Difference Between CDMA and WCDMA

Edited by Diffzy | Updated on: April 30, 2023


Difference Between CDMA and WCDMA

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In this era of the 21st century, tools that facilitate intercommunication have proven to be of the most significant importance. In the past, we used various technologies such as mobile phones, pagers, radios, etc. Most of our gadgets are linked to the internet, which is a direct result of the advent of the internet—whether we're talking about our laptops, televisions, mobile phones, or anything else. Nevertheless, we need to investigate the more essential characteristics of the available communication networks. What is their purpose, and how do they operate? CDMA and WCDMA both come into play at this point in the game.

CDMA and WCDMA are multiple access technologies used in telecommunication networks to access resources and services. Since spectrum is a finite resource directly connected to capacity, most theoretical air interface solutions emphasize spectrum efficiency. Radio networks worldwide employ other access mechanisms besides CDMA. Combinations of these access mechanisms are employed for efficient spectrum utilization. North America uses cdma2000, an expansion of TIA/EIA-95B-based CDMA, whereas Europe uses WCDMA.


CDMA is the technology used in 2G networks, while WCDMA is the technology utilized in 3G networks. This is the primary distinction between the two technologies. The abbreviation for Code Division Multiple Access (CDMA) is "CDMA." This is an algorithm that assists a user in capturing several channels that may be used within the same bandwidth in its most basic form. Therefore, layman's words improve connection quality by allowing more users to share a given amount of bandwidth.

Wideband Code Division Multiple Access is meant to be understood by the acronym WCDMA. It uses the same technology as CDMA but integrates it into the third-generation network. In addition to making it possible to utilize GSM and EDGE networks as UMTS, this also increased internet speed.

Code Division Multiple Access is a form of an algorithm that is used in the field of telecommunications. Its primary purpose is to increase the number of usable channels while maintaining the same bandwidth. WCDMA stands for Wideband CDMA and refers to the method of channel division known as code division. The most significant distinction between CDMA and WCDMA is the group of technologies each belongs to since here is where most differences can be found. CDMA is a 2G technology that is a direct rival to GSM, which is the technology that is currently being used the most extensively. WCDMA is a kind of third-generation (3G) wireless communications technology often combined with GSM to provide simultaneous support for 2G and 3G capabilities within the same region of service. WCDMA and CDMA do not fall under the same category since CDMA's 3G technology, known as EV-DO, and WCDMA's rival technology are incompatible.

WCDMA is a member of the 3G group of technologies, so it should come as no surprise that it can provide speeds far higher than those offered by basic 2G and make use of more contemporary services unavailable via those networks. WCDMA is also superior to the much slower CDMA in terms of its ability to access the internet and send and receive emails.

WCDMA makes use of a bandwidth that is much greater than that of CDMA, as the term "wideband" suggests. In contrast to CDMA, which utilizes frequency bands that are just 1.25 MHz wide on average, WCDMA employs frequency bands that are 5 MHz wide. It's a common misconception that the only thing that's changed with WCDMA is the bandwidth; in reality, the changes between the two are far more significant. This is because WCDMA wasn't developed from the CDMA architecture; instead, it was created from the ground up. Despite this, both systems continue to rely on code division to generate more channels while using the same amount of bandwidth. The algorithms used may differ, but the fundamental idea that underpins it remains the same.

Difference Between CDMA and WCDMA in Tabular Form

Parameters of Comparison CDMA WCDMA
Definition CDMA is an algorithm that allows for transmitting a more significant number of channels within a given bandwidth. WCDMA uses the same fundamental technology as CDMA but integrates this technology into GSM and EDGE.
Network They are utilized in 2G network systems. They are utilized throughout the 3G network.
Speed Comparatively slower than the WCDMA standard. A faster technology than CDMA.
GSM CDMA is a competitor to GSM in this regard. WCDMA can communicate with GSM.
Bandwidth 1.25 MHz. 5 MHz.

What is CDMA?

The abbreviation for Code Division Multiple Access (CDMA) is "CDMA." This is an algorithm that assists a user in capturing several channels that may be used within the same bandwidth in its most basic form. Therefore, in layman's words, it improves connection quality by allowing a more significant number of users to share a given amount of bandwidth. Thus, in a sense, CDMA multiplexes a variety of signals so that they may be squeezed into a single allotted bandwidth. CDMA typically works in the ultra-high-frequency range, often between 800 MHz and 2 GHz.

However, the manner of operation of CDMA should not be confused with the typical time and frequency multiplexing techniques. This is because, while using CDMA, a customer can access the network for the whole session, free from any disruptions that could otherwise occur. The primary reason is that this approach assigns a one-of-a-kind identifier to each user, making it possible to differentiate between various types of clients.

The operation of CDMA is a complex process that allows as many as 61 people to use the network simultaneously and accommodates them within the same 1.23 MHz bandwidth. There are sixty-four different Walsh codes. The algorithm can distinguish between the theoretical limitations and the calls with the assistance of these codes. On the other hand, in real-time applications, the actual number is often lower than this amount because of the constraints imposed by technological constraints and the goals of improving quality.

Utilizing CDMA comes with both benefits and drawbacks in its own right. The primary benefits of using CDMA include less interference brought on by transmission bursts, as well as the use of rake receivers, which improves receivers. The utilization of flexible transfer enables the switching of mobile stations without calling for a new contract with the operator.

CDMA has several drawbacks, the most significant of which are delays caused by the vast size of the code, the necessity of perfect time synchronization, and progressive transmission often saturates radio capacity.

Qualcomm was the company that developed CDMA. The military initially used it during World War II to prevent radio communications from being jammed by the Axis powers. Regarding information transmission, it utilizes frequency bands of 800 MHz and 1900 MHz.

To send data, CDMA makes use of a channel access mechanism. It provides complete access to the spectrum of bands to its customers so that they may make the most efficient use of the available bandwidth. Up to 61 people may be supported by each channel simultaneously. To better explain how CDMA works, let's use the example of a payphone room. The newly designed payphone area is more effective since a much greater number of individuals may utilize the same frequency channel at the same time. Four payphone stations are available in the CDMA payphone room, and each station can accommodate up to 61 individuals. The phone stations stand in for the frequency channels, and the individuals make up an analogy for the consumers of the CDMA network.

CDMA offers a payphone station that is comprised of 61 phones, in contrast to the GSM system, which only gives one phone that a maximum of eight individuals may share. As a result, any user may make a phone call at the same time and utilize the entire channel to transmit and receive information for as long as they like, as opposed to consuming a portion of the frequency channel for a certain length of time that was allotted to each user individually.

Because there are numerous persons broadcasting information simultaneously inside the same channel, there has to be a means to prevent one talk from crashing into or interfering with another. CDMA employs the technique of spread spectrum to encrypt or encode each communication with a randomly generated unique key to safeguard speech data and maintain its confidentiality. The only user who can decode the message is the one with the key, which is the message's recipient.

CDMA is the channel access mechanism in various mobile phone standards, such as IS-95 (CDMAONE), CDMA2000, and UMTS. This is because CDMA is both efficient and improves the level of security offered by mobile phone networks.

What is WCDMA?

In 1998, the European Telecommunications Standards Institute (ETSI) decided that the best terrestrial-air interface technique for the Frequency Division Duplex (FDD) frequency bands would be WCDMA. This decision was made for the Universal Mobile Telecommunications Systems (UMTS). For the transmission of data signals over the air interface, WCDMA uses channel bandwidths of either 5MHz, 10MHz, or 20MHz. Direct Sequence WCDMA is another process in which WCDMA combines the original signal with a code consisting of pseudo-random noise. Therefore, after the procedure, each user will have their unique code, and only those users who have the proper code will be able to decode the message. With the help of the pseudo signal, the original signal is modulated into a greater bandwidth, which causes the spectral components of the original signal to get obscured by the noise. The call will appear to the jammers as nothing but noise if they do not have the code.

Wideband Code Division Multiple Access is meant to be understood by the acronym WCDMA. It uses the same technology as CDMA but integrates it into the third-generation network. In addition to making it possible to utilize GSM and EDGE networks as UMTS, this also increased internet speed. WCDMA represents the transition from 2G to 3G and is thus orders of magnitude faster than its predecessor. This is a result of a very particular cause. CDMA is a rival to GSM; hence, they chose not to combine technology that would have allowed them to construct something quicker and more robust. On the other hand, WCDMA is an evolution of GSM and EDGE, culminating in UMTS's development. As a direct consequence, connection, capacity, and speed were all significantly improved.

WCDMA can support various technical connections, including cellular voice and text communications, as well as MMS and 3G. Direct Sequence Code Division Mechanism (DS-CDMA), also known as frequency division duplexing, is WCDMA's channel access method. Because of this, it can achieve more robust connectivity and faster speeds.

WCDMA supports two different modes:

  • Frequency Division Duplex, sometimes known as FDD, is a technique that divides users into two groups based on the software and hardware they use. They use the code in conjunction with the frequencies to distinguish amongst the users. There are two different frequencies in use. The uplink is provided by one of them, while the downlink is provided by the other.
  • In the Time Division Duplex (TDD) approach, in addition to the frequencies and code utilized in the FDD method, time is another aspect used to discriminate between the users. This method is similar to the FDD method.

WCDMA's benefits include faster connection speeds and more robust network infrastructure. The primary drawback of WCDMA is that it is not utilized everywhere, resulting in compatibility problems for many mobile phones and other devices.

WCDMA uses the Quadrature Phase Shift Keying (QPSK) modulation scheme as the modulation scheme by the original standard specified by the International Telecommunication Union (ITU) for 3G networks. This scheme can support data transfer rates of up to 384 kbps in mobile environments and up to 2 Mbps in stationary environments.

Main Differences Between CDMA and WCDMA in Points

  • The primary distinction between CDMA and WCDMA is that CDMA is an algorithm allowing additional channels to be sent over a single bandwidth. In contrast, WCDMA uses CDMA as its foundation while also including GSM and EDGE in its design.
  • WCDMA is used over 3G networks, while CDMA is utilized over 2G networks.
  • When compared to WCDMA, CDMA is a relatively sluggish technology.
  • While CDMA competes with GSM, WCDMA cooperates with it.
  • The bandwidth that CDMA runs in is 1.25 MHz, whereas the bandwidth that WCDMA operates in is 5 MHz.
  •  CDMA and WCDMA cannot be utilized together.
  •  When compared to CDMA, WCDMA delivers substantially quicker speeds.
  • Comparing the growth of CDMA in various European, US, and Japanese-based systems reveals that although most operate on a similar concept, they vary in terms of chip rate and channel shape.


In this day and age, when connections are more vital than ever, it is essential to ensure you are always connected. We want relationships that are not just powerful but also dependable and quick. The advancement of technology, whether in terms of software or hardware, occurs quickly to provide us with the advantages listed above.

CDMA and WCDMA are the results of this, and it is essential to note that this is not the last stage in the evolution of effective human communication. More of them are on the way, and they will have speeds that will boggle the imagination of a human being.


  • https://dl.acm.org/doi/abs/10.5555/525067
  • https://books.google.com/books?hl=en&lr=&id=DRO6CwAAQBAJ&oi=fnd&pg=PR5&dq=wcdma&ots=R6XtqSHTYf&sig=8RZQ4jYDxYKA88mQTz6kIom1pa0

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"Difference Between CDMA and WCDMA." Diffzy.com, 2024. Thu. 13 Jun. 2024. <https://www.diffzy.com/article/difference-between-cdma-and-wcdma-998>.

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