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

Governer, governer characteristics

governer characteristics

3-phase 4 wire meters with ct and md, 3-Phase 4 Wire Meters with CT and MD ...

3-Phase 4 Wire Meters with CT and MD If load is commonly more than 50 A, CT operated meters should be used. It is to be remembered that CTs should be properly selected for acc

Transistor, can you differentiate the alpha,beta and gamma

can you differentiate the alpha,beta and gamma

Crossmagnetisation, what is crossmagnetisation in dc generator

what is crossmagnetisation in dc generator

Choose compensating components for the circuit, Q. Figure gives the frequen...

Q. Figure gives the frequency-response graphs for a 709 op amp. Choose compensating components for the circuit to have a gain of 100 and a frequency response of up to 100 kHz.

Determine the node voltage by using kcl, Determine the node voltage by usin...

Determine the node voltage by using KCL: Determine the node voltage V and then current flowing through each element by using KCL. Solution Apply KCL at the node whose

Electonic principles, can you help with my electronic principle assignment

can you help with my electronic principle assignment

What is extended memory system, What is XMS? XMS: The memory system is ...

What is XMS? XMS: The memory system is splits in three major parts as: system area, XMS (extended memory system) and TPA (transient program area). The kind of microprocessor in

Reverse recovery characteristics, Reverse Recovery Characteristics At t...

Reverse Recovery Characteristics At the end of forward  conduction in diode  reverse current  flows for  a short  time. The  device  doesn't  attain its full blocking  capabili

Find the mmf needed to establish a magnetic flux, Q. Consider the toroid sh...

Q. Consider the toroid shown in figure made up of three ferromagnetic materials. Material a is nickel-iron alloy having a mean arc length la of 0.6 m; material b is medium silicon

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