Automatic modulation recognition is not only an important military subject but also an emerging topic for next generation software-defined radios. This paper reviews the concept of blind modulation classification algorithms, discusses the similarity and diversity of various approaches, indicates difference for military and commercial applications, and analyzes the automatic modulation recognition methods based on software-defined radios.

Dual-use of modulation recognition techniques for digital communication signals

In this paper, the reconstruction of the feedback polynomial as well as the initial state of a linear feedback shift register (LFSR) in a synchronous scrambler placed after a channel encoder is studied. The study is first based on the assumption that the channel is noiseless and then extended to the noisy channel condition. The dual words, which are orthogonal to the codewords generated by the channel encoder, are used in the reconstruction algorithm. The number of bits required by the new algorithm is compared with another recently proposed algorithm and results show that the number of bits required to do the reconstruction can be significantly reduced.

A Study on Reconstruction of Linear Scrambler Using Dual Words of Channel Encoder

This paper describes how cognitive radio (CR) could benefit from software-defined radio (SDR) compatible ultra-wide band (UWB) systems. It introduces the notion of umbilical cord that can keep a CR device connected to its surrounding world, thanks to sensing and low speed over-the-air reconfiguration (OTAR) means provided by low-data rate (LDR) systems, and to fast OTAR downloading facilities based on high-data rate (HDR) hot spots. A particular UWB architecture supporting SDR-compatible technological constraints is proposed as candidate to realize this promising combination of capabilities

/pdf/an-ultra-wide-band-umbilical-cord-for-cognitive-radio-16ef1k8vif.pdf

An ultra-wide band umbilical cord for cognitive radio systems

Blind identification of the feedback polynomial in a linear scrambler is an important component in the wireless communication systems which have the function of automatic standard recognition and parameter estimation. The following research contains three parts. In the first part, promotion model is deduced based on Cluzeau's model. Comparative analysis shows the advantage of computational complexity by use of the promotion model. In the second part, the improved method of estimation for the normalised standard deviation is proposed, which plays an important role for the computation time and precision. In the final part, simulation results explain the better practical application of my algorithm compared with Cluzeau's algorithm and XiaoBei-Liu's algorithm.

https://ietresearch.onlinelibrary.wiley.com/doi/pdf/10.1049/iet-com.2014.0109

Reconstructing the feedback polynomial of a linear scrambler with the method of hypothesis testing

The existing algorithm for reconstruction of the feedback polynomial in a linear scrambler relies on the assumption that the input sequence is produced by a biased memoryless source and the source bias is known and used for reconstruction. In this paper, the problem of reconstruction of the feedback polynomial in a linear scrambler without knowledge of the source bias is studied. An algorithm is proposed to reconstruct the scrambler without knowledge of the source bias and factors which affect the performance of this algorithm are discussed. A scheme which reduces the number of bits used in the reconstruction without affecting the detection capability of the reconstruction algorithm is also proposed in this paper.

Investigation on Scrambler Reconstruction with Minimum A Priori Knowledge

We developed an identification algorithm that can distinguish twelve kinds of modulation modes using a blind process aimed at automatic identification of unknown modulated signals. We also developed an adaptive receiver, installed this algorithm, and we carried out an experiment to evaluate the receiver's ability. By the result of the validation experiment, for linear digital modulation modes with S/N /spl ges/ 3 dB, for GMSK of nonlinear digital modulation modes with S/N /spl ges/ 18 dB, and for the FM of analog modulation modes with S/N /spl ges/ 12 dB, we got a performance of identification probability of over 90 % respectively. Furthermore, based on the identification results, we evaluated the adaptive demodulation process by using the developed system and confirmed its effectiveness.

H. Fujishima

Papers

An adaptive receiver based on software defined radio techniques