Alberto Rabbachin | Massachusetts Institute of Technology (MIT) (original) (raw)

Papers by Alberto Rabbachin

ABSTRACT Opportunistic spectrum access creates the opening of under-utilized portions of the lice... more ABSTRACT Opportunistic spectrum access creates the opening of under-utilized portions of the licensed spectrum for reuse, provided that the transmissions of secondary radios do not cause harmful interference to primary users. Therefore, it is important to characterize the effect of cognitive network interference due to such secondary spectrum reuse. In this paper, we show how a new statistical model for aggregate interference of a cognitive network, which accounts for the sensing procedure, secondary spatial reuse protocol, and environment-dependent conditions such as path loss, shadowing, and channel fading can be used to assess the aggregate interference in specific environments. Specifically, we consider scenarios like power controlled primary network, secondary network with interference avoidance mechanism, and non-circular coverage region.

2004 International Workshop on Ultra Wideband Systems Joint with Conference on Ultra Wideband Systems and Technologies. Joint UWBST & IWUWBS 2004 (IEEE Cat. No.04EX812), 2004

... As the UWB system is power limited by FCC regula-tions, the probability of synchronization is... more ... As the UWB system is power limited by FCC regula-tions, the probability of synchronization is ... We can also say that the channel spreading effect offers the pos-sibility to relax ... 5. CONCLUSION In this paper, a low complexity bit synchronization solu-tion has been presented for ...

EURASIP Journal on Wireless Communications and Networking, 2010

The European Commission has recently adopted specific power spectral density masks for ultra wide... more The European Commission has recently adopted specific power spectral density masks for ultra wideband (UWB) devices, with detect and avoid capabilities, for coexistence with licensed standards. Under these regulations, a novel approach for analyzing the UWB interference effects on the WiMAX downlink is provided in this paper by means of a novel theoretical computation of the bit error rate (BER), simulation results, and measurements in a conducted modality. New analytical BER expressions for both uncoded and coded WiMAX systems, impaired by a single multiband-OFDM (MB-OFDM) UWB interference signal, are obtained in this paper for a Rayleigh fading channel. The BER is expressed in terms of the characteristic function of the interference signal. The maximum permissible interference levels and the signal-to-interference (SIR) values, which allow the UWB interference effects to be considered negligible, are estimated in this paper from simulation and measurement results. The analysis considers a WiMAX receiver operating at its minimum sensitivity level. The BER, the symbol error probability (SEP), and the error vector magnitude (EVM) of the WiMAX link are the metrics employed to characterize the interference effects for both frequency hopping and nonfrequency hopping UWB interferers.

2012 IEEE 23rd International Symposium on Personal, Indoor and Mobile Radio Communications - (PIMRC), 2012

ABSTRACT In this paper we compare impulse-radio ultra wideband (IR-UWB) physical layer related me... more ABSTRACT In this paper we compare impulse-radio ultra wideband (IR-UWB) physical layer related medium access control (MAC) protocols, Slotted Aloha and optional preamble mode six of IEEE 802.15.4-2011, and preamble sense multiple access when the events of false alarm and miss-detection are introduced. Furthermore, a generalized multi-slot channel access scheme is proposed that can, with a proper selection of slots, represent any of the above MAC protocols. As a result of the generalization, an efficiency factor is then proposed, which allows for the protocols to be compared efficiently. At present, the challenge of designing a random access protocol suitable for IR-UWB is however, not completely solved. The generalized multi-slot model and efficiency factor help in determining the optimal number of slots, given certain preamble lengths and channel conditions. While there does not exist a globally optimal solution for all combinations of preamble length and signal-to-noise ratio, this paper shows that dividing the maximum MAC protocol data unit from 4 to 8 equally-sized slots, each with their own preamble, provides the best solution in all but the extreme cases.

2010 7th International Symposium on Wireless Communication Systems, 2010

ABSTRACT In this coexistence study, the effect of an Ultra Wideband (UWB) MB-OFDM signal, as defi... more ABSTRACT In this coexistence study, the effect of an Ultra Wideband (UWB) MB-OFDM signal, as defined in the ECMA-368 standard, on an S-band radar device working in the 3.1 GHz to 3.4 GHz range is investigated. An extensive series of 6460 measurements, done with 20 different radar waveforms and for various radar and UWB signal levels is analyzed, using a laboratory test bed specifically designed for this purpose. The interfered radar signal is acquired by a spectrum analyzer and then processed on a stand-alone PC. Different post-processing techniques are applied, depending on the type of the selected radar receiver structure.

2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications, 2006

Page 1. The 17th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communi... more Page 1. The 17th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'06) GML TOA ESTIMATION BASED ON LOW COMPLEXITY UWB ENERGY DETECTION Alberto Rabbachin and Ian Oppermann Benoıt Denis ...

2005 IEEE International Conference on Ultra-Wideband, 2005

The paper provides an evaluation of a noncoherent tWB system, which is suitable for low complexit... more The paper provides an evaluation of a noncoherent tWB system, which is suitable for low complexity, cost and data rate tWB wireless sensor networks with

2011 IEEE Global Telecommunications Conference - GLOBECOM 2011, 2011

ABSTRACT Wireless secrecy is becoming crucial in many commercial and governmental sectors. In thi... more ABSTRACT Wireless secrecy is becoming crucial in many commercial and governmental sectors. In this paper, the secrecy capacity of a wireless channel is analyzed in the presence of intentional network interference for denial of eavesdropping capability (DEC). We propose two different DEC strategies employing the closest interferer and the multiple interferers. We show the impact of the network interference on average and outage of secrecy capacity for the two DEC strategies with and without eavesdropper's countermeasures to create a region of interference neutralization. This work provides essentials for understanding how to increase wireless secrecy using intentional network interference.

2005 IEEE International Conference on Ultra-Wideband, 2005

This paper provides a theoretical comparison of different multi-pulse schemes for ultra-wideband ... more This paper provides a theoretical comparison of different multi-pulse schemes for ultra-wideband (UWB) transmitted reference (TR) which utilizes correlation based receivers. The performance comparison is based on a simplified analysis of signal-to-noise ratio (SNR) derivations of receiver output for different signal repetition structures using binary pulse position modulation (BPPM) and binary pulse amplitude modulation (BPAM). The results shows that the best solution is based on pair-wise combination of pulses for which succeeding pulses form the reference for subsequent pulses, significantly outperforms other schemes. The results also show that pulse repetition scheme with equal power pulses in a doublet structure does not provide a good solution from the perspective of SNR degradation.

2011 IEEE International Conference on Ultra-Wideband (ICUWB), 2011

A new statistical model for the aggregate UWB in- terference, which accounts for the parameters r... more A new statistical model for the aggregate UWB in- terference, which accounts for the parameters related to th es pec- trum sensing requested by the detect-and-avoid procedure and the environment dependent conditions such as fading, is proposed in this paper. We compute the parameters of a truncated-stable distribution used for characterizing the aggregate interference. We further show how to apply

IEEE Transactions on Aerospace and Electronic Systems, 2014

ABSTRACT In urban environment Global Navigation Satellite System (GNSS) signals are impaired by s... more ABSTRACT In urban environment Global Navigation Satellite System (GNSS) signals are impaired by strong fading and by the presence of several potential sources of interference that can severely affect the acquisition. The work presented here evaluates the acquisition performance for the most common acquisition strategies in terms of receiver operating characteristics (ROC) and studies the impact of fading and interference on the acquisition performance. Two different interference scenarios are considered: a single interferer and a network of interferers. We present a framework to evaluate the GNSS acquisition performance with respect to all relevant system parameters that jointly considers the acquisition method, the effect of radio signal propagation conditions, and the spatial distribution of the interfering nodes.

2007 IEEE International Conference on Ultra-Wideband, 2007

There has been an emerging interest in non-coherent interferer on AcR is evaluated in terms of bi... more There has been an emerging interest in non-coherent interferer on AcR is evaluated in terms of bit error probability ultrawideband (UWB) communications, particularly as a technol-(BEP) [8], but the effect of narrowband interference (NBI) on ogy for low-data rate UWB applications, due to its low-complexity ED has not been considered. and low-power consumption. In this paper, we evaluate the In this paper, we evaluate the performance of an ED receiver performance of the energy detector (ED) receiver in terms of bit error probability (BEP). We consider an ED receiver based on a conventional square-law detector and binary pulse based on a conventional square-law detector and binary pulse position modulation (BPPM). We derive BEP expressions for position modulation (BPPM). We analyze the BEP in a multipath the multipath fading channel, both in the absence and presence fading channel, both in the absence and presence of narrowband of interference. We consider two cases: 1) single NBI, where interference (NBI). We consider two cases: 1) single NBI, where the interfering node is located at a fixed distance from the the interfering node ls located at a fixed distance from the receiver, and 2) multiple NBI, where the interfering nodes are receiver, and 2) multiple NBI, where the interfering nodes scattered according to a spatial Poisson process. Our framework are scattered according to a spatial Poisson process. For the is simple enough to allow a tractable analysis and provide insights multiple NBI case, we use an interference model that has been that can be of value in the design of practical UWB systems considered in [9]-[13], where the interference is modeled as subject to Interference.' subject to interference. a superposition of a large number of NB interferers scattered according to a spatial Poisson point process. Our framework

2013 IEEE International Conference on Communications (ICC), 2013

Heterogeneous networks consisting of a macrocell tier and a small cell tier are considered an att... more Heterogeneous networks consisting of a macrocell tier and a small cell tier are considered an attractive solution to cope with the fierce increase of mobile traffic demand. Nevertheless, a massive deployment of small cell access points (SAPs) leads also to a considerable increase in energy consumption. Motivated by growing environmental awareness and the high price of energy, the design of energy efficient wireless systems for both macrocells and small cells becomes crucial. In this work, we analyze the trade-off between traffic offloading from the macrocell and the energy consumption of the small cell. Using tools from stochastic geometry, we define the user detection performance of the SAP and derive the small cell capacity accounting for the uncertainties associated with the random position of the user, the propagation channel, activity of the users, and the aggregate network interference. The proposed framework yields design guidelines for energy efficient small cells.

2013 IEEE International Conference on Communications Workshops (ICC), 2013

In urban environment, Global Navigation Satellite System (GNSS) signals are impaired by non-line-... more In urban environment, Global Navigation Satellite System (GNSS) signals are impaired by non-line-of-sight fading conditions and by the presence of potential sources of electromagnetic disturbance. This paper analyzes the impact of the wireless propagation medium and aggregate network interference by measuring the degradation of the acquisition performance expressed in terms of receiver operating characteristics (ROC). The presented framework allows to realistically evaluate the GNSS acquisition performance by jointly considering the effect of radio signal propagation conditions, interfering nodes spatial distribution, and other relevant environment dependent parameters. By means of numerical examples we elucidate the need for alternative positioning techniques in harsh urban environments.

2013 IEEE Wireless Communications and Networking Conference (WCNC), 2013

Heterogeneous networks consisting of a macrocell tier and a small cell tier are foreseen as one o... more Heterogeneous networks consisting of a macrocell tier and a small cell tier are foreseen as one of the solutions to meet the ever increasing mobile data demand. Since a massive deployment of small cell access points (SAPs) leads also to a considerable increase in energy consumption, the energy efficient design of those SAPs is crucial. Sleep mode techniques are a promising strategy to reduce the energy consumption, yet they require cognitive capabilities to detect the presence of a macrocell user. In this work, we define a fundamental limit on the interference density that allows robust user detection. Beyond this limit, which we call the interference wall, an energy efficient SAP design is impossible. In addition, we elucidate the relation between energy efficiency and sensing time using large deviations theory.

2013 IEEE International Conference on Communications (ICC), 2013

ABSTRACT The demand of communication confidentiality in wireless network is rapidly increasing. T... more ABSTRACT The demand of communication confidentiality in wireless network is rapidly increasing. The level of confidentiality can be enhanced by physical layer techniques exploiting intrinsic properties of a wireless network. We develop a framework for design and analysis of wireless network with secrecy that accounts for node distribution, propagation medium, and intentional interference. The framework enables the quantification of how intentional interference generated via legitimate network resources engineering mitigates the capability of the eavesdropping network. This research provides insight on the opportunistic use of legitimate network resources for enhancing network secrecy.

2010 IEEE Global Telecommunications Conference GLOBECOM 2010, 2010

In this paper, we propose a new statistical interference model for cognitive network based on the... more In this paper, we propose a new statistical interference model for cognitive network based on the amplitude aggregate interference, which accounts for the parameters related to the sensing procedure, spatial reuse protocol employed by secondary users, and environment dependent conditions like channel fading and shadowing. We derive the characteristic function and the nth cumulant of the cognitive network interference on the primary user. By using the theory of truncated-stable distribution, we show how we can approximate the cognitive network interference analytically. We further show how to apply our model to derive system performance measure such as bit error probability in the presence of cognitive network interference. Moreover, this work can serve to bring additional understanding of cognitive network interference for successful deployment of cognitive networks in the future.

2011 IEEE International Conference on Communications (ICC), 2011

Opportunistic spectrum access creates the opening of under-utilized portions of the licensed spec... more Opportunistic spectrum access creates the opening of under-utilized portions of the licensed spectrum for reuse, provided that the transmissions of secondary radios do not cause harmful interference to primary users. Therefore, it is important to characterize the effect of cognitive network interference due to such secondary spectrum reuse. In this paper, we show how a new statistical model for aggregate interference of a cognitive network, which accounts for the sensing procedure, secondary spatial reuse protocol, and environment-dependent conditions such as path loss, shadowing, and channel fading can be used to assess the aggregate interference in specific environments. Specifically, we consider scenarios like power controlled primary network, secondary network with interference avoidance mechanism, and non-circular coverage region.

2012 IEEE International Conference on Communications (ICC), 2012

ABSTRACT Upper layer wireless security relies on the computational intractability assumption for ... more ABSTRACT Upper layer wireless security relies on the computational intractability assumption for solving certain number-theoretic problems. These methods can be complemented by techniques that exploit, at the physical layer, the intrinsic properties of the wireless channel and interference. This paper considers communications with intrinsic secrecy in the presence of spatially distributed nodes, namely legitimate users, eavesdroppers, and interferers. We characterize the role of aggregate interference on intrinsic network secrecy, providing insights into regimes in which interference is beneficial for network secrecy.

ABSTRACT Opportunistic spectrum access creates the opening of under-utilized portions of the lice... more ABSTRACT Opportunistic spectrum access creates the opening of under-utilized portions of the licensed spectrum for reuse, provided that the transmissions of secondary radios do not cause harmful interference to primary users. Therefore, it is important to characterize the effect of cognitive network interference due to such secondary spectrum reuse. In this paper, we show how a new statistical model for aggregate interference of a cognitive network, which accounts for the sensing procedure, secondary spatial reuse protocol, and environment-dependent conditions such as path loss, shadowing, and channel fading can be used to assess the aggregate interference in specific environments. Specifically, we consider scenarios like power controlled primary network, secondary network with interference avoidance mechanism, and non-circular coverage region.

2004 International Workshop on Ultra Wideband Systems Joint with Conference on Ultra Wideband Systems and Technologies. Joint UWBST & IWUWBS 2004 (IEEE Cat. No.04EX812), 2004

... As the UWB system is power limited by FCC regula-tions, the probability of synchronization is... more ... As the UWB system is power limited by FCC regula-tions, the probability of synchronization is ... We can also say that the channel spreading effect offers the pos-sibility to relax ... 5. CONCLUSION In this paper, a low complexity bit synchronization solu-tion has been presented for ...

EURASIP Journal on Wireless Communications and Networking, 2010

The European Commission has recently adopted specific power spectral density masks for ultra wide... more The European Commission has recently adopted specific power spectral density masks for ultra wideband (UWB) devices, with detect and avoid capabilities, for coexistence with licensed standards. Under these regulations, a novel approach for analyzing the UWB interference effects on the WiMAX downlink is provided in this paper by means of a novel theoretical computation of the bit error rate (BER), simulation results, and measurements in a conducted modality. New analytical BER expressions for both uncoded and coded WiMAX systems, impaired by a single multiband-OFDM (MB-OFDM) UWB interference signal, are obtained in this paper for a Rayleigh fading channel. The BER is expressed in terms of the characteristic function of the interference signal. The maximum permissible interference levels and the signal-to-interference (SIR) values, which allow the UWB interference effects to be considered negligible, are estimated in this paper from simulation and measurement results. The analysis considers a WiMAX receiver operating at its minimum sensitivity level. The BER, the symbol error probability (SEP), and the error vector magnitude (EVM) of the WiMAX link are the metrics employed to characterize the interference effects for both frequency hopping and nonfrequency hopping UWB interferers.

2012 IEEE 23rd International Symposium on Personal, Indoor and Mobile Radio Communications - (PIMRC), 2012

ABSTRACT In this paper we compare impulse-radio ultra wideband (IR-UWB) physical layer related me... more ABSTRACT In this paper we compare impulse-radio ultra wideband (IR-UWB) physical layer related medium access control (MAC) protocols, Slotted Aloha and optional preamble mode six of IEEE 802.15.4-2011, and preamble sense multiple access when the events of false alarm and miss-detection are introduced. Furthermore, a generalized multi-slot channel access scheme is proposed that can, with a proper selection of slots, represent any of the above MAC protocols. As a result of the generalization, an efficiency factor is then proposed, which allows for the protocols to be compared efficiently. At present, the challenge of designing a random access protocol suitable for IR-UWB is however, not completely solved. The generalized multi-slot model and efficiency factor help in determining the optimal number of slots, given certain preamble lengths and channel conditions. While there does not exist a globally optimal solution for all combinations of preamble length and signal-to-noise ratio, this paper shows that dividing the maximum MAC protocol data unit from 4 to 8 equally-sized slots, each with their own preamble, provides the best solution in all but the extreme cases.

2010 7th International Symposium on Wireless Communication Systems, 2010

ABSTRACT In this coexistence study, the effect of an Ultra Wideband (UWB) MB-OFDM signal, as defi... more ABSTRACT In this coexistence study, the effect of an Ultra Wideband (UWB) MB-OFDM signal, as defined in the ECMA-368 standard, on an S-band radar device working in the 3.1 GHz to 3.4 GHz range is investigated. An extensive series of 6460 measurements, done with 20 different radar waveforms and for various radar and UWB signal levels is analyzed, using a laboratory test bed specifically designed for this purpose. The interfered radar signal is acquired by a spectrum analyzer and then processed on a stand-alone PC. Different post-processing techniques are applied, depending on the type of the selected radar receiver structure.

2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications, 2006

Page 1. The 17th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communi... more Page 1. The 17th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC'06) GML TOA ESTIMATION BASED ON LOW COMPLEXITY UWB ENERGY DETECTION Alberto Rabbachin and Ian Oppermann Benoıt Denis ...

2005 IEEE International Conference on Ultra-Wideband, 2005

The paper provides an evaluation of a noncoherent tWB system, which is suitable for low complexit... more The paper provides an evaluation of a noncoherent tWB system, which is suitable for low complexity, cost and data rate tWB wireless sensor networks with

2011 IEEE Global Telecommunications Conference - GLOBECOM 2011, 2011

ABSTRACT Wireless secrecy is becoming crucial in many commercial and governmental sectors. In thi... more ABSTRACT Wireless secrecy is becoming crucial in many commercial and governmental sectors. In this paper, the secrecy capacity of a wireless channel is analyzed in the presence of intentional network interference for denial of eavesdropping capability (DEC). We propose two different DEC strategies employing the closest interferer and the multiple interferers. We show the impact of the network interference on average and outage of secrecy capacity for the two DEC strategies with and without eavesdropper's countermeasures to create a region of interference neutralization. This work provides essentials for understanding how to increase wireless secrecy using intentional network interference.

2005 IEEE International Conference on Ultra-Wideband, 2005

This paper provides a theoretical comparison of different multi-pulse schemes for ultra-wideband ... more This paper provides a theoretical comparison of different multi-pulse schemes for ultra-wideband (UWB) transmitted reference (TR) which utilizes correlation based receivers. The performance comparison is based on a simplified analysis of signal-to-noise ratio (SNR) derivations of receiver output for different signal repetition structures using binary pulse position modulation (BPPM) and binary pulse amplitude modulation (BPAM). The results shows that the best solution is based on pair-wise combination of pulses for which succeeding pulses form the reference for subsequent pulses, significantly outperforms other schemes. The results also show that pulse repetition scheme with equal power pulses in a doublet structure does not provide a good solution from the perspective of SNR degradation.

2011 IEEE International Conference on Ultra-Wideband (ICUWB), 2011

A new statistical model for the aggregate UWB in- terference, which accounts for the parameters r... more A new statistical model for the aggregate UWB in- terference, which accounts for the parameters related to th es pec- trum sensing requested by the detect-and-avoid procedure and the environment dependent conditions such as fading, is proposed in this paper. We compute the parameters of a truncated-stable distribution used for characterizing the aggregate interference. We further show how to apply

IEEE Transactions on Aerospace and Electronic Systems, 2014

ABSTRACT In urban environment Global Navigation Satellite System (GNSS) signals are impaired by s... more ABSTRACT In urban environment Global Navigation Satellite System (GNSS) signals are impaired by strong fading and by the presence of several potential sources of interference that can severely affect the acquisition. The work presented here evaluates the acquisition performance for the most common acquisition strategies in terms of receiver operating characteristics (ROC) and studies the impact of fading and interference on the acquisition performance. Two different interference scenarios are considered: a single interferer and a network of interferers. We present a framework to evaluate the GNSS acquisition performance with respect to all relevant system parameters that jointly considers the acquisition method, the effect of radio signal propagation conditions, and the spatial distribution of the interfering nodes.

2007 IEEE International Conference on Ultra-Wideband, 2007

There has been an emerging interest in non-coherent interferer on AcR is evaluated in terms of bi... more There has been an emerging interest in non-coherent interferer on AcR is evaluated in terms of bit error probability ultrawideband (UWB) communications, particularly as a technol-(BEP) [8], but the effect of narrowband interference (NBI) on ogy for low-data rate UWB applications, due to its low-complexity ED has not been considered. and low-power consumption. In this paper, we evaluate the In this paper, we evaluate the performance of an ED receiver performance of the energy detector (ED) receiver in terms of bit error probability (BEP). We consider an ED receiver based on a conventional square-law detector and binary pulse based on a conventional square-law detector and binary pulse position modulation (BPPM). We derive BEP expressions for position modulation (BPPM). We analyze the BEP in a multipath the multipath fading channel, both in the absence and presence fading channel, both in the absence and presence of narrowband of interference. We consider two cases: 1) single NBI, where interference (NBI). We consider two cases: 1) single NBI, where the interfering node is located at a fixed distance from the the interfering node ls located at a fixed distance from the receiver, and 2) multiple NBI, where the interfering nodes are receiver, and 2) multiple NBI, where the interfering nodes scattered according to a spatial Poisson process. Our framework are scattered according to a spatial Poisson process. For the is simple enough to allow a tractable analysis and provide insights multiple NBI case, we use an interference model that has been that can be of value in the design of practical UWB systems considered in [9]-[13], where the interference is modeled as subject to Interference.' subject to interference. a superposition of a large number of NB interferers scattered according to a spatial Poisson point process. Our framework

2013 IEEE International Conference on Communications (ICC), 2013

Heterogeneous networks consisting of a macrocell tier and a small cell tier are considered an att... more Heterogeneous networks consisting of a macrocell tier and a small cell tier are considered an attractive solution to cope with the fierce increase of mobile traffic demand. Nevertheless, a massive deployment of small cell access points (SAPs) leads also to a considerable increase in energy consumption. Motivated by growing environmental awareness and the high price of energy, the design of energy efficient wireless systems for both macrocells and small cells becomes crucial. In this work, we analyze the trade-off between traffic offloading from the macrocell and the energy consumption of the small cell. Using tools from stochastic geometry, we define the user detection performance of the SAP and derive the small cell capacity accounting for the uncertainties associated with the random position of the user, the propagation channel, activity of the users, and the aggregate network interference. The proposed framework yields design guidelines for energy efficient small cells.

2013 IEEE International Conference on Communications Workshops (ICC), 2013

In urban environment, Global Navigation Satellite System (GNSS) signals are impaired by non-line-... more In urban environment, Global Navigation Satellite System (GNSS) signals are impaired by non-line-of-sight fading conditions and by the presence of potential sources of electromagnetic disturbance. This paper analyzes the impact of the wireless propagation medium and aggregate network interference by measuring the degradation of the acquisition performance expressed in terms of receiver operating characteristics (ROC). The presented framework allows to realistically evaluate the GNSS acquisition performance by jointly considering the effect of radio signal propagation conditions, interfering nodes spatial distribution, and other relevant environment dependent parameters. By means of numerical examples we elucidate the need for alternative positioning techniques in harsh urban environments.

2013 IEEE Wireless Communications and Networking Conference (WCNC), 2013

Heterogeneous networks consisting of a macrocell tier and a small cell tier are foreseen as one o... more Heterogeneous networks consisting of a macrocell tier and a small cell tier are foreseen as one of the solutions to meet the ever increasing mobile data demand. Since a massive deployment of small cell access points (SAPs) leads also to a considerable increase in energy consumption, the energy efficient design of those SAPs is crucial. Sleep mode techniques are a promising strategy to reduce the energy consumption, yet they require cognitive capabilities to detect the presence of a macrocell user. In this work, we define a fundamental limit on the interference density that allows robust user detection. Beyond this limit, which we call the interference wall, an energy efficient SAP design is impossible. In addition, we elucidate the relation between energy efficiency and sensing time using large deviations theory.

2013 IEEE International Conference on Communications (ICC), 2013

ABSTRACT The demand of communication confidentiality in wireless network is rapidly increasing. T... more ABSTRACT The demand of communication confidentiality in wireless network is rapidly increasing. The level of confidentiality can be enhanced by physical layer techniques exploiting intrinsic properties of a wireless network. We develop a framework for design and analysis of wireless network with secrecy that accounts for node distribution, propagation medium, and intentional interference. The framework enables the quantification of how intentional interference generated via legitimate network resources engineering mitigates the capability of the eavesdropping network. This research provides insight on the opportunistic use of legitimate network resources for enhancing network secrecy.

2010 IEEE Global Telecommunications Conference GLOBECOM 2010, 2010

In this paper, we propose a new statistical interference model for cognitive network based on the... more In this paper, we propose a new statistical interference model for cognitive network based on the amplitude aggregate interference, which accounts for the parameters related to the sensing procedure, spatial reuse protocol employed by secondary users, and environment dependent conditions like channel fading and shadowing. We derive the characteristic function and the nth cumulant of the cognitive network interference on the primary user. By using the theory of truncated-stable distribution, we show how we can approximate the cognitive network interference analytically. We further show how to apply our model to derive system performance measure such as bit error probability in the presence of cognitive network interference. Moreover, this work can serve to bring additional understanding of cognitive network interference for successful deployment of cognitive networks in the future.

2011 IEEE International Conference on Communications (ICC), 2011

Opportunistic spectrum access creates the opening of under-utilized portions of the licensed spec... more Opportunistic spectrum access creates the opening of under-utilized portions of the licensed spectrum for reuse, provided that the transmissions of secondary radios do not cause harmful interference to primary users. Therefore, it is important to characterize the effect of cognitive network interference due to such secondary spectrum reuse. In this paper, we show how a new statistical model for aggregate interference of a cognitive network, which accounts for the sensing procedure, secondary spatial reuse protocol, and environment-dependent conditions such as path loss, shadowing, and channel fading can be used to assess the aggregate interference in specific environments. Specifically, we consider scenarios like power controlled primary network, secondary network with interference avoidance mechanism, and non-circular coverage region.

2012 IEEE International Conference on Communications (ICC), 2012

ABSTRACT Upper layer wireless security relies on the computational intractability assumption for ... more ABSTRACT Upper layer wireless security relies on the computational intractability assumption for solving certain number-theoretic problems. These methods can be complemented by techniques that exploit, at the physical layer, the intrinsic properties of the wireless channel and interference. This paper considers communications with intrinsic secrecy in the presence of spatially distributed nodes, namely legitimate users, eavesdroppers, and interferers. We characterize the role of aggregate interference on intrinsic network secrecy, providing insights into regimes in which interference is beneficial for network secrecy.