Doris Bao

A Histogram-Based Segmentation Method for Wideband Spectrum Sensing in Cognitive Radios

This paper presents a new method for automatic radio spectrum segmentation. Spectrum segmentation serves as a first step to identify the subbands that are in use at a certain time, when a wide portion of the spectrum is observed. The proposed method, based on the evaluation of the histogram of the power spectral density of the received signal, is designed for obtaining a low processing complexity and to be implemented in a measurement instrument or a cognitive radio receiver. The proposed method is validated on emulated signals, and the results show good accuracy of the subband boundary estimation and a processing complexity much lower than the other segmentation methods.

Spectrum segmentation for wideband sensing of radio signals

Spectrum sensing is a key factor for either the development of Cognitive Radio or the implementation of instruments able to automatically monitor the radio spectrum. Within the process of spectrum sensing, segmentation aims to detect the boundaries of the transmission channels in a wide frequency range. The paper proposes a new spectrum segmentation method characterized by low processing time. The developed histogram-based method is described in the paper. Several experimental tests on emulated and actual signals are presented to prove the effectiveness of the method in terms of success percentage, processing time.

Session Initiation Protocol Automatic Debugger

This paper aims to propose a session initiation protocol (SIP) automatic debugger tool. It is a software instrument that will be used to verify the compliance of voice over Internet protocol (VoIP) devices, such as soft phones and VoIP gateways to the SIP specifications, and to test the interoperability of VoIP equipment produced by different manufacturers. Different tools are available on the market to conduct a compliance and interoperability validation phase. However, they often have features limited to packet capturing and decoding, or they are simulation tools that often require a complex developing phase to define the behavior of each test. The proposed tool, instead, can be inserted into an SIP network and is capable of observing and analyzing, in an automatic way, the communication steps. It operates by executing three subsequent phases. In the first phase, the SIP messages flowing in the network are captured. Then, a second phase is in charge of grouping SIP messages into transactions and dialog. Finally, a third phase operates by comparing the message flow with a set of predefined rules. Rules have been classified in two groups. Rules belonging to the first group, called static rules, have been obtained by the direct analysis of SIP specifications. Rules belonging to the second group, called dynamic rules, have been obtained by experience with SIP compliance and interoperability testing (with the support of SIP testing experts). When verification of some rules fails, an output is reported by indicating the rule that failed and a list of possible fault causes. The tool has been validated in a laboratory network in different scenarios. Some sample test cases, which have been extracted by these scenarios and show the capability of the SIP automatic debugger tool in finding compliance and interoperability faults, are also presented in this paper.

Subspace-based joint multiband detection for wideband spectrum sensing

The paper presents a new method for the simultaneous detection of signals occupying separate portions of an observed wide frequency band. The method is based on the subspace decomposition of the covariance matrix of the observed signal. The proposed method does not rely on the knowledge of the noise power and gives good results in terms of correct detections and false alarm rate, even for low SNR values.