Embedded redundant array of independent drives (eRAID) architecture was proposed for a high-capacity solid-state drive (SSD) controller, which applies an embedded redundant array of independent drives (RAID) engine to drive and manage an array of independent embedded multimedia card (eMMC) modules. However, the performance of its random access was limited by the eMMC’s uncontrollable timing during data stripping among the eMMC channels. This brief solves this issue using the nonvolatile memory express (NVMe) engine embedded in the controller and a reorganized buffer stripping mechanism. An SSD controller with peripheral component interconnect express (PCIe) Gen$3^{\ast} 4$Lane interface was designed to verify the capacity and performance, and it was manufactured into a silicon integrated circuit (IC) using a 55-nm semiconductor process. This architecture provides a prospective way to eliminate external dynamic random access memory (DRAM) buffers while maintaining a high random access speed.

A semi-blind algorithm based on expectation propagation (EP) is proposed for multi-cell massive MIMO systems with spatially and temporally correlated channels. The performance of the algorithm in channel estimation and data detection is obtained from simulations and compared to other approaches. The results show that with only K pilots, where K is the number of users in the cell, the channel estimation performance of the proposed method approaches a lower bound as the number of BS antennas or the number of data symbols per frame increase. As expected, for time-varying channels, the proposed algorithm clearly outperforms those designed for block-fading channel models.

Abstract In this article, we propose a new pilot mapping method to jointly estimate the channel state information of the user while reducing the interference effects of multiuser multicell mobile scenarios. The problem of achieving the wireless performance of the minimum mean square error (MMSE) receiver with the maximum ratio (MR) combiner for massive multiple‐input multiple‐output (MIMO) systems in the frequency bands of 2.5 GHz and 28 GHz is addressed. By transmitting fewer pilots in the uplink communications and arranging those pilots to reduce interuser interference, we can achieve higher spectral efficiency (SE) with the MR and MMSE receivers. Numerical results show significantly fewer floating‐point operations for MIMO processing when the proposed pilot mapping strategy is combined with Kalman filtering estimation and MR processing, achieving an SE comparable to the MMSE receiver.

In this work, Vehicle-to-everything (V2X) wireless communications performance is analyzed, in order to account for inherent scenario complexity, in the deployment phase of wireless systems towards the implementation of a Context Aware environment. An urban environment has been simulated by means of an in-house three-dimensional (3D) Ray Launching algorithm, coupled with a microscopic vehicular movement simulator, accounting for embedded urban elements as well as variable traffic densities within the complex environment. Large-scale and small-scale results are presented, as well as statistical analysis of the impact of different traffic densities. A campaign of measurements in the same real scenario has been performed, showing good agreement with wireless channel estimations for the considered frequency. These results can aid in V2X deployment configurations in urban environments, in order to minimize power consumption, optimize interference levels and increase overall system performance.

In this work, a comparative analysis is performed to study the bit error rate and error vector magnitude achieved with the least‐squares (LS), the minimum mean squared error (MSE), and the Kalman filter (KF) channel estimators when these are applied to the maximum‐ratio combining (MRC) and the regularised zero‐forcing (RZF) receivers. The MSE achieved with the different channel estimators was also compared by varying the noise and interference power at the receiver. The proposed methodology relies on the characterisation of a massive multiple‐input multiple‐output (MIMO) channel with a quasi‐deterministic radio channel generator and a cyclic prefix orthogonal frequency division multiplexing link‐level radio simulation. The fifth‐generation (5G) new radio (NR) frame structure was used to perform channel estimation and equalisation for operation frequencies below 6 GHz. Numerical results show that the MRC receiver achieves its maximum performance with the KF estimator, especially at low signal‐to‐noise ratio scenarios, while the RZF receiver achieves its maximum performance with the LS estimation even in high interference scenarios.

In this paper, intra-wagon wireless communication performance is analyzed, in order to account for inherent scenario complexity in the deployment phase of wireless systems toward the implementation of a context-aware environment. A real commercial passenger wagon has been simulated by means of an in-house-developed 3-D ray launching code, accounting for embedded wagon elements as well as variable user densities within the passenger wagon. Onboard measurements of a designed and deployed wireless sensor network are obtained, showing good agreement with wireless channel estimations for two different frequencies of operation. Energy consumption behavior and user density impact have also been analyzed and estimated as a function of network topology and the operational mode. These results can aid in wireless transceivers deployment configurations, in order to minimize power consumption, optimize interference levels, and increase overall service performance.

Wireless Reconfigurable Networks (WRN) are prone to several routing security attacks such as packet dropping, data integrity, selective forwarding, black holes, and wormholes. In this paper, we introduce an interference and outage probability analysis of the distributed security attack detection and defense method (DDM) for WRN proposed. The accuracy capabilities of the method are analyzed under nearest neighbor case of interference and Rayleigh fading outage conditions. The analysis is commanded where a dynamic adversary is introduced, under several network densities and transmission ranges over a network where node mobility disallowed. Several network parameters like packet overhead and successfully received packet as well as the detection accuracy of the method are evaluated. We found that the best performance of the method is attained under high node density when node mobility is introduced.

Ad hoc wireless networks consist of mobile nodes which present problems related to routing and maintenance of the point-to-point links due to mobility. A problem related to the node population and the node mobility is the connectivity, which can be low when nodes are organized in different groups and these groups are isolated. We present measures of connectivity and introduce a measure of fragility of the network according to the number of paths towards reachable nodes. We show that for a large node population, the connectivity tends to be Gaussian.

This paper presents a new approach to improve performance in wireless ad-hoc networks using a Behavior-Based Architecture. The DSR protocol was used and four levels of competence based on strategies to improve the cache were implemented: sort routes, prefer fresher routes, selection, and disperse traffic. A conflict solver was implemented to solve counter level commands. Three different activation criteria for the conflict solver were developed, generating instances of the architecture. Two metrics were used to evaluate the performance of the ad-hoc network: end-to-end delay and dropped packet average for the voice and data services, respectively. Six scenarios were analyzed showing the increase of the network performance with respect to the original DSR protocol.

The purpose of this work is to present realistic behaviour of slotted Aloha (S-Aloha), used as request access channel (RACH), with good performance regarding stability, efficiency, delay and capacity of traffic control. We present modelling and simulation of those parameters, which most influence the performance in terms of stability, and efficiency of the MAC technique based on S-Aloha. Considering particularly those aspects that degrade in greater scale the response of the system, such as: retransmission algorithm, capture effect and radio channel effects, we show that throughput can be improved by 70% and can be stabilised. Therefore, if we use S-Aloha as request access channel (RACH), it could be a good alternative for third-generation systems.

In this article, we use reservation code multiple access (RCMA) to integrate voice and data services in a CDMA network. We obtain the capacity of the number of voice and data terminals supported, as well as the necessary buffer size in the data terminals to achieve such capacity. We evaluate the performance of the system in terms of the message loss probability and considering buffer management techniques. We conclude that RCMA is a good option for the integration of voice and data services in CDMA.

We propose a model to evaluate a wireless ATM network considering mobility of the users and network overload as variables to evaluate the performance. We use the Pascal approximation to obtain the blocking probabilities in the ATM network and a multidimensional birth-death process for the wireless network. The ATM network considers fixed routing. The model presented provides an insight into the effects that mobility has on the performance and call admission control decisions.

We evaluate the effects of mobility and reservations on new call blocking and handoff blocking in multirate wireless networks. The model evaluated uses fixed channel assignment (FCA) with priority for handoffs over new call arrivals by reserving a number of channels for handoff calls in all the cells. The performance measures used are new call blocking and handoff drop probabilities. The methodology used is that of implied costs which we calculate from the the network net revenue which considers the revenue generated by accepting a new call into the network as well as the cost of a handoff drop in any cell. Simulation and numerical results are presented showing the accuracy of the model. We present numerical results showing the effect of reservations on the call blocking probability. The implied cost analysis shows that mobility has a significant knock-on effect on the traffic elsewhere in the network and we capture this effect through the net revenue which is sensitive to the level of mobility. We calculate the sum revenue for a given network by maximizing the net revenue using implied costs in a gradient descent algorithm. This analysis indicates that in the case of multiple classes of traffic the call carrying capacity of the network is sensitive to the choice of reservation parameters.

Shadow prices are calculated for least loaded routing (LLR) and aggregated least busy alternative (ALBA) routing in circuit-switched networks for the blocking probability obtained from fixed point algorithms. Numerical results are presented for the calculation of these shadow prices in small networks. As an application of these shadow prices, we also formulate a constrained optimization problem to calculate the sum capacity of LLR and ALBA for a given network. Comparison of the sum capacities indicate that the optimization using shadow prices results in a significant improvement. This provides evidence that matching capacity distribution to traffic is important even when adaptive routing schemes such as LLR and ALBA are used in the network. We also calculate upper bounds on the sum capacity which serve to indicate how well the optimized LLR and ALBA perform. The numerical results also confirm that with a small number of states the capacity of ALBA approaches that of LLR.