Sang-hyun Woo

Combined effects of RF impairments in the future IEEE 802. 11n WLAN systems

In this paper, the overall performance degradation of an IEEE 802.11n WLAN system due to MIMO RF interference, AM-AM distortion of power amplifier, IQ mismatches, phase noise and their combined effects in transmitter are investigated. To extract more relevant values of RF impairments, we observed constellation diagram and the error vector magnitude (EVM) of the complete RF/modem link as a figure of merit. In addition, we propose the novel and first method for the model of the MIMO RF interference from the neighboring RF chains. We also study the implication of its presence on the performance when coupled with other RF impairments. By analyzing the experimental results, the range of values for MIMO interference, PA backoff, gain/phase error, and phase noise can be determined over which a IEEE 802.11n WLAN transmitter operates while maintaining a tolerable level of performance.

Effects of RF impairments in transmitter for the future beyond-3G communications systems

In this paper, the performance degradation of a MIMO OFDM-based beyond-3G system, due to various impairments in the radio frequency (RF) circuitry such as AM-AM distortion of power amplifier (PA), in-phase/quadrature-phase (IQ) mismatch effects, is investigated. In order to accurately assess the overall effects of RF impairments on the system performance, constellation diagram and power spectral density (PSD) of the waveform as well as the traditional quantitative figures of merits like error vector magnitude (EVM) of the complete baseband/RF link are used. By analyzing the experimental results, the specification for the RF impairments that ensures a tolerable level of performance can be determined