3. Think of a phase diagram and the points representing valid symbols for a PSK

Question

3. Think of a phase diagram and the points representing valid symbols for a PSK scheme (see figure 2.29).

a) How can a receiver decide which symbol was originally sent when a received "point" lies somewhere in between other points in the diagram?

b) In regards to error detection/correction, why is it difficult to code more and more bits per phase shift?

4.

a) Explain how handoffs are initiated in first generation cellular systems.

b) Explain how handoffs are initiated in second generation (and later) cellular systems.

c) Why is MAHO possible for second-generation cell phones but not for first generation phones?

Explanation / Answer

Please post the figure 2.29 i couldn.t see it..

A) If thinking in such points, for a received signal the corresponding point in the phase
diagram is compared to the surrounding points, e.g. by measuring the distance to the other
points. (Thinking in such points here only is for easier understanding, not for the real
processing inside receivers.) A received point then is corrected to the allowed point which
has nearest distance. In this way errors in phase (or, amplitude, considering QAM) can be
detected and corrected. Having now more and more points, the risk increases to

Related Questions

Navigate

• Browse (All)
• Browse 3
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.