Undesired signal power estimation based on estimated superposed band for multicarrier transmission

Superposed multicarrier transmission scheme is known to improve frequency utilization efficiency where several wireless systems share spectrum. On superposed band, log likelihood ratio (LLR) cannot be set correctly due to interference, which results in BER (Bit Error Rate) degradation. Forward error correction (FEC) metric masking is proposed to suppress the effect of interference. In this technique, LLRs corresponding to superposed band is set to zero, because received bits corresponding to superposed band is unreliable. This scheme requires superposed band detection and does not consider channel estimation error. We proposed an iterative estimation technique for undesired signal power in [6]. Although this scheme does not require superposed detection beforehand, due to the estimation error of undesired signal power, BER is degraded. In this paper, we propose an estimation technique for undesired signal power and superposed band to calculate LLR correctly. This scheme estimates the superposed band within 1 packet and based on the information about the superposed band, undesired signal power is estimated using pilot symbols. Simulation results show that as the number of pilot symbols increases, BER of our proposed scheme becomes better than that of [6] and gets closer to the BER when the estimation of undesired signal power is perfect.