Takuji Mochizuki

Evaluation on detection capability of down-link signals of mobile WiMAX and 3GPP LTE for detect-and-avoid in UWB systems

The present article describes the experimental result of victim system detection by UWB wireless system to contribute for Japanese UWB regulatory discussion, in which a mitigation, including detect-and-avoid (DAA), technology implementation in the frequency range of 3.4 to 4.8 GHz is a major technical topic. A FPGA based MB-OFDM UWB receiver with 528 MHz sampling rate and 128 points FFT capability was prepared for this purpose and mobile WiMAX and 3GPP LTE were selected as victim systems to be detected. Various baseband victim signals generated by a vector signal generator were detected at various detect conditions and signal-to-noise ratios and time to detection was measured. In this experiment, 99% probability detection was achieved within 2.4 seconds.

Experimental evaluation of avoid performance with various victim systems to enable DAA for UWB

In most Asian and European countries, detect-and-avoid (DAA) is required at UWB low band (3.1–4.8 GHz). In Japan, we conducted evaluation experiments on the performance of DAA until March of 2010, which was a part of a three-year campaign to provide results of literature review and technical evaluation for the purpose of accomplishing Japanese UWB regulation. In this paper, experiment results on the avoid performance are presented. Three types of victim systems, 3GPP LTE, Mobile WiMAX, and an experimental IMT Advanced Test-bed, were used in the experiments. The UWB system was built based on WiMedia specifications at the UWB low band. A notch was created in the UWB spectrum where a victim signal was going to appear. The notch was created by nullifying the related subcarriers in combination with the use of a filter or applying a window function. The interference effects of UWB to victim systems were evaluated by examining the bit error rate (BER) or packet error rate (PER) performance. Our results show that when the width and depth of the notch satisfy certain conditions, the interference level introduced by UWB can be below the permitted level in regulations.