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Advantages and disadvantages of FDMA, TDMA, 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.

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).

(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.

✓ Answer checked by Claude Opus 5.5 (high effort)

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