The Experts below are selected from a list of 507 Experts worldwide ranked by ideXlab platform
Frederico Santos - One of the best experts on this subject based on the ideXlab platform.
-
VTC Fall - UMTS Common Channel Sensitivity Analysis
IEEE Vehicular Technology Conference, 2006Co-Authors: Nuno Pratas, Antonio Rodrigues, Frederico SantosAbstract:The UMTS common transport channels forward access channel (FACH) and the random access channel (RACH) are two of the three fundamental channels for a functional implementation of an UMTS network. Most signaling procedures, such as the registration procedure, make use of these channels and as such it is necessary that both channels be available across the cell radius. This requirement makes the choice of the transmission parameters a fundamental one. This paper presents a sensitivity analysis regarding the transmission parameters of two UMTS common channels: RACH and FACH. Optimization of these channels is performed and values for the key transmission parameters in both common channels are obtained. On RACH these parameters are the message to preamble Offset, the initial SIR target and the preamble Power step while on FACH it is the transmission Power Offset.
-
UMTS Common Channel Sensitivity Analysis
IEEE Vehicular Technology Conference, 2006Co-Authors: Nuno Pratas, Antonio Rodrigues, Frederico SantosAbstract:The UMTS common transport channels forward access channel (FACH) and the random access channel (RACH) are two of the three fundamental channels for a functional implementation of an UMTS network. Most signaling procedures, such as the registration procedure, make use of these channels and as such it is necessary that both channels be available across the cell radius. This requirement makes the choice of the transmission parameters a fundamental one. This paper presents a sensitivity analysis regarding the transmission parameters of two UMTS common channels: RACH and FACH. Optimization of these channels is performed and values for the key transmission parameters in both common channels are obtained. On RACH these parameters are the message to preamble Offset, the initial SIR target and the preamble Power step while on FACH it is the transmission Power Offset.
Arumugam Nallanathan - One of the best experts on this subject based on the ideXlab platform.
-
UAV-Aided Multi-Way NOMA Networks with Residual Hardware Impairments.
arXiv: Information Theory, 2020Co-Authors: Xingwang Li, Qunshu Wang, Theodoros A. Tsiftsis, Zhiguo Ding, Arumugam NallanathanAbstract:In this paper, we study an unmanned aerial vehicle (UAV)-aided non-orthogonal multiple access (NOMA) multi-way relaying networks (MWRNs). Multiple terrestrial users aim to exchange their mutual information via an amplify-and-forward (AF) UAV relay. Specifically, the realistic assumption of the residual hardware impairments (RHIs) at the transceivers is taken into account. To evaluate the performance of the considered networks, we derive the analytical expressions for the achievable sum-rate (ASR). In addition, we carry out the asymptotic analysis by invoking the affine expansion of the ASR in terms of \emph{high signal-to-noise ratio (SNR) slope} and \emph{high SNR Power Offset}. Numerical results show that: 1) Compared with orthogonal multiple access (OMA), the proposed networks can significantly improve the ASR since it can reduce the time slots from $\left[ {\left( {M - 1} \right)/2} \right] + 1$ to 2; and 2) RHIs of both transmitter and receiver have the same effects on the ASR of the considered networks.
-
UAV-Aided Multi-Way NOMA Networks with Residual Hardware Impairments
IEEE Wireless Communications Letters, 1Co-Authors: Xingwang Li, Qunshu Wang, Theodoros A. Tsiftsis, Zhiguo Ding, Arumugam NallanathanAbstract:In this paper, we study an unmanned aerial vehicle (UAV)-aided non-orthogonal multiple access (NOMA) multi-way relaying networks (MWRNs). Multiple terrestrial users aim to exchange their mutual information via an amplify-and-forward (AF) UAV relay. Specifically, the realistic assumption of the residual hardware impairments (RHIs) at the transceivers is taken into account. To evaluate the performance of the considered networks, we derive the analytical expressions for the achievable sum-rate (ASR). In addition, we carry out the asymptotic analysis by invoking the affine expansion of the ASR in terms of high signal-to-noise ratio (SNR) slope and high SNR Power Offset. Numerical results show that: 1) Compared with orthogonal multiple access (OMA), the proposed networks can significantly improve the ASR since it can reduce the time slots from (M-1)/2+1 to 2; and 2) RHIs of both transmitter and receiver have the same effects on the ASR of the considered networks.
Ofer Zeitouni - One of the best experts on this subject based on the ideXlab platform.
-
On Certain Large Random Hermitian Jacobi Matrices With Applications to Wireless Communications
IEEE Transactions on Information Theory, 2009Co-Authors: Nathan Levy, Oren Somekh, Shlomo Shamai, Ofer ZeitouniAbstract:In this paper we study the spectrum of certain large random Hermitian Jacobi matrices. These matrices are known to describe certain communication setups. In particular, we are interested in an uplink cellular channel which models mobile users experiencing a soft-handoff situation under joint multicell decoding. Considering rather general fading statistics we provide a closed-form expression for the per-cell sum-rate of this channel in high signal-to-noise ratio (SNR), when an intra-cell time-division multiple-access (TDMA) protocol is employed. Since the matrices of interest are tridiagonal, their eigenvectors can be considered as sequences with second-order linear recurrence. Therefore, the problem is reduced to the study of the exponential growth of products of two-by-two matrices. For the case where K users are simultaneously active in each cell, we obtain a series of lower and upper bound on the high-SNR Power Offset of the per-cell sum-rate, which are considerably tighter than previously known bounds.
-
On certain large random Hermitian Jacobi matrices with applications to wireless communications
2008 IEEE International Symposium on Information Theory, 2008Co-Authors: Nathan Levy, Oren Somekh, Shlomo Shamai, Ofer ZeitouniAbstract:In this paper we study the spectrum of certain large random Hermitian Jacobi matrices. These matrices are known to describe certain communication setups. In particular we are interested in an uplink cellular channel which models mobile users experiencing a soft-handoff situation under joint multicell decoding. Considering rather general fading statistics we provide a closed form expression for the per-cell sum-rate of this channel in high-SNR, when an intra-cell TDMA protocol is employed. Since the matrices of interest are tridiagonal, their eigenvectors can be considered as sequences with second order linear recurrence. Therefore, the problem is reduced to the study of the exponential growth of products of two by two matrices. For the case where K users are simultaneously active in each cell, we obtain a series of lower and upper bounds on the high-SNR Power Offset of the per-cell sum-rate, which are considerably tighter than previously known bounds.
-
ISIT - On certain large random Hermitian Jacobi matrices with applications to wireless communications
2008 IEEE International Symposium on Information Theory, 2008Co-Authors: Nathan Levy, Oren Somekh, Shlomo Shamai, Ofer ZeitouniAbstract:In this paper we study the spectrum of certain large random Hermitian Jacobi matrices. These matrices are known to describe certain communication setups. In particular we are interested in an uplink cellular channel which models mobile users experiencing a soft-handoff situation under joint multicell decoding. Considering rather general fading statistics we provide a closed form expression for the per-cell sum-rate of this channel in high-SNR, when an intra-cell TDMA protocol is employed. Since the matrices of interest are tridiagonal, their eigenvectors can be considered as sequences with second order linear recurrence. Therefore, the problem is reduced to the study of the exponential growth of products of two by two matrices. For the case where K users are simultaneously active in each cell, we obtain a series of lower and upper bounds on the high-SNR Power Offset of the per-cell sum-rate, which are considerably tighter than previously known bounds.
Nuno Pratas - One of the best experts on this subject based on the ideXlab platform.
-
VTC Fall - UMTS Common Channel Sensitivity Analysis
IEEE Vehicular Technology Conference, 2006Co-Authors: Nuno Pratas, Antonio Rodrigues, Frederico SantosAbstract:The UMTS common transport channels forward access channel (FACH) and the random access channel (RACH) are two of the three fundamental channels for a functional implementation of an UMTS network. Most signaling procedures, such as the registration procedure, make use of these channels and as such it is necessary that both channels be available across the cell radius. This requirement makes the choice of the transmission parameters a fundamental one. This paper presents a sensitivity analysis regarding the transmission parameters of two UMTS common channels: RACH and FACH. Optimization of these channels is performed and values for the key transmission parameters in both common channels are obtained. On RACH these parameters are the message to preamble Offset, the initial SIR target and the preamble Power step while on FACH it is the transmission Power Offset.
-
UMTS Common Channel Sensitivity Analysis
IEEE Vehicular Technology Conference, 2006Co-Authors: Nuno Pratas, Antonio Rodrigues, Frederico SantosAbstract:The UMTS common transport channels forward access channel (FACH) and the random access channel (RACH) are two of the three fundamental channels for a functional implementation of an UMTS network. Most signaling procedures, such as the registration procedure, make use of these channels and as such it is necessary that both channels be available across the cell radius. This requirement makes the choice of the transmission parameters a fundamental one. This paper presents a sensitivity analysis regarding the transmission parameters of two UMTS common channels: RACH and FACH. Optimization of these channels is performed and values for the key transmission parameters in both common channels are obtained. On RACH these parameters are the message to preamble Offset, the initial SIR target and the preamble Power step while on FACH it is the transmission Power Offset.
S. Verdu - One of the best experts on this subject based on the ideXlab platform.
-
High-SNR Power Offset in multi-antenna Ricean channels
IEEE International Conference on Communications 2005. ICC 2005. 2005, 2005Co-Authors: A.m. Tulino, A. Lozano, S. VerduAbstract:In the high-SNR regime, the multi-antenna mutual information behaves as an affine function of SNR|/sub dB/, described by the multiplexing gain, which quantifies the multiplicative increase as function of the number of antennas, and the Power Offset (zero-order term in dB). The conventional high-SNR analysis that considers only the multiplexing gain is unable to assess the impact of channel features such as the Rician factor since, irrespective thereof, the multiplexing gain equals the minimum of the number of transmit and receive antennas. The impact of the Rician factor at high SNR can be conveniently quantified through the corresponding Power Offset, which this paper evaluates in closed-form.
-
ICC - High-SNR Power Offset in multi-antenna Ricean channels
IEEE International Conference on Communications 2005. ICC 2005. 2005, 2005Co-Authors: A.m. Tulino, A. Lozano, S. VerduAbstract:In the high-SNR regime, the multi-antenna mutual information behaves as an affine function of SNR|/sub dB/, described by the multiplexing gain, which quantifies the multiplicative increase as function of the number of antennas, and the Power Offset (zero-order term in dB). The conventional high-SNR analysis that considers only the multiplexing gain is unable to assess the impact of channel features such as the Rician factor since, irrespective thereof, the multiplexing gain equals the minimum of the number of transmit and receive antennas. The impact of the Rician factor at high SNR can be conveniently quantified through the corresponding Power Offset, which this paper evaluates in closed-form.
-
High-SNR Power Offset in multiantenna communication
IEEE Transactions on Information Theory, 2005Co-Authors: A. Lozano, A.m. Tulino, S. VerduAbstract:The analysis of the multiple-antenna capacity in the high-SNR regime has hitherto focused on the high-SNR slope (or maximum multiplexing gain), which quantifies the multiplicative increase as a function of the number of antennas. This traditional characterization is unable to assess the impact of prominent channel features since, for a majority of channels, the slope equals the minimum of the number of transmit and receive antennas. Furthermore, a characterization based solely on the slope captures only the scaling but it has no notion of the Power required for a certain capacity. This paper advocates a more refined characterization whereby, as a function of SNR|/sub dB/, the high-SNR capacity is expanded as an affine function where the impact of channel features such as antenna correlation, unfaded components, etc., resides in the zero-order term or Power Offset. The Power Offset, for which we find insightful closed-form expressions, is shown to play a chief role for SNR levels of practical interest.
-
ISIT - High-SNR Power Offset in multiantenna communication
International Symposium onInformation Theory 2004. ISIT 2004. Proceedings., 2004Co-Authors: A. Lozano, A.m. Tulino, S. VerduAbstract:In this paper, the high-SNR multiantenna capacity with coherent receivers on the multiplexing gain, i.e., the multiplicative increase as function of the number of antennas is analyzed. For most channels of interest, such multiplexing gain equals the minimum of the number of transmit and receive antennas. This traditional characterization, however, is unable to quantify the impact of many relevant channel features. As a function of SNR, the capacity is very well approximated, from moderate SNR on, as an affine function. The impact of the various channel features is captured in the Power Offset (in dB) or zero-order term in the affine expansion.
-
High-SNR Power Offset in multiantenna communication
International Symposium onInformation Theory 2004. ISIT 2004. Proceedings., 2004Co-Authors: A. Lozano, A.m. Tulino, S. VerduAbstract:In this paper, the high-SNR multiantenna capacity with coherent receivers on the multiplexing gain, i.e., the multiplicative increase as function of the number of antennas is analyzed. For most channels of interest, such multiplexing gain equals the minimum of the number of transmit and receive antennas. This traditional characterization, however, is unable to quantify the impact of many relevant channel features. As a function of SNR, the capacity is very well approximated, from moderate SNR on, as an affine function. The impact of the various channel features is captured in the Power Offset (in dB) or zero-order term in the affine expansion.
