Short-range wireless technologies are known to transmit voice, audio, image, and video messages in real time. Energy consumption\nand transmission reach are critical in such networks, especially for portable and power autonomous devices. The\npurpose of the Voice over Zigbee technology is to provide a competitive offering that excels in these performance aspects. Due to\nthe CSMA-CA mechanism implemented in the 802.15.4 layer, a well-designed strategy must be considered in Zigbee to create a\nrobust, reliable, and full-duplex conversation. In past efforts, we proved that the radio channel of Zigbee has enough bandwidth to\nsupport a full-duplex conversation with narrow-band voice codecs. Our embedded implementation of the Speex voice codec\ntargeted the development of a low-cost, ultralow-power, long-range wireless headset using Zigbee technology to transmit voice in\nfull-duplex mode for use with leading PC VoIP programs. Furthermore, we presented the real environment performance\nevaluation and power consumption tests involving the developed headset prototype. Talk time is comparable to Bluetooth\nincluding at the power budget, the codec processing, and analogue audio interface, but its deep-sleep lifetime more than doubles\nthe Bluetooth performance. This was one of the very few successful efforts to port a voice codec on an ultralow-power DSP for use\nwith power sensitive Zigbee applications, which is highly cited in the literature, proving additionally that using an open-source\ncodec can deliver similar voice quality, reducing the total system cost.Thecurrent paper elaborates on the embedded parallelism of\nthe Speex implementation and the exploitation of the DSP architectural parallelism which critically enabled the Voice over Zigbee\napplication on the ultralow-power DSP platform. Another significant contribution of this work is towards understanding and\nresolving the challenges faced when trying to achieve good quality transmission of media over constrained devices and networks.\nThe way to new ultralow-power voice-related Zigbee and constrained network applications is open.
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