Enhanced Trellis Coded Multiple Access (ETCMA)

We propose an enhanced version of trellis coded multiple access (TCMA), an overloaded multiple access scheme that outperforms the original TCMA in terms of achieved spectral efficiency. Enhanced TCMA (ETCMA) performs simultaneous transmission of multiple data streams intended for users experiencing similar signal-to-noise ratios and can be employed both in the uplink and in the downlink of wireless systems, thus overcoming one of the main limitations of TCMA. Thanks to a new receiver algorithm, ETCMA is capable of delivering a significantly higher spectral efficiency. We show that ETCMA approaches the capacity of the Additive White Gaussian Noise channel for a wide range of signal-to-noise ratios.Comment: 5 pages, 5 figure

Single-Frequency Network Terrestrial Broadcasting with 5GNR Numerology

L'abstract è presente nell'allegato / the abstract is in the attachmen

ADSL analogno sučelje

In this paper the Asymmetric Digital Subscriber Line (ADSL) analog front end (AFE) designs are described and compared. AFE is the part of ADSL modems most responsible for quality signal transmission over phone wires. It can be divided into the transmitting path (TX) circuitry, the receiving path (RX) circuitry and the hybrid network and transformer. The operations and realizations of each functional block are presented. There are the D/A converter, the filter and the line driver in the TX path and the voltage gain amplifier, the filter and the A/D converter in the RX path. The hybrid network and transformer process signals in both directions. Different fabrication technologies are used for the practical realizations of the AFE chip. The directions of the further developing are notified.U radu su opisane i uspoređene izvedbe ADSL analognog sučelja. Analogno sučelje kao dio ADSL modema najodgovornije je za kvalitetan prijenos signala preko telefonskih žica. Može se podijeliti u sklopove predajnog puta, prijamnog puta i hibridnu mrežu s transformatorom. Prikazan je rad i izvedbe svakog funkcijskog bloka. To su D/A pretvornik, filtar i izlazno pojačalo u predajnom putu te ulazno pojačalo, filtar i A/D pretvornik u prijamnom putu. Hibridna mreža i transformator prosljeđuju signale u oba smjera. Za praktičnu izvedbu AFE čipa koriste se razne tehnologije. Naznačene su smjernice daljnjeg razvoja

ADSL analogno sučelje

In this paper the Asymmetric Digital Subscriber Line (ADSL) analog front end (AFE) designs are described and compared. AFE is the part of ADSL modems most responsible for quality signal transmission over phone wires. It can be divided into the transmitting path (TX) circuitry, the receiving path (RX) circuitry and the hybrid network and transformer. The operations and realizations of each functional block are presented. There are the D/A converter, the filter and the line driver in the TX path and the voltage gain amplifier, the filter and the A/D converter in the RX path. The hybrid network and transformer process signals in both directions. Different fabrication technologies are used for the practical realizations of the AFE chip. The directions of the further developing are notified.U radu su opisane i uspoređene izvedbe ADSL analognog sučelja. Analogno sučelje kao dio ADSL modema najodgovornije je za kvalitetan prijenos signala preko telefonskih žica. Može se podijeliti u sklopove predajnog puta, prijamnog puta i hibridnu mrežu s transformatorom. Prikazan je rad i izvedbe svakog funkcijskog bloka. To su D/A pretvornik, filtar i izlazno pojačalo u predajnom putu te ulazno pojačalo, filtar i A/D pretvornik u prijamnom putu. Hibridna mreža i transformator prosljeđuju signale u oba smjera. Za praktičnu izvedbu AFE čipa koriste se razne tehnologije. Naznačene su smjernice daljnjeg razvoja

Analysis and Design of Non-Orthogonal Multiple Access (NOMA) Techniques for Next Generation Wireless Communication Systems

The current surge in wireless connectivity, anticipated to amplify significantly in future wireless technologies, brings a new wave of users. Given the impracticality of an endlessly expanding bandwidth, there’s a pressing need for communication techniques that efficiently serve this burgeoning user base with limited resources. Multiple Access (MA) techniques, notably Orthogonal Multiple Access (OMA), have long addressed bandwidth constraints. However, with escalating user numbers, OMA’s orthogonality becomes limiting for emerging wireless technologies. Non-Orthogonal Multiple Access (NOMA), employing superposition coding, serves more users within the same bandwidth as OMA by allocating different power levels to users whose signals can then be detected using the gap between them, thus offering superior spectral efficiency and massive connectivity. This thesis examines the integration of NOMA techniques with cooperative relaying, EXtrinsic Information Transfer (EXIT) chart analysis, and deep learning for enhancing 6G and beyond communication systems. The adopted methodology aims to optimize the systems’ performance, spanning from bit-error rate (BER) versus signal to noise ratio (SNR) to overall system efficiency and data rates. The primary focus of this thesis is the investigation of the integration of NOMA with cooperative relaying, EXIT chart analysis, and deep learning techniques. In the cooperative relaying context, NOMA notably improved diversity gains, thereby proving the superiority of combining NOMA with cooperative relaying over just NOMA. With EXIT chart analysis, NOMA achieved low BER at mid-range SNR as well as achieved optimal user fairness in the power allocation stage. Additionally, employing a trained neural network enhanced signal detection for NOMA in the deep learning scenario, thereby producing a simpler signal detection for NOMA which addresses NOMAs’ complex receiver problem

Applications of microprocessors in digital high frequency radio communications

This thesis describes the application of VLSI devices to channel evaluation and communication techniques over ionospheric radio paths. Digital signal processing techniques using microprocessors and charge coupled devices are described in detail. A novel method for observing interference and fading patterns on HF channels is described. Error control coding schemes and digital modulation techniques are combined in a design for an adaptive modem for use over HF radio links. Results of narrow-band interference measurements, error patterns and coding performance are presented