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Definition

IEEE 802.15.4 is the standard for “Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Low-Rate Wireless Personal Area Networks (LR-WPANs)”

Table of Contents

Maximum Values

Superframe Structure

The communication of IEEE 802.15.4 networks is structured into Superframes, which is the perdiod between two coordinator beacons. Each superframe consists of an active and an inactive period but the length of the inactive perdiod may be zero.

  ||      active        |  inactive    || 
  ||   CAP |  CFP       |              || 
  ||       |            |              || 
Beacon                               Beacon

Frame Structure

                            +-------------------------------+
                            | MAC head |   MAC   | MAC foot |
                            |   (MHR)  | payload |  (MFR)   |
                            +-------------------------------+
                              \                           /
+-------------------------------------------------------+
|  Sync. header  |  PHY header  |     PHY payload       |
|     (SHR)      |    (PHR)     |        (PSDU)         |
+-------------------------------------------------------+

A cyclic redundancy check (CRC) is used to detect errors in every PSDU.

Access Methods

Deterministic and Synchronous Multi-channel Extension (DSME)

If several coordinators are present, the communication is structured into Multi-Superframes. A multi-superframe consists of repeated superframes, each of which consists of an Enhanced Beacon frame, a CAP and a CFP.

Device Types

A full-Function Device (FFD) is a device that is capable of serving as a personal area network (PAN) coordinator.

A Reduced-Function Device (RFD) is a device that is not capable of serving as a coordinator and is intended for applications that are extremely simple.


Topologies

Physical Layer 1 (PHY)

Features

868 MHz 2.4 GHz
Modulation BPSK O-QPSK
Channels 1 16
Bit Rate 20 kbps 250 kbps
Symbols 1 bit/smyb 4 bit/symb
Chips/Symbol 15 32

PHY Header (6 byte)

Channels

Medium Access Layer 2 (MAC)

Beacon Enabled

Slots: * Contention Access Period (CAP): competetive access with CSMA/CA or ALOHA, collisions possible * Contention Free Period (CFP): slots are asigned to individual devices

References

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