When I was doing my internship at the East-West Center’s Communication Institute and eventually graduate work at the University of Hawaii, I had the chance to interact with Professor “Norm” Abramson. At first, it was while interning with the National Computerization Policy Program, and then I audited his Satellite Communications class as that was a significant focus of my MA thesis. As an intern and master’s degree student, I did not exactly command his attention, but it was good to meet him and occasionally cross paths on the beaches and in the waters off of Diamond Head and Waikiki. Now, I teach a broadband course that covers local area network protocols and wireless communications where ALOHA and slotted ALOHA protocols are fundamental technologies.

Here, Dr. Abramson gives a talk at the East-West Center on the history of ALOHAnet including how it used Intel’s first microprocessor, the 4004. He also talks how it will continue to influence new developments in wireless communications. He is introduced in the video by the CIO and future president of the University of Hawaii, David Lassner.

Originally designed as a radio communication network ALOHAnet, which connected computers on different Hawaiian Islands, pioneered techniques for handling data collisions over shared communication channels. Using microwave radio transmissions, ALOHAnet protocols allowed multiple devices to share the same communication channel. It introduced a simple but effective way of managing “collisions” that might occur when two devices transmit data simultaneously.

If a collision occurred, the Aloha protocol allowed devices to detect and retry transmission after a random delay, significantly improving the efficiency of shared communication channels. The ALOHA protocol was also one of the first “random access” methods, enabling devices to send data without waiting for authorization or a fixed schedule. This innovation was a breakthrough for networks where many devices, such as wireless and satellite networks, shared the same medium.

Ethernet

Bob Metcalfe cited the ALOHA protocol as directly influencing Ethernet’s design. While working on his PhD at Harvard, Metcalfe went to Hawaii to study the Aloha protocols. He then went to Xerox PARC in Menlo Park California, to develop networking technology for the Aloha Alto computer systems they were developing with Stanford University. More famous for its graphical user interface that Apple would “pirate” for the Lisa and Mac a few years later, the Aloha Alto would adapt and enhance ALOHAnet’s channel-sharing techniques for wired connections. With this Metcalfe laid the groundwork for what became the Ethernet standard, which went on to dominate LAN technology.

Ethernet’s approach to transmitting data in packets was initiated by the ARPAnet’s packet-based structure, which sent data in discrete units. ALOHAnet demonstrated how packet-switching could enable more efficient and flexible communication between multiple users over a shared channel, a principle central to Ethernet and other LAN technologies. ALOHAnet’s use of radio channels showed how digital data could be transmitted wirelessly, paving the way for both Ethernet’s early development and later wireless local area network (WLAN) technologies.

Although Aloha protocols initally handled collisions simply by retransmitting after a random delay, this concept was expanded upon by Ethernet’s CSMA/CD (Carrier Sense Multiple Access with Collision Detection) protocol. CSMA/CD built on ALOHA’s collision-detection mechanism to allow faster, more reliable data transfer in wired networks. Rather than transmitting indiscriminately, CSMA would “listen” to make sure no one else is transmitting before sending out its packets. Collisions can still occur, primarily because of signal propagation delays, so CSMA/CD was developed to adjust to collisions that still might occur. To free up more of the channel, CSMA/CD was also designed to be able to transmit only part of a packet (called a frame in LANs) at times.

Ethernet has become indispensable for high-speed networking and high-capacity applications for data centers, corporate networks, and manufacturing automation. Ethernet has reached extraordinary speeds ranging from 10 Mbps to 100 Mbps, 1 Gigabit Ethernet, 10 Gigabit Ethernet, and higher-speed Ethernet up to 400 Gbps, primarily for advanced networks and data centers. While cabling can be cumbersome and expensive, Ethernet supports high data transfer rates with low latency and minimal data loss and can scale from small home networks to enterprise-level setups while compatible across devices from different manufacturers.

Wireless Communications

ALOHAnet also demonstrated the potential of wireless networking, inspiring future wireless data transmission systems. By showing how to handle contention and collisions in a shared radio network, it became a foundational model for mobile and wireless data communication systems where devices contend for the same wireless spectrum. Many modern wireless technologies, including Wi-Fi networks, rely on concepts that originated with ALOHAnet for managing access to shared channels and retransmitting after collision. Many principles used in Wi-Fi, such as carrier-sensing and collision handling, were modeled on ALOHA’s methods, adapted for higher-speed and more complex wireless environments.

Techniques derived from ALOHA’s collision handling have been integrated into cellular network standards. Modern mobile networks, especially in early generations (2G, 3G, LTE, 5G) adapted variants of ALOHA for handling data requests in base stations and handling multiple simultaneous transmissions over limited spectrum. For example, spread spectrum techniques in cellular networks and CSMA/CD methods in Wi-Fi borrow principles directly from ALOHA, adapted to high-density environments. Spread spectrum systems spread a signal over a wider frequency band than the original message while transmitting at the same signal power, making it harder to intercept or jam.

Abramson’s approach to data transmission over ALOHAnet helped popularize the concept of decentralized network architectures. Unlike traditional telecommunications systems, which often relied on centralized control, the ALOHA protocol allowed for a more flexible and robust form of data transmission. This decentralized model influenced satellite communications, where satellite networks often need to function independently in distributed environments. This model was influential in shaping the architecture of distributed and resilient communication networks, where remote or isolated nodes (e.g., satellites or base stations in remote areas) must handle communication independently.

Satellite Communications

Abramson’s work also contributed to the advancement of satellite Internet, including Starlink, where random access protocols allow for the efficient use of satellite bandwidth, especially in remote and rural areas where terrestrial infrastructure is limited. Random access techniques became crucial for enabling multiple users to communicate through a shared satellite link. Slotted ALOHA and spread spectrum ALOHA also allowed for more efficient and flexible satellite communication systems. These methods have been used extensively in satellite-based messaging, data collection from remote sensors, and early VSAT (Very Small Aperture Terminal) systems.

Many IoT systems that use satellite networks for low-cost, wide-coverage communication rely on techniques similar to ALOHA for uplink data transmission from devices to satellites. This is particularly important for applications like remote sensing, environmental monitoring, and asset tracking, where many devices need to transmit sporadic bursts of data over long distances.

Lasting Impact

Abramson’s work at the University of Hawaii inspired a generation of engineers and researchers in telecommunications to explore new, more efficient methods of managing bandwidth and addressing congestion. His contributions continue to inform R&D in telecommunications, from satellite communications and mobile networks to next-generation IoT and 5G protocols, which employ refined versions of random access and collision avoidance methods. Abramson’s work effectively laid the groundwork for these standard practices. His protocols became foundational in textbooks and engineering curricula, influencing fields as diverse as digital communications theory, networking equipment, and data transmission protocols.

Robert X. Cringely interviewed Norm Abramson about why he moved to the University of Hawaii.

The success and influence of ALOHAnet proved that multiple devices could share the same communication medium effectively, ultimately helping shape the modern landscape of wired and wireless networking. Abramson’s impact on satellite communications and telecommunications can be seen in the widespread adoption of random access protocols, the development of mobile and wireless standards, and the rise of decentralized communication models. His foundational work with the ALOHA protocol allowed for efficient use of shared communication channels and inspired innovations that are integral to modern satellite networks, mobile communications, and IoT applications.

Citation APA (7th Edition)

Pennings, A.J. (2024, Nov 14) The Lasting Impact of ALOHAnet and Norman Abramson. apennings.com https://apennings.com/how-it-came-to-rule-the-world/the-lasting-impact-of-alohanet-and-norman-abramson/

Notes

[1] Abramson, N. (2009, Dec) THE ALOHAnet — Surfing for Wireless Data. IEEE Communications Magazine. https://www.eng.hawaii.edu/wp-content/uploads/2020/06/THE-ALOHANET-%E2%80%94-SURFING-FOR-WIRELESS-DATA.pdf

Share

© ALL RIGHTS RESERVED

---

Anthony J. Pennings, PhD is a Professor at the Department of Technology and Society, State University of New York, Korea and Research Professor at Stony Brook University. He teaches broadband policy and ICT for sustainable development. Previously, he was on the faculty of New York University where he taught digital economics and media management. He also taught in the Digital Media MBA at St. Edwards University in Austin, Texas, where he lives when not in South Korea.

Related

Category: characteristics of digital media, digital destruction, enabling frameworks, global communications, how IT came to rule the world, intellectual property, mobile technologies, science and technology studies, space systems
Tags: Aloha protocol > ALOHANET > Alto Aloha Net > Bob Metcalfe > Carrier Sense Multiple Access (CSMA) > CSMA/CD > Ethernet > Norman Abramson

Comments

Comments are closed.