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In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer: the layer most closely associated with the physical connection between devices. The physical layer provides an electrical, mechanical, and procedural interface to the transmission medium.
The physical-layer specifications of the Ethernet family of computer network standards are published by the Institute of Electrical and Electronics Engineers (IEEE), which defines the electrical or optical properties and the transfer speed of the physical connection between a device and the network or between network devices.
Another provision is the definition of power classes. This includes the limitation of the maximum supply voltage and supply current for intrinsically safe power supply . Further topics that are specified in the port profile specification are wiring rules, pin assignments for terminals and connectors as well as shielding and grounding rules.
In computer networking, a wireless access point (WAP) (also just access point (AP)) is a networking hardware device that allows other Wi-Fi devices to connect to a wired network or wireless network. As a standalone device, the AP may have a wired or wireless connection to a switch or router , but in a wireless router it can also be an integral ...
IEEE 802.3 is a working group and a collection of standards defining the physical layer and data link layer's media access control (MAC) of wired Ethernet.The standards are produced by the working group of the Institute of Electrical and Electronics Engineers (IEEE).
The standard defines both the physical (Layer 1) and data-link (Layer 2) layers of the OSI model. The first edition of the 802.15.4 standard was released in May 2003. Several standardized and proprietary networks (or mesh) layer protocols run over 802.15.4-based networks, including IEEE 802.15.5, Zigbee, Thread, 6LoWPAN, WirelessHART, and ...
The physical layer also specifies how encoding occurs over a physical signal, such as electrical voltage or a light pulse. For example, a 1 bit might be represented on a copper wire by the transition from a 0-volt to a 5-volt signal, whereas a 0 bit might be represented by the transition from a 5-volt to a 0-volt signal.
This layer deals with the physical plugs, sockets, electrical/optical specifications and the required line codes. The physical layer includes the medium over which the digital signals are transmitted. It can be twisted pair, coaxial cable, optical fiber, wireless, or other transmission media.