Advanced mobile phone system, Electrical Engineering

Assignment Help:

Q. Advanced Mobile Phone System?

Cellular systems employed cells with a radius in the range of 5-18 km. The base station usually transmitted at a power level of 35 W or less, and the mobile users transmitted at a power level of about 3 W, so that signals did not propagate beyond immediately adjacent cells. By making the cells smaller and reducing the radiated power, frequency reuse, bandwidth efficiency, and the number of mobile users have been increased. With the advent of small and powerful integrated circuits (which consume very little power and are relatively inexpensive), the cellular radio concept has been extended to various types of personal communication services using low-power hand-held sets (radio transmitter and receivers).

With analog cellular,or AMPS (Advanced Mobile Phone System), calls are transmitted in sound waves at 800 MHz to 900 MHz. This was the first mobile phone technology available in early 1980s. Digital cellular,or D-AMPS (Digital AMPS), transmits calls in bits at the same frequency as analog cellular, with improved sound quality and security. To send numerous calls at once, D-AMPS phones use either CDMA (Code Division Multiple Access) or TDMA (Time Division Multiple Access) technology; but CDMA phones won't work in TDMA areas, and vice versa. A dual-mode unit can switch to analog transmission outside of the more limited digital network.

PCS (Personal Communications Service) phones transmit at 1800 MHz to 1900 MHz and are smaller and more energy efficient. To get around the limited coverage, a dual-band digital phone (which switches to the lower digital frequency) and a trimode phone (which works in AMPS, D-AMPS, or PCS areas) has been developed. The GSM (Global System for Messaging communications) is the most widely accepted transmission method for PCS phones.


Related Discussions:- Advanced mobile phone system

Determine the value of maximum power, Determine the value of maximum power:...

Determine the value of maximum power: Determine the value of load resistance, R L for which the source shall transfer the maximum power. Also determine the value of maximum p

Show implementation of synchronous counter using d flip-flop, Q. Consider t...

Q. Consider the synchronous counter shown in Figure of the text. (a) Draw its timing diagram. (b) Show the implementation of the same synchronous counter using D flip-flops.

Colpitts oscillator circuit design, i would like to construct a colpitts os...

i would like to construct a colpitts oscillator using a series lc tank circuit as a feedback. the circuit will have a frequency of 150 Khz and it will drop when varying the value o

Design the synchronous sequential circuit for state diagram, Design the Syn...

Design the Synchronous Sequential Circuit for State Diagram Illustration: - We wish to design the synchronous sequential circuit whose state diagram The kind of flip-f

Explain the neg instruction, Explain the NEG instruction. NEG: Two's c...

Explain the NEG instruction. NEG: Two's complement or arithmetic sign inversion (NEG). The NEG instruction two's complements a number that means that the arithmetic sign of a

Determine the resultant mmf, Q. The N-coil windings of a three-phase, two-p...

Q. The N-coil windings of a three-phase, two-pole machine are supplied with currents ia,ib, and ic, which producemmfs given by F a = Ni a cos θm; F b = Ni b cos(θm - 120°); and

What is transconductance, Q. What is transconductance? Explain its signific...

Q. What is transconductance? Explain its significance from the transfer characteristics. Transconductance is the transistor gain of the JFET; it indicates the amount of control

Project, electrical project produse eneargy desingn

electrical project produse eneargy desingn

BASIC ELECTRICLE, kindly tell me which text book is usefull forlearn the ba...

kindly tell me which text book is usefull forlearn the basic electricle.

Bjt, bias compensation using diode and thermistor

bias compensation using diode and thermistor

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd