Updated March 4, 2023
What is CDMA?
The CDMA is expanded as code-division multiple access and it is implemented in commercial mobile communications to effectively use the radio spectrum. It is used as a military technique at the early stages of world war II by the British government to break the chain of German invasions of traffic transmissions. CDMA is popularly called spread-spectrum methods that enable several users to utilize the same frequency and time in the allotted space and band. Every separated conversation is encrypted with the support of a digital pseudo-random sequence. The working of CDMA, its applications, advantages, and disadvantages are briefly explained in this article.
Why we Use CDMA?
CDMA is the best example of multi-access methods where numeral transmitters transmit the information using the channel allotted for single communication. CDMA enables multiple users to make use of the same band frequencies and permit to share without any interaction between the users. It employs the spread spectrum method with a unique coding method. It is the standard access method that follows mobile phone applications. It is called cdmaone which has its 3G evolutions. The CDMA2000 comes under CDMA, but UMTS where the 3G standards are used by GSM carriers which works on wideband CDMA, TD-SCDMA, TD-CDMA, and radio technologies.
The inherent merits of CDMA are more than FDMA and TDMA like capacity, security, soft handoff. The CDMA turns to be a winner in wireless services and technologies. It enables far significant development and utilizes broadband devices like a wireless modem in laptops, GPS units, and also the other innovated trending wireless devices.
For commercial purposes, the support of CDMA is to maximum speed in Push to Talk, Push to mail services. In walky-talky devices, the push to talk option is enabled to use it effectively at the allotted frequency. The services are released with service charges which makes the operator of CDMA happy and cost-effective.
How does CDMA work?
The Code Division Multiple Access entirely differs from time division multiple access. The CDMA, after data digitization, expands out of the date over the complete available bandwidth. It overlapped many calls to each other on a channel that is allotted with a particular sequence code. CDMA makes the data to be transmitted in small chunks over the several frequencies which are available to make use at any time allotted in computed range. The data of all the users can be sent in a similar method to the wide range of the spectrum. The signal of the user is widely spread of spectrum. The signal of the users is widespread in the complete bandwidth by special coding. At the end of the receiver, the same special code is used to recover the signal and data. The system of CDMA needs a much precise time stamp on every piece of the signal. Mostly ten or eight separate calls are generated out in the particular space of channel as a single analog call. The spread spectrum techniques such as frequency hopping and direct sequence are the popular ones used as communication channels.
Frequency hopping is the simple idea that transmits the data over a widely broad spectrum. The frequency can be instantly switched from one circuit to another. The receiver and transmitter are synchronized for every duration with an accurate clock system and pseudo generator system which makes the frequency hopping a very unique and simple one. The direct sequence is the popular spectrum method where the data signal is reproduced by a code of pseudo-random noise. A pseudo-random noise is sequence chunks which are represented as values of 1 and -1 or it can also be 1 or 0 that is polar or non-polar. The numerous chips that lie within the code are called a code period. The digitalized data can be coded directly with higher frequency and that code can be generated in a pseudo-random method. The receiver can be used to produce the same code which relates the obtained signal to extract the data.
Advantages and Disadvantages
The usage of CDMA throws many advantages which became the main reason to be adopted by 3G mobile telecommunications.
- It provides an increment in security and capacity. Here one of the principles claims the CDMA which offers constant enhancement in network capacity. In the CDMA technique, the voice and data packets are segregated by using codes that are transmitted by using codes, and then it is transferred by utilizing the wide area of frequencies. Since much space is allotted for information in CDMA which becomes more standardized and attracted to the 3G speed in the usage of mobile internet.
- CDMA provides an easy way for a terminal to interact with dual base stations at a single time. At this time, the prior or old link is discontinued and the newly created link is established. It enhances the reliability of handoff or handover from one particular base station to another base station.
- CDMA gained more attention in every attribute and it has allowed many special updates that are required for the mobile telecommunication systems.
- The channel pollution where the signals are congested in cell sites that are presented in the phone of the subscriber but make no one dominant. When any worse situation arises, the audio quality is degraded.
- The capabilities of international roaming are lacked in CDMA when it is compared with GSM
- The capability to change or upgrade the other handset is not comfortable in CDMA, because the information of network service for the phone is inbuilt in the actual phone wherein GSM, this option can be used by SIM card.
- It offers only the restricted variety in the handset since at present it is only involved with mobile companies that rely on GSM technology.
Conclusion
CDMA is measured as an increased mode in wireless communication and is considered for a safe mode of data transmission and fast gibing in 3G. Now it’s ruling the world by incorporating GSM techniques to provide maximum speed LTE or 4G internet services. The working and application of CDMA are briefly explained in this article along with its limitations.
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