ABSTRACT In this paper we investigate a signal design method to increase spectral efficiency and ... more ABSTRACT In this paper we investigate a signal design method to increase spectral efficiency and to limit high peak to average power ratio (PAPR) input signal combinations to OFDM sub-carriers. It reduces PAPR level of an OFDM system without decreasing bandwidth utilization. The system design also shows how a set of concatenated Walsh Hadamard (WH) codes can be used to spread a block of information bits to increase number of orthogonal spreading codes while keeping the spreading factor at a low level
An exact expression for the joint density of three correlated Rician variables is not available i... more An exact expression for the joint density of three correlated Rician variables is not available in the open literature. In this letter, we derive new infinite series representations for the trivariate Rician probability density function (pdf) and the joint cumulative distribution function (cdf). Our results are limited to the case where the inverse covariance matrix is tridiagonal. This case seems
Blind sensing for identifying unused frequency bands is of particular interest in cognitive radio... more Blind sensing for identifying unused frequency bands is of particular interest in cognitive radio and ultra wide-band ap- plications. Energy detection is one such method proposed to identify the presence of an unknown band-limited deter- ministic signal. In this paper, by using an alternative series representation of the Marcum-Q function, the exact average detection probability over the Nakagami-m fading channel
Although the topic of multiple-input multiple-output (MIMO) based orthogonal frequency division m... more Although the topic of multiple-input multiple-output (MIMO) based orthogonal frequency division multiplexing (OFDM) over different fading channels is well investigated, its closed form symbol error rate (SER) expressions and performance results employing orthogonal space time block codes (OSTBCs) over uncorrelated frequency-selective Nakagami-m fading channels are still not available. The closed form expressions are extremely useful for evaluating system's performance without
The performance of a two hop amplify-and-forward relay system, where the source-relay and the rel... more The performance of a two hop amplify-and-forward relay system, where the source-relay and the relay-destination channels experience Rayleigh and Rician fading, respectively, is investigated with relay selection. Partial relay selection is considered, where the relay is selected based on instantaneous and partial knowledge of the channel (source-relay). We derive an exact expression for the outage probability and a lower bound for the average bit error probability, where the bound becomes tight at medium to high signal-to-noise ratios. Also we provide simulation results to support the theoretical analysis.
Intersymbol interference (ISI) is a major cause of degradation in the receiver performance of hig... more Intersymbol interference (ISI) is a major cause of degradation in the receiver performance of high-speed data communications systems. This arises mainly due to limited bandwidth available. The minimum Euclidean distance between any two symbol sequences is an important parameter in this case at moderate to high signal to noise ratios. It is proven here that as ISI increases the minimum distance strictly decreases when the worst case scenario is considered. From this it follows that the minimum eigenvalue of the worst case ISI channel of a given length is unique.
2013 IEEE Wireless Communications and Networking Conference (WCNC), 2013
ABSTRACT We propose an energy-efficient method to enable the data collection of wireless sensor n... more ABSTRACT We propose an energy-efficient method to enable the data collection of wireless sensor networks (WSNs) assisted by a cellular network. They use the same radio resources in an underlay manner resulting in bandwidth efficiency improvements. During the sensor data collection (SDC) period, the cellular user functions as a mobile sink node while keeping the normal cellular traffic, and multicarrier code-division multiple-access (MC-CDMA) transmission is utilized in the sensor-to-sink. Since the energy of sensor symbols from MC-CDMA transceiver is small and spread in the frequency domain, it eventually gives only rise to noise-level of each sub-carrier. After formulating the SDC procedure, we analyze the bit error probability of both the cellular traffic and sensor transmission. From the simulation results, the proposed algorithm is proved to be efficient.
2000 IEEE International Conference on Personal Wireless Communications. Conference Proceedings (Cat. No.00TH8488), 2000
Abstract Channel assignment is the key to spectrum management. In this paper, the channel assignm... more Abstract Channel assignment is the key to spectrum management. In this paper, the channel assignment problem is modeled as a graph coloring formulation. The task of assigning a limited number of channels to transmitters under a set of constraints in an efficient way is ...
ABSTRACT In this paper we investigate a signal design method to increase spectral efficiency and ... more ABSTRACT In this paper we investigate a signal design method to increase spectral efficiency and to limit high peak to average power ratio (PAPR) input signal combinations to OFDM sub-carriers. It reduces PAPR level of an OFDM system without decreasing bandwidth utilization. The system design also shows how a set of concatenated Walsh Hadamard (WH) codes can be used to spread a block of information bits to increase number of orthogonal spreading codes while keeping the spreading factor at a low level
An exact expression for the joint density of three correlated Rician variables is not available i... more An exact expression for the joint density of three correlated Rician variables is not available in the open literature. In this letter, we derive new infinite series representations for the trivariate Rician probability density function (pdf) and the joint cumulative distribution function (cdf). Our results are limited to the case where the inverse covariance matrix is tridiagonal. This case seems
Blind sensing for identifying unused frequency bands is of particular interest in cognitive radio... more Blind sensing for identifying unused frequency bands is of particular interest in cognitive radio and ultra wide-band ap- plications. Energy detection is one such method proposed to identify the presence of an unknown band-limited deter- ministic signal. In this paper, by using an alternative series representation of the Marcum-Q function, the exact average detection probability over the Nakagami-m fading channel
Although the topic of multiple-input multiple-output (MIMO) based orthogonal frequency division m... more Although the topic of multiple-input multiple-output (MIMO) based orthogonal frequency division multiplexing (OFDM) over different fading channels is well investigated, its closed form symbol error rate (SER) expressions and performance results employing orthogonal space time block codes (OSTBCs) over uncorrelated frequency-selective Nakagami-m fading channels are still not available. The closed form expressions are extremely useful for evaluating system's performance without
The performance of a two hop amplify-and-forward relay system, where the source-relay and the rel... more The performance of a two hop amplify-and-forward relay system, where the source-relay and the relay-destination channels experience Rayleigh and Rician fading, respectively, is investigated with relay selection. Partial relay selection is considered, where the relay is selected based on instantaneous and partial knowledge of the channel (source-relay). We derive an exact expression for the outage probability and a lower bound for the average bit error probability, where the bound becomes tight at medium to high signal-to-noise ratios. Also we provide simulation results to support the theoretical analysis.
Intersymbol interference (ISI) is a major cause of degradation in the receiver performance of hig... more Intersymbol interference (ISI) is a major cause of degradation in the receiver performance of high-speed data communications systems. This arises mainly due to limited bandwidth available. The minimum Euclidean distance between any two symbol sequences is an important parameter in this case at moderate to high signal to noise ratios. It is proven here that as ISI increases the minimum distance strictly decreases when the worst case scenario is considered. From this it follows that the minimum eigenvalue of the worst case ISI channel of a given length is unique.
2013 IEEE Wireless Communications and Networking Conference (WCNC), 2013
ABSTRACT We propose an energy-efficient method to enable the data collection of wireless sensor n... more ABSTRACT We propose an energy-efficient method to enable the data collection of wireless sensor networks (WSNs) assisted by a cellular network. They use the same radio resources in an underlay manner resulting in bandwidth efficiency improvements. During the sensor data collection (SDC) period, the cellular user functions as a mobile sink node while keeping the normal cellular traffic, and multicarrier code-division multiple-access (MC-CDMA) transmission is utilized in the sensor-to-sink. Since the energy of sensor symbols from MC-CDMA transceiver is small and spread in the frequency domain, it eventually gives only rise to noise-level of each sub-carrier. After formulating the SDC procedure, we analyze the bit error probability of both the cellular traffic and sensor transmission. From the simulation results, the proposed algorithm is proved to be efficient.
2000 IEEE International Conference on Personal Wireless Communications. Conference Proceedings (Cat. No.00TH8488), 2000
Abstract Channel assignment is the key to spectrum management. In this paper, the channel assignm... more Abstract Channel assignment is the key to spectrum management. In this paper, the channel assignment problem is modeled as a graph coloring formulation. The task of assigning a limited number of channels to transmitters under a set of constraints in an efficient way is ...
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