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Cyber-physical systems (CPSs) are characterized by integrating computation and physical processes. To cope with the challenges of the application of the CPSs in all kinds of environments, especially the cellular vehicle-to-everything (C-V2X) which needs high quality end-to-end communication, the robustness and reliability for CPSs are very crucial. Aiming at the technical challenges of information transmission caused by the fading effect and the fast time-varying characteristics of the channel for C-V2X communication, an improved Tomlinson–Harashima precoding (THP) algorithm for multiple input multiple output (MIMO) systems is proposed. Channel state information (CSI) and correlation are exploited to compensate instantaneous CSI, which could reflect current real-time channel status exactly. Further, the iterative water filling power allocation algorithm and the multiuser scheduling algorithm based on the greedy algorithm are jointly optimized and applied to the THP, which could improve the system performance. Simulation results show that the proposed algorithm can be efficiently applied to high-speed mobility scenarios and improve bit error ratio (BER) performance as well as spectrum utilization.

6G vehicle-to-everything (V2X) communication will be combined with vehicle automatic driving technology and play an important role in automatic driving. However, in 6G V2X systems, vehicle users have the characteristics of high-speed movement. Therefore, how to provide stable and reliable wireless link quality and improve channel gain has become a problem that must be solved. To solve this problem, a new multi-user scheduling algorithm based on block diagonalization (BD) precoding for 6G ultra-massive multiple-input multiple-output (MIMO) systems is proposed in this paper. The algorithm takes advantage of the sensitive nature of BD precoding to channel correlation, uses the Pearson coefficient after matrix vectorization to measure the channel correlation between users, defines the scheduling factor to measure the channel quality according to the user noise enhancement factor, and jointly considers the influence of the correlation between user channels and channel quality, ensuring the selection of high-quality channels while minimizing channel correlation. Simulation results show that compared with the multi-user scheduling algorithm based on subspace correlation, condition number, and geometric angle, the proposed algorithm can obtain higher user channel gain, effectively reduce the system bit error rate, and can be applied to 6G V2X communication.

A complementary M-ary orthogonal spreading (CMOS) architecture with orthogonal frequency division multiplexing (OFDM) is proposed to improve performance of bit-error rate (BER) and spectrum efficiency for high frequency (HF) communications. The CMOS-OFDM architecture is based on orthogonal complementary pairs with their central elements being zero. It is well known that complementary pairs theoretically reduce peak-to-mean envelope power ratio (PMEPR) of OFDM due to their ideal aperiodic auto-correlation properties. However, many practical OFDM applications, such as HF OFDM and IEEE 802.11, require that no data should be modulated to direct current (DC) subcarrier, which will destroy ideal properties of traditional complementary pairs and hence increase their PMEPRs. Compared with traditional complementary pairs, the proposed zero-centre complementary pairs (ZCCPs) in CMOS-OFDM architecture may maintain ideal properties and hence be more suitable for OFDM systems as long as zero element in the centre is modulated to DC subcarrier. The corresponding simulation results and numerical analyses over the HF fading channel modelled by ITU-R F.1487 are provided. Different from the previous researches on HF OFDM systems, the proposed HF CMOS-OFDM architecture using the constructed ZCCPs not only possesses excellent BER performance, but also may firmly resist PMEPR to 3 dB or near to 3 dB.

In this letter, we present a generalized orthogonal Golay complementary sequence (OGCS) set that consists of multiple subsets, therein, each subset is a conventional OGCS set, and any two sequences from different subsets have three-valued low in-phase cross-correlation (IPCC). At the cost of slight reduction of IPCC performance, the number of sequences in our set is enormously enlarged. When our set is applied to high frequency $M$ -ary spread spectrum communication link with orthogonal frequency division multiplexing modulation, the peak-to-mean envelope power ratio of the transmitted signal can be controlled not to exceed 3 dB, and the data rate can be higher than the one from the existing sequence sets. Finally, the simulation results show a desirable tradeoff between bit error rate and spectral efficiency.

The efficient allocation of multi-interface multi-channel Wireless Mesh Network channel resources is a hot topic recently. Effective channel management mechanisms need to be designed to ensure the full and efficient use of channel resources. In this paper, combined with the channel load that network buyers perceived, the channel reassignment problem of multi-interface multi-channel Wireless Mesh Network is modeled as a simple auction model, and the LBAM mechanism based on load balance is proposed and designed. LBAM not only meets the strategy-proofness, but also achieves high channel utilization and buyer satisfaction ratio showed by the simulation experiments. At the same time, due to the consideration of channel load condition in the design of LBAM, simulation experiments also analyzed that it has a significant effect on the improvement of network throughput when the network load is heavy.

Based on spread spectrum technique, two wireless video transmission schemes are designed and implemented in this paper, namely direct sequence spread spectrum (DSSS) scheme and multi-code spread spectrum (MCSS) scheme. We use software defined radio (SDR) method for hardware implementation of two schemes, where a XILINX Virtex-4 field programmable gate array (FPGA) for the transmitter and another Virtex-5 FPGA for the receiver. In order to evaluate their performance, we compared the two designed schemes with our previous work on orthogonal frequency division multiplexing (OFDM) scheme. The experimental results show that two schemes of DSSS and MCSS have better anti-jamming performance than OFDM scheme at the cost of spectrum efficiency. Also, DSSS scheme possesses higher power efficiency than MCSS scheme and OFDM scheme due to its lower peak-to-average power ratio.

Based on the sampling-concatenating operation with any integer interval, a large number of orthogonal subsets are designed for M-ary spread spectrum (MSS) communications with orthogonal frequency division multiplexing (OFDM) modulation. Any two sequences in the designed subset are orthogonal to each other, that is, the in-phase cross-correlation (IPCC) between them is equal to zero. Compared with the previous researches, the designed multiple subsets may possess more sequences at the cost of the peak-to-mean envelope power ratio (PMEPR) and inter-subset IPCC, which will be suitable for MSS-OFDM communications where the larger number of sequences means higher data rate. We provide a simple example to show how the designed algorithm works, and the corresponding performance of PMEPR and IPCC is analyzed.

The Limited channel allocation, especially the variable width channel allocation is a significant challenge in Wireless Mesh Networks. There are always some problems for fixed bandwidth channel allocation, such as low resource utilization, load imbalance, low efficiency and so on. To cope with the problems, in this paper, we formulate the variable-width channel allocation for the rational and selfish nodes in the network. Firstly, we propose a load balance and variable-width channel allocation strategy for Wireless Mesh Networks, based on the combination of the non-cooperative game theory and the charging mechanism. Then, the existence of Nash Equilibrium was demonstrated. Finally, we have evaluated the better performance of the Nash Equilibrium Strategy in load balance, system utility and fairness by simulation.

In cognitive networks, cognitive users need to continuously monitor spectrum to detect the presence of primary users. Cooperative sensing can make good use of network resource, obtain higher detection probability. In this paper, we give a brief introduction of the scheme of cooperative sensing. We show that by allowing the cognitive users operating in the same band with TDMA mode we can reduce the detection and thus increase the overall agility.Then we introduce a cooperation scheme with multi-partners base on D-S theory. Simulation results show that this cooperative sensing scheme can improve the detection probability, improve the agility gain of the network.

Based on the concept of cognitive radio (CR) and the idea of no-hit zone (NHZ), a novel cognitive frequency hopping code division multiple access (FH-CDMA) system is proposed, and the related FH sequences with NHZ are designed. When sensing spectrum usage from primary users, the cognitive FH-CDMA system employing NHZ FH sequences can flexibly change hopping frequencies to avoid interference to primary users while the whole FH-CDMA network can continue to be kept orthogonal without multiple access interference (MAI).

In recent years, wavelet-based video coding schemes have attracted considerable attention in the image coding community. In this paper, a new algorithm of three-dimensional wavelet transform (3D-WT) for video coding is presented. The main difference between it and the traditional 3D-WT algorithm is temporal decomposition. The proposed algorithm performs the temporal decomposition of a video sequence in a more efficient way, which is on the basis of several groups separated from the original video sequence. The requirements of processing memory for the proposed algorithm is also analyzed and compared with that of the traditional algorithm. Experimental results show that the proposed algorithm exhibits lower memory demands and better performance of video coding than the traditional 3D-WT algorithm