Laboratory Experiment of Blind Adaptive Array with Subcarrier Transmission Power Assignment in Spectrum Superposing Scenarios

Abstract

This paper experimentally validates the basic feasibility of our proposed blind adaptive array (BAA) with subcarrier transmission power assignment (STPA) scheme using a prototype. The proposed STPA-BAA enables spectrum superposing without any channel state information between two different wireless communication systems: employing STPA-BAA to the secondary system, inter-system interference from/to the primary system can be suppressed. Exploiting the characteristics of constant modulus algorithm (CMA) and power inversion (PI), the secondary transmitter provides two levels of power density for each subcarrier: high and low levels. It enables the secondary receiver to suppress interference with almost the same level of the desired signal. It is also effective in reducing interference to the primary receiver that has no interference suppression function. This paper conducts laboratory experiments of spectrum superposition in two multicarrier systems by wired setup. 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.

Operational range increasement for STPA-BAA spectrum superposing using subcarrier modulation adaptation

“…The power of total transmission is controlled so as to equal that of the conventional one. Exploiting such STPA strategy as a priori information, it enables the interference suppression when SIR total is nearly 0 dB and its effectiveness was clarified through computer simulation [2] and experiment [3]. Remaining issue is that operational region provided by STPA-BAA reduces in lower SNR region; non-negligible bit error is caused due to low-level subcarriers.…”

“…This scheme is joint application of blind adaptive array (BAA) and subcarrier transmission power assignment (STPA) as shown in Fig. 1(b) [2,3]. Interference signals are suppressed by BAA and the BAA is not required a priori information.…”

Stabilised blind interference suppression of constant modulus‐based adaptive array over Rayleigh fading channels by initial antenna selection

“…null steering) function. Initialisation using PI weight is effective to precisely extract smaller desired signal thanks to the interference suppression function of subsequent CMA [25]. Another approach is an weight norm control [26] which minimises the output amplitude fluctuation by providing additional constraint.…”