Improved time diversity for LTE over satellite using split multicode transmission

An improved time diversity technique is proposed for deploying the 3GPP LTE air-interface over satellite mobile links. It overcomes the FEC performance loss resulting from the use of a short transmit-time-interval (TTI) in LTE. By using transport block expansion, code block segmentation, advanced rate matching and automatic retransmissions, the FEC coded block is split over as many TTIs as is necessary to break the channel correlation without any reduction in the user data rate

Link performance of LTE vs. WiMAX for satellite mobile broadband

In this paper, we investigate and compare the performance of the IEEE mobile WiMAX and the 3GPP LTE terrestrial air interfaces over GEO satellite links with amplifier nonlinearity and mobile wideband fading, in order to have an insight into which would be a better candidate for ubiquitous mobile broadband delivery. Both air-interfaces are compared in terms of achievable single-link capacities for a 5MHz channel. Link-level computer simulations are also carried out to establish their block-error-rate performance. Although both standards share a lot of similarity, simulation results show that they can differ in performance as a result of their subcarrier multiplexing schemes and the variants of OFDMA implemented. © 2010 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved

Link performance of LTE vs. WiMAX for satellite mobile broadband

In this paper, we investigate and compare the performance of the IEEE mobile WiMAX and the 3GPP LTE terrestrial air interfaces over GEO satellite links with amplifier nonlinearity and mobile wideband fading, in order to have an insight into which would be a better candidate for ubiquitous mobile broadband delivery. Both air-interfaces are compared in terms of achievable single-link capacities for a 5MHz channel. Link-level computer simulations are also carried out to establish their block-error-rate performance. Although both standards share a lot of similarity, simulation results show that they can differ in performance as a result of their subcarrier multiplexing schemes and the variants of OFDMA implemented. © 2010 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved

Improved single frequency estimation with wide acquisition range

An improved method for estimating the frequency of a single complex sinusoid in complex additive white Gaussian noise is proposed. The method uses a modified version of the weighted linear predictor to achieve optimal accuracy at low/moderate SNR while retaining its speed and wide acquisition range. Consequently, it has an advantage over known methods that use the weighted phase averager since they suffer from an increased threshold effect at frequencies approaching the full estimation range

Improved time diversity for LTE over satellite using split multicode transmission

An improved time diversity technique is proposed for deploying the 3GPP LTE air-interface over satellite mobile links. It overcomes the FEC performance loss resulting from the use of a short transmit-time-interval (TTI) in LTE. By using transport block expansion, code block segmentation, advanced rate matching and automatic retransmissions, the FEC coded block is split over as many TTIs as is necessary to break the channel correlation without any reduction in the user data rate

Signal-to-noise ratio estimation algorithm for advanced DVB-RCS systems

This paper presents a signal-to-noise ratio (SNR) estimation algorithm for advanced Digital Video Broadcasting - Return Channel via Satellite (DVB-RCS) systems using adaptive coding and modulation (ACM) in the reverse link of broadband satellite systems. Due to the absence of a repetitive pilot symbol structure, SNR estimation has to be performed using the fixed symbol preamble data. Moreover, sporadic nature of data traffic on the return link causes variation in interference level from slot to slot and, therefore, the estimation has to be done within one traffic slot duration. Hence, it becomes necessary to use a combination of data-aided (DA) and decision-directed (DD) algorithms so as to make use of traffic data. A non-data-aided (NDA) estimator that was previously proposed by the authors for binary phase shift keying (BPSK) and QPSK schemes is extended to 8-PSK in a decision directed manner. This estimator shows improved performance over existing estimators. The inherent bias of DD approach at low values of SNR is reduced by using a hybrid approach, i.e. using the proposed estimator at moderate/high values of SNR and the moments-based estimator (M2M4) at low values of SNR. Overall improved performance of the proposed hybrid estimator, in terms of accuracy and complexity, makes it an attractive choice for implementing ACM in advanced DVB-RCS systems

Improved Preamble-Aided Timing Estimation for OFDM Systems

An improved method for estimating the frame/symbol timing offset in preamble-aided OFDM systems is presented. It uses a conventional preamble structure and combines autocorrelation techniques with restricted cross-correlation to achieve a near-ideal timing performance without significant increase in complexity. Computer simulations show that the method is robust in both AWGN and fading multipath channels, achieving better performance than the existing methods.</p