Mark Van Bladel

Bio: Mark Van Bladel is an academic researcher from Ghent University. The author has contributed to research in topics: Time division multiple access & Impulse noise. The author has an hindex of 1, co-authored 4 publications receiving 13 citations.

Digital HDTV broadcasting over the CATV distribution system

Abstract: This contribution deals with the digital broadcasting of HDTV channels over the cable television (CATV) distribution system, using either single-carrier QAM or an orthogonal frequency division multiplex (OFDM) of many QAM carriers to represent an HDTV channel. Assuming that no error-correcting codes are used, we investigate two distinct cases: in the first case, a few HDTV channels are transmitted among many analog TV channels, whereas in the second case all transmitted channels are HDTV channels. We show that in the first case the transmit power of an HDTV channel can be substantially reduced (by about 10 dB or more) as compared to the transmit power of an analog TV channel, while still maintaining a satisfactory bit error rate (BER). In the second case, not only a considerable reduction of the total transmit power but also a reduction of amplifier cost and an increase of the number of TV channels can be achieved. Single-carrier QAM is found to perform slightly better (at most about 1 or 2 dB) than a multi-carrier QAM.

Cable modem architectures adapted to the noise problem in the upstream direction for multiple-access hybrid fiber coax networks

Abstract: As interactive services require more bandwidth, high speed access networks must follow this trend. Although a Hybrid FiberCoax (HFC) system provides a large bandwidth, many problems occur due to the accumulation of the ingress and impulse noise.In this paper the properties of the ingress and impulse noise will be explained based on a measurement campaign on differentnetworks.The most striking result of the measurement campaign is the large dynamic and time—dependent behavior of the ingress noise.This dynamic behavior is an important factor in designing an upstream communication system. We show that for this reasonoptimized receivers will contain adaptive equalizers. This is illustrated by the performance analysis of a TDMA and an OFDM—CDMA system. Both systems are compared under the same environment. The results of this comparison shows how both canobtain the same performance.Considering the implications of both the TDMA and the CDMA system when using an equalizer in the head—end receiver, re-quirements for a total HFC network architecture are given. Especially synchronization and initialization issues must be ad-dressed.

Performance of a RS-coded QPSK cable modem for TDMA communication over the return channel of HFC networks

Abstract: This paper deals with communication over the return path channel of a cable TV (CATV) network designed as a HFC network. First, the main impairments are identified to be ingress noise and impulse noise. A TDMA receiver scheme suited for this application is then derived. It is shown that the performance of such a TDMA system substantially improves by using equalization to combat peaks in the ingress spectrum. With respect to impulse noise, error probability calculations are presented to determine the level of error correction that is required in order to obtain the target bit error rate of 10-8.

n of Multiple Access Techniques in the Presence of Narrowband Interference

Abstract: 1 2 ABSTRACT: This paper presents a comparison of several multiple access techniques in the presence of narrow- band interference. The analysis covers tinie- division multiple access (TDMA), code-division multiple access (CDMA), and orthogonal frequency- division multiple access (OFDMA). The results indicate that contrary to a common belief, CDMA with pseudo-noise spreading sequences is more sensitive to narrowband interference than is TDMA. Another finding is that orthogonal GDMA behaves similarly to OFDMA in the sense that the degradation is not the same for all users. Finally, the results confirm the superiority of OFDMA to all other multiple accc:ss techniques in this environment.

BER sensitivity of OFDM systems to carrier frequency offset and Wiener phase noise

Abstract: In this contribution the transmission of M-PSK and M-QAM modulated orthogonal frequency division multiplexed (OFDM) signals over an additive white Gaussian noise (AWGN) channel is considered. The degradation of the bit error rate (BER), caused by the presence of carrier frequency offset and carrier phase noise is analytically evaluated. It is shown that for a given BER degradation, the values of the frequency offset and the linewidth of the carrier generator that are allowed for OFDM are orders of magnitude smaller than for single carrier systems carrying the same bit rate. >

Bidirectional point to multipoint network using multicarrier modulation

Abstract: A two-way point to multipoint data transmission system comprises an upstream unit, a plurality of downstream units, and a transmission line connecting the downstream units to the upstream unit. At least one headend modem is located at the upstream unit and at least one downstream modem is located at the downstream units. The modems employ multitone orthogonal frequency division multiplexing (OFDM) to establish two-way communication between the upstream and downstream units. The OFDM has a tone spacing selected to minimize the ingress of electromagnetic interference at least in the upstream direction.

Method for the common transmission of digital and analogue modulated radio broadcasting and/ or television broadcasting signals

Abstract: The invention relates to a method used for common transmission of digital and analogue modulated radio broadcasting and/or television broadcasting signals, in particular on a broadband cable system. The method provides for at least one digital radio broadcasting and/or television broadcasting signal, in addition to an analogue television broadcasting signal, to be transmitted in at least one channel, the frequency spectrum (40) of at least one digital radio broadcasting and/or television broadcasting signal being restricted to a frequency range which is smaller than the width of the at least one channel. To reduce the analogue television broadcasting signal influence from the at least one digital radio broadcasting and/ or television broadcasting signal, the at least one digital radio broadcasting and/or television broadcasting signal has to be below a predetermined signal level, and the peak level of the analogue television broadcasting signal has to exceed a predetermined value which is substantially higher than the predetermined signal level of the at least one digital radio broadcasting and/or television broadcasting signal. To prevent cross modulation between the analogue and digital modulated radio broadcasting and/or television broadcasting signals, the amplitude of the frequency spectrum of the at least one digital radio broadcasting and/or television broadcasting signal to be below a predetermined value which is substantially smaller than the amplitude of the image carrier of the analogue television broadcasting signal.

DVB-T signal over cable TV network and phase noise requirements

Abstract: We study the quality of terrestrial digital video broadcasting (DVB-T) transmission over a cable TV network. Generally, when terrestrial digital TV signals are distributed by cable TV, a conversion from DVB-T (OFDM) to DVB-C (single carrier) is needed in the head-end. In order to avoid this costly conversion and to transmit the DVB-T signal directly in the existent cable channel, many requirements have to be satisfied. It is known that phase noise represents the main limitation for OFDM based systems. In this contribution, we demonstrate the sensitivity of the OFDM system to phase noise effects by using a dynamic model for the CATV channel. We conclude by giving the specifications for a converter that should allow the DVB-T system to function in the CATV network.

Implementation of Zero Forcing and MMSE equalization techniques in OFDM

Abstract: The objective of this project is to study a communication system using orthogonal carriers, OFDM. The focus of the study is the implementation of Zero Forcing and MMSE equalization techniques in order to reduce the interference mitigation. Then, proceed to the comparison between both equalizers. A discrete-time OFDM system will be tested and analysed with the both equalizers. What is expected is to compare de Bit Error Rate (BER) of the system using both equalizers. To design the system Matlab will be used. A discrete-time 4-QAM OFDM system using Cyclic Prefix, Equalization and AWGN will be implemented. The project starts with a test of a theoretical system, with an ideal channel in order to verify the good implementation in Matlab. Once the theoretical system is verified that works correctly, the system will be analysed using three different channels and the two equalizers. The BER and symbol constellation after using each equalizer will be compared and commented in each one of the three channels. The main objective is to know which equalizer is better in determinates conditions.