The IEEE 802.15.4 standard specifies the PHY and MAC layers of Low-Rate Wireless Personal Area Networks (LR-WPANs) 1.The IEEE 802.15.4 PHY and MAC layers provide the basis of other higher-layer standards, such as ZigBee, WirelessHart®, 6LoWPAN and MiWi.Such standards find application in home automation and sensor networking and are highly relevant to the Internet of. This example shows how to generate and decode MAC frames of the IEEE® 802.15.4™ standard 1 using the Communications Toolbox™ Library for the ZigBee® Protocol. This article on WLAN MAC protocol describes WLAN MAC frame format as per IEEE 802.11 wifi MAC standard. The WLAN MAC frame consists of MAC header, body and FCS. The MAC header contains frame control field, duration field, address fields and sequence control field.
This example shows how to generate waveforms, decode waveforms and compute BER curves for different PHY specifications of the IEEE® 802.15.4™ standard [ 1], using the Communications Toolbox™ Library for the ZigBee® Protocol.
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Background
The IEEE 802.15.4 standard specifies the PHY and MAC layers of Low-Rate Wireless Personal Area Networks (LR-WPANs) [ 1 ]. The IEEE 802.15.4 PHY and MAC layers provide the basis of other higher-layer standards, such as ZigBee, WirelessHart®, 6LoWPAN and MiWi. Such standards find application in home automation and sensor networking and are highly relevant to the Internet of Things (IoT) trend.
Physical Layer Implementations of IEEE 802.15.4
The original IEEE 802.15.4 standard and its amendments specify multiple PHY layers, which use different modulation schemes and support different data rates. These physical layers were devised for specific frequency bands and, to a certain extent, for specific countries. This example provides functions that generate and decode waveforms for the physical layers proposed in the original IEEE 802.15.4 specification (OQPSK in 2.4 GHz, BPSK in 868/915 MHz), IEEE 802.15.4b (OQPSK and ASK in 868/915 MHz), IEEE 802.15.4c (OQPSK in 780 MHz) and IEEE 802.15.4d (GFSK and BPSK in 950 MHz).
These physical layers specify a format for the PHY protocol data unit (PPDU) that includes a preamble, a start-of-frame delimiter (SFD), and the length and contents of the MAC protocol data unit (MPDU). The preamble and SFD are used for frame-level synchronization. In the following description, the term symbol denotes the integer index of a chip sequence (as per the IEEE 802.15.4 standard), not a modulation symbol (i.e., a complex number).
- OQPSK PHY: All OQPSK PHYs map every 4 PPDU bits to one symbol. The 2.4 GHz OQPSK PHY spreads each symbol to a 32-chip sequence, while the other OQPSK PHYs spread it to a 16-chip sequence. Dragon age origins presets mod. Then, the chip sequences are OQPSK modulated and passed to a half-sine pulse shaping filter (or a normal raised cosine filter, in the 780 MHz band). For a detailed description, see Clause 10 in [ 1 ].
- BPSK PHY: The BPSK PHY differentially encodes the PPDU bits. Each resulting bit is spread to a 15-chip sequence. Then, the chip sequences are BPSK modulated and passed to a normal raised cosine filter. For a detailed description, see Clause 11 in [ 1 ].
- ASK PHY: The ASK PHY uses BPSK modulation for the preamble and the SFD only. The remaining PPDU bits, i.e., the PHY header (PHR) and the MPDU, are first mapped to 20-bit symbols in the 868 MHz band and to 5-bit symbols in the 915 MHz band. Each symbol is spread to a 32-chip sequence using a technique known as Parallel Sequence Spread Spectrum (PSSS) or Orthogonal Code Division Multiplexing (OCDM). The chip sequence is then ASK modulated and passed to a root raised cosine filter. For a detailed description, see Clause 12 in [ 1 ].
- GFSK PHY: The GFSK PHY first whitens the PPDU bits using modulo-2 addition with a PN9 sequence. The whitened bits are then GFSK modulated. For a detailed description, see Clause 15 in [ 1 ].
Waveform Generation, Decoding and BER Curve Calculation
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This code illustrates how to use the waveform generation and decoding functions for different frequency bands and compares the corresponding BER curves.
Further Exploration
You can further explore the following generator and decoding functions:
- lrwpan.PHYGeneratorOQPSK, lrwpan.PHYDecoderOQPSKNoSync and lrwpan.PHYDecoderOQPSK
- lrwpan.PHYGeneratorBPSK and lrwpan.PHYDecoderBPSK
- lrwpan.PHYGeneratorASK and lrwpan.PHYDecoderASK
- lrwpan.PHYGeneratorGFSK and lrwpan.PHYDecoderGFSK
Selected Bibliography
- IEEE 802.15.4-2011 - IEEE Standard for Local and metropolitan area networks--Part 15.4: Low-Rate Wireless Personal Area Networks (LR-WPANs)
IEEE 802.15 is a working group of the Institute of Electrical and Electronics Engineers (IEEE) IEEE 802 standards committee which specifies wireless personal area network (WPAN) standards. There are 10 major areas of development, not all of which are active.
The number of Task Groups in IEEE 802.15 varies based on the number of active projects. The current list of active projects can be found on the IEEE 802.15 web site.
IEEE 802.15.1: WPAN / Bluetooth[edit]
Task group one is based on Bluetooth technology. It defines physical layer (PHY) and Media Access Control (MAC) specification for wireless connectivity with fixed, portable and moving devices within or entering personal operating space. Standards were issued in 2002 and 2005.[1][2]
IEEE 802.15.2: Coexistence[edit]
Task group two addresses the coexistence of wireless personal area networks (WPAN) with other wireless devices operating in unlicensed frequency bands such as wireless local area networks (WLAN). The IEEE 802.15.2-2003 standard was published in 2003[3] and task group two went into 'hibernation'.[4]
IEEE 802.15.3: High Rate WPAN[edit]
IEEE 802.15.3-2003[edit]
IEEE 802.15.3-2003 is a MAC and PHY standard for high-rate (11 to 55 Mbit/s) WPANs. The standard can be downloaded via the IEEE Get program,[5] which is funded by IEEE 802 volunteers.
IEEE 802.15.3a[edit]
IEEE P802.15.3a was an attempt to provide a higher speed Ultra wideband PHY enhancement amendment to IEEE 802.15.3 for applications which involve imaging and multimedia. The members of the task group were not able to come to an agreement choosing between two technology proposals, Multi-band Orthogonal Frequency Division Multiplexing (MB-OFDM) and Direct Sequence UWB (DS-UWB), backed by two different industry alliances and was withdrawn in January 2006.[6] Documents related to the development of IEEE 802.15.3a are archived on the IEEE document server.[7]
IEEE 802.15.3b-2006[edit]
IEEE 802.15.3b-2005 amendment was released on May 5, 2006. It enhanced 802.15.3 to improve implementation and interoperability of the MAC. This amendment include many optimizations, corrected errors, clarified ambiguities, and added editorial clarifications while preserving backward compatibility. Among other changes, the amendment defined the following new features:[8]
- a new MAC layer management entity (MLME) service access point (SAP)
- implied acknowledgment policy that allow polling
- logical link control/subnetwork access protocol (LLC/SNAP) headers
- multicast address assignment
- multiple contention periods in a superfame
- a method for relinquishing channel time to another device in the PAN
- faster network recover in the case when the piconet coordinator (PNC) abruptly disconnects
- a method for a device to return information about signal quality of a received packet.
IEEE 802.15.3c-2009[edit]
IEEE 802.15.3c-2009 was published on September 11, 2009. The task group TG3c developed a millimeter-wave-based alternative physical layer (PHY) for the existing 802.15.3 Wireless Personal Area Network (WPAN) Standard 802.15.3-2003. The IEEE 802.15.3 Task Group 3c (TG3c) was formed in March 2005. This mmWave WPAN is defined to operate in the 57–66 GHz range. Depending on the geographical region, anywhere from 2 to 9 GHz of bandwidth is available (for example, 57–64 GHz is available as unlicensed band defined by FCC 47 CFR 15.255 in North America). The millimeter-wave WPAN allows very high data rate, short range (10 m) for applications including high speed internet access, streaming content download (video on demand, HDTV, home theater, etc.), real time streaming and wireless data bus for cable replacement. A total of three PHY modes were defined in the standard:[9]
- Single carrier (SC) mode (up to 5.3 Gbit/s)
- High speed interface (HSI) mode (single carrier, up to 5 Gbit/s)
- Audio/visual (AV) mode (OFDM, up to 3.8 Gbit/s).
IEEE 802.15.4: Low Rate WPAN[edit]
Protocol stack for 802.15.4
IEEE 802.15.4-2003 (Low Rate WPAN) deals with low data rate but very long battery life (months or even years) and very low complexity. The standard defines both the physical (Layer 1) and. IEEE Standards Association. doi:10.1109/IEEESTD.2005.96290. ISBN0-7381-4707-9. Retrieved June 30, 2011.
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External links[edit]
Retrieved from 'https://en.wikipedia.org/w/index.php?title=IEEE_802.15&oldid=948128350'