1,721,036 research outputs found
Serial Multicode Direct Sequence Spread Spectrum with Applications to Satellite Navigation Pilot Channels
No full textIn this paper we introduce Serial Bicode and Serial Multicode Direct Sequence Spread Spectrum (DSSS) and we extend them to Code Division Multiple Access (CDMA). To each user are assigned two or more spreading codes. The information is associated to these codes, which are alternated within a single DSSS signal. The performance of the new techniques for incoherent demodulation is analyzed. Additionally, we present the application to the construction of data-less pilot channels for satellite navigation systems. Alternative codes can be used to embed a pattern or a message that, when recognized, allows to quickly solve time ambiguity and simplify initial synchronization for MEO and LEO scenarios
Implementation of 5G beamforming techniques on cylindrical arrays
Full text linkIn this paper we study the performance of a Uniform Cylindrical Array for a 5G base station working in the mmW region. Conventional and Capon beamforming design are considered. A comparison against a base station equipped with three Uniform Planar Arrays, one per sector, is presented. Average per-user achievable rate results are provided with different system configuration in terms of network loading and number of antennas, showing that Uniform Cylindrical Array could represent an interesting solution for 5GmmW networks
Assessment of MU-MIMO schemes with cylindrical arrays under 3GPP 3D channel model for B5G networks
Full text linkBeyond 5G technologies promise groundbreaking advances on the performance of cellular networks, by taking advantage of Massive MIMO in mmWave scenarios. The aim of this study is to analyze and test the performance of a 5G cell site equipped with large antenna arrays. It is of particular interest the comparison between the typical trisector cell design with a planar array for each sector, and the less investigated cylindrical array, able to maintain a constant pattern through the whole azimuthal range. To validate our analysis, we adopt the latest 3GPP-compliant 3D channel model and we evaluate the performance of multi-user and multi-layer precoding and combining schemes. Several MIMO configurations are taken into account, and we show that cylindrical arrays can improve the overall system performance, both in terms of achievable per-user rate and outage probability
On the detection of DNA periodicities by spectral analysis and adaptive mappings: Cost functions comparison
No full textMulti-Layer Multi-User MIMO with Cylindrical Arrays under 3GPP 3D Channel Model for B5G/6G Networks
Full text linkMassive MIMO technology has significantly enhanced the performance of 5G networks, and its potential is poised for further expansion in the upcoming 6G standard. Large antenna arrays at the transmitter, combined with multiple antennas at each user can enable multi-user multi-layer MIMO data transmission. In this paper, we study the potential benefits of a cylindrical array arrangement in a 3D scenario, compared to the conventional trisector planar array configuration. In fact, cylindrical arrays allow for more uniform coverage of the cell, don't suffer from beam broadening, and can mitigate the sector-edge problem. For this purpose, we assess the effectiveness of multi-user and multi-layer precoding and combining strategies using cylindrical arrays outfitted with both single and dual-polarized antenna elements, under the most recent 3GPP-compliant 3D channel model for 5G, and by taking into account impairments due to an imperfect channel estimation. Results and comparisons with planar arrays in terms of sum-rate, spectral efficiency and outage are provided for outdoor Line-of-Sight (LOS), outdoor Non-LOS, and indoor users. They highlight the benefits of using cylindrical arrays in realistic 3D scenarios, even when the planar arrays of the different sectors are coordinated to operate as a single array. This makes them an interesting solution for next-generation 6G networks
Quadratic Forms in Random Matrices with Applications in Spectrum Sensing
Full text linkQuadratic forms with random kernel matrices are ubiquitous in applications of multivariate statistics, ranging from signal processing to time series analysis, biomedical systems design, wireless communications performance analysis, and other fields. Their statistical characterization is crucial to both design guideline formulation and efficient computation of performance indices. To this end, random matrix theory can be successfully exploited. In particular, recent advancements in spectral characterization of finite-dimensional random matrices from the so-called polynomial ensembles allow for the analysis of several scenarios of interest in wireless communications and signal processing. In this work, we focus on the characterization of quadratic forms in unit-norm vectors, with unitarily invariant random kernel matrices, and we also provide some approximate but numerically accurate results concerning a non-unitarily invariant kernel matrix. Simulations are run with reference to a peculiar application scenario, the so-called spectrum sensing for wireless communications. Closed-form expressions for the moment generating function of the quadratic forms of interest are provided; this will pave the way to an analytical performance analysis of some spectrum sensing schemes, and will potentially assist in the rate analysis of some multi-antenna systems
A Simplified Application of Ordered Statistics Decoding to Single Parity Check Product Codes
Full text linkIn this paper we consider Ordered Statistics Decoding and we discuss some ideas aiming to reduce its complexity. As a case study, we focus on Single Parity Check Product Codes. First, we investigate how to simplify the construction of a reliable basis by exploiting the code structure. Then, we consider the iterative application of Soft-Input Soft-Output Ordered Statistics Decoding with small order to lower-dimensional subcodes. Results show that these simplified algorithms, both stand-alone and iterative, are still able to approach Maximum Likelihood Decoding of Single Parity Check Product Codes
Energy detection spectrum sensing with discontinuous primary user signal
No full textThis paper addresses the problem of spectrum sensing for cognitive radio, in the case of a primary signal characterized by a discontinuous channel occupation within the considered sensing window. Under such conditions, the performance of two different energy detectors is investigated. The first one (Energy Average Detector) decides whether the channel is free or busy on the basis of the energy sample average; the second one (Energy Threshold Detector) performs a soft estimation of the channel occupation probability by comparing the energy samples with a proper threshold. For both the detectors, an analytical model is derived and validated through simulation, and the optimal decision threshold is found as a function of the primary signal parameter
An algorithm to compute the free distance of turbo codes
No full textA new algorithm for computing the free distance of turbo codes is applied to the CCSDS and the UMTS standard codes. Results on the free distance behaviour for increasing interleaver length are also presented
Software-Defined Radio Implementation of a LoRa Transceiver
Full text linkThe number of applications of low-power wide-area networks (LPWANs) has been growing quite considerably in the past few years and so has the number of protocol stacks. Despite this fact, there is still no fully open LPWAN protocol stack available to the public, which limits the flexibility and ease of integration of the existing ones. The closest to being fully open is LoRa; however, only its medium access control (MAC) layer, known as LoRaWAN, is open and its physical and logical link control layers, also known as LoRa PHY, are still only partially understood. In this paper, the essential missing aspects of LoRa PHY are not only reverse engineered, but also, a new design of the transceiver and its sub-components are proposed and implemented in a modular and flexible way using GNU Radio. Finally, some examples of applications of both the transceiver and its components, which are made to be run in a simple setup by using cheap and widely available off-the-shelf hardware, are given to show how the library can be used and extended
- …
