Jongmin Park

A wideband analog multi-resolution spectrum sensing (MRSS) technique for cognitive radio (CR) systems

Spectrum sensing technology is most vital to the implementation of a CR system using dynamic spectrum resource management. This paper suggested a CR system architecture with a wideband dual-stage spectrum sensing technique - a coarse and a fine spectrum sensing. Specifically, the coarse spectrum sensing technique adopted wavelet transforms in this architecture to provide a multi-resolution spectrum sensing (MRSS) feature. Analog implementation of the MRSS block offers wideband, low-power, and real-time operation. From the system simulation results, MRSS achieved 15-, 20-, and 30-dB detection margin for FM, VSB, and OFDM signals, having the corresponding signal power of -110, -120, and -120 dBm, respectively

A Fully Integrated UHF-Band CMOS Receiver With Multi-Resolution Spectrum Sensing (MRSS) Functionality for IEEE 802.22 Cognitive Radio Applications

Fast and accurate spectrum sensing is one of the most important functions in a cognitive radio (CR) seeking to use the licensed but unoccupied spectrum segments. In this paper, we present a fully integrated CMOS receiver with a CR spectrum sensing capability in the UHF band. We propose multi-resolution spectrum sensing (MRSS), which is a digitally-assisted analog energy detection technique. Without using bulky analog filters, detection bandwidth can be flexibly controlled by correlating the received analog signals with window signal generated by built-in digital window generator. The integrated chip has been fabricated in a standard 0.18-mumm CMOS technology, and has achieved 32 dB of detection dynamic range with minimum detection sensitivity of -74 dBm by using a 100-kHz cos4 window.

A Fully-Integrated UHF Receiver with Multi-Resolution Spectrum-Sensing (MRSS) Functionality for IEEE 802.22 Cognitive-Radio Applications

Recently, cognitive radio (CR) technology has been proposed as a way of increasing spectrum utilization efficiency. A CR system seeks to use the unoccupied spectrum segments by sensing the spectrum before transmitting to preserve the rights of privileged primary users (Haykin, 2006). IEEE 802.22 is the working group on wireless regional area network (WRAN) for the license-exempt use of the U.S. TV broadcasting band. Such use requires that new transceivers possess CR functionality. A fully-integrated CMOS receiver is presented with a CR spectrum-sensing functionality of arbitrary detection bandwidth over the UHF band. This capability is called multi-resolution spectrum sensing (MRSS).

WLC05-1: A Cognitive Radio (CR) System Employing A Dual-Stage Spectrum Sensing Technique : A Multi-Resolution Spectrum Sensing (MRSS) and A Temporal Signature Detection (TSD) Technique

Spectrum sensing technology is most vital to the implementation of a CR system using dynamic spectrum resource management. This paper suggested a CR system architecture with a wideband dual-stage spectrum sensing technique - a coarse and a fine spectrum sensing. Specifically, a coarse spectrum sensing technique adopted wavelet transforms in this architecture to provide a multi-resolution spectrum sensing (MRSS) feature. Analog implementation of the MRSS block offers wideband, low-power, and real-time operation. A fine spectrum sensing technique used the beneficial properties of auto-correlation in time domain - temporal signature detection (TSD). This TSD technique enables identifying the unique signature feature of each specific signal type. Moreover, this feature detection technique in time domain realizes simple and fast spectrum-detection compared to spectral feature detection methods.

A Cognitive Radio (CR) Testbed System Employing a Wideband Multi-Resolution Spectrum Sensing (MRSS) Technique

A cognitive radio (CR) access technique is a promising solution for the dynamic spectrum resource usage. This paper presented a CR testbed system employing a wideband multi-resolution spectrum sensing (MRSS) technique. Analog implementation of the MRSS block offers wideband, low-power, and real-time operation. The MRSS experiments were performed using the developed CR testbed system. The experiment results showed that the MRSS technique detected wideband 100-MHz spectrum in a sparse or a precise manner without any increase of hardware burden. Moreover, this MRSS technique detected a variety of sophisticated signal formats adopted in the current and emerging wireless standards - IS-95, WCDMA, GSM, EDGE, Wi-Fi (IEEE802.Ha/b/g), ATSC, DVB, etc.

A 122-mW Low-Power Multiresolution Spectrum-Sensing IC With Self-Deactivated Partial Swing Techniques

A low-power multiresolution spectrum-sensing (LP-MRSS) IC utilizing self-deactivated partial swing techniques is fabricated in 0.18-¿m complementary metal-oxide-CMOS technology. The LP-MRSS is composed of a low-power digital window generator, analog correlators, low-power pipeline analog-to-digital converters, and a fast-sweeping frequency synthesizer. The LP-MRSS dissipates 122 mW at a 1.8-V supply voltage achieving an approximately 33% power reduction over the previous MRSS IC.

A Cross-layer Cognitive Radio Testbed for the Evaluation of Spectrum Sensing Receiver and Interference Analysis

Cognitive radio (CR) technology has been proposed as a promising solution for maximizing the utilization of already-crowded spectrum resources. As new algorithms, circuits and systems are developed for CR technology, it is essential to have a reconfigurable testbed system for their verification. A multistandard, fully software driven, cross-layer CR testbed has been developed to support thorough testing of CR system and custom designed integrated circuits (ICs). This paper presents details of cross-layer CR testbed and three demonstrations of testbed usage; (a) cognitive radio system concept demonstration, (b) multi-resolution spectrum sensing (MRSS) receiver IC evaluation, (c) interference analysis for UWB coexistence with WiMax. With this reconfigurable testbed, a new idea can be easily verified, demonstrated and extended to further research.

Interference Analysis and Sensing Threshold of Detect and Avoid (DAA) for UWB Coexistence with WiMax

Although ultra wideband (UWB) is a promising wireless technology for the future due to its high data rate, low power consumption, and low cost, its worldwide acceptance is conditioned by coexistence issues because of the frequency overlap with other wireless standards such as WiMax. In many countries, a detect and avoid (DAA) scheme has been promoted as a means to mitigate interference and it is now regarded as an indispensable solution for commercialization of UWB. A detailed specification for DAA can be determined by analyzing co-channel interference for a victim receiver. This paper presents a quantitative interference analysis using desired to undesired (D/U) signal power ratio as well as verification results using an equipment-based WiMax testbed. Finally, the D/U ratio results were used to determine minimum keep-out distance and the sensing threshold level for DAA in a UWB device.

Implementation Issues of A Wideband Multi-Resolution Spectrum Sensing (MRSS) Technique for Cognitlve Radio (CR) Systems

Spectrum sensing is a key function for a cognitive radio (CR) system. An analog-based multi-resolution spectrum sensing (MRSS) technique was proposed as a flexible, low-power, high-speed spectrum-sensing solution. In this paper, implementation issues of the MRSS technique are investigated, and the corresponding practical specifications are suggested. First, nonlinear effects from a voltage-controlled oscillator (VCO) and multipliers are explored. System simulation results show that harmonic distortion components of VCO and wavelet-pulse power levels should be controlled to alleviate these nonlinear effects. Afterward, I/Q phase- and gain-mismatch effects ore addressed. Specifically, narrow-band signals are more sensitive to these gain and phase mismatches compared to broadband digital modulated signals. Overall, phase mismatch is more sensitive than gain mismatch on MRSS performance, showing a linear degradation of a detected power-level up to a 60-degree phase-mismatch

Analog integrator and analog-to-digital converter effect on a Multi-Resolution Spectrum Sensing (MRSS) for cognitive radio systems

The proposed multi-resolution spectrum sensing (MRSS) technique is a flexible, low-power, high-speed spectrum-sensing solution for cognitive radio systems. Meanwhile, impairments of analog building blocks may degrade the accuracy of the proposed MRSS performance. In this paper, the effect of non-idealities of an integrator is explored. The dominant pole position is suggested to be less than 20% of the spectrum-sensing resolution- bandwidth. Then, the quantization effect of an analog-to-digital converter (ADC) is addressed when one of a linear amplifier and logarithmic amplifier is present in front of the ADC, respectively. A 7-bit ADC is suggested when a high-dynamic- range logarithmic amplifier is accompanied.