In this paper, an adaptive integrated framework is devised to provide continuous video service fr... more In this paper, an adaptive integrated framework is devised to provide continuous video service from a base station to multiple secondary users over a cognitive radio network. A channel allocation algorithm is introduced to adaptively assign the available channels to the secondary users while taking into considerations their buffer occupancies as well as the maximum available bit budget and the deadlines of the video frames. The proposed scheme aims at improving the video quality by increasing the number of received enhancement layers for each transmitted video frame. This is done by jointly adapting the modulation levels and channel coding while benefiting from frames retransmissions, when possible, to guarantee their successful reception when they can still meet their deadlines. The simulation results show that the proposed scheme reacts to the variations in channel conditions as well the dynamics of the playback buffers at the secondary users’ end by representing the transmitted video information at the highest possible bit rates while exploiting the scalability feature of the encoded video frames. This is reflected in the improved perceptual quality as received by the secondary users with uninterrupted playback.
We investigate the performance of modified non orthogonal multiple access (NOMA) which uses the m... more We investigate the performance of modified non orthogonal multiple access (NOMA) which uses the modified low complexity Vertical Bell Laboratories Layered Space Time (C-V-BLAST) in an uplink massive multiple-input-multiple-output (MIMO) deployment with distributed single-antenna users and a large base-station array. Unlike previous work which assumes no spreading, we focus on the scenario where signal spreading is included by using the Gold Code family. It is shown that the proposed scheme provides a significant performance improvement over the conventional V-BLAST system for a large MIMO deployment when the number of transmit and receive antennas are comparable by exploiting the extra dimension added by the spreading to mitigate the interference. However, for a massive MIMO system, both schemes provide similar performance. We also show that the proposed scheme has a much better performance when the average received power for the users is the same, a scenario that the C-V-BLAST scheme struggles with due to its dependence on the ordering of users according to their power levels.
We investigate the performance of a spread spectrum non-orthogonal multiple access (NOMA) system ... more We investigate the performance of a spread spectrum non-orthogonal multiple access (NOMA) system that uses a low complexity Vertical Bell Laboratories Layered Space Time (C-V-BLAST) scheme in an uplink massive multiple-input-multiple-output (MIMO) deployment with single transmit antenna per user. Both synchronous and asynchronous scenarios are considered with channel imperfections and using different types of spreading codes under a power decay or shadow fading channel model. Simulations show that under the power decay model there is no impact of the code type or code length on the performance, especially for massive MIMO with large number of receive antennas. However, when the shadow fading channel model is used, we observe significant difference in the performance with Walsh codes and Gold codes providing the best performance for the synchronous and asynchronous situations, respectively. When the number of antennas at the receiver is small, spreading provides a vital gain over the traditional C-V-BLAST system.
2019 International Conference on Communications, Signal Processing, and their Applications (ICCSPA)
Recently, a New Radio (NR) structure has been proposed for fifth generation (5G) mobile radio sys... more Recently, a New Radio (NR) structure has been proposed for fifth generation (5G) mobile radio systems to support higher data rates and low latency scenarios. In this paper, we investigate the performance of 5G New Radio (5GNR) using precoding for Interference Alignment (IA). The system is based on an OFDM structure following the NR scheme with zero forcing receiver. It is shown that with proper selection of the precoder, an improvement of about one order of magnitude in the bit error rate due to IA is achieved. Index Terms– 5GNR, Interference alignment, MIMO, zero forcing.
2018 27th Wireless and Optical Communication Conference (WOCC), 2018
We investigate the performance of a spread spectrum non-orthogonal multiple access (NOMA) system ... more We investigate the performance of a spread spectrum non-orthogonal multiple access (NOMA) system that uses a low complexity Vertical Bell Laboratories Layered Space Time (C-V-BLAST) scheme in an uplink massive multiple-input-multiple-output (MIMO) deployment with single transmit antenna per user. Both synchronous and asynchronous scenarios are considered with channel imperfections and using different types of spreading codes under a power decay or shadow fading channel model. Simulations show that under the power decay model there is no impact of the code type or code length on the performance, especially for massive MIMO with large number of receive antennas. However, when the shadow fading channel model is used, we observe significant difference in the performance with Walsh codes and Gold codes providing the best performance for the synchronous and asynchronous situations, respectively. When the number of antennas at the receiver is small, spreading provides a vital gain over the traditional C-V-BLAST system.
In this paper, an adaptive integrated framework is devised to provide continuous video service fr... more In this paper, an adaptive integrated framework is devised to provide continuous video service from a base station to multiple secondary users over a cognitive radio network. A channel allocation algorithm is introduced to adaptively assign the available channels to the secondary users while taking into considerations their buffer occupancies as well as the maximum available bit budget and the deadlines of the video frames. The proposed scheme aims at improving the video quality by increasing the number of received enhancement layers for each transmitted video frame. This is done by jointly adapting the modulation levels and channel coding while benefiting from frames retransmissions, when possible, to guarantee their successful reception when they can still meet their deadlines. The simulation results show that the proposed scheme reacts to the variations in channel conditions as well the dynamics of the playback buffers at the secondary users’ end by representing the transmitted v...
International Journal of Interdisciplinary Telecommunications and Networking, 2020
The recently proposed extension of the LTE operation to the unlicensed spectrum, known as LTE-Unl... more The recently proposed extension of the LTE operation to the unlicensed spectrum, known as LTE-Unlicensed (LTE-U), is not only expected to alleviate the congestion in the licensed band but is expected to result in an increase in the network capacity, as well. Unfortunately, such extension is challenged by a coexistence problem with wireless technologies operating in the unlicensed spectrum, especially Wi-Fi. Therefore, this article employs time series forecasting methods to enable efficient LTE coexistence with Wi-Fi. This is done by enabling the LTE-U Home eNodeB (HeNB) to avoid collisions with Wi-Fi by predicting the state of the unlicensed channels prior to using them. Specifically, this research proposes a recurrent neural network-based algorithm that utilizes Long Short Term Memory (LSTM) networks with time series decomposition to predict the state of the channels in the unlicensed spectrum. The authors investigate the performance of the proposed approach using extensive simulat...
This paper investigates the tracking of DS/SS signals based on an adaptive filtering technique. I... more This paper investigates the tracking of DS/SS signals based on an adaptive filtering technique. It is shown that a previously proposed system for code acquisition is also capable of code tracking and, by performing both acquisition and tracking with the same circuitry, significant simplification in the overall DS/SS receiver is gained. Analytical results show that the proposed scheme has a
The paper is focused on estimating the signal-to-interference ratio (SIR) per multipath component... more The paper is focused on estimating the signal-to-interference ratio (SIR) per multipath component in CDMA systems operating over frequency selective Rayleigh fading channels. A per-path SIR estimator is proposed and its performance is compared to the Cramer-Rao bound (CRB) derived for this problem. To account for the hardware limitations of portable mobile terminals, a low complexity version of the estimator
In this paper, a new scheme for delay estimation of multipath components in a direct-sequence spr... more In this paper, a new scheme for delay estimation of multipath components in a direct-sequence spread spectrum system is presented. The proposed scheme is based on a conventional energy detector followed by an independent component analysis (ICA) algorithm. The ICA algorithm effectively decomposes the received signal into the independent paths and noise term and hence provides information about the delay
In current and next 3G and beyond Mobile wireless systems, sharing the radio access network has b... more In current and next 3G and beyond Mobile wireless systems, sharing the radio access network has become an important issue for 3G mobile operators. Sharing network infrastructure amongst operators offers an alternative solution to reduce the investment in the coverage phase of ...
The impact of chip waveform shaping on the synchronization performance of DS-CDMA signals is inve... more The impact of chip waveform shaping on the synchronization performance of DS-CDMA signals is investigated. Acquisition and tracking performance are compared for signals with both full-response and partial response pulses. To ensure fair comparison, all pulses are prefiltered to occupy the same bandwidth. It is shown that full-response pulses significantly outperform the partial-response waveforms from the acquisition performance prospective. However,
In this paper, an adaptive integrated framework is devised to provide continuous video service fr... more In this paper, an adaptive integrated framework is devised to provide continuous video service from a base station to multiple secondary users over a cognitive radio network. A channel allocation algorithm is introduced to adaptively assign the available channels to the secondary users while taking into considerations their buffer occupancies as well as the maximum available bit budget and the deadlines of the video frames. The proposed scheme aims at improving the video quality by increasing the number of received enhancement layers for each transmitted video frame. This is done by jointly adapting the modulation levels and channel coding while benefiting from frames retransmissions, when possible, to guarantee their successful reception when they can still meet their deadlines. The simulation results show that the proposed scheme reacts to the variations in channel conditions as well the dynamics of the playback buffers at the secondary users’ end by representing the transmitted video information at the highest possible bit rates while exploiting the scalability feature of the encoded video frames. This is reflected in the improved perceptual quality as received by the secondary users with uninterrupted playback.
We investigate the performance of modified non orthogonal multiple access (NOMA) which uses the m... more We investigate the performance of modified non orthogonal multiple access (NOMA) which uses the modified low complexity Vertical Bell Laboratories Layered Space Time (C-V-BLAST) in an uplink massive multiple-input-multiple-output (MIMO) deployment with distributed single-antenna users and a large base-station array. Unlike previous work which assumes no spreading, we focus on the scenario where signal spreading is included by using the Gold Code family. It is shown that the proposed scheme provides a significant performance improvement over the conventional V-BLAST system for a large MIMO deployment when the number of transmit and receive antennas are comparable by exploiting the extra dimension added by the spreading to mitigate the interference. However, for a massive MIMO system, both schemes provide similar performance. We also show that the proposed scheme has a much better performance when the average received power for the users is the same, a scenario that the C-V-BLAST scheme struggles with due to its dependence on the ordering of users according to their power levels.
We investigate the performance of a spread spectrum non-orthogonal multiple access (NOMA) system ... more We investigate the performance of a spread spectrum non-orthogonal multiple access (NOMA) system that uses a low complexity Vertical Bell Laboratories Layered Space Time (C-V-BLAST) scheme in an uplink massive multiple-input-multiple-output (MIMO) deployment with single transmit antenna per user. Both synchronous and asynchronous scenarios are considered with channel imperfections and using different types of spreading codes under a power decay or shadow fading channel model. Simulations show that under the power decay model there is no impact of the code type or code length on the performance, especially for massive MIMO with large number of receive antennas. However, when the shadow fading channel model is used, we observe significant difference in the performance with Walsh codes and Gold codes providing the best performance for the synchronous and asynchronous situations, respectively. When the number of antennas at the receiver is small, spreading provides a vital gain over the traditional C-V-BLAST system.
2019 International Conference on Communications, Signal Processing, and their Applications (ICCSPA)
Recently, a New Radio (NR) structure has been proposed for fifth generation (5G) mobile radio sys... more Recently, a New Radio (NR) structure has been proposed for fifth generation (5G) mobile radio systems to support higher data rates and low latency scenarios. In this paper, we investigate the performance of 5G New Radio (5GNR) using precoding for Interference Alignment (IA). The system is based on an OFDM structure following the NR scheme with zero forcing receiver. It is shown that with proper selection of the precoder, an improvement of about one order of magnitude in the bit error rate due to IA is achieved. Index Terms– 5GNR, Interference alignment, MIMO, zero forcing.
2018 27th Wireless and Optical Communication Conference (WOCC), 2018
We investigate the performance of a spread spectrum non-orthogonal multiple access (NOMA) system ... more We investigate the performance of a spread spectrum non-orthogonal multiple access (NOMA) system that uses a low complexity Vertical Bell Laboratories Layered Space Time (C-V-BLAST) scheme in an uplink massive multiple-input-multiple-output (MIMO) deployment with single transmit antenna per user. Both synchronous and asynchronous scenarios are considered with channel imperfections and using different types of spreading codes under a power decay or shadow fading channel model. Simulations show that under the power decay model there is no impact of the code type or code length on the performance, especially for massive MIMO with large number of receive antennas. However, when the shadow fading channel model is used, we observe significant difference in the performance with Walsh codes and Gold codes providing the best performance for the synchronous and asynchronous situations, respectively. When the number of antennas at the receiver is small, spreading provides a vital gain over the traditional C-V-BLAST system.
In this paper, an adaptive integrated framework is devised to provide continuous video service fr... more In this paper, an adaptive integrated framework is devised to provide continuous video service from a base station to multiple secondary users over a cognitive radio network. A channel allocation algorithm is introduced to adaptively assign the available channels to the secondary users while taking into considerations their buffer occupancies as well as the maximum available bit budget and the deadlines of the video frames. The proposed scheme aims at improving the video quality by increasing the number of received enhancement layers for each transmitted video frame. This is done by jointly adapting the modulation levels and channel coding while benefiting from frames retransmissions, when possible, to guarantee their successful reception when they can still meet their deadlines. The simulation results show that the proposed scheme reacts to the variations in channel conditions as well the dynamics of the playback buffers at the secondary users’ end by representing the transmitted v...
International Journal of Interdisciplinary Telecommunications and Networking, 2020
The recently proposed extension of the LTE operation to the unlicensed spectrum, known as LTE-Unl... more The recently proposed extension of the LTE operation to the unlicensed spectrum, known as LTE-Unlicensed (LTE-U), is not only expected to alleviate the congestion in the licensed band but is expected to result in an increase in the network capacity, as well. Unfortunately, such extension is challenged by a coexistence problem with wireless technologies operating in the unlicensed spectrum, especially Wi-Fi. Therefore, this article employs time series forecasting methods to enable efficient LTE coexistence with Wi-Fi. This is done by enabling the LTE-U Home eNodeB (HeNB) to avoid collisions with Wi-Fi by predicting the state of the unlicensed channels prior to using them. Specifically, this research proposes a recurrent neural network-based algorithm that utilizes Long Short Term Memory (LSTM) networks with time series decomposition to predict the state of the channels in the unlicensed spectrum. The authors investigate the performance of the proposed approach using extensive simulat...
This paper investigates the tracking of DS/SS signals based on an adaptive filtering technique. I... more This paper investigates the tracking of DS/SS signals based on an adaptive filtering technique. It is shown that a previously proposed system for code acquisition is also capable of code tracking and, by performing both acquisition and tracking with the same circuitry, significant simplification in the overall DS/SS receiver is gained. Analytical results show that the proposed scheme has a
The paper is focused on estimating the signal-to-interference ratio (SIR) per multipath component... more The paper is focused on estimating the signal-to-interference ratio (SIR) per multipath component in CDMA systems operating over frequency selective Rayleigh fading channels. A per-path SIR estimator is proposed and its performance is compared to the Cramer-Rao bound (CRB) derived for this problem. To account for the hardware limitations of portable mobile terminals, a low complexity version of the estimator
In this paper, a new scheme for delay estimation of multipath components in a direct-sequence spr... more In this paper, a new scheme for delay estimation of multipath components in a direct-sequence spread spectrum system is presented. The proposed scheme is based on a conventional energy detector followed by an independent component analysis (ICA) algorithm. The ICA algorithm effectively decomposes the received signal into the independent paths and noise term and hence provides information about the delay
In current and next 3G and beyond Mobile wireless systems, sharing the radio access network has b... more In current and next 3G and beyond Mobile wireless systems, sharing the radio access network has become an important issue for 3G mobile operators. Sharing network infrastructure amongst operators offers an alternative solution to reduce the investment in the coverage phase of ...
The impact of chip waveform shaping on the synchronization performance of DS-CDMA signals is inve... more The impact of chip waveform shaping on the synchronization performance of DS-CDMA signals is investigated. Acquisition and tracking performance are compared for signals with both full-response and partial response pulses. To ensure fair comparison, all pulses are prefiltered to occupy the same bandwidth. It is shown that full-response pulses significantly outperform the partial-response waveforms from the acquisition performance prospective. However,
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