Physical layer

This layer may be implemented by a PHY chip.

A PHY, an abbreviation for "physical layer", is an electronic circuit, usually implemented as a chip, required to implement physical layer functions of the OSI model.

The shapes and properties of the electrical connectors, the frequencies to broadcast on, the line code to use and similar low-level parameters, are specified here.

In computing, electrical connectors are considered a physical interface and constitute part of the physical layer in the OSI model of networking.

Within the semantics of the OSI model, the physical layer translates logical communications requests from the data link layer into hardware-specific operations to cause transmission or reception of electronic signals.

The data link layer provides the functional and procedural means to transfer data between network entities and might provide the means to detect and possibly correct errors that may occur in the physical layer.

In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer.

WAN technologies generally function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer.

In practice, the concept was marred by proliferation of incompatible physical layer and network protocol implementations, and a plethora of methods of sharing resources.

In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer.

The physical layer is responsible for the transmission and reception of unstructured raw data between a device and a physical transmission medium.

Transmission technologies and schemes typically refer to physical layer protocol duties such as modulation, demodulation, line coding, equalization, error control, bit synchronization and multiplexing, but the term may also involve higher-layer protocol duties, for example, digitizing an analog signal, and data compression.

In this context, multiplexing is provided by the physical layer.

A network’s physical topology is a particular concern of the physical layer of the OSI model.

In digital communication systems, the physical layer gross bitrate, raw bitrate, data signaling rate, gross data transfer rate or uncoded transmission rate (sometimes written as a variable R b or f b ) is the total number of physically transferred bits per second over a communication link, including useful data as well as protocol overhead.

The Internet protocol suite, as defined in RFC 1122 and RFC 1123, is a high-level networking description used for the Internet and similar networks.

These perform functions, such as framing, to prepare the Internet layer packets for transmission, and finally transmit the frames over a physical medium.

The basic difference between a parallel and a serial communication channel is the number of electrical conductors used at the physical layer to convey bits.

The Ethernet physical layer is the physical layer functionality of the Ethernet family of computer network standards.

Ethernet over twisted pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network.

Multiplexing is provided by the Physical Layer of the OSI model, while multiple access also involves a media access control protocol, which is part of the Data Link Layer.

It specifies the physical layer and media access control for LR-WPANs, and is maintained by the IEEE 802.15 working group, which defined the standard in 2003.

In the OSI model, autonegotiation resides in the physical layer.

ITU-T Recommendation (the ITU's term for standard) G.9960, which received approval on October 9, 2009, specified the physical layers and the architecture of G.hn.

Ethernet was the result of research conducted at Xerox PARC in the early 1970s, and later evolved into a widely implemented physical and link layer protocol.

RS-485 only specifies electrical characteristics of the generator and the receiver: the physical layer.

IEEE 802.11 is part of the IEEE 802 set of LAN protocols, and specifies the set of media access control (MAC) and physical layer (PHY) protocols for implementing wireless local area network (WLAN) Wi-Fi computer communication in various frequencies, including but not limited to 2.4 GHz, 5 GHz, and 60 GHz frequency bands.

The technology covers the physical layer, while other technologies and protocols such as LoRaWAN (Long Range Wide Area Network) cover the upper layers.

The shapes and properties of the electrical connectors, the frequencies to broadcast on, the line code to use and similar low-level parameters, are specified here.