The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Nambirajan Seshadri - One of the best experts on this subject based on the ideXlab platform.
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a space time coding modem for High Data Rate wireless communications
IEEE Journal on Selected Areas in Communications, 1998Co-Authors: Ayman Fawzy Naguib, Vahid Tarokh, Nambirajan Seshadri, A R CalderbankAbstract:This paper presents the theory and practice of a new advanced modem technology suitable for High-Data-Rate wireless communications and presents its performance over a frequency-flat Rayleigh fading channel. The new technology is based on space-time coded modulation (STCM) with multiple transmit and/or multiple receive antennas and orthogonal pilot sequence insertion (O-PSI). In this approach, Data is encoded by a space-time (ST) channel encoder and the output of the encoder is split into N streams to be simultaneously transmitted using N transmit antennas. The transmitter inserts periodic orthogonal pilot sequences in each of the simultaneously transmitted bursts. The receiver uses those pilot sequences to estimate the fading channel. When combined with an appropriately designed interpolation filter, accuRate channel state information (CSI) can be estimated for the decoding process. Simulation results of the proposed modem, as applied to the IS-136 cellular standard, are presented. We present the frame error Rate (FER) performance results as a function of the signal-to-noise ratio (SNR) and the maximum Doppler frequency, in the presence of timing and frequency offset errors. Simulation results show that for a 10% FER, a 32-state eight-phase-shift keyed (8-PSK) ST code with two transmit and two receive antennas can support Data Rates up to 55.8 kb/s on a 30-kHz channel, at an SNR of 11.7 dB and a maximum Doppler frequency of 180 Hz. Simulation results for other codes and other channel conditions are also provided. We also compare the performance of the proposed STCM scheme with delay diversity schemes and conclude that STCM can provide significant SNR improvement over simple delay diversity.
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space time coded ofdm for High Data Rate wireless communication over wideband channels
Vehicular Technology Conference, 1998Co-Authors: Dakshi Agrawal, Ayman Fawzy Naguib, Vahid Tarokh, Nambirajan SeshadriAbstract:There has been an increasing interest in providing High Data-Rate services such as video-conferencing, multimedia Internet access and wide area network over wideband wireless channels. Wideband wireless channels available in the PCS band (2 GHz) have been envisioned to be used by mobile (High Doppler) and stationary (low Doppler) units in a variety of delay spread profiles. This is a challenging task, given the limited link budget and severity of wireless environment, and calls for the development of novel robust bandwidth efficient techniques which work reliably at low SNRs. To this end, we design a space-time coded orthogonal frequency division multiplexing (OFDM) modulated physical layer. This combines coding and modulation. Space-time codes were previously proposed for narrowband wireless channels. These codes have High spectral efficiency and opeRate at very low SNR (within 2-3 dB of the capacity). On the other hand, OFDM has matured as a modulation scheme for wideband channels. We combine these two in a natural manner and propose a system achieving Data Rates of 1.5-3 Mbps over a 1 MHz bandwidth channel. This system requires 18-23 dB (resp. 9-14 dB) receive SNR at a frame error probability of 10/sup -2/ with two transmit and one receive antennas (resp. two transmit and two receive antennas). As space-time coding does not require any form of interleaving, the proposed system is attractive for delay-sensitive applications.
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space time codes for High Data Rate wireless communication performance criterion and code construction
IEEE Transactions on Information Theory, 1998Co-Authors: Vahid Tarokh, Nambirajan Seshadri, A R CalderbankAbstract:We consider the design of channel codes for improving the Data Rate and/or the reliability of communications over fading channels using multiple transmit antennas. Data is encoded by a channel code and the encoded Data is split into n streams that are simultaneously transmitted using n transmit antennas. The received signal at each receive antenna is a linear superposition of the n transmitted signals perturbed by noise. We derive performance criteria for designing such codes under the assumption that the fading is slow and frequency nonselective. Performance is shown to be determined by matrices constructed from pairs of distinct code sequences. The minimum rank among these matrices quantifies the diversity gain, while the minimum determinant of these matrices quantifies the coding gain. The results are then extended to fast fading channels. The design criteria are used to design trellis codes for High Data Rate wireless communication. The encoding/decoding complexity of these codes is comparable to trellis codes employed in practice over Gaussian channels. The codes constructed here provide the best tradeoff between Data Rate, diversity advantage, and trellis complexity. Simulation results are provided for 4 and 8 PSK signal sets with Data Rates of 2 and 3 bits/symbol, demonstrating excellent performance that is within 2-3 dB of the outage capacity for these channels using only 64 state encoders.
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space time codes for High Data Rate wireless communication mismatch analysis
International Conference on Communications, 1997Co-Authors: Vahid Tarokh, Ayman Fawzy Naguib, Nambirajan Seshadri, A R CalderbankAbstract:We revisit space-time codes for a mobile communication system that employs multiple antennas at the base station and optional antenna diversity at the mobile station. The realistic case when the channel state is not completely known is considered. It is assumed that the channel estimator extracts the fade coefficients using orthogonal pilot tones. Mismatch analysis is then carried out. It is proved that in the absence of ideal channel state information the design criteria for space-time codes developed in Tarokh et al. (1997) is still valid for the equal energy constellation case. Using our derivation, it is observed that channel estimation techniques commonly used over rapidly fading channels can be used in conjunction with space-time codes provided that the number of transmit antennas is small.
A R Calderbank - One of the best experts on this subject based on the ideXlab platform.
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a space time coding modem for High Data Rate wireless communications
IEEE Journal on Selected Areas in Communications, 1998Co-Authors: Ayman Fawzy Naguib, Vahid Tarokh, Nambirajan Seshadri, A R CalderbankAbstract:This paper presents the theory and practice of a new advanced modem technology suitable for High-Data-Rate wireless communications and presents its performance over a frequency-flat Rayleigh fading channel. The new technology is based on space-time coded modulation (STCM) with multiple transmit and/or multiple receive antennas and orthogonal pilot sequence insertion (O-PSI). In this approach, Data is encoded by a space-time (ST) channel encoder and the output of the encoder is split into N streams to be simultaneously transmitted using N transmit antennas. The transmitter inserts periodic orthogonal pilot sequences in each of the simultaneously transmitted bursts. The receiver uses those pilot sequences to estimate the fading channel. When combined with an appropriately designed interpolation filter, accuRate channel state information (CSI) can be estimated for the decoding process. Simulation results of the proposed modem, as applied to the IS-136 cellular standard, are presented. We present the frame error Rate (FER) performance results as a function of the signal-to-noise ratio (SNR) and the maximum Doppler frequency, in the presence of timing and frequency offset errors. Simulation results show that for a 10% FER, a 32-state eight-phase-shift keyed (8-PSK) ST code with two transmit and two receive antennas can support Data Rates up to 55.8 kb/s on a 30-kHz channel, at an SNR of 11.7 dB and a maximum Doppler frequency of 180 Hz. Simulation results for other codes and other channel conditions are also provided. We also compare the performance of the proposed STCM scheme with delay diversity schemes and conclude that STCM can provide significant SNR improvement over simple delay diversity.
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space time codes for High Data Rate wireless communication performance criterion and code construction
IEEE Transactions on Information Theory, 1998Co-Authors: Vahid Tarokh, Nambirajan Seshadri, A R CalderbankAbstract:We consider the design of channel codes for improving the Data Rate and/or the reliability of communications over fading channels using multiple transmit antennas. Data is encoded by a channel code and the encoded Data is split into n streams that are simultaneously transmitted using n transmit antennas. The received signal at each receive antenna is a linear superposition of the n transmitted signals perturbed by noise. We derive performance criteria for designing such codes under the assumption that the fading is slow and frequency nonselective. Performance is shown to be determined by matrices constructed from pairs of distinct code sequences. The minimum rank among these matrices quantifies the diversity gain, while the minimum determinant of these matrices quantifies the coding gain. The results are then extended to fast fading channels. The design criteria are used to design trellis codes for High Data Rate wireless communication. The encoding/decoding complexity of these codes is comparable to trellis codes employed in practice over Gaussian channels. The codes constructed here provide the best tradeoff between Data Rate, diversity advantage, and trellis complexity. Simulation results are provided for 4 and 8 PSK signal sets with Data Rates of 2 and 3 bits/symbol, demonstrating excellent performance that is within 2-3 dB of the outage capacity for these channels using only 64 state encoders.
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space time codes for High Data Rate wireless communication mismatch analysis
International Conference on Communications, 1997Co-Authors: Vahid Tarokh, Ayman Fawzy Naguib, Nambirajan Seshadri, A R CalderbankAbstract:We revisit space-time codes for a mobile communication system that employs multiple antennas at the base station and optional antenna diversity at the mobile station. The realistic case when the channel state is not completely known is considered. It is assumed that the channel estimator extracts the fade coefficients using orthogonal pilot tones. Mismatch analysis is then carried out. It is proved that in the absence of ideal channel state information the design criteria for space-time codes developed in Tarokh et al. (1997) is still valid for the equal energy constellation case. Using our derivation, it is observed that channel estimation techniques commonly used over rapidly fading channels can be used in conjunction with space-time codes provided that the number of transmit antennas is small.
Vahid Tarokh - One of the best experts on this subject based on the ideXlab platform.
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a space time coding modem for High Data Rate wireless communications
IEEE Journal on Selected Areas in Communications, 1998Co-Authors: Ayman Fawzy Naguib, Vahid Tarokh, Nambirajan Seshadri, A R CalderbankAbstract:This paper presents the theory and practice of a new advanced modem technology suitable for High-Data-Rate wireless communications and presents its performance over a frequency-flat Rayleigh fading channel. The new technology is based on space-time coded modulation (STCM) with multiple transmit and/or multiple receive antennas and orthogonal pilot sequence insertion (O-PSI). In this approach, Data is encoded by a space-time (ST) channel encoder and the output of the encoder is split into N streams to be simultaneously transmitted using N transmit antennas. The transmitter inserts periodic orthogonal pilot sequences in each of the simultaneously transmitted bursts. The receiver uses those pilot sequences to estimate the fading channel. When combined with an appropriately designed interpolation filter, accuRate channel state information (CSI) can be estimated for the decoding process. Simulation results of the proposed modem, as applied to the IS-136 cellular standard, are presented. We present the frame error Rate (FER) performance results as a function of the signal-to-noise ratio (SNR) and the maximum Doppler frequency, in the presence of timing and frequency offset errors. Simulation results show that for a 10% FER, a 32-state eight-phase-shift keyed (8-PSK) ST code with two transmit and two receive antennas can support Data Rates up to 55.8 kb/s on a 30-kHz channel, at an SNR of 11.7 dB and a maximum Doppler frequency of 180 Hz. Simulation results for other codes and other channel conditions are also provided. We also compare the performance of the proposed STCM scheme with delay diversity schemes and conclude that STCM can provide significant SNR improvement over simple delay diversity.
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space time coded ofdm for High Data Rate wireless communication over wideband channels
Vehicular Technology Conference, 1998Co-Authors: Dakshi Agrawal, Ayman Fawzy Naguib, Vahid Tarokh, Nambirajan SeshadriAbstract:There has been an increasing interest in providing High Data-Rate services such as video-conferencing, multimedia Internet access and wide area network over wideband wireless channels. Wideband wireless channels available in the PCS band (2 GHz) have been envisioned to be used by mobile (High Doppler) and stationary (low Doppler) units in a variety of delay spread profiles. This is a challenging task, given the limited link budget and severity of wireless environment, and calls for the development of novel robust bandwidth efficient techniques which work reliably at low SNRs. To this end, we design a space-time coded orthogonal frequency division multiplexing (OFDM) modulated physical layer. This combines coding and modulation. Space-time codes were previously proposed for narrowband wireless channels. These codes have High spectral efficiency and opeRate at very low SNR (within 2-3 dB of the capacity). On the other hand, OFDM has matured as a modulation scheme for wideband channels. We combine these two in a natural manner and propose a system achieving Data Rates of 1.5-3 Mbps over a 1 MHz bandwidth channel. This system requires 18-23 dB (resp. 9-14 dB) receive SNR at a frame error probability of 10/sup -2/ with two transmit and one receive antennas (resp. two transmit and two receive antennas). As space-time coding does not require any form of interleaving, the proposed system is attractive for delay-sensitive applications.
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space time codes for High Data Rate wireless communication performance criterion and code construction
IEEE Transactions on Information Theory, 1998Co-Authors: Vahid Tarokh, Nambirajan Seshadri, A R CalderbankAbstract:We consider the design of channel codes for improving the Data Rate and/or the reliability of communications over fading channels using multiple transmit antennas. Data is encoded by a channel code and the encoded Data is split into n streams that are simultaneously transmitted using n transmit antennas. The received signal at each receive antenna is a linear superposition of the n transmitted signals perturbed by noise. We derive performance criteria for designing such codes under the assumption that the fading is slow and frequency nonselective. Performance is shown to be determined by matrices constructed from pairs of distinct code sequences. The minimum rank among these matrices quantifies the diversity gain, while the minimum determinant of these matrices quantifies the coding gain. The results are then extended to fast fading channels. The design criteria are used to design trellis codes for High Data Rate wireless communication. The encoding/decoding complexity of these codes is comparable to trellis codes employed in practice over Gaussian channels. The codes constructed here provide the best tradeoff between Data Rate, diversity advantage, and trellis complexity. Simulation results are provided for 4 and 8 PSK signal sets with Data Rates of 2 and 3 bits/symbol, demonstrating excellent performance that is within 2-3 dB of the outage capacity for these channels using only 64 state encoders.
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space time codes for High Data Rate wireless communication mismatch analysis
International Conference on Communications, 1997Co-Authors: Vahid Tarokh, Ayman Fawzy Naguib, Nambirajan Seshadri, A R CalderbankAbstract:We revisit space-time codes for a mobile communication system that employs multiple antennas at the base station and optional antenna diversity at the mobile station. The realistic case when the channel state is not completely known is considered. It is assumed that the channel estimator extracts the fade coefficients using orthogonal pilot tones. Mismatch analysis is then carried out. It is proved that in the absence of ideal channel state information the design criteria for space-time codes developed in Tarokh et al. (1997) is still valid for the equal energy constellation case. Using our derivation, it is observed that channel estimation techniques commonly used over rapidly fading channels can be used in conjunction with space-time codes provided that the number of transmit antennas is small.
Ayman Fawzy Naguib - One of the best experts on this subject based on the ideXlab platform.
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a space time coding modem for High Data Rate wireless communications
IEEE Journal on Selected Areas in Communications, 1998Co-Authors: Ayman Fawzy Naguib, Vahid Tarokh, Nambirajan Seshadri, A R CalderbankAbstract:This paper presents the theory and practice of a new advanced modem technology suitable for High-Data-Rate wireless communications and presents its performance over a frequency-flat Rayleigh fading channel. The new technology is based on space-time coded modulation (STCM) with multiple transmit and/or multiple receive antennas and orthogonal pilot sequence insertion (O-PSI). In this approach, Data is encoded by a space-time (ST) channel encoder and the output of the encoder is split into N streams to be simultaneously transmitted using N transmit antennas. The transmitter inserts periodic orthogonal pilot sequences in each of the simultaneously transmitted bursts. The receiver uses those pilot sequences to estimate the fading channel. When combined with an appropriately designed interpolation filter, accuRate channel state information (CSI) can be estimated for the decoding process. Simulation results of the proposed modem, as applied to the IS-136 cellular standard, are presented. We present the frame error Rate (FER) performance results as a function of the signal-to-noise ratio (SNR) and the maximum Doppler frequency, in the presence of timing and frequency offset errors. Simulation results show that for a 10% FER, a 32-state eight-phase-shift keyed (8-PSK) ST code with two transmit and two receive antennas can support Data Rates up to 55.8 kb/s on a 30-kHz channel, at an SNR of 11.7 dB and a maximum Doppler frequency of 180 Hz. Simulation results for other codes and other channel conditions are also provided. We also compare the performance of the proposed STCM scheme with delay diversity schemes and conclude that STCM can provide significant SNR improvement over simple delay diversity.
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space time coded ofdm for High Data Rate wireless communication over wideband channels
Vehicular Technology Conference, 1998Co-Authors: Dakshi Agrawal, Ayman Fawzy Naguib, Vahid Tarokh, Nambirajan SeshadriAbstract:There has been an increasing interest in providing High Data-Rate services such as video-conferencing, multimedia Internet access and wide area network over wideband wireless channels. Wideband wireless channels available in the PCS band (2 GHz) have been envisioned to be used by mobile (High Doppler) and stationary (low Doppler) units in a variety of delay spread profiles. This is a challenging task, given the limited link budget and severity of wireless environment, and calls for the development of novel robust bandwidth efficient techniques which work reliably at low SNRs. To this end, we design a space-time coded orthogonal frequency division multiplexing (OFDM) modulated physical layer. This combines coding and modulation. Space-time codes were previously proposed for narrowband wireless channels. These codes have High spectral efficiency and opeRate at very low SNR (within 2-3 dB of the capacity). On the other hand, OFDM has matured as a modulation scheme for wideband channels. We combine these two in a natural manner and propose a system achieving Data Rates of 1.5-3 Mbps over a 1 MHz bandwidth channel. This system requires 18-23 dB (resp. 9-14 dB) receive SNR at a frame error probability of 10/sup -2/ with two transmit and one receive antennas (resp. two transmit and two receive antennas). As space-time coding does not require any form of interleaving, the proposed system is attractive for delay-sensitive applications.
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space time codes for High Data Rate wireless communication mismatch analysis
International Conference on Communications, 1997Co-Authors: Vahid Tarokh, Ayman Fawzy Naguib, Nambirajan Seshadri, A R CalderbankAbstract:We revisit space-time codes for a mobile communication system that employs multiple antennas at the base station and optional antenna diversity at the mobile station. The realistic case when the channel state is not completely known is considered. It is assumed that the channel estimator extracts the fade coefficients using orthogonal pilot tones. Mismatch analysis is then carried out. It is proved that in the absence of ideal channel state information the design criteria for space-time codes developed in Tarokh et al. (1997) is still valid for the equal energy constellation case. Using our derivation, it is observed that channel estimation techniques commonly used over rapidly fading channels can be used in conjunction with space-time codes provided that the number of transmit antennas is small.
Jeffery S Stone - One of the best experts on this subject based on the ideXlab platform.
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High Data Rate few mode transmission over graded index single mode fiber using 850 nm single mode vcsel
Optics Express, 2019Co-Authors: Kangmei Li, Xin Chen, Jason Hurley, Jeffery S Stone, Mingjun LiAbstract:A few-mode transmission system is proposed using 850 nm single-mode VCSEL based transceivers over graded-index single-mode fibers for High Data Rate Data center applications. A graded-index single-mode fiber that supports two mode groups at 850 nm window with a High modal bandwidth of 48.3 GHz·km is realized for the first time. 25 Gb/s transmission experiments using a 850 nm single-mode VCSEL over such fiber demonstRate that the system can support a link distance up to 1.5 km. Additionally, link model analysis provides more insights on how fiber and single-mode VCSEL parameters impact the system performance.
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High Data Rate few mode transmission over graded index single mode fiber using 850 nm single mode vcsel
Optics Express, 2019Co-Authors: Xin Chen, Jason Hurley, Jeffery S StoneAbstract:A few-mode transmission system is proposed using 850 nm single-mode VCSEL based transceivers over graded-index single-mode fibers for High Data Rate Data center applications. A graded-index single-mode fiber that supports two mode groups at 850 nm window with a High modal bandwidth of 48.3 GHz·km is realized for the first time. 25 Gb/s transmission experiments using a 850 nm single-mode VCSEL over such fiber demonstRate that the system can support a link distance up to 1.5 km. Additionally, link model analysis provides more insights on how fiber and single-mode VCSEL parameters impact the system performance.
