A sub-space method to detect multiple wireless microphone signals in TV band white space

Abstract

The main hurdle in the realization of dynamic spectrum access systems from the physical layer perspective is the reliable sensing of low power licensed users. One such scenario shows up in the unlicensed use of the TV bands where the TV band devices are required to sense extremely low power wireless microphones (WMs). The lack of technical standards among various wireless manufacturers and the resemblance of certain WM signals to narrow-band interference signals, such as spurious emissions, further aggravate the problem. Due to these uncertainties, it is extremely difficult to abstract the features of WM signals and hence develop robust sensing algorithms. To partly counter these challenges, we develop a two-stage sub-space algorithm that detects multiple narrow-band analog frequency-modulated signals generated by WMs.The performance of the algorithm is verified by using the real WM signals experimentally captured under low SNR conditions. The problem of differentiating between the WM and other narrow-band signals is left as future work.

Detecting Multi-ChannelWireless Microphone User Emulation Attacks in White Space with Noise

“…We use the terms "wireless channel" and "acoustic channel" to represent the channels experienced by RF signal and sound, respectively. All SNR's in this work are measured over the effective bandwidth of a FM signal which is at the level of 50 KHz, while those in some other works are measured over the entire 6MHz TV band [3,8,20]. The -3 dB SNR in this work is equivalent to -23.4 dB in those works, and is close to the limitation of those FM signal detection schemes.…”

“…We assume that the power of s m (t) is above the noise floor at each WSD in all scenarios, so that f m can be estimated by the WSD [8]. Since f m can only be a multiple of 25 kHz [10], the WSD is able to adjust its estimates on f m according to this rule.…”

“…WSDs perform spectrum sensing on white space to avoid collisions to the signals from PUs (incumbent signals), mainly including TV signals and wireless microphone (WM) signals. Many spectrum sensing techniques are proposed to detect these two types of incumbent signals [3,8,12,16,20]. When PUs emerge, SUs are required to evacuate from the spectrum in order to avoid interference to PUs.…”

Detecting multi-channel wireless microphone user emulation attacks in white space with noise

“…These three scenarios are illustrated in figure 1. We assume that the power of s m (t) is above the noise floor at each WSD in all scenarios, so that f m for m = 1, ..., M can be estimated by the WSD [11]. Since f m can only be a multiple of 25 kHz [12], the WSD is able to adjust its estimates on f m according to this rule.…”

Energy Detection Technique for Spectrum Sensing in Cognitive Radio: A Survey

“…To achieve its aims, the 802.22 standard utilizes CR technology to ensure that no undue interference is caused to television services using the television bands. The standard is under development and is currently in draft form [31], [32].…”