A popular physical layer used in wireless sensor networks is the IEEE 802.15.4 standard, which provides for a single coding scheme with constant data rate regardless of channel properties and noise conditions. This paper proposes and simulates a simple steganography method to embed additional information in 802.15.4 data packets when link quality permits, with a modest increase in signal to noise ratio (SNR) required for the same error performance of the underlying 802.15.4 communication. By

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... anding the code set to include a cluster of 31 ancillary codes for each original 802.15.4 code word, 5 bits can be steganographically overlaid on each 4 bit legacy symbol, allowing this additional data to be transmitted without the knowledge of legacy 802.15.4 receivers over links of greater than 1.95 dB SNR. Increasing the information content by 3.5 dB in this manner can lower the overall energy per bit to noise ratio by 0.1 dB.