Wireless Communication
The midterm will include 4
problems (each with multiple parts) on the following topics. Sample questions are given below to help you
study. Problems will include both
calculation and “explain” parts. You may
use your portfolio and calculator, but no textbook. Be sure that you copy the important
graphs/tables from your book and put them in your portfolio. The exam is 1 hour long.
Suggested exam-taking
strategy: Look through all the
questions, and begin with the one you feel most confident. Write down all of the information you need to
solve the problem (equation, values of the variables that go into the equation,
etc.). Do this for all of the
problems. Leave the actual calculations
(calculator-punching) until last.
Partial credit is given, and more of this partial credit is given for
the set-up of the problem than for the calculator-punching. Remember to write down what you are
thinking/doing, so that if you make mistakes, I can give you partial credit. NO credit will be given for answers (even if
correct) if nothing is given to show how you obtained them. (ie.
Don’t just program all the equations in your calculator, and write down the
answer without writing down the equation.)
Cellular Basics
1.
Describe how a
cellular telephone system works, the major parts (from PSTN to mobile), how a
call is made, etc.
2.
Understand
the major types of systems in use today (with emphasis on GSM and AMPS) What are the
aspects that are different/similar between the various systems?
Frequency Planning
# of channels, # of cells,
size of cells
3.
Given the
available bandwidth and bandwidth of a channel, how many channels are in a
given cell, cluster, and system?
Understand the different types of channels (voice, control, etc.) and
how they are distributed within the system.
co-channel interference
4.
Given N, find the
S/I for cochannel
interference, and determine if it meets system specifications. Or, given the required S/I, determine what N
needs to be.
5.
Determine
the minimum radius of a cell for a given S/I.
adjacent channel
interference
6.
Determine
the S/I ratio for a typical system.
trunking
and grade of service
7.
Calculate traffic
intensity for the system, channel, or user.
8.
Determine
the grade of service given the number of channels and traffic intensity.
cell splitting , cell sectoring
9. Determine how cell splitting or sectoring affects
the answers to questions 3-8.
Path Loss / Large Scale
Fading
** For the following sections
on large and small scale fading, be sure you understand the basis of how the
equations/formulas/etc. were derived, what approximations were made, and what
the limitations are on when you should/should not use these models. You will not be asked to derive the
equations, but should be able to explain what they are based on.
Field Theory
Friiss
transmission equation
9.
For a
given distance, antenna gains, received power required, and frequency,
determine the required basestation power. Be sure you understand what
Reflection
10.
Determine
the reflected and transmitted field and power levels for given incident angle,
frequency, and materials (electrical properties would be given). Be sure you also understand the polarization
of the fields.
Ground Bounce
11.
Calculate
the field and power received given antenna heights, gains, and frequency.
Diffraction
12.
Determine if you
are in a peak or shadow fresnel
diffraction region.
13.
Understand
the effect of diffraction and its significance (what does it do in the system).
Rough surface scattering
Global path loss models
Link Budgets
(combination of all chapters)
14.
Be able to
calculate the power received given power transmitted and measured losses within
the system. Determine when you should
use a given path loss or fading model, and be able to include it in the link
budget.
15.
Explain the
importance of path balance, and be able to determine appropriate base station
power to achieve path balance.