Clustered cell-free networking paves a new way for enabling scalable joint transmission among access points (APs) by partitioning the whole network into non-overlapping sub-networks. Previous works adopted clustering algorithms, graph partitioning methods or conventional continuous optimization theories to partition a network based on the channels between all users and all APs, resulting in huge channel measurement and computational costs. This makes these methods difficult to be implemented in practical systems since the optimal network partition could vary frequently due to user mobility. In addition, existing methods were usually designed for specific clustered cell-free networking problems with different optimization algorithms employed. In this paper, we leverage deep reinforcement learning (DRL) for clustered cell-free networking so as to rapidly adapt to user movements in dynamic environments, and propose a deep deterministic policy gradient based clustered cell-free networking (DDPG-C2F) framework that can be adapted in various application scenarios. Moreover, in our framework, only one single channel needs to be estimated at each AP as the input of the neural network, which greatly reduces the channel measurement costs for clustered cell-free networking, and the training and inference costs of our framework. The proposed DDPG-C2F framework is then applied to various clustered cell-free networking problems with different objectives and constraints to demonstrate its performance. Simulation results show that our framework outperforms existing baselines in all scenarios. Moreover, we show that the proposed framework can reduce the handover cost over user mobility, and is robust to dynamic scenarios with random user joining or leaving.

Using a testing platform, composed by off-the-shell and commercial products, this paper describes and implements a Near Field Communication (NFC) authentication system based on encrypted and biometric features. With Radio Frequency Identification (RFID) tags and readers, operating in the HF band, a novel gesture recognition pattern is designed and tested. In addition to the biometric signature, an encryption mechanism is implemented following the design of previous work by other authors. Finally, it is evaluated the security of the system, summarizing the results obtained.

Recently, a measurement campaign for characterizing the channels in underground subway environments was conducted in Shanghai, China. Downlink signals transmitted by 46 universal mobile telecommunication system cells deployed along a 34-km-long subway were collected. Channel impulse responses are extracted from the data received in the common pilot channels, based on which parameters of multipath components are estimated by using a high-resolution parameter algorithm derived using the space-alternating generalized expectation-maximization principle. Multiple time-evolving clusters are obtained, each representing the channel from a remote-radio-unit of a base station to the receiver. Based on a total of 98 time-evolving clusters, channels observed in the station scenario and the tunnel scenario are modeled separately for their distinctive behaviors in many aspects, particularly in the variations of clusters’ trajectories. Intracluster characteristics parameterized by cluster delay and Doppler frequency spreads,$K$-factor, and dependences among these parameters are investigated. Intercluster parameters, including coexisting cluster number, delay offset, power offset, and cross correlations, are investigated for the station scenario. A path loss model is established for the tunnel scenario.

In this paper, we review how ITT entered the communication market in Spain and we look at events that took place in the aftermath, leading to the acquisition of the Spanish telephone system.

This article takes a look at the life and accomplishments of Francisco Salva of Spain, including his work with an electric telegraph system. The author states that information herein is based on the original report and some practical demonstrations that Salva presented to the Barcelona Academy of Sciences in 1804.

Leonardo Torres Quevedo is a world-renowned Spanish engineer. His fields of interest were very extensive and included mechanics, aeronautics, and automatics. During his life, he received numerous awards and scientific honors. He was a member of the Spanish Royal Academy of Sciences (1901), a member of the Spanish Society of Physics and Chemists (1916), a member of the Spanish Royal Academy of Language (1920), an associate member of the French Academy of Sciences (1927), and an honorary member of the Geneva Society of Physics and Natural History. He also received the Echegaray Gold Medal from the Spanish Royal Academy of Sciences in 1916 and was appointed president of this prestigious institution in 1928.

On 29 December 1926, His Majesty King Alfonso XIII, accompanied by His Royal Highness the Infante Fernando and the President of the Spanish government, General Primo de Rivera, presided at the inaugural formalities of the automatic telephone service in the city of Madrid. The formal ceremony was held at the exchange located in the district of Salamanca. This event was the culmination of a project designed by the International Telephone and Telegraph Corporation (IT&T) and carried out by the Compania Telefonica Nacional de Espana (CTNE) in just 16 months. A totally independent and entirely new telephone plant was installed together with the existing one, so the substitution of automatic for manual service was done in one effort, in contrast to the general and common practice in other large cities. The installation of equipment in the local exchanges, the laying of the underground cable network, the placement of telephones at subscribers' houses, and also the construction of new buildings were done simultaneously in a well-planned and coordinated way. And amazingly, no detail was forgotten. Even an advertising campaign to instruct the subscribers in the proper use of the dial instrument was organized and successfully implemented.