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Short note: Means of bandwidth utilization

Short answer

Bandwidth utilization is achieved by multiplexing (FDM, TDM, WDM) to efficiently share a link when its capacity exceeds signal bandwidth, and by spread-spectrum techniques (FHSS, DSSS) that deliberately widen bandwidth for security and jamming resistance. Multiplexing aims for efficiency; spreading aims for protection.

Write a short note on means of bandwidth utilization.

Bandwidth utilization means making the best use of the available bandwidth of a link, which can be done in two ways: multiplexing and spreading.

Multiplexing

Several signals share one link efficiently when the link bandwidth is larger than each signal needs.

  • FDM: each signal gets its own frequency band (analog; radio, TV).
  • TDM: each signal gets its own time slot (digital; telephone). May be synchronous or statistical.
  • WDM: different light wavelengths carry different signals in an optical fibre (a form of FDM for light). DWDM packs many wavelengths.
 FDM: bands side by side  | f1 | f2 | f3 |
 TDM: slots in turn       |A|B|C|A|B|C|

Spreading (spread spectrum)

The bandwidth of a signal is widened for security and anti-jamming, not for efficiency.

  • FHSS: carrier hops among frequencies in a PN pattern.
  • DSSS: each bit is replaced by many chips, so the signal occupies a larger band.

Comparison of purpose

  • Multiplexing: efficiency, link bandwidth > signal bandwidth.
  • Spreading: protection against eavesdropping and jamming, signal bandwidth is deliberately increased.

CDMA uses spreading for sharing the same band.

✓ Answer checked by Claude Sonnet 5.5

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