PHY-Level Collision Avoidance
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PHY-Level Collision Avoidance
PHY-Level Collision Avoidance (PLCA) is a component of the Ethernet reconciliation sublayer (between the PHY and the MAC) defined within IEEE 802.3 clause 148. The purpose of PLCA is to avoid the shared medium collisions and associated retransmission overhead. PLCA is used in 802.3cg (10BASE-T1), which focuses on bringing Ethernet connectivity to short-haul embedded internet of things and low throughput, noise-tolerant, industrial deployment use cases. In order for a multidrop 10BASE-T1S standard to successfully compete with CAN XL, some kind of arbitration was necessary. The linear arbitration scheme of PLCA somewhat resembles that of the Byteflight, but PLCA was designed from scratch to accommodate the existing shared medium Ethernet MACs with their busy sensing mechanisms. Operation Under a PLCA scheme all nodes are assigned unique sequential numbers (IDs) in the range from 0 to N. Zero ID corresponds to a special "coordinator" node that during the idle intervals t ...
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Reconciliation Sublayer
The physical coding sublayer (PCS) is a networking protocol sublayer in the Fast Ethernet, Gigabit Ethernet, and 10 Gigabit Ethernet standards. It resides at the top of the physical layer (PHY), and provides an interface between the physical medium attachment (PMA) sublayer and the media-independent interface (MII). It is responsible for data encoding and decoding, scrambling and descrambling, alignment marker insertion and removal, block and symbol redistribution, and lane block synchronization and deskew. Description The Ethernet PCS sublayer is at the top of the Ethernet physical layer (PHY). The hierarchy is as follows: * Data link layer (Layer 2) ** Logical link control (LLC) sublayer ** Medium access control (MAC) sublayer *** Reconciliation sublayer (RS)This sublayer processes PHY local/remote fault messages and handles DDR conversion * PHY Layer (Layer 1) ** Physical coding sublayer (PCS)This sublayer determines when a functional link has been established, provides rate ...
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Linear Arbitration
In mathematics, the term ''linear'' is used in two distinct senses for two different properties: * linearity of a ''function'' (or '' mapping''); * linearity of a ''polynomial''. An example of a linear function is the function defined by f(x)=(ax,bx) that maps the real line to a line in the Euclidean plane R2 that passes through the origin. An example of a linear polynomial in the variables X, Y and Z is aX+bY+cZ+d. Linearity of a mapping is closely related to '' proportionality''. Examples in physics include the linear relationship of voltage and current in an electrical conductor (Ohm's law), and the relationship of mass and weight. By contrast, more complicated relationships, such as between velocity and kinetic energy, are ''nonlinear''. Generalized for functions in more than one dimension, linearity means the property of a function of being compatible with addition and scaling, also known as the superposition principle. Linearity of a polynomial means that its degree is ...
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Computer Networking
A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or by wireless communication. The devices may be connected in a variety of network topologies. In order to communicate over the network, computers use agreed-on rules, called communication protocols, over whatever medium is used. The computer network can include personal computers, Server (computing), servers, networking hardware, or other specialized or general-purpose Host (network), hosts. They are identified by network addresses and may have hostnames. Hostnames serve as memorable labels for the nodes and are rarely changed after initial assignment. Network addresses serve for locating and identifying the nodes by communication protocols such as the Internet Protocol. Computer networks may be classified by many criteria, including the tr ...
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Ethernet
Ethernet ( ) is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3. Ethernet has since been refined to support higher bit rates, a greater number of nodes, and longer link distances, but retains much backward compatibility. Over time, Ethernet has largely replaced competing wired LAN technologies such as Token Ring, FDDI and ARCNET. The original 10BASE5 Ethernet uses a thick coaxial cable as a shared medium. This was largely superseded by 10BASE2, which used a thinner and more flexible cable that was both less expensive and easier to use. More modern Ethernet variants use Ethernet over twisted pair, twisted pair and fiber optic links in conjunction with Network switch, switches. Over the course of its history, Ethernet data transfer rates have been increased from the original to the lates ...
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Internet Of Things
Internet of things (IoT) describes devices with sensors, processing ability, software and other technologies that connect and exchange data with other devices and systems over the Internet or other communication networks. The IoT encompasses Electronic engineering, electronics, Telecommunications engineering, communication, and computer science engineering. "Internet of things" has been considered a misnomer because devices do not need to be connected to the public internet; they only need to be connected to a network and be individually addressable. The field has evolved due to the convergence of multiple technologies, including ubiquitous computing, commodity sensors, and increasingly powerful embedded systems, as well as machine learning.Hu, J.; Niu, H.; Carrasco, J.; Lennox, B.; Arvin, F.,Fault-tolerant cooperative navigation of networked UAV swarms for forest fire monitoring Aerospace Science and Technology, 2022. . Older fields of embedded systems, wireless sensor netw ...
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Exponential Backoff
Exponential backoff is an algorithm that uses feedback to multiplicatively decrease the rate of some process, in order to gradually find an acceptable rate. These algorithms find usage in a wide range of systems and processes, with radio networks and computer networks being particularly notable. Exponential backoff algorithm An exponential backoff algorithm is a form of closed-loop control system that reduces the rate of a controlled process in response to adverse events. For example, if a smartphone app fails to connect to its server, it might try again 1 second later, then if it fails again, 2 seconds later, then 4, etc. Each time the pause is multiplied by a fixed amount (in this case 2). In this case, the adverse event is failing to connect to the server. Other examples of adverse events include collisions of network traffic, an error response from a service, or an explicit request to reduce the rate (i.e. ''back off''). The rate reduction can be modelled as an exponenti ...
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Transmission Opportunity
Transmission or transmit may refer to: Science and technology * Power transmission ** Electric power transmission ** Transmission (mechanical device), technology that allows controlled application of power *** Automatic transmission *** Manual transmission * Signal transmission, the process of sending and propagating an analogue or digital information signal ** Analogue transmission, the process of sending and propagating an analogue signal ** Data transmission, the process of sending and propagating digital information ** Signaling (telecommunications), transmission of meta-information related to the actual transmission * Monetary transmission mechanism, process by which asset prices and general economic conditions are affected as a result of monetary policy decisions * Pathogen transmission, the passing of a disease from an infected host individual or group to a particular individual or group * Cellular signaling, transmission of signals within or between living cells * Heredit ...
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Heartbeat (computing)
In computer science, a heartbeat is a periodic signal generated by hardware or software to indicate normal operation or to synchronize other parts of a computer system. Heartbeat mechanism is one of the common techniques in mission critical systems for providing high availability and fault tolerance of network services by detecting the network or systems failures of nodes or daemons which belongs to a network cluster—administered by a master server—for the purpose of automatic adaptation and rebalancing of the system by using the remaining redundant nodes on the cluster to take over the load of failed nodes for providing constant services. Usually a heartbeat is sent between machines at a regular interval in the order of seconds; a heartbeat message. If the endpoint does not receive a heartbeat for a time—usually a few heartbeat intervals—the machine that should have sent the heartbeat is assumed to have failed. Heartbeat messages are typically sent non-stop on a per ...
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Network Node
In networking, a node (, ‘knot’) is either a redistribution point or a communication endpoint within telecommunication networks. A physical network node is an electronic device that is attached to a network, and is capable of creating, receiving, or transmitting information over a communication channel. In data communication, a physical network node may either be data communication equipment (such as a modem, hub, bridge or switch) or data terminal equipment (such as a digital telephone handset, a printer or a host computer). A passive distribution point such as a distribution frame or patch panel is not a node. Computer networks In data communication, a physical network node may either be data communication equipment (DCE) such as a modem, hub, bridge or switch; or data terminal equipment (DTE) such as a digital telephone handset, a printer or a host computer. If a network is a local area network (LAN) or wide area network (WAN), every LAN or WAN node that par ...
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PHY-Level Collision Avoidance
PHY-Level Collision Avoidance (PLCA) is a component of the Ethernet reconciliation sublayer (between the PHY and the MAC) defined within IEEE 802.3 clause 148. The purpose of PLCA is to avoid the shared medium collisions and associated retransmission overhead. PLCA is used in 802.3cg (10BASE-T1), which focuses on bringing Ethernet connectivity to short-haul embedded internet of things and low throughput, noise-tolerant, industrial deployment use cases. In order for a multidrop 10BASE-T1S standard to successfully compete with CAN XL, some kind of arbitration was necessary. The linear arbitration scheme of PLCA somewhat resembles that of the Byteflight, but PLCA was designed from scratch to accommodate the existing shared medium Ethernet MACs with their busy sensing mechanisms. Operation Under a PLCA scheme all nodes are assigned unique sequential numbers (IDs) in the range from 0 to N. Zero ID corresponds to a special "coordinator" node that during the idle intervals t ...
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Byteflight
Byteflight is an automotive databus created by BMW and partners Motorola, Elmos Semiconductor and Infineon to address the need for a modernized safety-critical, fault tolerant means of electronic communication between automotive components. It is a message-oriented protocol. As a predecessor to FlexRay, byteflight uses a hybrid synchronous/asynchronous TDMA based means of data transfer to circumvent deficiencies associated with pure event-triggered databuses. It was first introduced in 2001 on the BMW 7 Series (E65). Eclipse 500 The Eclipse 500 (model EA500) is a very light jet (VLJ) originally produced by Eclipse Aviation of Albuquerque, New Mexico, United States. The company was founded in 1998 to develop the 1997 Williams V-Jet II demonstrator. The prototype first ... jet aeroplanes use Byteflight to connect the avionics displays.Eclipse 500 Avionics Architecture diagram in Data frame In Byteflight terminology, a data frame is called a ''telegraph''. A telegraph ...
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CAN Bus
A controller area network bus (CAN bus) is a vehicle bus standard designed to enable efficient communication primarily between electronic control units (ECUs). Originally developed to reduce the complexity and cost of electrical wiring in automobiles through multiplexing, the CAN bus protocol has since been adopted in various other contexts. This Broadcasting (networking), broadcast-based, Message passing, message-oriented protocol ensures data integrity and prioritization through a process called Arbiter (electronics), arbitration, allowing the highest priority device to continue transmitting if multiple devices attempt to send data simultaneously, while others back off. Its reliability is enhanced by Differential signalling, differential signaling, which mitigates electrical noise. Common versions of the CAN protocol include CAN 2.0, CAN FD, and CAN XL which vary in their data rate capabilities and maximum data payload sizes. History Development of the CAN Bus (computing), ...
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