Efficient branch and bound algorithms for prototype filter optimization in OQAM‐OFDM systems

Abstract

In this paper, we address the prototype filter optimization problem in the offset quadrature amplitude modulation-based orthogonal frequency division multiplexing system and propose a series of efficient branch and bound (BB)-based methods to greatly reduce the convergence time of the optimization problem. Specifically, we first propose a constraint judge method to determine whether a subset has the possibility to obtain a feasible solution and remove the subsets that have no feasible solutions. Then, we propose a searching strategy to further decrease the number of iterations. Moreover, we propose an efficient convex relaxation method to reduce the calculation time of each iteration. Simulation results show that the proposed methods can guarantee the same global optimal solution as generated by the conventional˛-based BB (˛BB) algorithm, and the BB algorithm combining the three proposed methods achieves much lower convergence time.KEY WORDS: offset quadrature amplitude modulation-based orthogonal frequency division multiplexing (OQAM-OFDM); prototype filter; branch and bound; OFDM

A prototype filter design based on channel estimation for OQAM/OFDM systems

“…To avoid these disadvantages, the Box-BB algorithm [7] is proposed. The Box-BB algorithm to solve optimization problem P2 is as follows.…”

“…The box-based branch and bound (Box-BB) method can solve this problem. Wu et al proposed this method to decrease the number of iterations [7]. The method converged quickly and obtained the global optimum.…”

Prototype filter design for FBMC systems via evolutionary PSO algorithm in highly doubly dispersive channels

“…f / that maximise the utility function must be derived. The same as (21) and (23) optimisation problem can be written for Figure 2(c). In order to design the prototype filter by using the numerical methods, we reformulate the proposed design procedure based on the samples of h.t/.…”

“…Hence, the maximal bandwidth efficiency is achieved. However, the prototype filters implied in the OQAM/OFDM scheme, such as the root square Nyquist filter [19], the isotropic orthogonal transform algorithm (IOTA) filter [20] and the proposed method in [21] cannot satisfy the orthogonality condition for the proposed time-frequency constellation in here. In [22], the prototype filter is designed based on the knowing of the channel scattering function in transmitter and receiver.…”

Prototype Filter Design Based on Channel Estimation for FBMC/OQAM Systems

“…In order to reduce the computational complexity, the α-based branch and bound (αBB) algorithm is used to design the prototype filter in [10]. In [11], the box-based branch and bound (Box-BB) method based on αBB algorithm is proposed to decrease the number of iterations. Spectral factorization is employed to design the final prototype filter in [12], but this method is unstable because the factor is chosen randomly.…”