Citizens are expected to require the growth of multiple Internet of Things (IoT) -based applications to improve public and private services. According to their concept, smart cities seek to improve the efficiency, reliability, and resilience of these services. Consequently, this paper searches for a new vision for resolving problems related to the quick deployment of a wireless sensor network (WSN) by using a sizing model and considering the capacity and coverage of the concentrators. Additionally, three different routing models of these technology resources are presented as alternatives for each WSN deployment to ensure connectivity between smart meters and hubs required for smart metering. On the other hand, these solutions must reduce costs when this type of wireless communication network is deployed. The present work proposes various optimization models that consider the physical and network layers in order to integrate different wireless communication technologies, thus reducing costs in terms of the minimum number of data aggregation points. Using a heterogeneous wireless network can reduce resource costs and energy consumption in comparison to a single cellular technology, as proposed in previous works. This work proposes a sizing model and three different models for routing wireless networks. In each case, constraints are evaluated and can be associated with different real-world scenarios. This document provides an optimization model that encompasses all of the proposed constraints; due to the combinatorial nature of the problem, this would require a heuristic technique.

Generalized Frequency Division Multiplexing (GFDM) has been recently proposed for next generation 5G mobile networks. A disadvantage of GFDM, similarly to the other multicarrier signals, is its high peak-to-average-power ratio (PAPR), Large PAPR signals can easily saturate the transmit power amplifier and cause degradation in BER performance and out-of-band emissions. In this work we investigate the performance of GFDM in presence nonlinearity effects in the transmission channel, with the aim to explore the effectiveness of some PAPR reduction techniques to mitigate OOB radiation and error performance degradation. To reduce PAPR we consider clipping techniques with iterative receiver, companding and selective mapping techniques, and for performance comparison we also evaluate IFDMA. The simulation results show that Clipping techniques delivers the best result, whereas IFDMA is able to maintain an acceptable performance level with low complexity in the receiver.

In this paper we explore the advantage of combining M-QAM modulations, LDPC codes, and IFDMA multi-access techniques in order to increase the capacity of the system, reduce the peak-to-average power ratio (PAPR) and to improve the BER performance. The simulation results show that our proposal provides better performance, even allowing significant reductions, of about 1 dB, in the PARP of the high-level modulation schemes, such as 64-QAM. In addition, the spectral efficiency and BER, using LDPC codes (FEC), provides a considerable advantage and low complexity respect to traditional systems.

This paper presents an experimental result on the measurement of the lobular radiation pattern of directional antennas (Yagi) obtained by applying a SDR (Software Defined Radio) system for the homologation and verification of the antenna performance. The measurement depends on the energy absorbed by the antenna when it is used to received a RF signal of short wave.

The legacy access networks should provide higher capacity, rate and spectral efficiency due to high demand of data transmission. In this context our proposal is the combining of LDPC codes with MIMO systems channels in order to improve the reliability and capacity in the transmission for massive connectivity. This system is proposed for the development of new technologies over SDR systems. MIMO techniques such as Alamouti-STBC offer some benefits such as greater network access capabilities that help to make transmission more reliable, while LDPC codes give higher transmission reliability because they have a good error correction codes and offer an approximation to the limit of capacity established by Shannon. The results show that the BER performance and the capacity improves when the Rayleigh channel is used. In this context, the system can support high quality of information and high rates in the transmission. In addition, we present the techniques of frame synchronization for real transmission as Barker codes, in order to reduce the error of transmission.

The deployment of heterogeneous networks (HetNets) is a way to increase the network capacity and release part of the traffic generated by users inside a cell to small-scale wireless networks for service. In this context, the main problem is managing the interference due to the coexistence of small cells and macro cells. In this paper, a QoS-aware Resource Allocation (RA) algorithm jointly working with admission control (AC) over a two-tier HetNet scenario is investigated in the presence of both the pilot-symbols for channel estimation and the channel estimation error. The RA algorithm allows two users, the macro cell user (CU) and small cell user (SU), to simultaneously share the same resource block. Moreover, system performance and fairness are improved by including adaptive power allocation to users over resource blocks. In the framework of RA with proportional rate constraints, a novel algorithm is designed by including the effects of pilot-aided channel estimation. The algorithm is able to distribute the same proportional rate to all CUs and SUs, even in the presence of channel estimation error. Relevant numerical results for the downlink of a two-tier HetNet with pilot-aided channel estimation show that the rate dispersion is driven to zero while the sum-rate is maximized, and the average user rate penalty with respect to a perfect-CSI scenario may rise to 20%.