With the surge of Internet of Things (IoT) applications using unmanned aerial vehicles (UAVs), there is a huge demand for an excellent complexity/power efficiency trade-off and channel fading resistance at the physical layer. In this paper, we consider the blind equalization of short-continuous-phase-modulated (CPM) burst for UAV-aided IoT. To solve the problems of the high complexity and poor convergence of short-burst CPM blind equalization, a novel turbo blind equalization algorithm is proposed based on establishing a new expectation–maximization Viterbi (EMV) algorithm and turbo scheme. Firstly, a low complexity blind equalization algorithm is obtained by applying the soft-output Lazy Viterbi algorithm within the EM algorithm iteration. Furthermore, a set of initializers that achieves a high global convergence probability is designed by the blind channel-acquisition (BCA) method. Meanwhile, a soft information iterative process is used to improve the system performance. Finally, the convergence, bit error rate, and real-time performance of iterative detection can be further improved effectively by using improved exchange methods of extrinsic information and the stopping criterion. The analysis and simulation results show that the proposed algorithm achieves a good blind equalization performance and low complexity.

With the standardization and commercialization of 5G, research on 6G technology has begun. In this paper, a new low-complexity soft-input–soft-output (SISO) adaptive detection algorithm for short CPM bursts is proposed for low-power, massive Internet of Things (IoT) connectivity in 6G. First, a time-invariant trellis is constructed on the basis of truncation in order to reduce the number of states. Then, adaptive channel estimators, recursive least squares (RLS), or least mean squares (LMS), are assigned to each hypothetical sequence by using the recursive structure of the trellis, and per-survivor processing (PSP) is used to improve the quality of channel estimation and reduce the number of searching paths. Then, the RLS adaptive symbol detector (RLS-ASD) and LMS adaptive symbol detector (LMS-ASD) could be acquired. Compared to using a least-squares estimator, the RLS-ASD avoids matrix inversion for the computation of branch metrics, while the LMS-ASD further reduces the steps in the RLS-ASD at the cost of performance. Lastly, a soft information iteration process is used to further improve performance via turbo equalization. Simulation results and analysis show that the RLS-ASD improves performance by about 1 dB compared to the state-of-the-art approach in time-variant environments while keeping a similar complexity. In addition, the LMS-ASD could further significantly reduce complexity with a power loss of approximately 1 dB. Thus, a flexible choice of detectors can achieve a trade-off of performance and complexity.

In this paper, a MVDR-beamformer-based anti-jamming scheme by using covariance matrix reconstruction (CMR) is proposed only with little prior knowledge. First, the lacking prior knowledge is divided into two parts, including steering vector and covariance matrix, where the former is acquired by adopting sliding window in Capon spatial spectrum and the latter is extracted by integrating over angular sectors complementary to sliding window. Then, we develop two efficient approximate methods to reduce the complexity. In proposed-1 methods, the Gauss-Legendre quadrature (GLQ) is used to simply the integral operation. Furthermore, the proposed-2 method employs the iterative conjugate gradient to avoid the explicit inversion of the matrix by updating the beam vectors with iterative techniques. Finally, simulation results show that the proposed beamformer can achieve good performance only with little prior konwledge, which can further attain a flexible tradeoff between complexity and performance by using approximate methods..

This article investigates a problem involving the collection of data from sensor nodes (SNs) with heterogeneous information aging speed (IAS) by an unmanned aerial vehicle (UAV) in a dense obstacle environment. The objective is to minimize the average age of information (AoI) of the SNs through UAV path planning. The problem is challenging due to the tight coupling of obstacle avoidance, information timeliness, and the heterogeneity of SNs. Directly solving this path planning problem is difficult, and the conventional approach involves planning the access sequence without considering obstacle avoidance and then optimizing the UAV trajectory while incorporating safety constraints. However, optimizing the trajectory for safe flight introduces changes in the flight time cost, resulting in the average AoI not reaching its minimum value. To address this, a UAV safe flight network is first established by generating trajectories using a combination of A*‐based and successive convex approximation (SCA)‐based algorithms. Subsequently, a genetic algorithm (GA)‐based method is employed and compared with the time greedy strategy. The numerical results demonstrate that the time greedy strategy, which aligns with intuitive understanding, can achieve a smaller total UAV flight time, while the proposed method effectively minimizes the average AoI of SNs.