Hiding Data in OFDM Symbols of IEEE 802.11 Networks

This paper presents a new steganographic method called WiPad (Wireless Padding). It is based on the insertion of hidden data into the padding of frames at the physical layer of WLANs (Wireless Local Area Networks). A performance analysis based on a Markov model, previously introduced and validated by the authors in [10], is provided for the method in relation to the IEEE 802.11 a/g standards. Its results prove that maximum steganographic bandwidth for WiPad is as high as 1.1 Mbit/s for data frames and 0.44 Mbit/s for acknowledgment (ACK) frames. To the authors' best knowledge this is the most capacious of all the known steganographic network channels.Comment: 6 pages, 8 figures, 1 tabl

Performance Evaluation of IEEE 802.11 DCF Networks

Abstract. The paper presents a new analytical saturation throughput model of IEEE 802.11 DCF (Distributed Coordination Function) with basic access in adhoc mode. The model takes into account freezing of the backoff timer when a station senses a busy channel. It is shown that taking into account this feature of DCF is important in modeling saturation throughput – yields more accurate results than models known from literature. The proposed analytical model also takes into account the effect of transmission errors. Keywords: WLAN, IEEE 802.11, DCF, CSMA/CA, modelin