The " DIX-group " with Gary Robinson ( DEC ), Phil Arst ( Intel ), and Bob Printis ( Xerox ) submitted the so-called " Blue Book " CSMA / CD specification as a candidate for the LAN specification.

In addition to CSMA / CD, Token Ring ( supported by IBM ) and Token Bus ( selected and henceforward supported by General Motors ) were also considered as candidates for a LAN standard.

As early as March 1982 ECMA TC24 with its corporate members reached agreement on a standard for CSMA / CD based on the IEEE 802 draft.

Because the DIX proposal was most technically complete and because of the speedy action taken by ECMA which decisively contributed to the conciliation of opinions within IEEE, the IEEE 802. 3 CSMA / CD standard was approved in December 1982.

* CSMA / CD and CSMA / CA " backoff " waiting time and frame retransmissions after detected collisions.

One faction wanted to keep CSMA / CD in order to keep it pure Ethernet, even though the collision domain problem limited the distances to one tenth that of 10BASE-T. Another faction wanted to change to a polling architecture from the hub ( they called it " Demand Priority Protocol ") in order to maintain the 10baseT distances, and also to make it a deterministic protocol.

When Ethernet became Fast Ethernet, it continued to use the Carrier Sense Multiple Access With Collision Detection ( CSMA / CD ) mechanism to manage traffic on the network cable.

Carrier sense multiple access with collision avoidance ( CSMA / CA ) in computer networking, is a network multiple access method in which carrier sensing is used, but nodes attempt to avoid collisions by transmitting only when the channel is sensed to be " idle ".

It is particularly important for wireless networks, where the collision detection of the alternative CSMA / CD method is not possible for technical reasons.

CSMA / CA is a protocol that operates in the Data Link Layer ( Layer 2 ) of the OSI model.

Simplified Algorithm of CSMA / CA

Although CSMA / CA has been used in a variety of wired communication systems, it is particularly beneficial in a wireless LAN due to a common problem of multiple stations being able to see the Access Point, but not each other.

CSMA / CA performance is based largely upon the modulation technique used to transmit the data between nodes.

Studies show that under ideal propagation conditions ( simulations ), Direct Sequence Spread Spectrum ( DSSS ) provides the highest throughput for all nodes on a network when used in conjunction with CSMA / CA and the IEEE 802. 11 RTS / CTS exchange under light network load conditions.

* Apple's LocalTalk implemented CSMA / CA on an electrical bus using a three-byte jamming signal.

* IEEE 802. 15. 4 ( Wireless PAN ) uses CSMA / CA

* The ITU-T G. hn standard, which provides a way to create a high-speed ( up to 1 Gigabit / s ) local area network using existing home wiring ( power lines, phone lines and coaxial cables ), uses CSMA / CA as a channel access method for flows that don't require guaranteed quality of service, specifically the CSMA / CARP variant.

* CSMA / CA RTS / CTS Simulation

tr: CSMA / CA

ca: CSMA / CA

cs: CSMA / CA

da: CSMA / CA

eu: CSMA / CA

it: CSMA / CA

he: Carrier sense multiple access # CSMA / CA

nl: CSMA / CA

ja: CSMA / CA

pl: CSMA / CA

pt: CSMA / CA

CSMA / CD is used to improve CSMA performance by terminating transmission as soon as a collision is detected, thus shortening the time required before a retry can be attempted.

CSMA can be the abbreviated form of more than one thing:

By having the collision occur at the NIC ( local ) and not on the wire ( late ) CSMA / CD implementation can take more control over the situation.

A multiplexing technique may be further extended into a multiple access method or channel access method, for example TDM into Time-division multiple access ( TDMA ) and statistical multiplexing into carrier sense multiple access ( CSMA ).

In CSMA / CA collision avoidance is used to improve the performance of CSMA by attempting to be less " greedy " on the channel.

Point-to-point networks may either use unslotted CSMA / CA or synchronization mechanisms ; in this case, communication between any two devices is possible, whereas in “ structured ” modes one of the devices must be the network coordinator.

In CSMA / CD networks such as ethernet, Network Interface Controllers ( NICs ) wait a minimum of the slot time ( which should be a constant, NOT dependent on the individual network-i. e., it is a standard across all CSMA / CD networks that use a common NIC ) before transmitting, allowing time ( the maximum theoretical time-slot time ) for the pulse to reach the NIC that intends to send.

Since beacon frames are sent using the mandatory 802. 11 carrier sense multiple access / collision detection ( CSMA / CD ) algorithm, the access point must wait if a client device is sending a frame when the beacon is to be sent.

Collision avoidance is used to improve the performance of the CSMA method by attempting to divide the channel somewhat equally among all transmitting nodes within the collision domain.

CSMA / CD is used to improve CSMA performance by terminating transmission as soon as a collision is detected, and reducing the probability of a second collision on retry.

O-persistent CSMA is used by CobraNet, LonWorks and the controller area network.

Since bit errors are very rare in wired networks, Ethernet does not provide flow control or automatic repeat request ( ARQ ), meaning that incorrect packets are detected but only cancelled, not retransmitted ( except in case of collisions detected by the CSMA / CD MAC layer protocol ).

Finally, devices in Beacon Oriented networks that have low latency real-time requirements may also use Guaranteed Time Slots ( GTS ), which by definition do not use CSMA.

Important features include real-time suitability by reservation of guaranteed time slots, collision avoidance through CSMA / CA and integrated support for secure communications.

Within superframes contention occurs between their limits, and is resolved by CSMA / CA.

Data transfers to the coordinator require a beacon synchronization phase, if applicable, followed by CSMA / CA transmission ( by means of slots if superframes are in use ); acknowledgment is optional.

The first offered singulation protocol is the ALOHA protocol, originally used decades ago in ALOHAnet and very similar to CSMA / CD used by Ethernet.

WMM replaces the traditional Wi-Fi DCF distributed coordination function for traditional CSMA / CA wireless frame transmission with EDCF, Enhanced Distributed Coordination Function, which according to version 1. 1 of the WMM specifications by the Wi-Fi Alliance, defines four Access Categories ( AC_BK, AC_BE, AC_VI, AC_VO ) labels, for the EDCA Enhanced Distributed Channel Access parameters that are used by a WMM-enabled station to control how long it shall set its TXOP Transmission Opportunity, according to the information transmitted by the access point to the station, and is implemented for wireless QoS between over RF media.