Industrial Robot Monitoring System (IRMS) is an important guarantee to maintain the normal operation of industrial robot systems. For IRMSs in the edge-cloud environment, live migration technology enables them to improve system resource utilization and reliability such as dynamic resource management or fault tolerance without interrupting monitoring services. Therefore, it is important to research the optimization of live migration for IRMS. For multi-container migration, parallel migration can reduce service downtime, serial migration can reduce pre-copy migration time, and hybrid migration with a reasonable serial-parallel relationship can combine the advantages of both. In this paper, we propose a multi-container migration architecture based on shared bandwidth, which considers the resource-constrained characteristics of the edge-cloud environment. Moreover, we present a multi-container hybrid migration planning model with the total migration time as the optimization objective, which uses a matrix representation of serial-parallel relationship. To solve this model, we develop a heuristic algorithm based on a hybrid Tabu-Evolutionary algorithm. The algorithm can find the dominant solution quickly by global search and improve the solution quality by subspace search. The experimental results show that the proposed algorithm can quickly give the hybrid migration strategy for a set of containers, effectively reducing the total migration time.

The paper integrates space-time coding (STC) techniques and the multiple-input multiple-output (MIMO) antenna architecture with multicarrier code-division multiple access (MC-CDMA) systems. For brevity, we call such integration space-time coded MIMO MC-CDMA systems. A numerical model for the space-time coded MIMO MC-CDMA system is presented in detail. Successively, by exploiting subspace decomposition techniques, a novel blind identification method is derived for downlink wireless channels in the space-time coded MIMO MC-CDMA system. As there is no need of pilot symbols to identify wireless channels between multiple-transmit and multiple-receive antennas, our proposed algorithm can finely keep the spectrum efficiency of the space-time coded MIMO MC-CDMA system. Computer simulation results demonstrate the validity and the performance of our proposed algorithm.

In order to hold fine spectral efficiency, it is meaningful to investigate multicarrier code-division multiple access (MC-CDMA) systems without cyclic prefix (CP), which are unavoidably corrupted by the hostile intersymbol interference (ISI) so that we can call them as ISI-corrupted MC-CDMA systems. Moreover, combining multiple antennas with ISI-corrupted MC-CDMA systems is advantageous in suppressing cochannel interference. Hence, this paper applies multiple antennas to the base station of ISI-corrupted MC-CDMA systems over frequency-selective fading channels. A joint spatio-temporal estimation method of uplink vector channel is then derived based on the singular value decomposition (SVD) technique. Computer simulations illustrate that our algorithm is more robust against noise and can well mitigate multiple access interference (MAI) in multiuser scenarios.

In multicarrier code-division multiple access (MC-CDMA) systems over the finite impulse response (FIR) channel, a usual approach for combating the resultant hostile intersymbol interference (ISI) is via addition of a cyclic prefix (CP) to each transmitted data block. However, ISI is eliminated at the cost of reduction in spectral efficiency. In order to recover spectral efficiency, it is meaningful to investigate MC-CDMA systems without CP. This paper explores the multiuser detection for the MC-CDMA system without CP. We interpret the MC-CDMA system without CP as an equivalently time-domain ISI-corrupted direct sequence (DS-) CDMA system with specific spreading codes. Successively, based on this representation, a time-domain linear minimum mean square error (MMSE) multiuser detection scheme is derived for the MC-CDMA system without CP. Computer simulations illustrate both the validity and the overall performance of the proposed multiuser detection scheme.

Based on the ESPRIT-like method, a closed-form CDMA signal and DOA estimation approach without the knowledge of space-time channel and training sequence is presented in this paper. An auxiliary matrix is constructed by exploiting the special structure of the antenna array. The symbol vector and DOA are obtained from an eigenvalue-eigenvector pair of the auxiliary matrix even under imperfect carrier recovery. The carrier offset can be acquired easily by exploiting the finite alphabet property of the transmitted symbols. In comparison with conventional space-time linear multiuser detector, in which the knowledge of space-time channel is assumed known, the proposed method has the advantage of lower computation at the expense of little performance degradation. Finally, numeral simulations are presented.

Multicarrier modulation code division multiple access (MCM-CDMA) technique or orthogonal frequency division multiplexing code division multiple access (OFDM-CDMA) scheme can sufficiently utilize the available spectrum and meet the demand of diverse multimedia services, therefore it is broadly considered as an effective approach for future wireless multimedia communications. In this paper, based on software-defined radio (SDR), by exploiting the discrete Fourier transform (DFT) and inverse discrete Fourier transform (IDFT), a general baseband digital model for different OFDM-CDMA schemes is developed. Moreover, the corresponding matrix representation is addressed.

The constant modulus property of communication signals, such as FM and phase-modulated signals, are often used in blind separation of multiple users. Because there are no training sequences needed, the system transmission efficiency is increased. When extended to the space-time domain, the new schemes have potentially greater performance than conventional ones. In this paper a feedback adaptive space-time constant modulus algorithm (FAST-CMA) is proposed for DS-CDMA multiuser detection. First the uplink channel model is built with receiving K synchronous communication signals that are transmitted through a MIMO-FIR channel. Based on this channel model, we compare and analyze the FAST-CMA with cascade-type constant modulus algorithm (CT-CMA) and space-time type constant modulus algorithm (ST-CMA). The FAST-CMA can combat both ISI and MAI without stringent power control and training sequence, and it is preferable to CT-CMA and approximately has the same performance as the ST-CMA. It has faster convergence rate, and less computational complexity than ST-CMA. Numerical simulations can illustrate the effectiveness of this algorithm.

The multicarrier code division multiple access (MC-CDMA) technique is known to be appropriate for high-data-rate wireless communications due to its robustness to multipath fading and its capability of handling high-data-rate transmissions with a simple one-tap equalizer. This paper investigates a uniform linear antenna array at the base station for macrocell MC-CDMA systems in a frequency-selective fading channel environment, and develops a blind space-frequency channel estimator for an MC-CDMA system with antenna array. As a by-product, the direction-of-arrivals (DOAs) can also be estimated. By constructing a specific auxiliary matrix including both the space-frequency channel and DOA information, and performing eigen decomposition on it, we can obtain the closed-form solution of space-frequency channels and DOAs for all active users within the macrocell. The overall performance of this novel scheme is demonstrated by extensive computer simulations.

Many blind channel estimation methods have been proposed for direct sequence (DS) CDMA systems, so we can certainly use them to estimate the finite impulse response (FIR) channel for the multicarrier code division multiple access (MC-CDMA) system. In this paper, we interpret the MC-CDMA system as an equivalently DS-CDMA system with specific spreading codes. Then, an equivalently blind time-domain channel estimator is derived for the MC-CDMA uplink, which is based on second-order statistics of the received data. Because there is no need of a large amount of sampling data, this method is greatly suitable for the fast time varying wireless channels. By exploiting singular value decomposition (SVD) and the finite alphabet property of transmitted symbols, the time-domain channel impulse response (CIR) for the MC-CDMA can be accurately identified. Computer simulations illustrate both the validity and the overall performance of the proposed estimator.

Joint spatial-temporal multiuser detection (MUD) schemes for DS-CDMA systems with antenna arrays have drawn much attention, which has continued unabated. We derive the equivalent spatial-temporal MUD scheme for MC-CDMA systems with antenna arrays. A uniform linear array (ULA) is applied to the base station of the MC-CDMA system. We first describe the equivalent time-domain DS-CDMA interpretation for the MC-CDMA system. Based on this interpretation, by utilizing the finite alphabet property of the transmitted symbols, an equivalent spatial-temporal multiuser detector is derived for the MC-CDMA system with the ULA over frequency-selective fading channels. Computer simulations illustrate that our algorithm is more robust against noise and can well mitigate multiple access interference (MAI) in multiuser scenarios. In particular, our novel scheme has the potential of providing the anticipated MUD performance gains with a complexity that would be manageable for MC-CDMA systems.

Joint space-time multiuser detection provides a significant performance improvement over cascade space-time multiuser detection. But its computation load makes it impossible to be applied in practical situations. We propose a wavelet-based multiresolution-beamspace approach. Using the multiresolution of wavelets, it reduces the computation load of joint space-time multiuser detector in DS-CDMA. It is a tradeoff between the cascade and joint space-time processing. In applying wavelets to an array problem, we discuss the multiresolution in an array signal. Simulations show that there is a reduction of the computational load and compared with other beamspace methods, it improves the performance.