Experimental Verification of Spectrum Superposing in Two Different Systems by Blind Adaptive Array with Subcarrier Transmission Power Assignment

We previously proposed blind adaptive array (BAA) with subcarrier transmission power assignment (STPA) that enables spectrum superposing without any channel state information. This paper experimentally validates the basic feasibility of the proposed scheme using fabricated prototype; interference suppression performance of the proposed system with STPA-BAA and its interference reduction performance to the conventional system. Exploiting characteristics of constant modulus algorithm (CMA) and power inversion (PI), the transmitter of the proposed system provides two levels of power density for each subcarrier: high and low level. The receiver then uses CMA or PI to appropriately suppress interference on each subcarrier. Low-level subcarrier by the proposed system is also effective in reducing interference to the conventional system which has no interference suppression function. This paper conducts indoor experiments by wired setup of spectrum superposition in two multicarrier systems. Though the practical performance of STPA-BAA is limited due to the quantization level or dynamic range of the transceiver, effectiveness of the proposed scheme is confirmed. Improved operational SIR range of the proposed and the conventional system are presented.