Milestone-Proposal:ALOHANET (aka ALOHA System): Difference between revisions

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|a9=Holmes Hall is the College of Engineering Building on the University of Hawaii at Manoa campus and provides unobstructed access to general public
|a9=Holmes Hall is the College of Engineering Building on the University of Hawaii at Manoa campus and provides unobstructed access to general public
|a10=University of Hawaii
|a10=University of Hawaii
|a4=The ALOHAnet was comprised of two distinct components:
|a4=ALOHAnet (aka ALOHA System) was a computing landmark, both because it was the first to connect computers via radio communications and secondly because it introduced the computing world to a new method of medium access (ALOHA random access protocol).
1. The ALOHA protocol.  The ALOHA protocol was the first wireless radio packet-based communications system that allowed computer communications across the water to the campuses on the islands of Kaua’i, Mau’I, and Hawai’i.  The ALOHA protocol allowed each client to send its data without controlling when it was sent, with an acknowledgment/retransmission scheme used to deal with collisions. This approach radically reduced the complexity of the protocol and the networking hardware, since nodes do not need negotiate "who" is allowed to speak.
Its network architecture was dictated by two fundamental choices:
2. The ALOHAnet (aka ALOHA System) consisted of terminals connected to a central hub at the main University of Hawai’i campus in Manoa Valley on the Island of Oah’u. Spoke terminals were located at geographically dispersed University of Hawai’I campuses on Oah’u, Kaua’I, Mau’I, and Hawai’i.   ALOHAnet's primary importance was its use of a shared medium for client transmissions. Unlike the ARPANET where each node could only talk directly to a node at the other end of a wire or satellite circuit, in ALOHAnet all client nodes communicated with the hub on the same frequency.  This solution became known as a pure ALOHA, or random-access channel, and was the basis for subsequent Ethernet development and later Wi-Fi networks.  Various versions of the ALOHA protocol (such as Slotted ALOHA) also appeared later in satellite communications, and were used in wireless data networks such as ARDIS, Mobitex, CDPD, and GSM. Also important was ALOHAnet's use of the outgoing hub channel to broadcast packets directly to all clients on a second shared frequency, using an address in each packet to allow selective receipt at each client node.  Two frequencies were used so that a device could both receive acknowledgments regardless of transmissions. The Aloha network introduced the mechanism of randomized multiple access, which resolved device transmission collisions by transmitting a package immediately if no acknowledgement is present, and if no acknowledgment was received, the transmission was repeated after a random waiting time.  
• two-channel star configuration of the network and,
3. The technological significance of Pure ALOHA and Slotted ALOHA Protocols are presented next.
• the use of random accessing for user transmissions.
Pure ALOHA
The initial purpose of the ALOHA SYSTEM was to provide a systematically different designer interaction for radio communications. This alternative method allows the system to determine when and where radio communications are "preferable" to wired communications. It made practical means of communication and made accessibility of differing networks plausible.
The ALOHAnet was comprised of two distinct components: the ALOHA protocol and the ALOHA System.
Pure ALOHA protocol. Boxes indicate frames. Shaded boxes indicate frames which have collided.
1. The ALOHA protocol.  The ALOHA protocol was the first wireless radio packet-based communications system that allowed computer communications across the water to the campuses on the islands of Kaua’i, Mau’i, and Hawai’i.  The ALOHA protocol allowed each client to send its data without controlling when it was sent, with an acknowledgment/retransmission scheme used to deal with collisions. This approach radically reduced the complexity of the protocol and the networking hardware, since nodes do not need negotiate "who" is allowed to speak.
The version of the protocol (now called "Pure ALOHA", and the one implemented in ALOHAnet) was quite simple:
The original version of ALOHA used two distinct frequencies in a hub configuration, with the hub machine broadcasting packets to everyone on the "outbound" channel, and the various client machines sending data packets to the hub on the "inbound" channel. If data was received correctly at the hub, a short acknowledgment packet was sent to the client; if an acknowledgment was not received by a client machine after a short wait time, it would automatically retransmit the data packet after waiting a randomly selected time interval. This acknowledgment mechanism was used to detect and correct for "collisions" created when two client machines both attempted to send a packet at the same time.
• If you have data to send, send the data
The primary importance of the ALOHA protocol was its use of a shared medium for client transmissions. Unlike the ARPANET where each node could only talk directly to a node at the other end of a wire or satellite circuit, in ALOHAnet all client nodes communicated with the hub on the same frequency.  This solution became known as a pure ALOHA, or random-access channel, and was the basis for subsequent Ethernet development and later Wi-Fi networks.  Various versions of the ALOHA protocol (such as Slotted ALOHA) also appeared later in satellite communications and were used in wireless data networks such as ARDIS, Mobitex, CDPD, and GSM.  
• If, while you are transmitting data, you receive any data from another station, there has been a message collision. All transmitting stations will need to try resending "later".
Also important was ALOHAnet's use of the outgoing hub channel to broadcast packets directly to all clients on a second shared frequency, using an address in each packet to allow selective receipt at each client node.  Two frequencies were used so that a device could both receive acknowledgments regardless of transmissions. The ALOHA network introduced the mechanism of randomized multiple access, which resolved device transmission collisions by transmitting a package immediately if no acknowledgement is present, and if no acknowledgment was received, the transmission was repeated after a random waiting time.  
Note that the first step implies that Pure ALOHA does not check whether the channel is busy before transmitting. Since collisions can occur and data may have to be sent again, ALOHA cannot use 100% of the capacity of the communications channel. How long a station waits until it transmits, and the likelihood a collision occurs are interrelated, and both affect how efficiently the channel can be used. This means that the concept of "transmit later" is a critical aspect: the quality of the backoff scheme chosen significantly influences the efficiency of the protocol, the ultimate channel capacity, and the predictability of its behavior.
2. The ALOHA network was a pioneering computer network that used a new method of medium access (ALOHA random access) and experimental ultra-high frequency (UHF) for its operation, since frequency assignments for radio communications to and from a computer were not available for commercial applications in the 1970s.
To assess Pure ALOHA, there is a need to predict its throughput, the rate of (successful) transmission of frames. (This discussion of Pure ALOHA's performance follows Tanenbaum.[14]) First, let's make a few simplifying assumptions:
The ALOHA System received assignments as an experimental service in the government UHF band of 406 to 420 MHz, where spectrum space was available. Reasonably priced commercial radio equipment was found to be available in this frequency region and radio band crowding was not severe in Hawaii.
• All frames have the same length.
But even before such frequencies were assigned there were two other media available for the application of an ALOHA channel – cables & satellites. In the 1970s ALOHA random access was employed in the nascent Ethernet cable-based network and then in the Marisat (now Inmarsat) satellite network.
• Stations cannot generate a frame while transmitting or trying to transmit. (That is, if a station keeps trying to send a frame, it cannot be allowed to generate more frames to send.)
The ALOHAnet (aka ALOHA System) consisted of terminals connected to a central hub at the main University of Hawai’i campus in Manoa Valley on the Island of Oah’u. Spoke terminals were located at geographically dispersed University of Hawai’i campuses on Oah’u, Kaua’i, Mau’i, and Hawai’i.
The population of stations attempts to transmit (both new frames and old frames that collided) according to a Poisson distribution.
From a computer networking protocol viewpoint:
Let "T" refer to the time needed to transmit one frame on the channel, and let's define "frame-time" as a unit of time equal to T. Let "G" refer to the mean used in the Poisson distribution over transmission-attempt amounts: that is, on average, there are G transmission-attempts per frame-time.
a) this is known as a hub-and-spoke, or star configuration.
b) As is in any computer network, a hub transmits identical information out of all ports except the incoming port.
The maximum throughput is 0.5/e frames per frame-time (reached when G = 0.5), which is approximately 0.184 frames per frame-time. This means that, in Pure ALOHA, only about 18.4% of the time is used for successful transmissions.
c) During this time period, computer networking was linked back to a mainframe and were basically time-shared based terminal systems.
Another simple and mathematical way to establish the equation for throughput in Pure ALOHA (and in Slotted ALOHA) is as follows:


Consider what needs to happen for frames to be transmitted successfully. Let T represent the frame time. For simplicity, it is assumed that the contention begins at t=0. Then if exactly one node sends during interval t=0 to t=T and no node tries between t=T to t=2T, then the frame will be transmitted successfully. Similarly during all next time intervals t=2nT to t=(2n+1)T, exactly one node sends and during t=(2n+1)T to t=(2n+2)T no node tries to send where n=1,2,3, ... , then the frames are successfully transmitted. But in pure ALOHA, the nodes begin transmission whenever they want to do so without checking that what other nodes are doing at that time. Thus sending frames are independent events, that is, transmission by any particular node neither affects nor is affected by the time of start of transmission by other nodes. Let G be the average number of nodes that begin transmission within period T (the frame time).
The historical, social significance of ALOHAnet (aka ALOHA System) is that it laid the communications foundation for mobile, wireless, satellite, and Internet as we know it today.  Technologically:  
But for successful transmission of a frame, both the events should occur simultaneously. That is during period t=2nT to t=(2n+1)T, exactly one node begins transmission and during t=(2n+1)T to t=(2n+2)T no node begins transmission.
  a.  Demonstrated general principles about the relationship between information theory and the design of real information systems.   
Throughput is intended to mean the probability of successful transmission during minimum possible period.
b.  It was the first wireless radio packet-based communications system.
Similarly for slotted ALOHA, a frame will be successfully transmitted, if exactly one node will begin transmission at the beginning of any particular time slot (equal to frame time T).
c . Operational in June 1971; the first public demonstration of a wireless packet data network.
Disadvantages of Pure ALOHA:
d.  Referenced as foundation for the Ethernet protocol [Bob Metcalfe's 1973 Ethernet memo describes a networking system based on an earlier experiment in networking called the Aloha network.
1) Time is wasted
2) Data is lost
Slotted ALOHA
An improvement to the original ALOHA protocol was "Slotted ALOHA", which introduced discrete timeslots and increased the maximum throughput.[15] A station can start a transmission only at the beginning of a timeslot, and thus collisions are reduced. In this case, only transmission-attempts within 1 frame-time and not 2 consecutive frame-times need to be considered, since collisions can only occur during each timeslot.
The maximum throughput is 1/e frames per frame-time (reached when G = 1), which is approximately 0.368 frames per frame-time, or 36.8%.
Slotted ALOHA is used in low-data-rate tactical satellite communications networks by military forces, in subscriber-based satellite communications networks, mobile telephony call setup, set-top box communications and in the contactless RFID technologies.
4. The historical, social significance of ALOHAnet (aka ALOHA System) is presented next.
The ALOHAnet (aka ALOHA System) laid the communications foundation for mobile, wireless, satellite, and Internet as we know it today.  Technologically:  1.  Demonstrated general principles about the relationship between information theory and the design of real information systems.  2.  It was the first wireless radio packet-based communications system. 3. Operational in June 1971; the first public demonstration of a wireless packet data network. 4.  Referenced as foundation for the Ethernet protocol [Bob Metcalfe's 1973 Ethernet memo describes a networking system based on an earlier experiment in networking called the Aloha network.
The ALOHA network was a pioneering computer networking that used a new method of medium access (ALOHA random access) and experimental ultra high frequency (UHF) for its operation, since frequency assignments for communications to and from a computer were not available for commercial applications in the 1970s.
But even before such frequencies were assigned there were two other media available for the application of an ALOHA channel – cables & satellites. In the 1970s ALOHA random access was employed in the nascent Ethernet cable based network and then in the Marisat (now Inmarsat) satellite network.
In the early 1980s frequencies for mobile networks became available, and in 1985 frequencies suitable for what became known as Wi-Fi were allocated in the US. These regulatory developments made it possible to use the ALOHA random-access techniques in both Wi-Fi and in mobile telephone networks.
In the early 1980s frequencies for mobile networks became available, and in 1985 frequencies suitable for what became known as Wi-Fi were allocated in the US. These regulatory developments made it possible to use the ALOHA random-access techniques in both Wi-Fi and in mobile telephone networks.
ALOHA channels were used in a limited way in the 1980s in 1G mobile phones for signaling and control purposes.  In the late 1980s, the European standardization group GSM who worked on the Pan-European Digital mobile communication system GSM greatly expanded the use of ALOHA channels for access to radio channels in mobile telephony. In addition SMS message texting was implemented in 2G mobile phones. In the early 2000s additional ALOHA channels were added to 2.5G and 3G mobile phones with the widespread introduction of GPRS, using a slotted-ALOHA random-access channel combined with a version of the Reservation ALOHA scheme first analyzed by a group at BBN.
ALOHA channels were used in a limited way in the 1980s in 1G mobile phones for signaling and control purposes.  In the late 1980s, the European standardization group GSM who worked on the Pan-European Digital mobile communication system GSM greatly expanded the use of ALOHA channels for access to radio channels in mobile telephony. In addition, SMS message texting was implemented in 2G mobile phones. In the early 2000s additional ALOHA channels were added to 2.5G and 3G mobile phones with the widespread introduction of GPRS, using a slotted-ALOHA random-access channel combined with a version of the Reservation ALOHA scheme first analyzed by a group at BBN.  
The initial purpose of the THE ALOHA SYSTEM is to provide a systematically different designer interaction for radio communications. This alternative method allows the system to determine when and where radio communications are "preferable" to wired communications. It made practical means of communication and made accessibility of differing networks plausible.
This solution became known as a pure ALOHA, or random-access channel, and was the basis for subsequent Ethernet development and later Wi-Fi networks.  Various versions of the ALOHA protocol (such as Slotted ALOHA) also appeared later in satellite communications and were used in wireless data networks such as ARDIS, Mobitex, CDPD, and GSM.
The original version of ALOHA used two distinct frequencies in a hub configuration, with the hub machine broadcasting packets to everyone on the "outbound" channel, and the various client machines sending data packets to the hub on the "inbound" channel. If data was received correctly at the hub, a short acknowledgment packet was sent to the client; if an acknowledgment was not received by a client machine after a short wait time, it would automatically retransmit the data packet after waiting a randomly selected time interval. This acknowledgment mechanism was used to detect and correct for "collisions" created when two client machines both attempted to send a packet at the same time.
Today, random access packets are everywhere —in Wi-Fi, your mobile phone, Ethernet, cable, satellite communications, V2V, M2M, IoT.
ALOHAnet's primary importance was its use of a shared medium for client transmissions. Unlike the ARPANET where each node could only talk directly to a node at the other end of a wire or satellite circuit, in ALOHAnet all client nodes communicated with the hub on the same frequency. This meant that some sort of mechanism was needed to control who could talk at what time. The ALOHAnet solution was to allow each client to send its data without controlling when it was sent, with an acknowledgment/retransmission scheme used to deal with collisions. This approach radically reduced the complexity of the protocol and the networking hardware, since nodes do not need negotiate "who" is allowed to speak.  
This solution became known as a pure ALOHA, or random-access channel, and was the basis for subsequent Ethernet development and later Wi-Fi networks.  Various versions of the ALOHA protocol (such as Slotted ALOHA) also appeared later in satellite communications, and were used in wireless data networks such as ARDIS, Mobitex, CDPD, and GSM.
Also important was ALOHAnet's use of the outgoing hub channel to broadcast packets directly to all clients on a second shared frequency, using an address in each packet to allow selective receipt at each client node.  Two frequencies were used so that a device could both receive acknowledgments regardless of transmissions. The Aloha network introduced the mechanism of randomized multiple access, which resolved device transmission collisions by transmitting a package immediately if no acknowledgement is present, and if no acknowledgment was received, the transmission was repeated after a random waiting time.
Network architecture
Two fundamental choices which dictated much of the ALOHAnet design were the two-channel star configuration of the network and the use of random accessing for user transmissions.
The two-channel configuration was primarily chosen to allow for efficient transmission of the relatively dense total traffic stream being returned to users by the central time-sharing computer. An additional reason for the star configuration was the desire to centralize as many communication functions as possible at the central network node (the Menehune), minimizing the cost of the original all-hardware terminal control unit (TCU) at each user node.
The random-access channel for communication between users and the Menehune was designed specifically for the traffic characteristics of interactive computing. In a conventional communication system a user might be assigned a portion of the channel on either a frequency-division multiple access (FDMA) or time-division multiple access (TDMA) basis. Since it was well known that in time-sharing systems [circa 1970], computer and user data are bursty, such fixed assignments are generally wasteful of bandwidth because of the high peak-to-average data rates that characterize the traffic.
To achieve a more efficient use of bandwidth for bursty traffic, ALOHAnet developed the random-access packet switching method that has come to be known as a pure ALOHA channel. This approach effectively dynamically allocates bandwidth immediately to a user who has data to send, using the acknowledgment/retransmission mechanism described earlier to deal with occasional access collisions. While the average channel loading must be kept below about 10% to maintain a low collision rate, this still results in better bandwidth efficiency than when fixed allocations are used in a bursty traffic context.
Two 100 kHz channels in the experimental UHF band were used in the implemented system, one for the user-to-computer random-access channel and one for the computer-to-user broadcast channel. The system was configured as a star network, allowing only the central node to receive transmissions in the random-access channel. All user TCUs received each transmission made by the central node in the broadcast channel. All transmissions were made in bursts at 9600 bit/s, with data and control information encapsulated in packets.
Each packet consisted of a 32-bit header and a 16-bit header parity check word, followed by up to 80 bytes of data and a 16-bit parity check word for the data. The header contained address information identifying a particular user so that when the Menehune broadcast a packet, only the intended user's node would accept it.
Menehune
The central node communications processor was an HP 2100 minicomputer called the Menehune, which is the Hawaiian language word for "imp", or dwarf people, and was named for its similar role to the original ARPANET Interface Message Processor (IMP) which was being deployed at about the same time. In the original system, the Menehune forwarded correctly received user data to the UH central computer, an IBM System 360/65 time-sharing system. Outgoing messages from the 360 were converted into packets by the Menehune, which were queued and broadcast to the remote users at a data rate of 9600 bit/s. Unlike the half-duplex radios at the user TCUs, the Menehune was interfaced to the radio channels with full-duplex radio equipment.
Remote units
The original user interface developed for the system was an all-hardware unit called an ALOHAnet Terminal Control Unit (TCU), and was the sole piece of equipment necessary to connect a terminal into the ALOHA channel. The TCU was composed of a UHF antenna, transceiver, modem, buffer and control unit. The buffer was designed for a full line length of 80 characters, which allowed handling of both the 40- and 80-character fixed-length packets defined for the system. The typical user terminal in the original system consisted of a Teletype Model 33 or a dumb CRT user terminal connected to the TCU using a standard RS-232C interface. Shortly after the original ALOHA network went into operation, the TCU was redesigned with one of the first Intel microprocessors, and the resulting upgrade was called a PCU (Programmable Control Unit).
Additional basic functions performed by the TCU's and PCU's were generation of a cyclic-parity-check code vector and decoding of received packets for packet error-detection purposes, and generation of packet retransmissions using a simple random interval generator. If an acknowledgment was not received from the Menehune after the prescribed number of automatic retransmissions, a flashing light was used as an indicator to the human user. Also, since the TCU's and PCU's did not send acknowledgments to the Menehune, a steady warning light was displayed to the human user when an error was detected in a received packet. Thus it can be seen that considerable simplification was incorporated into the initial design of the TCU as well as the PCU, making use of the fact that it was interfacing a human user into the network.
Later developments
In later versions of the system, simple radio relays were placed in operation to connect the main network on the island of Oahu to other islands in Hawaii, and Menehune routing capabilities were expanded to allow user nodes to exchange packets with other user nodes, the ARPANET, and an experimental satellite network.
|a6=The ALOHA Protocol is the communications foundation for a variety of applications involving joint use of a given medium by potentially interfering systems, and laid the foundation for mobile, wireless, satellite, and Internet communications as we know it today. The protocol, in its most concise form, says transmit at will. If interference is detected, retransmit some random time later. What can be simpler? Yet, despite its apparent simplicity, such a protocol was not at all obvious at the time of its invention and initial deployment.  ALOHA packet systems were originally described by Abramso n
|a6=The ALOHA Protocol is the communications foundation for a variety of applications involving joint use of a given medium by potentially interfering systems, and laid the foundation for mobile, wireless, satellite, and Internet communications as we know it today. The protocol, in its most concise form, says transmit at will. If interference is detected, retransmit some random time later. What can be simpler? Yet, despite its apparent simplicity, such a protocol was not at all obvious at the time of its invention and initial deployment.  ALOHA packet systems were originally described by Abramso n
("The ALOHA System--Another Alternative for Compute r
("The ALOHA System--Another Alternative for Compute r

Revision as of 03:22, 11 February 2020


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Docket #:2018-09

This Proposal has been approved, and is now a Milestone


To the proposer’s knowledge, is this achievement subject to litigation? No

Is the achievement you are proposing more than 25 years old? Yes

Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes

Did the achievement provide a meaningful benefit for humanity? Yes

Was it of at least regional importance? Yes

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes

Has an IEEE Organizational Unit agreed to arrange the dedication ceremony? Yes

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes

Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes


Year or range of years in which the achievement occurred:

1966 - 1971. Activated June 1971

Title of the proposed milestone:

ALOHAnet (aka ALOHA System): Communications Foundation for Wireless, Mobile, Satellite, and Internet – 1966 - 1971

Plaque citation summarizing the achievement and its significance:

Plaque citation summarizing the achievement and its significance:

ALOHAnet (aka ALOHA System), the first wireless packet data network, was developed at the University of Hawaii and became operational in 1971. It introduced ALOHA random access, a new method of accessing a communication medium, and used experimental ultra high frequency. ALOHA random access influenced the design of Ethernet, satellite, mobile, and wireless networks.

200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.


IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.


In what IEEE section(s) does it reside?

IEEE Hawaii Section

IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

Unit: IEEE Hawaii Section
Senior Officer Name: Kishore Erukulapati

IEEE Organizational Unit(s) arranging the dedication ceremony:

Unit: IEEE Hawaii Section
Senior Officer Name: Kishore Erukulapati

IEEE section(s) monitoring the plaque(s):

IEEE Section: IEEE Hawaii Section
IEEE Section Chair name: Kishore Erukulapati

Milestone proposer(s):

Proposer name: John Imperial
Proposer email: Proposer's email masked to public

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):

2540 Dole Street, Holmes Hall, Honolulu, Hawaii 9682221.29681 N, 157.81657 W

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. Intended site of the milestone plaque is where ALOHANET (aka ALOHA System) was developed, invented, tested, and demonstrated.First public demonstration of a wireless packet network and random access protocols was activated on June 1971.Site is the University of Hawaii College of Engineering - Holmes Hall

Are the original buildings extant?

Yes

Details of the plaque mounting:

Exact location is to be yet to be determined. Milestone plaque will be mounted on the outside of the concrete building, ground floor.

How is the site protected/secured, and in what ways is it accessible to the public?

Holmes Hall is the College of Engineering Building on the University of Hawaii at Manoa campus and provides unobstructed access to general public

Who is the present owner of the site(s)?

University of Hawaii

What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include justification here. (see section 6 of Milestone Guidelines)

ALOHAnet (aka ALOHA System) was a computing landmark, both because it was the first to connect computers via radio communications and secondly because it introduced the computing world to a new method of medium access (ALOHA random access protocol). Its network architecture was dictated by two fundamental choices: • two-channel star configuration of the network and, • the use of random accessing for user transmissions. The initial purpose of the ALOHA SYSTEM was to provide a systematically different designer interaction for radio communications. This alternative method allows the system to determine when and where radio communications are "preferable" to wired communications. It made practical means of communication and made accessibility of differing networks plausible. The ALOHAnet was comprised of two distinct components: the ALOHA protocol and the ALOHA System. 1. The ALOHA protocol. The ALOHA protocol was the first wireless radio packet-based communications system that allowed computer communications across the water to the campuses on the islands of Kaua’i, Mau’i, and Hawai’i. The ALOHA protocol allowed each client to send its data without controlling when it was sent, with an acknowledgment/retransmission scheme used to deal with collisions. This approach radically reduced the complexity of the protocol and the networking hardware, since nodes do not need negotiate "who" is allowed to speak. The original version of ALOHA used two distinct frequencies in a hub configuration, with the hub machine broadcasting packets to everyone on the "outbound" channel, and the various client machines sending data packets to the hub on the "inbound" channel. If data was received correctly at the hub, a short acknowledgment packet was sent to the client; if an acknowledgment was not received by a client machine after a short wait time, it would automatically retransmit the data packet after waiting a randomly selected time interval. This acknowledgment mechanism was used to detect and correct for "collisions" created when two client machines both attempted to send a packet at the same time. The primary importance of the ALOHA protocol was its use of a shared medium for client transmissions. Unlike the ARPANET where each node could only talk directly to a node at the other end of a wire or satellite circuit, in ALOHAnet all client nodes communicated with the hub on the same frequency. This solution became known as a pure ALOHA, or random-access channel, and was the basis for subsequent Ethernet development and later Wi-Fi networks. Various versions of the ALOHA protocol (such as Slotted ALOHA) also appeared later in satellite communications and were used in wireless data networks such as ARDIS, Mobitex, CDPD, and GSM. Also important was ALOHAnet's use of the outgoing hub channel to broadcast packets directly to all clients on a second shared frequency, using an address in each packet to allow selective receipt at each client node. Two frequencies were used so that a device could both receive acknowledgments regardless of transmissions. The ALOHA network introduced the mechanism of randomized multiple access, which resolved device transmission collisions by transmitting a package immediately if no acknowledgement is present, and if no acknowledgment was received, the transmission was repeated after a random waiting time. 2. The ALOHA network was a pioneering computer network that used a new method of medium access (ALOHA random access) and experimental ultra-high frequency (UHF) for its operation, since frequency assignments for radio communications to and from a computer were not available for commercial applications in the 1970s. The ALOHA System received assignments as an experimental service in the government UHF band of 406 to 420 MHz, where spectrum space was available. Reasonably priced commercial radio equipment was found to be available in this frequency region and radio band crowding was not severe in Hawaii. But even before such frequencies were assigned there were two other media available for the application of an ALOHA channel – cables & satellites. In the 1970s ALOHA random access was employed in the nascent Ethernet cable-based network and then in the Marisat (now Inmarsat) satellite network. The ALOHAnet (aka ALOHA System) consisted of terminals connected to a central hub at the main University of Hawai’i campus in Manoa Valley on the Island of Oah’u. Spoke terminals were located at geographically dispersed University of Hawai’i campuses on Oah’u, Kaua’i, Mau’i, and Hawai’i. From a computer networking protocol viewpoint: a) this is known as a hub-and-spoke, or star configuration. b) As is in any computer network, a hub transmits identical information out of all ports except the incoming port. c) During this time period, computer networking was linked back to a mainframe and were basically time-shared based terminal systems.

The historical, social significance of ALOHAnet (aka ALOHA System) is that it laid the communications foundation for mobile, wireless, satellite, and Internet as we know it today. Technologically:

a.  Demonstrated general principles about the relationship between information theory and the design of real information systems.  

b. It was the first wireless radio packet-based communications system. c . Operational in June 1971; the first public demonstration of a wireless packet data network. d. Referenced as foundation for the Ethernet protocol [Bob Metcalfe's 1973 Ethernet memo describes a networking system based on an earlier experiment in networking called the Aloha network. In the early 1980s frequencies for mobile networks became available, and in 1985 frequencies suitable for what became known as Wi-Fi were allocated in the US. These regulatory developments made it possible to use the ALOHA random-access techniques in both Wi-Fi and in mobile telephone networks. ALOHA channels were used in a limited way in the 1980s in 1G mobile phones for signaling and control purposes. In the late 1980s, the European standardization group GSM who worked on the Pan-European Digital mobile communication system GSM greatly expanded the use of ALOHA channels for access to radio channels in mobile telephony. In addition, SMS message texting was implemented in 2G mobile phones. In the early 2000s additional ALOHA channels were added to 2.5G and 3G mobile phones with the widespread introduction of GPRS, using a slotted-ALOHA random-access channel combined with a version of the Reservation ALOHA scheme first analyzed by a group at BBN. This solution became known as a pure ALOHA, or random-access channel, and was the basis for subsequent Ethernet development and later Wi-Fi networks. Various versions of the ALOHA protocol (such as Slotted ALOHA) also appeared later in satellite communications and were used in wireless data networks such as ARDIS, Mobitex, CDPD, and GSM. Today, random access packets are everywhere —in Wi-Fi, your mobile phone, Ethernet, cable, satellite communications, V2V, M2M, IoT.

What obstacles (technical, political, geographic) needed to be overcome?

The ALOHA Protocol is the communications foundation for a variety of applications involving joint use of a given medium by potentially interfering systems, and laid the foundation for mobile, wireless, satellite, and Internet communications as we know it today. The protocol, in its most concise form, says transmit at will. If interference is detected, retransmit some random time later. What can be simpler? Yet, despite its apparent simplicity, such a protocol was not at all obvious at the time of its invention and initial deployment. ALOHA packet systems were originally described by Abramso n ("The ALOHA System--Another Alternative for Compute r Communication," Proceedings of the AFIPS Fall Joint Compute r Conference, Vol . 37, 1970, pp . 281-285) . In an ALOHA a singl e broadcast channel is shared by a number of communicating devices . In the version originally described by Abramson, every devic e transmits its packets independent of any other device or an y specific time . That is, the device transmits the whole packet a t a random point in time ; the device then times out for receivin g an acknowledgment . If an acknowledgment is not received, it i s assumed that a collision occured with a packet transmitted b y some other device and the packet is retransmitted after a rando m additional waiting time (to avoid repeated collisions) . Under a certain set of assumptions, Abramson showed that the effectiv e capacity of such a channel is l/(2e) .

TECHNICAL The basic idea was radio communications – as an alternative to telephones. Radio communications is a broadcast medium and allows things to be performed via multiple access. As Dr. Norman Abramson stated, “Well, we don't have to be limited to one channel per user. We could do some more efficient things with radio." "Something much more sensible for radio can be done here than assigning a single channel for every user in the network. That's crazy. That won't work." "Look, we can't assign one channel per user. We want to think about -- although we may never build it - - we want to think about a system with hundreds of users, something practical for that. You can't have hundreds of channels. Now what can you do for that situation?" I and others were aware of the spread spectrum and multiple access through spread spectrum at that point, and the idea of simply transmitting the data in bursts was sort of a natural one. The telephone system, especially then in Hawaii, was inadequate for data and appeared not to make sense at that time. ALOHAnet became operational in June,1971, providing the first public demonstration of a wireless packet data network. POLITICAL In 1966, when Dr. Norman Abramson came to the University of Hawaii, there was very little research activity, much less funded-research activity. Dr. Norman Abramson got the University of Hawaii funded under Project THEMIS – a Department of Defense program to support developing, second-rank or have-not universities with research funds. At this point in time, Project THEMIS provided the largest amount of research project funds that the University of Hawaii had ever received to fund the ALOHA System. One of the reasons was certainly that -- my impression, and I think this was common in a lot of people, was that to do something different with radio communications means that sooner or later, you're going to have to fight the FCC, and I didn't want to do that. I was faculty, a professor, and I truly felt I had no capability in that kind of area and I wouldn't do very well at it, so I really couldn't see myself as trying to shake up the FCC and have them change their rules. That meant that I was thinking of operating under the existing rules, and Aloha wouldn't allow you to operate under existing rules. As a research project, it was quite interesting, but to look further to operational and commercial systems GEOGRAPHIC The goal was to use low-cost commercial radio equipment to connect users on Oahu and the other Hawaiian Islands with a central time-sharing computer on the main Oahu campus.

What features set this work apart from similar achievements?

ALOHANET was the first public demonstration of a wireless radio packet-based communications system utilizing a random-access protocol (pure ALOHA). ALOHAnet, also known as the ALOHA System,[1][2][3] or simply ALOHA, was a pioneering computer networking system developed at the University of Hawaii. ALOHAnet became operational in June, 1971, providing the first public demonstration of a wireless packet data network.[4][5] ALOHA originally stood for Additive Links On-line Hawaii Area.[6]

The ALOHAnet used a new method of medium access (ALOHA random access) and experimental ultra high frequency (UHF) for its operation, since frequency assignments for communications to and from a computer were not available for commercial applications in the 1970s. But even before such frequencies were assigned there were two other media available for the application of an ALOHA channel – cables & satellites. In the 1970s ALOHA random access was employed in the nascent Ethernet cable based network[7] and then in the Marisat (now Inmarsat) satellite network.[8]

In the early 1980s frequencies for mobile networks became available, and in 1985 frequencies suitable for what became known as Wi-Fi were allocated in the US.[9] These regulatory developments made it possible to use the ALOHA random-access techniques in both Wi-Fi and in mobile telephone networks.

ALOHA channels were used in a limited way in the 1980s in 1G mobile phones for signaling and control purposes.[10] In the late 1980s, the European standardisation group GSM who worked on the Pan-European Digital mobile communication system GSM greatly expanded the use of ALOHA channels for access to radio channels in mobile telephony. In addition SMS message texting was implemented in 2G mobile phones. In the early 2000s additional ALOHA channels were added to 2.5G and 3G mobile phones with the widespread introduction of GPRS, using a slotted-ALOHA random-access channel combined with a version of the Reservation ALOHA scheme first analyzed by a group at BBN.

Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.

N. Abramson, "Development of the ALOHANET," in IEEE Transactions on Information Theory, vol. 31, no. 2, pp. 119-123, March 1985.�doi: 10.1109/TIT.1985.1057021 M. Schwartz and N. Abramson, "The Alohanet - surfing for wireless data [History of Communications]," in IEEE Communications Magazine, vol. 47, no. 12, pp. 21-25, Dec. 2009.�doi: 10.1109/MCOM.2009.5350363 Abramson, N. 1982. "Fundamentals of Packet Multiple Access for Satellite Networks," IEEE Journal on Selected Areas in Communications 10(2):309-316. Entrepreneurial Capitalism & Innovation: �A History of Computer Communications �1968 - 1988�By James Pelkey https://www.computer.org/csdl/proceedings/afips/1975/5083/00/50830203.pdf

Managing Requirements Knowledge, International Workshop on ...

 ALOHA packet broadcasting - A retrospect
 Year: 1975, Volume: 1, Pages: 203
 DOI Bookmark:10.1109/AFIPS.1975.17
 Authors: R. Binder  / N. Abramson / F. F. Kuo / A. Okinaka / D. Wax

https://apps.dtic.mil/dtic/tr/fulltext/u2/a122775.pdf

ALOHA PACKET SYSTEM With and Without Slots.pdf

http://www.wirelesscommunication.nl/reference/chaptr06/randacc.htm

UCSC Recognition -ALOHANet (aka ALOHA System).png

https://www.clear.rice.edu/comp551/papers/Abramson-Aloha.pdf THE ALOHA SYSTEM—Another alternative for computer communications* by NORMAN ABRAMSON University of Hawaii Honolulu, Hawaii

https://apps.dtic.mil/dtic/tr/fulltext/u2/a098684.pdf COMPUTER NETWORKS – THE ALOHA SYSTEM

https://www.cybertelecom.org/notes/internet_history70s.htm ALOHANet July: Norman Abramson builds ALOHANet, using DARPA and NAVY funding. [Nerds 2.0.1] [Roberts, Computer Science Museum 1988] ARPA provides a Terminal Interface Processor to ALOHANet [Nerds p 103] [Roberts, Net Chronology] [Abbate p 115] ALOHAnet became operational in 1971. Lore has it that Abramsom primarily wanted to go surfing. Design objectives: "The original goal of the Aloha System was to investigate the use of radio communications as an alternative to the telephone system for computer communications and to “determine those situations where radio communications are preferable to conventional wire communications”" [Abramson 2009]

Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to ieee-history@ieee.org. Please see the Milestone Program Guidelines for more information.

Computer History Museum Interview of Norman “Norm” Abramson Interviewed by: James L. Pelkey Recorded: October 13, 1988 Menlo Park, California http://archive.computerhistory.org/resources/access/text/2013/05/102746645-05-01-acc.pdf

Milestone supporting documentaton; Computer History Museum

Milestone supporting documentation. Certmag

ALOHANET: The World's First Wireless LAN Posted on January 31, 2007 by cmadmin

https://www.youtube.com/watch?v=y72gYcQeais YouTube link addressing ALOHANET (in Chinese)

https://youtu.be/0DF6ekaFC8U

https://www.youtube.com/watch?v=vLxEZtl1iAQ (in Hindi)

https://www.youtube.com/watch?v=y72gYcQeais (in Chinese)

https://apps.dtic.mil/dtic/tr/fulltext/u2/a122775.pdf

https://disco.ethz.ch/alumni/pascalv/refs/rn_1975_roberts.pdf

http://www.wirelesscommunication.nl/reference/chaptr06/randacc.htm

UCSC Recognition - ALOHANET (aka ALOHA System).png

https://www.clear.rice.edu/comp551/papers/Abramson-Aloha.pdf THE ALOHA SYSTEM—Another alternative for computer communications* by NORMAN ABRAMSON University of Hawaii Honolulu, Hawaii

https://apps.dtic.mil/dtic/tr/fulltext/u2/a098684.pdf COMPUTER NETWORKS – THE ALOHA SYSTEM

https://www.cybertelecom.org/notes/internet_history70s.htm ALOHANet July: Norman Abramson builds ALOHANet, using DARPA and NAVY funding. [Nerds 2.0.1] [Roberts, Computer Science Museum 1988] ARPA provides a Terminal Interface Processor to ALOHANet [Nerds p 103] [Roberts, Net Chronology] [Abbate p 115] ALOHAnet became operational in 1971. Lore has it that Abramsom primarily wanted to go surfing. Design objectives: "The original goal of the Aloha System was to investigate the use of radio communications as an alternative to the telephone system for computer communications and to “determine those situations where radio communications are preferable to conventional wire communications”" [Abramson 2009]

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