To address the challenges of reliable and efficient short-packet communication in the Internet of Things (IoT), especially under ultra-reliable low-latency communication (URLLC) constraints, this work optimizes the design of short polar codes tailored for low-power IoT devices. To improve the reliability of short polar codes under successive cancellation list (SCL) decoders, we introduce a novel heuristic optimization algorithm guided by a unified metric. This algorithm carefully balances the tradeoff between the number of minimum-weight codewords (a.k.aerror coefficient) and the reliability of selected information subchannels. Through a guided and deliberate disruption of the partial order property of polar codes, our algorithm reduces the error coefficient to enhance maximum likelihood (ML) decoding performance, while managing the impact on subchannel reliability. Numerical results demonstrate a consistent and significant improvement over the baseline RM-Polar and Gaussian Approximation (GA) constructions across various code parameters. Furthermore, our approach features low offline design complexity, achieving state-of-the-art or highly competitive performance against other advanced schemes, particularly at low code rates. This makes our method highly suitable for URLLC, as the resulting optimized codes can be deployed on existing 5G hardware with zero additional on-device decoding complexity, while the achievable coding gain directly translates into transmission energy savings.

Motivated by the vision of establishing the moon as a deep space internet gateway for human exploration of the universe, we focus on the design of a lunar communication and navigation integrated (CNI) satellite constellation. We first introduce the fibonacci lattice virtual observation point (VOP) model with better uniform and stochastic distribution properties. Based on this, we derive objectives related to coverage, power, quadruple overlap, and geometric dilution of precision combined with earth-moon difference analysis, along with multiple multi-objective optimization problems (MOPs). The solution incorporates the pareto model, non-dominated sorting genetic algorithm-II (NSGA-II), and constellation system construction. Inspired by the lunar frozen orbit, a constellation configuration called hybrid inclination (HyInc) Walker is proposed and theoretically analyzed. Extensive simulation results are shown, including the revelation of the advantages of the HyInc Walker configuration and its coverage equalization capability. The design of this first lunar integrated constellation and the proposed HyInc Walker configuration is of founding significance and highly migratory.

In this paper, we first introduce an efficient method for estimating weight distributions of polar codes and polarization-adjusted convolutional (PAC) codes. Based on a recursive algorithm of computing the weight enumerating functions of polar cosets, this method focuses on two key objectives: accurately determining the number of low-weight codewords and quickly approximating the distribution of high-weight codewords. Then we optimize the Reed Muller-Gaussian Approximation (RM-GA) rate profiling scheme with the help of the proposed method aiming at reducing the truncated union bound (TUB). Simulation results demonstrate that the proposed hybrid method maintains competitively low complexity while effectively achieving the objectives. The TUB-improved RM-GA rate profiling scheme for polar codes exhibits a performance improvement of nearly 1 dB at 10–4compared to GA and around 0.3 dB improvement compared to RM-GA. The proposed scheme for PAC codes also achieves an enhancement of approximately 0.52 dB at 10–5compared to the commonly used RM-GA scheme.

Age of information (AoI) defines the freshness of status update in real-time systems, such as the Industrial Internet of Things (IIoT), and can be affected by delays and transmission error probability. To improve the reliability of data transmissions, the recent AoI works on physical layer considered applying practical coding schemes. Since polar codes can be strictly proved to achieve the channel capacity, this article makes an effort to comprehensively investigate and optimize the AoI performance in a polar-coded status update system. First, we propose a practical code-based status update system that takes full consideration of encoding, transmission, propagation, decoding, and feedback delays in AoI analysis. Then, we analyze and derive the average AoI of the proposed system with various transmission protocols. The simulation results of a polar-coded system validate the theoretical analysis and show that hybrid automatic repeat request (HARQ) achieves better AoI performance than non-HARQ. To optimize AoI in polar-coded status update system, we further improve the designs for HARQ with chase combining (HARQ-CC) and HARQ with incremental redundancy (HARQ-IR), respectively. The design signal-to-noise ratio (SNR), puncturing length of HARQ-CC are optimized by traversal, while the code lengths for each transmission and maximum transmission times of HARQ-IR are optimized by the greedy algorithm. Simulation results show that the proposed HARQ can achieve better average AoI performance than traditional HARQ.

Deep space communication systems play a key role in human endeavors for lunar basing, Mars, and further cosmic exploration. In pursuit of establishing the Moon as a deep space Internet portal for future human exploration, a lunar communication and navigation integrated (CNI) satellite constellation design is intended into consideration. Based on Fibonacci lattice virtual observation point model, featuring better uniformity and stochasticity, we derive objectives related to access coverage, power, quadruple coverage, and geometric dilution of precision (GDOP), together with multiple multi-objective optimization problems (MOPs) combined with Earth-Moon difference analysis to explore better utilization of overall resources in the lunar integrated constellation. The pareto model, non-dominated sorting genetic algorithm-II (NSGA-II), and the construction of the constellation system are incorporated into the solution to pursue a higher guiding value. In particular, inspired by the lunar frozen orbit (LFO), the hybrid inclination (HyInc) Walker configuration is proposed with theoretical validation and simulation evaluation, showing some superiority over traditional Walker and remains generalizable. Extensive simulation and comprehensive analysis are performed, including the pareto-optimal integrated constellations and the revelation of HyInc Walker’s coverage equalization capability, with the latter being less studied. The entire constellation design process of this work is highly migratory and the proposed perspective of the configuration is enlightening.

Energy efficiency and information freshness are two fundamentally critical performance metrics in real-time status update systems which can be measured by energy cost (EC) and age of information (AoI), respectively. This paper examines the AoI and EC performance of the hybrid automatic repeat request with incremental redundancy (HARQ-IR) scheme in code-based status update systems and presents unified results that can generally depict the average AoI and EC over block fading channels. First, we propose a practical code-based status update system that fully takes into account the impact of information processing and long-distance transmission in performance analysis. Then, we analyze and derive the average AoI/EC expressions for HARQ-IR scheme, which are unified results over block fading channels. The simulations of different transmission protocols validate our explicit results and show that there is a distance threshold on whether to retransmit the failed updates. Based on the simulation results, it appears that system AoI/EC demand will affect distance threshold values, which provide guidance for future designs of age-energy tradeoff transmission schemes.