IEEE 802.15.4

IEEE 802.15.4 is a standard created and maintained by consultants which specifies the physical layer and media access control for low-rate wireless personal area networks (LR-WPANs). It is maintained by the IEEE 802.15 working group, which has defined it in 2003. It is the basis for the ZigBee,ISA100.11a,WirelessHART, MiWi, and Thread specifications, each of which further extends the standard by developing the upper layers which are not defined in IEEE 802.15.4. Alternatively, it can be used with 6LoWPAN and standard Internet protocols to build a wireless embedded Internet.

Overview

IEEE standard 802.15.4 intends to offer the fundamental lower network layers of a type of wireless personal area network (WPAN) which focuses on low-cost, low-speed ubiquitous communication between devices. It can be contrasted with other approaches, such as Wi-Fi, which offer more bandwidth and require more power. The emphasis is on very low cost communication of nearby devices with little to no underlying infrastructure, intending to exploit this to lower power consumption even more.

IEEE 1344

IEEE 1344 is a standard that defines parameters for synchrophasors for power systems. The standard added extension to the IRIG-B time code to cover year, time quality, daylight saving time, local time offset and leap second information. IEEE 1344 was superseded by IEEE C37.118 in 2005 and the time extensions were adopted as part of the IRIG timing standard in the 2004 edition.

IRIG-B timecode consists of 100 bits, repeated each second. Every tenth bit is a "position identifier", and most of the remainder encode the current time (date, hour, minute and second). Bits 60–68 and 70–78 are reserved for other uses; IEEE 1344 is such a use. It defines the bits as follows:

The DST and leap warning bits are set no more than 59 seconds before the indicated change, and indicate the change at the end of the minute. During a leap second, the warning bit should be set, the seconds field should show "60", and the Straight Binary Seconds field should equal 60 + 60 × minutes + 3600 × hours. The next second, the leap second warning bit should be clear, and the SBS field will repeat. Since negative leap seconds have never happened, and almost certainly never will, the LS bit is always 0.

IEEE 802.3

IEEE 802.3 is a working group and a collection of IEEE standards produced by the working group defining the physical layer and data link layer's media access control (MAC) of wired Ethernet. This is generally a local area network technology with some wide area network applications. Physical connections are made between nodes and/or infrastructure devices (hubs, switches, routers) by various types of copper or fiber cable.

802.3 is a technology that supports the IEEE 802.1 network architecture.

802.3 also defines LAN access method using CSMA/CD.

Communication Standards

See also

References

External links