# Intrinsic Interference Cancellation Scheme for FBMC-OQAM Systems Based on Power Multiplexing
## 1 Introduction
The auxiliary pilot (AP) method was put forward based on the scattered-pilot structure, and it inserted an auxiliary pilot at the location around the pilot symbol to eliminate intrinsic interference completely at the transmitter [17]. However, it is infeasibly greedy for power because the average power overhead of the auxiliary pilot is twice the average power of the data symbol. Another method with a low power cost adopts linear coding means, but intrinsic interference has notable residuals because the coding length cannot be too long [18]. The coded auxiliary pilot (CAP) method can be combined with the AP method and the linear coding method to completely eliminate intrinsic interference with a low power overhead, but it still needs auxiliary pilots [19]. Recently, a method named \"frame repetition\" eliminated intrinsic interference based on frame repetition, in which QAM symbols are transmitted instead of OQAM symbols [20; 21]. It only needed two columns of symbols as the pilot overhead compared with the IAM method, but the frame repetition led to increased sensitivity to the channel coherence time. In summary, these methods put an interference cancellation scheme at the transmitter and thus brought the receiver signal recovery a good condition. However, these methods all eliminate intrinsic interference by sacrificing data symbols named \"auxiliary pilots\", resulting in a non-negligible decrease in spectral efficiency, especially in severe channel conditions, which need a high density of pilots. Some other methods need no auxiliary pilot but utilized iterations, but they all have an infeasible computation complexity. This article proposes a new intrinsic interference cancellation method in the FBMC system without iterations or sacrificing data symbols. In the transmitter, data symbols around pilot symbols are first coded by the power multiplexing matrix, and then, the conventional CAP method is adopted to cancel intrinsic interference completely and to sacrifice a few data symbols. In contrast, these sacrificed data symbols are recovered by our successive interference cancellation scheme in the receiver, which contributes to a higher data rate. The simulation results show that the proposed method has a higher spectral efficiency and similar power efficiency compared with the CAP method, without a notable decrease in BER performance. The rest of this paper is organized as follows. Section 2 introduces the intrinsic interference of FBMC and the traditional CAP method. In Section 3, the proposed method is explained in detail. Finally, the simulation results and conclusions are given in Sections 4 and 5, respectively. The following notations are used in this article. Uppercase and lowercase boldface denote matrices and vectors, respectively. The superscripts \((\cdot)^{T}\) and \((\cdot)^{H}\) stand for the transpose and conjugate transpose, respectively. \(\|\cdot\|\) means the Euclidean norm of a vector. \(\mathbb{E}\{\,\cdot\,\}\) represents the expectation, and \(\Re\{\,\cdot\,\}\) denotes the real parts. \(tr\{\,\cdot\,\}\) is the matrix trace operator, and \(\mathcal{CN}(\,\cdot\,)\) represents the complex Gaussian probability distribution function.