The IEEE 802.15
.4a model is a generic channel model using log-distance path gain, and a modified Saleh-Valenzuela model for multipath effects.
 IEEE Standard for Local and metropolitan area networks--Part 15.4: Low-Rate Wireless Personal Area Networks (LR-WPANs) Amendment 1: MAC sublayer, IEEE Std 802.15
.4e-2012 (Amendment to IEEE Std 802.15
.4-2011), (2011) 1-225.
Considering the communications stack illustrated in Figures 2 and 3, we start by noting that encryption can be enabled at either the physical and data-link layers, for communications in the WSN domain using IEEE 802.15
.4 symmetric encryption, or on the other hand with DTLS or IPSec at higher layers of the communications stack.
The interaction between sub-bands is ensured by a Time Frequency Code (TFC) allowing the hopping process where more details are given in .The UWB channel model follow IEEE 802.15
.3a standard  where we distinguish four channel models namely CM1, CM2, CM3 and CM4 which differs by various features.
Most of the communication in WSN is based on the IEEE 802.15
.4 standard (discussed in Section 7.3).
WLAN and IEEE 802.15
.4 WPAN using NS-2", International Journal of Computer Applications, Vol.
There are competitors to ZigBee that do not necessarily follow the IEEE 802.15
With its patented technologies, the company leads the way in next-generation wireless solutions designed for the multibillion dollar WLAN 802.11b/g/a/n/ac, MIMO, IoT / M2M, 802.15
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There are mainly two standard schemes of UWB formulated by IEEE 802.15
.3a, that is, the multiband-based orthogonal frequency division multiplexing (MB-OFDM) and impulse-radio-based direct sequence UWB (DS-UWB) .
ZigBee is based on the 802.15
specification of the Institute of Electrical and Electronics Engineers Standards Association.
Some deployments take advantage of IEEE 802.15
.4g Smart Utility Networks or EN 13757 M-Bus.