--- title: "Advantages and disadvantages of FDMA, TDMA, CDMA" subject: "Wireless Communication" chapter: 7 key: "semester_7/wireless_communication:fdma-tdma-cdma-pros-cons" source: https://www.bctengineer.com/q/semester_7/wireless_communication/fdma-tdma-cdma-pros-cons site: BCT Engineering --- # Advantages and disadvantages of FDMA, TDMA, CDMA Wireless Communication · Chapter 7: Multiple Access in Wireless Communication - Asked in: 2073 Magh, 4 marks - Video: [Comparison of FDMA, TDMA and CDMA - Multiple Access - FDMA vs TDMA vs CDMA](https://www.youtube.com/watch?v=anxrpFA3d5I) — Padmasri Naban - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/wireless_communication/fdma-tdma-cdma-pros-cons - Whole chapter: https://www.bctengineer.com/md/semester_7/wireless_communication/chapter-7 ## Question State the advantages and disadvantages (two of each) of: (i) Frequency Division Multiple Access (FDMA) (ii) Time Division Multiple Access (TDMA) (iii) Code Division Multiple Access (CDMA). ## Short answer FDMA: simple hardware, no equalization; needs guard bands and wastes idle channels. TDMA: shared carrier saves transceivers, discontinuous transmission saves battery; needs tight synchronization and equalizers. CDMA: universal frequency reuse and soft handoff; suffers near-far problem and self-jamming. ## Answer #### (i) FDMA - Advantages: 1. Simple hardware; no complex synchronisation or framing needed. 2. Narrowband channels with low ISI, so equalization is usually not needed. - Disadvantages: 1. Needs guard bands and costly, sharp RF filters; one transceiver per user at the base station. 2. An idle channel cannot be used by others, wasting spectrum; capacity is low. #### (ii) TDMA - Advantages: 1. One carrier is shared by several users, so fewer transceivers; duplexer not needed. 2. Discontinuous transmission saves battery and allows mobile-assisted handoff in idle slots; variable bit rate by giving more slots. - Disadvantages: 1. Tight time synchronisation and guard times needed; overhead bits reduce efficiency. 2. High burst rate causes ISI, so adaptive equalizers are needed. #### (iii) CDMA - Advantages: 1. Universal frequency reuse (no frequency planning) and soft capacity, giving high capacity. 2. Soft handoff and RAKE receiver use multipath, improving call quality; good privacy. - Disadvantages: 1. Near-far problem; needs fast and precise power control. 2. Self-jamming due to imperfect code orthogonality; complex receivers and synchronisation. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Which is a disadvantage of FDMA? A. Needs complex adaptive equalizers B. Idle channels cannot be used by others, wasting spectrum C. Needs tight time synchronisation D. Suffers self-jamming Answer: B. FDMA channels are dedicated to one user, so idle channels are wasted; equalization and sync are TDMA matters. (Key point: FDMA disadvantage) 2. Why is equalization usually not needed in FDMA? A. Because of soft handoff B. Because of RAKE receivers C. Because of discontinuous transmission D. Because narrowband channels have low ISI Answer: D. Narrow channels have low symbol rate and so low intersymbol interference. (Key point: FDMA advantage) 3. Why do TDMA systems need adaptive equalizers? A. The high burst rate causes ISI B. They use many transceivers C. They have guard bands D. They use soft handoff Answer: A. The high transmission burst rate makes multipath ISI significant. (Key point: TDMA disadvantage) 4. Which is an advantage of TDMA? A. Universal frequency reuse B. Discontinuous transmission saves battery and allows mobile-assisted handoff in idle slots C. Soft capacity D. RAKE reception Answer: B. The mobile transmits only in its slot and can measure neighbours in idle slots. (Key point: TDMA advantage) 5. Which pair are disadvantages of CDMA? A. Hard handoff and frequency planning B. Guard bands and sharp filters C. Near-far problem and self-jamming from imperfect code orthogonality D. Duplexer needed and low privacy Answer: C. CDMA needs power control for near-far and suffers self-jamming. (Key point: CDMA disadvantage) ## Related in Wireless Communication - [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 - [Multiple access, TCDMA and TDFH](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Atcdma-tdfh) — 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× - [TDMA, CDMA and SDMA](https://www.bctengineer.com/question.md?key=semester_7%2Fwireless_communication%3Atdma-cdma-sdma) — Wireless Communication, chapter 7 ## Related in other subjects - [FDMA vs TDMA; T1 and E1 hierarchy](https://www.bctengineer.com/question.md?key=semester_6%2Fcommunication_systems%3Afdma-tdma-t1-e1) — Communication Systems, chapter 5 - [Multiple access protocols](https://www.bctengineer.com/question.md?key=semester_7%2Fcomputer_networks_and_security%3Amultiple-access-protocols) — Computer Networks and Security, chapter 3, asked 2× - [Multiple access in IEEE 802.5](https://www.bctengineer.com/question.md?key=semester_7%2Fcomputer_networks_and_security%3Aieee-802-5-access) — Computer Networks and Security, chapter 3 - [Multiplexing vs multiple access](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Amux-vs-multiple-access) — Data Communication, chapter 6