The large-scale deployment of wireless sensor networks is indispensable to the success of Internet of Things. Considering dynamic spectrum access and the limited spectrum resources in cognitive radio sensor networks, sub-Nyquist spectrum sensing based on the modulated wideband converter is introduced. Since the transmission signals are usually modulated by different carrier frequencies, the interested spectrum can be modeled as the multiband signal. Modulated wideband converter (MWC) is an attractive alternative among several sub-Nyquist sampling systems because it has been implemented in practice and the frequency support reconstruction algorithm is the most important part in MWC. However, most existing reconstruction methods require the sparse information, which is difficult to acquire in practical scenarios. In this paper, we propose a blind multiband signal reconstruction method, referred to as the statistics multiple measurement vectors (MMV) iterative algorithm to bypasses the above problem. By exploiting the jointly sparse property of MMV model, the supports can be obtained by statistical analysis for the reconstruction results. Simulation results show that, without the sparse prior, the statistics MMV iterative algorithm can accurately determine the support of the multiband signal in a wide range of signal-to-noise ratio by using various numbers of sampling channels.

Sub-Nyquist Spectrum Sensing Based on Modulated Wideband Converter in Cognitive Radio Sensor Networks

Frequency hopping (FH) communications are widely used in Satcom systems. The latest FH systems have exceeded 3 GHz with hop rates up to 100 000 hops/s. Traditional spectrum sensing systems hardly monitor such signals. Modulated wideband converter (MWC) is an emerging compressive sampling structure applied to sample multiband signals. This article analyses the effects of the nonlinearity of analog devices and proposes an optimization method based on a greedy algorithm for mixing sequences to make reconstruction performance uniform across sub-bands. To correct the errors caused by the nonideality of analog front end circuits between the theoretical sensing matrix and the practical one, we also develop a calibrating method that obtains all the sensing matrix coefficients through a single measurement. In conventional MWC, out-band noise will be blended during reconstruction. Instead of matrix factorization, we reserve signal characters and designed sliding filters to improve narrowband signals reconstruction sensitivities. We produced a four-branch MWC principle prototype for FH signal detection. The sensing bandwidth is 3 GHz, and the sampling rate is 400 MHz, whereas the reconstruction sensitivity is as low as 13-dB in-band signal-to-noise.

Implementation of Mixing Sequence Optimized Modulated Wideband Converter for Ultra-Wideband Frequency Hopping Signals Detection

This paper is devoted to the proposal of a highly efficient symbol synchronization subsystem for Software Defined Radio. The proposed feedback phase-locked loop timing synchronizer is suitable for parallel implementation on an FPGA. The polyphase FIR filter simultaneously performs matched-filtering and arbitrary interpolation between acquired samples. Determination of the proper sampling instant is achieved by selecting a suitable polyphase filterbank using a derived index. This index is determined based on the output either the Zero-Crossing or Gardner Timing Error Detector. The paper will extensively focus on simulation of the proposed synchronization system. On the basis of this simulation, a complete, fully pipelined VHDL description model is created. This model is composed of a fully parallel polyphase filterbank based on distributed arithmetic, timing error detector and interpolation control block. Finally, RTL synthesis on an Altera Cyclone IV FPGA is presented and resource utilization in comparison with a conventional model is analyzed.

/pdf/symbol-synchronization-for-sdr-using-a-polyphase-filterbank-8grlz0gkv7.pdf

Symbol Synchronization for SDR Using a Polyphase Filterbank Based on an FPGA

In this paper, a new method of demodulation of continuous phase binary FSK signal is presented, during FSK demodulation, the FSK signal produces In-phase signal (I(t)) and Quadrature signal (Q(t)). And method of Gardner synchronization is used for bit synchronization. When using Gardner synchronization, some changes must be made so that it is suitable for FSK demodulation. It can resist 7% of frequency deviation. And it gets lower bit error rate than traditional method of coherent demodulation when SNR is the same. What's more, there is only 0.1dB SNR loss, 9.78 dB to 9.88 dB, when the bit error rate is 1e-3 when we compare demodulation with Gardner synchronization to optimal receiver demodulation.

Demodulation of continuous phase 2FSK signal with Gardner synchronization

Software Radio Technology and Applications to Law Enforcement Joseph Mitola ifi The MITRE Corporation, McLean, VA 22102 (jmito1amitre.org) Law enforcement use of radio includes the rapid creation of networks for the dozens of law enforcement organizations whocome together in situations as diverse as the TWA 800 disaster in New York or the SunFest celebration in Palm Beach'. Thesoftware radio is a proven technology for rapidly building such interoperable networks, including seamless bridging acrosssub-networks ofdifferent frequency bands, channel modulations and information formats. In addition, law enforcement mustmanage the costs of related radio base station infrastructure, mobile units and handsets. The software radio is a collection ofengineering techniques for creating radio infrastructure that can be programmed for new standards and that can be dynaini-cally updated with new software personalities even "over the air", reducing the need to purchase new hardware to remaincurrent with emerging radio interface standards. Although relatively expensive today, continuing DoD, federal and commer-cial investment in software radio technology will bring products within the reach of law enforcement applications within thenext few years. The Modular Multifunction Information Transfer Systems (MMITS) Forum provides further impetus for costreductions through the market efficiencies of open architecture. This article summarizes software radio technology and keytrends in the marketplace including the progress of the MMITS forum. Expanded law enforcement participation in this fo-rum would accelerate the availability of low cost products for law enforcement.Keywords: Software radio, multiband, multimode, digital signal processing, MM[TS forum, SPEAKeasy, digital radio

Software radio technology and applications to law enforcement

This paper discusses the mathematical model and implements the physical verification when Carrier synchronization (carrier loop) and Timing synchronization (Gardner algorithm) working simultaneously. Firstly, a brief analysis of the above mentioned systems is completed, and the functional simulation is accomplished by Verilog HDL code on ModelSim platform. In addition, a systematic analysis is done for the workflow and interrelation of Carrier synchronization and Timing synchronization when both of them are active. Finally, we implement the hardware verification on the Stratix series field programmable gate array (FPGA) device EP3SL150F1152C2N of Altera Company, and give the engineering results through the RF part and space transmission.

Synchronization for QDPSK —Costas loop and Gardner algorithm using FPGAs

The modulated wideband converter (MWC) is a recently proposed compressive sampling system to acquire the blind multiband signals, which we can only know the number of bands and their widths. The process of quantization is inevitable in engineer realization. In this paper, we consider the limiting case of 1-bit quantization, which preserves only the sign information of measurements, and a group binary iterative hard thresholding lp method solving multiple measurement vector problems (M-GBIHTlp) was proposed to recover the wideband signals under MWC system. The proposed algorithm utilizes the group sparsity of recovered signal, of which the nonzero locations are piecewise together. Experiments show that the proposed algorithm achieve higher reconstruction probability than the existed simultaneous binary iterative hard thresholding I2 norm (SBIHTI2) algorithm, particularly in low signal to noise ratio (SNR).

Recovery of multiband signals using group binary compressive sensing

Periodically non-uniform sampling (PNS) is considered as an effective approach for multi-band signal sampling. Reconstruction of signal from PNS can be achieved without distortion under the assumption that the signal is perfectly band-limited. However, most signals in practice could not meet such requirement, thus the sampling parameters play an important role on the quality of reconstructed signal. In this paper, an optimization method of sampling parameter is proposed in the presence of non-ideality condition. The optimization method deals with time shifts of each sampling channel at fixed sampling rate and is based on minimizing the 2-norm of coefficients function of the reconstruction filters. Simulation results are provided to demonstrate the effectiveness of the proposed method.

Lingyun Zhou

Papers

Synchronization for QDPSK —Costas loop and Gardner algorithm using FPGAs

Recovery of multiband signals using group binary compressive sensing

Parameter optimization in reconstruction of multiband signal from periodically non-uniform sampling