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

Active filter design, Design a wide band pass filter with cut-off frequency...

Design a wide band pass filter with cut-off frequency f L = 400 kHz, f H = 600 kHz, and a pass-band gain = 10. The roll-off rate at the cut-off frequency should be at least 4

Determine the motor current and speed, A dc series motor is connected to a ...

A dc series motor is connected to a load. The torque varies as the square of the speed.With the diverter-circuit open, the motor takes 20 A and runs at 500 r/min. Determine the mot

Explain index mode and base address mode, Explain index mode and base addre...

Explain index mode and base address mode (with examples) available in microprocessors. Index Mode and Base Address Mode: Address supplied through the instruction is adde

Find an expression for the power absorbed by the load, Q. For the circuit o...

Q. For the circuit of Figure: (a) Find an expression for the power absorbed by the load as a function of RL. (b) Plot the power dissipated by the load as a function of the lo

Society in engineering, Cite a specific example in which the engineer must ...

Cite a specific example in which the engineer must provide maximum efficiency for a given cost

Realize the function f by a k map using 0s, Q. Given the following truth ta...

Q. Given the following truth table: (a) Realize the function f by a K map using 0s. (b) Realize the function f by a K map using 1s.

Covert analog signal into digital signal, Covert Analog Signal into Digital...

Covert Analog Signal into Digital Signal A strain gauge is used in Wheatstone Bridge configuration. The output from the Wheatstone Bridge varies from zero to a maximum strain

Can you explain about slew rate, Q. Can you explain about Slew Rate? Sl...

Q. Can you explain about Slew Rate? Slew (or slewing) rate is a measure of how fast the output voltage can change. It is given by the maximum value of dvo/dt , which is normall

Control strategies - power supplies , Control Strategies Equation shows...

Control Strategies Equation shows  that output  voltage V0 can be controlled through α and this duty cycle  α can be varied by various  strategies which are as follows.

Electrical Engineering Design Report, hi there i just need help for Electri...

hi there i just need help for Electrical Engineering Design Report about any topic (prefer charger and inverter) which should be include Summary,Table of contents,Introduction,Body

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