Wireless Sensor Networks For CDMA: Amplifiers, Mixers, And Multiplexing Techniques Essay.

What does an amplifier do and why is one needed in a radio system?

Discuss about the Wireless Sensor Networks for Introduction to CDMA.

An amplifier is mainly an electronic component that can boost an electric current or some signals. Amplifiers are primarily used to amplify signals like let just say someone has hearing aid, the machine takes the sound all around the surroundings and then just increases its strength; this process is called amplification. Amplifiers are just known to amplify weak signals too strong signals. Amplifiers are the best option to regain a particular signal that is lost during the transmission (Freeman, 2007). It catches the signal, regenerates the actual signal and sends it to the receiver. Use of amplifiers is the most common thing in the case of transmission. Modulation-Demodulation, Coder-Decoder use amplification in each and every occasion. As a whole, it can be considered that amplifiers are mainly there to regenerate the lost signal so that efficiency of the sender and satisfactory level of the receiver are maintained.

An amplifier can be used in radio systems very efficiently. It is mainly the modified amplifier that generally magnifies the high-frequency signals. It is used in radio system. The frequency in which the large number of improvement occurs in a particular radio frequency (known as RF) amplifiers are made of inconstant by frequently changing the capacitance as well as the inductance of a, particularly tuned circuit (Hussain, 2005). The request of amplification is very typical like firstly it receives the signal from the antenna earlier it is assorted with the local noise signals. The primary detector of the radio receiver receives the signal at first. The amplifier which is followed by the detector is a particular type of amplifier called the immediate frequency amplifier. The primary justification of rf amplifier can be done through its tuning ability over the assigned input frequencies. The shunt capacitance is mainly causes a problem for the improvement of a resistance-capacitance joined amplifier. Then it turns out to be the portion of the tuning capacitance in the amplifier. In this way, the high gain at radio frequency is permitted.

The above description tells us the clear picture about the use of an amplifier in the radio system. The range of frequency of a radio system is mainly restricted and after receiving the signal from the antenna, many noisy signals can be attached to the primary signal that can cause a problem. Then the rf amplifier and if amplifier comes into play (Feucht, 2010). The detector also plays a vital role in it. 

What is the purpose of a mixer? Include a discussion of sidebands in your answer.

Mixer

A mixer is an electronic device. It is mainly used to combine, changing and routing the volume level. It also combines the dynamic and timbre of several audio signals. For example, Microphone can be used by singers as well as mics can be used in acoustic instruments. For example, mics are used on drums as well as saxophones. The mixer can lead an essential role to transmit signals from electric as well as electronic instruments (Mangeot, 2005). Electric bass, the synthesizer is an example of such electric instruments. Analog and digital signals can be controlled by Mixer from 2010. It depends on the type of the mixer. A combined output signal can be produced by the summation of the modified signals. The signals are broadcasted by the user through a sound reinforcement system. The mixer can be used in several applications. The application includes several recording studios, sound reinforcements system, dance clubs, nightclubs, film production and television. The combined signal of two microphones can be combined by a typical application. The signals are transmitted to an amplifier which controls one pair of signal concurrently (Liu, Zhang and Yang, 2012). In the case of live performance, the signal which transmitted from the mixer goes directly to the amplifier. The amplifier must be plugged into the cabinet of the speaker. There are only two channels are provided in DJ mixer. It mixes two recording player.

The mixer can also provide phantom power in capacitor microphones. It also provides pain control for changing the position of sound control. The mixer can also play an essential role for filtering and equalization. It can be the primary purpose of a mixer. It activates the sound engineer who boosts the sound frequency as well as cut the sound frequency to develop the quality of the sound.

Mixer mainly uses in the digital processing techniques to attach three different input audio signals into one single output audio signal. It also manipulates every input signal modulation. It also maintains the high and low pass filters in its each audio channel independently. A mixer mainly provides the ability to observe each audio signal channels without providing any master output. A single, equalized and mixed signal can be obtained by the user from three different audio input signals. It provides an important role for mixing two songs as well as combine instrumental tracks together and create a passage of complex music.

Compare and contrast the multiplexing techniques CDMA and FDMA in the area of wireless networking?

IQ

To identify the process for maximizing the information transmission, it is crucial to introduce IQ mixers. It allows user for modulating the in-phase as well as quadrature components of career concurrently (Edlich, 2013). It uses for the multiplexing of two modulating signals.

Block Diagram

Fig: 1

Sources: https://www.markimicrowave.com/blog/2013/06/iq-image-reject-and-single-sideband-mixers/

Image reject mixer can be used to allow a user to catch a signal in the crowded environment. It is overpowering the adjacent image signal. Image request mixer is also responsible for releasing the requirements of receiver filter. 

The single sideband mixer is mainly used to allow a user for up converting to a signal; it up-converts the signal into a career while overpowering frequency signal of the similar image (Archer, 2006). It is also responsible for releasing the requirements of the transmission signal.

Fig: 2

Sources: https://www.markimicrowave.com/blog/2013/06/iq-image-reject-and-single-sideband-mixers/

CDMA

CDMA mainly refers to the fact of conversion of analog-to-digital signals. It is mainly done with the help of the spread spectrum technology. In this case, audio input is mostly manipulating into binary elements. It helps the receiver to follow the exact transmitter frequency (Abu-Rgheff, 2007). The CDMA channel normally has a range which is 1.23MHz wide. The Soft handoff scheme is used by CDMA networks that minimize signal fragmentation as a receiver which passes from one to another cell. The perfect mixture of spread spectrum modes as well as digital methods which support additional times as numerous signals per unit bandwidth as the analog modes. The nationwide roaming facility is provided by this technique as CDMA is companionable with the different cellular machineries (Engels and Petré, 2006). CDMA One is known as the original CDMA standards. A transmission speed of up to 14.4 Kbps can be offered by CDMA on its single channel. It can afford a capacity of 115 Kbps in an eight channel form. It is also to be notified that CDMA2000 as well as Wideband CDMA which send data as many times quicker. 

Unlike FDMA, CDMA separates calls by codes where each and every particular bit of a discussion is marked with a particular as well as unique code. In this process the system receives a call then it assigns the particular unique code in that specific conversation. Then the data is divided into minor parts as well as tagged with the exclusive code given to that specific conversation of which they are the parts of. After this part, the data is sent through some frequencies which are available to use at any specific time in a particularly mentioned series.  At the end of the transmission, the receiver then recollects or regathers the codes to gain the actual message or data or signal. The technique of CDMA is mainly based on the separation of codes. That differs CDMA from FDMA.

FDMA is standing for Frequency division multiple access. It is mainly the channel manipulation method through which multiple admittance protocols are used in a network. A unique allocation or different frequency can be sent to the user by this multiplexing technique (Koo et al., 2002). FDMA is used for wireless and satellite communication. It also co-ordinates the uses among several users. This technique mainly allocates for the wireless cellular phones. Here FDMA technique communicates into 30 channels.

In FDMA, almost maximum users share frequency channel as well as the satellite transponder. But only every user transmits the signal at a single frequency. Every channel can contain digital service as well as voice conversation. It also carries digital data. In AMPS (Advanced Mobile Phone Services), FDMA leads a primary role to give better services. Here every channel can be assigned to one single user at the same time. That is the primary function of FDMA. FDMA is also be used in the TACS (Total Access Communication System).

Unlike CDMA, in FDMA all channels are in an idle state when not in use. The bandwidth of the communication channel is comparatively narrow. It is also known as Narrowband system. To spread the symbol time, there is no need of equalization in FDMA. In this technique, analog signals can be most suitable. Also for continuous transmission, there is no need for synchronization. In the case of duplexing, FDMA combined with FDD. It is based on the separation of frequency. 

References

Abu-Rgheff, M. (2007). Introduction to CDMA wireless communications. Amsterdam: Academic.

Archer, J. (2006). A 80–100 GHz image-reject passive-HEMT mixer. Microwave And Optical Technology Letters, 48(12), 2429-2433. https://dx.doi.org/10.1002/mop.21953

Edlich, T. (2013). Recursive spatial multiplexing. Kassel: Kassel University Press GmbH.

Engels, M. & Petré, F. (2006). Broadband fixed wireless access. New York: Springer.

Feucht, D. (2010). Designing amplifier circuits. Raleigh, NC: SciTech Pub.

Freeman, R. (2007). Radio system design for telecommunications. New York: IEEE.

Hussain, A. (2005). Advanced RF engineering for wireless systems and networks. Hoboken, N.J.: IEEE Press.

Koo, I., Yang, J., Ahmad, A., & Kim, K. (2002). Erlang capacity analysis of hybrid FDMA/CDMA systems supporting multi-class services according to channel assignment methods. Int. J. Commun. Syst., 15(10), 867-880. https://dx.doi.org/10.1002/dac.569

Liu, L., Zhang, P., & Yang, J. (2012). Development of a high quality wireless sound reinforcement system. The Journal Of The Acoustical Society Of America, 131(4), 3503-3503. https://dx.doi.org/10.1121/1.4709240

Mangeot, A. (2005). Mixer. Norwich: Egg Box Publishing.