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

Describe CCIT hierarchical structure, Q. Describe CCITT  hierarchical  stru...

Q. Describe CCITT  hierarchical  structure  of  switching  and  routing  using  block schematic.  Ans: Hierarchical network are capable of handling heavy traffic where req

Explain working of inverting amplifier, Q. Explain working of Inverting Amp...

Q. Explain working of Inverting Amplifier? One common op-amp circuit is shown in Figure. For the case of finite voltage gain Ao of an op amp that is otherwise ideal, the output

Find temperature coefficient of resistance in semiconductors, Semi-conducto...

Semi-conductors have temperature coefficient of resistance.  (A) Negative                                    (B) Positive (C) Both positive and negative        (D) none o

General purpose diodes - types of power diodes , General Purpose Diodes ...

General Purpose Diodes The  general purpose  diodes  have relatively high reverse recovery time. The  diodes are general  made  by diffusion. They  are used  in low  speed  app

Digital electronics, In a certain chemical-processing plant, a liquid chemi...

In a certain chemical-processing plant, a liquid chemical is used in a manufacturing process. The chemical is stored in three different tanks. A level sensor in each tank produces

State norton''s theorem, Norton's Theorem Nortons Theorem states: "A...

Norton's Theorem Nortons Theorem states: "Any linear circuit containing several energy sources and resistances can be replaced by a single Constant Current generator in para

Explain modulation and sampling, Q. Explain Modulation and sampling? Mo...

Q. Explain Modulation and sampling? Modulation is the process whereby the amplitude (or another characteristic) of a wave is varied as a function of the instantaneous value of

PIC Controller Programming, I want to do programming in PIC controller and ...

I want to do programming in PIC controller and it needs to be done on particular development board.

Disadvantages - high level languages, Disadvantage - High  level  Langua...

Disadvantage - High  level  Languages a.Computational time is more as compared to  machine languages. b.Requires more  memory. c.Requires the knowledge of specific rules

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