-fdma-vs-cdma) — Wireless Communication, chapter 7
- [Frequency hopped multiple access (FHMA)](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Afhma-operation) — Wireless Communication, chapter 7, asked 5×