Direct Sequence Spread Spectrum Steganographic Scheme for IEEE 802.15.4
  This work addresses the issues related to network steganography in IEEE 802.15.4 Wireless Personal Area Networks (WPAN). The proposed communication scheme employs illicit Direct Sequence Spread Spectrum code sequences for the transmission of steganographic data. The presented approach is a compromise between minimising the probability of covert channel disclosure and providing robustness against random errors and a high steganographic data rate. The conducted analyses show that it is possible to create a covert channel with a data rate comparable to the raw data rate of IEEE 802.15.4 without much impact on the perceived receiver sensitivity, the Chip Error Rate and the Bit Error Rate. 
Elzbieta Zielinska, Krzysztof Szczypiorski
cs.CR