Suppression of narrowband interference in frequency-hopping spread spectrum (FH-SS) systems is treated in this paper. First, we analyze the effect of continuous-wave tone interference in noncoherent binary frequency-shift keying (BFSK) signaling with FH-SS. Based on this analysis, a new receiver for FH-SS systems is proposed, including a transform-domain interference suppression module. The algorithm is executed in two steps: 1) interference detection and 2) signal reconstruction. The novelty of this suppression algorithm is the combination of the undecimated wavelet packet transform with frequency shifts of the received signal to center the narrowband interference in a subband. Once the subband that contains the interference has been determined, the algorithm removes this subband and then reconstructs the signal. The performance of this receiver has been evaluated in a variety of situations with different types of narrowband interference. The results obtained show the improvement of the proposed receiver in comparison to the traditional FH-SS receiver.

Communication networks have become a critical element in the development of smart cities. The information flows generated by thousands of sensors and systems must be managed to assure the adequate guarantees of quality, availability and security. This work introduces the SimulCity tool, which assists in the design of a smart city’s communications convergent network. SimulCity allows a flexible simulation of different scenarios where multiple heterogeneous sources of Human Type Communications (HTC) and Machine Type Communications (MTC) compete for limited bandwidth resources. SimulCity evaluates the impact of new services on the performance of a municipal communications network and, consequently, assists the modification of network values to optimize bandwidth and reduce costs. Several network characteristics can be easily configured in SimulCity, such as the definition of traffic sources, the parametrization of different network mechanisms, access admission control, Quality of Service (QoS), and traffic in the Multiprotocol Label Switching (MPLS) network. SimulCity was used to simulate different projects in the smart city of Valencia (Spain). Specifically, SimulCity was used to study the impact on the Valencia City Council’s communications network of several new services: the solid waste collection supervision, the street lighting management, the control of regulated parking areas, and the upgrade of voice and video communications systems of the city government buildings. The results obtained have allowed the analysis of the impact that these new services have on the existing network and perform an adequate dimensioning of the future municipal communications network. INDEX TERMS.

A new algorithm for narrowband interference suppression in direct-sequence spread-spectrum (DS-SS) communications is presented. The algorithm combines the undecimated wavelet packet transform (UWPT) with frequency shifts to confine the interference energy in a subband that is subsequently eliminated. Computer simulation shows a robust performance that appears to be independent of the interference frequency