Understanding Interim Standard 95 (IS-95) and its significance in CDMA Technology


In the world of mobile telecommunications, understanding the evolution of wireless technology is crucial for appreciating today's advanced networks. One key milestone in this journey is Interim Standard 95 (IS-95), a groundbreaking digital cellular technology that paved the way for Code Division Multiple Access (CDMA).

In this article, we'll unravel the intricacies of IS-95 and explore its significance in shaping CDMA as we know it. Join us on this fascinating deep dive into telecom history and discover how IS-95 helped revolutionize mobile communication!

Understanding Interim Standard 95 (IS-95)

Interim Standard 95 (IS-95) is a CDMA-based digital cellular technology that was developed by Qualcomm and introduced as the first-ever CDMA-based mobile network.

Definition and Overview

Interim Standard 95 (IS-95), also known as CDMAOne, is a seminal digital cellular technology developed by Qualcomm in the early 1990s. It was the first-ever implementation of Code Division Multiple Access (CDMA) in mobile telecommunications, and it paved the way for numerous advances in wireless communication. As a second-generation (2G) cellular technology, IS-95 marked a significant departure from earlier analog systems and set new standards for capacity, efficiency, and call quality. IS-95's impact can still be felt today, as its principles have influenced the development of advanced wireless protocols like LTE and Wi-Fi, as well as 4G and 5G telecommunication systems.

Key Technical aspects of IS-95 in CDMA Technology

Interim Standard 95 (IS-95) is a CDMA-based digital cellular technology that operates on the North American Standard frequency band. Its key technical aspects include the use of spread-spectrum techniques for multiple access and interference rejection, and frequency reuse to increase network capacity and reduce interference. These features contribute to a reliable connection with high-quality voice calls and fast data transfer rates, even in areas with poor signal quality or high levels of interference. Additionally, IS-95's graceful degradation ensures that call quality degrades gradually rather than rapidly under extreme conditions.

Differences between IS-95 and earlier Mobile Network Standards

One of the key differences between IS-95 and earlier mobile network standards lies in the way the technologies handle data transmission, spectrum efficiency, and capacity. The table below highlights these differences in a more detailed manner.



Earlier Mobile Network Standards (1G/AMPS)

Data Transmission

IS-95 utilizes CDMA technology, which allows multiple users to share the same bandwidth, resulting in efficient data transmission.

Earlier standards like AMPS used analog Frequency Division Multiple Access (FDMA) technology, which assigns a dedicated frequency to each user, resulting in less efficient use of bandwidth.

Spectrum Efficiency

IS-95's CDMA technology offers improved spectrum efficiency by allowing more simultaneous calls within the same frequency range.

1G systems had limited spectrum efficiency due to their analog FDMA technology.


IS-95 offers increased capacity compared to its predecessors, thanks to CDMA's ability to support more users within the same bandwidth

Earlier mobile network standards struggled with limited capacity due to their less efficient use of available bandwidth.

Call Quality and Coverage

IS-95 provides enhanced call quality and coverage due to its digital nature and ability to reduce interference and noise.

1G networks suffered from poor call quality and limited coverage due to their analog systems and greater susceptibility to interference and noise.

Technology Generation

IS-95 is a second-generation (2G) cellular technology.

Earlier mobile network standards, such as AMPS, were first-generation (1G) cellular technologies

Advantages of IS-95 in CDMA Technology

IS-95 provides increased network capacity and efficiency, enhanced call quality and coverage, as well as reduced interference and noise.

Increased Capacity and Efficiency

  • IS-95 allows simultaneous communications between multiple users

  • Utilizes frequency reuse techniques to reduce interference and noise levels

  • More users can be accommodated without degrading quality of service

  • Efficient use of bandwidth maximizes available resources

  • Reduces costs for mobile operators by improving spectrum efficiency

Enhanced Call Quality and Coverage

  • Improved voice clarity and audio quality

  • Seamless handovers between cells for reliable communication

  • Paved the way for the development of 3G and 4G technologies

  • Higher capacity for calls without interference

  • Maintains connectivity for mobile devices moving between cell sites

Reduced Interference and Noise

  • Uses spread spectrum technology to minimize interference

  • Frequency reuse patterns reduce co-channel interference

  • Better call quality and coverage over larger geographic areas

  • Fewer dropped calls and clearer communication for users

  • More reliable roaming capabilities due to reduced signal degradation

Evolution of IS-95 and its significance in CDMA Technology

IS-95 went through several protocol revisions and developments that increased its efficiency and capacity, ultimately leading to its adoption as the North American standard for CDMA technology; this standard had a significant impact on the growth of CDMA technology and paved the way for future mobile communication advancements.

Protocol revisions and development

IS-95 underwent several protocol revisions and developments over the years, which greatly improved its performance and efficiency. Here are some of the key revisions and developments −

  • IS-95a − The first version of IS-95 was released in 1993 as IS-95a, which supported voice calls and data transmission at a maximum speed of 14.4 kbps.

  • IS-95b − In 1996, IS-95b was introduced, which increased the data transfer rate to 64 kbps by using High Rate Packet Data (HRPD) technology.

  • CDMA2000 − In 2000, the CDMA Development Group (CDG) introduced CDMA2000, an upgraded version of IS-95 that supported higher data rates and improved voice quality.

  • EV-DO − Enhanced Voice/Data Optimized (EV-DO) is a further upgrade to CDMA2000 that supports even higher data rates up to 3.1 Mbps, making it suitable for applications such as video streaming.

  • Hybrid operation − Another development in IS-95 was hybrid operation mode, which enabled CDMA handsets to operate on both analog AMPS and digital IS-95 networks.

Overall, these protocol revisions and developments helped to improve the network capacity, call quality, and data transfer rates of IS-95/CDMA technology over time.

Comparison with other CDMA Standards

The comparison of IS-95 with other CDMA standards can be seen in the table below, showcasing the key differences and improvements made over time.

CDMA Standards



Call Quality



IS-95 (CDMAOne)

Increased compared to earlier mobile network standards

Higher, thanks to spread spectrum technology

Enhanced by digital voice coding and signal processing

Better due to efficient use of frequencies

Reduced due to the use of spread spectrum technology


Significantly better than IS-95

Improved data rates and better support for high-speed data services

Further improvements in voice quality and latency

Increased coverage through enhanced modulation and coding schemes

Advanced interference cancellation techniques


Comparable capacity to CDMA2000

Optimized for high-speed data services and multimedia applications

High-quality voice services with wideband codecs

Flexible deployment options for increased coverage

Adaptive interference management and mitigation

4G (LTE)

Significant increase compared to previous CDMA standards

High efficiency with improved spectral utilization

Exceptional voice quality with Voice over LTE (VoLTE) technology

Vast coverage and support for multiple frequency bands

Advanced interference cancellation and suppression techniques


In conclusion, Interim Standard 95 (IS-95) played a significant role in the evolution of CDMA technology. Its introduction as a second-generation cellular network was groundbreaking and paved the way for further innovations in the wireless communication industry.

The advantages of IS-95 over other mobile network standards include increased capacity and efficiency, enhanced call quality and coverage, reduced interference and noise levels, among others. Although it has been replaced by newer technologies like 5G, IS-95 remains an important milestone in the history of mobile communication. As we look towards the future of wireless networks, we can rest assured that innovative technologies will continue to emerge and revolutionize our world in exciting ways!

Updated on: 13-Apr-2023

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