Sung Hyun Hwang

First Cognitive Radio Networking Standard for Personal/Portable Devices in TV White Spaces

Recent FCC rules allowing unlicensed use on a secondary basis of the Television White Spaces (TVWS) promise a whole new set of possible applications. The first step towards realizing these applications is the creation and adoption of industry standards. In this paper we present the first such standard for personal/portable devices in the TVWS that complies fully with the existing FCC rules while retaining flexibility for use with other regulatory domains. We describe the physical (PHY) and medium access control (MAC) layers specified in the standard and present performance results to demonstrate the robustness and spectral efficiency of the proposed protocols.

Design and Verification of IEEE 802.22 WRAN Physical Layer

This paper describes the design and verification of IEEE 802.22 WRAN physical layer. The WRAN physical layer is fundamentally based on the IEEE 802.16e system, but the OFDMA parameters including preamble structure and pilot pattern are newly designed by considering the WRAN channel environments. In this paper, we present the simulation models and results by using appropriate synchronization and channel estimation algorithms. From the results of those simulations, we can obtain 90% preamble detection probability at SNR more than -5 dB, and we can synchronize the CPE to the BS within 2 % of sub-carrier spacing at SNR more than about 1 dB. Moreover, by using the LMMSE algorithm to estimate the channel, we can reduce the performance degradation of 0.2~0.5 dB compared to ideal channel estimation. In conclusion, we have found that the proposed receiver meets the functional requirement document (FRD) for WRAN physical layer.

An Adaptive OFDMA Platform for IEEE 802.22 Based on Cognitive Radio

CR is the key technology that will enable flexible, efficient and reliable spectrum use by adapting the radios characteristics to the real-time conditions of the environment. In this paper, an adaptive OFDMA platform is presented to satisfy the requirements of IEEE 802.22, the first standard based on the CR. In the system, two channel types are supported to apply different AMC methods according to user channel environments. Simulation results are also provided to find a better way in constructing diversity subchannels when AMC is performed with average SNR over the whole subcarriers

Time-domain signal combining with cyclic delay and phase shift for PAPR reduction in OFDM systems

For orthogonal frequency division multiplexing (OFDM), we propose a new peak-to-average power ratio (PAPR) reduction scheme with low complexity based on time domain signal combining. The proposed scheme superposes an OFDM signal and its phase shifted cyclic delay signal to generate a signal candidate with lower PAPR. It is shown that the proposed scheme provides PAPR performance performance comparable to the conventional schemes for with lower complexity.

A novel low power WLAN operation scheme for multiple wake-up receivers

In this paper, a novel low power Wireless Local Area Network (WLAN) operation scheme for multiple low power receivers is proposed. Recently, substantial amount of Internet of Things (IoT) devices are used for various applications, and their delay and energy consumption requirements vary depending on their applications. Therefore, the tradeoff between power saving and delay should be carefully considered when power saving scheme is designed for different traffic patterns. In this paper, an efficient low power operation scheme of many low power devices with options to meet the requirements of power consumption and delay.

A Pragmatic PAPR Reduction Scheme for Multiple Antenna OFDM with Frequency Switched Transmit Diversity

This paper provides a low-complexity scheme for peak-to-average power ratio (PAPR) reduction without side information for frequency switched transmit diversity orthogonal frequency division multiplexing (FSTD-OFDM). The proposed scheme generates multiple signal candidates (SCs) by dividing parallel data symbols into subparts and mapping the subparts onto the antennas under a criterion reducing the correlation between the SCs to select one SC with minimum PAPR. The proposed scheme is shown to provide reasonably good PAPR performance at a lower complexity than the conventional schemes. In addition, the proposed scheme can detect the transmitted SC via energy detection without side information.