I am a University Academic Fellow (Assistant Professor) at the University of Leeds in the broad area of Communication Supervisors: Mounir Ghogho and Desmond C. McLernon Address: School of Electronics and Electrical Engineering University of Leeds LS2 9JT, United Kingdom
Wireless infrared and free space optic communication are very strong candidates for next generati... more Wireless infrared and free space optic communication are very strong candidates for next generation indoor wireless networks. Infrared diffuse communication provides high speed data transmission which is more economic then traditional fiber optic systems. Moreover it provides greater security than its counter part, i.e. radio frequency wireless communication, mainly due to its confined illumination. However the infrared wireless communication is not employed due to power limitations, alignment problems and performance degradation under severe weather conditions. In such conditions MIMO based signal processing techniques derived on parallels from wireless communication can be employed to provide better performance. In this paper we present a novel design for more reliable transmission. The proposed design is base on rate 1/2 Orthogonal Coding Scheme in combination with Virtual Fragmentation. Furthermore we discuss the cross layer architecture where by channel knowledge can be exploited by upper layers in order to efficiently decode the data, hence adapting to the channel conditions.
ABSTRACT In this article, we derive a closed form expression for the radius of a guard zone (re) ... more ABSTRACT In this article, we derive a closed form expression for the radius of a guard zone (re) required at a primary receiver operating in the presence of a cognitive radio network while ensuring the primary's desired quality of service (QoS). We demonstrate that re is not only strongly coupled with the primary's QoS requirement but it is also dependent upon the secondary network's connectivity, medium access, QoS and routing mechanisms.
This paper presents an analytical approach to quantify energy efficiency (EE), i.e., the bits per... more This paper presents an analytical approach to quantify energy efficiency (EE), i.e., the bits per Joule performance of a large scale interference limited random wireless ad hoc network. Energy consumption is investigated at physical, medium access control (MAC) and routing layers. Communication between a user and its destination is facilitated by multihop relaying and Slotted ALOHA based MAC protocol. Energy consumption of user's communication hardware platform is analyzed considering the transceiver architecture. Geometry of the forwarding areas resulting from two different long hop routing protocols is explicitly considered in the analysis. The link model is formulated to cater for user's desired QoS while considering the network interference and the spatial/channel uncertainties. EE performance of the network is quantified from single-hop forward progress, node isolation and hop statistics. Optimal MAP which maximizes the network EE is also investigated. Analytical results are supported by Monte Carlo simulations. It is shown that several hypothesis established in existing literature which ignores network interference and fading do not hold in large scale interference limited ad hoc network.
In a recent letter, Lichte et al. proposed a closed form approximation of the expected aggregate ... more In a recent letter, Lichte et al. proposed a closed form approximation of the expected aggregate interference caused by a random network of interferers. Modeling the positions of the latter by a Poisson point process with density and assuming a guard disc of radius g around the receiver, the authors derived the expected interference as 2P=((2)g2), where is the path loss exponent and P is the transmit power of each interferer. In this letter, we demonstrate that this result can be obtained by applying the well-known Campbell’s theorem in a straight-forward manner. We also point out that the Laplace transform of the aggregate interference is well known in the literature, and hence moments of the interference can be easily obtained from existing results.
In this paper, we consider a 802.22 type cognitive radio network. We assume that, the communicati... more In this paper, we consider a 802.22 type cognitive radio network. We assume that, the communication in such a network is subjected to the small scale fading, modeled by Rayleigh distribution. Considering the deterministic network geometry we develop the analytical framework to characterize the interference and outage of the primary network.
A new generic statistical fading model for wireless ad hoc networks is proposed. Besides small sc... more A new generic statistical fading model for wireless ad hoc networks is proposed. Besides small scale fading, our proposed model incorporates the variations due to geometry, i.e. the statistical distribution of transmission and reception distances. The geometry-inclusive fading model presented here can also be considered as a generalization of several prior studies. Consequently, it is valid for any arbitrary but realistic numeric value of parameters. We assume that nodes are distributed according to a Poisson point process, while small scale fading is modeled using a Rayleigh distribution. Under these assumptions, we formulate a statistical framework to determine the probability density function (PDF) and the cumulative density function (CDF) of fading coefficients. Several applications of this fading model are highlighted. Lastly, we employ the developed analytical machinery to show that the fading in ad hoc networks can not be characterized alone by the statistical distribution of the multipath impairment process. Rather, the distribution of the link distances is also required to accurately model the overall random wireless impairment process. Besides link distances, the intensity/density of nodes in a region and path loss exponent determined by the enviornment, also plays a vital role in accurate characterization
A solution to the coverage problem in wireless sensor networks provides the total number of senso... more A solution to the coverage problem in wireless sensor networks provides the total number of sensors that are required to cover a given area of deployment. While prior studies have proposed different formulations and solutions to this problem, these studies have not addressed the problem of
minimum cost coverage in which full coverage is achieved by using the minimum number of sensor nodes for an arbitrary geometric shape region. In this paper, we present a geometric solution to the minimum cost coverage problem under a deterministic deployment. Furthermore, we present a probabilistic coverage solution which provides a relationship between the probability of coverage and the number of Randomly deployed sensors in an arbitrarily-shaped region. We
demonstrate that for virtually 100% probability of coverage, random deployment needs approximately seven times more sensors as compared to a deterministic setup.
One of the fundamental problems in the wireless sensor networks is the coverage problem. The cove... more One of the fundamental problems in the wireless sensor networks is the coverage problem. The coverage problem fundamentally address the quality of service (surveillance or monitoring) provided in the desired area. In past, several studies have proposed different formulation and solutions to this problem. Nevertheless none of them has addressed minimum cost solution to the coverage problem. In this paper we consider minimum cost wireless sensor network which provides full coverage to any arbitrary geometric profile under deterministic/random deployment. We then formulate probabilistic coverage model which provides k -coverage probability for minimum cost wireless sensor
networks.
Wireless infrared and free space optic communication are very strong candidates for next generati... more Wireless infrared and free space optic communication are very strong candidates for next generation indoor wireless networks. Infrared diffuse communication provides high speed data transmission which is more economic then traditional fiber optic systems. Moreover it provides greater security than its counter part, i.e. radio frequency wireless communication, mainly due to its confined illumination. However the infrared wireless communication is not employed due to power limitations, alignment problems and performance degradation under severe weather conditions. In such conditions MIMO based signal processing techniques derived on parallels from wireless communication can be employed to provide better performance. In this paper we present a novel design for more reliable transmission. The proposed design is base on rate 1/2 Orthogonal Coding Scheme in combination with Virtual Fragmentation. Furthermore we discuss the cross layer architecture where by channel knowledge can be exploited by upper layers in order to efficiently decode the data, hence adapting to the channel conditions.
ABSTRACT In this article, we derive a closed form expression for the radius of a guard zone (re) ... more ABSTRACT In this article, we derive a closed form expression for the radius of a guard zone (re) required at a primary receiver operating in the presence of a cognitive radio network while ensuring the primary's desired quality of service (QoS). We demonstrate that re is not only strongly coupled with the primary's QoS requirement but it is also dependent upon the secondary network's connectivity, medium access, QoS and routing mechanisms.
This paper presents an analytical approach to quantify energy efficiency (EE), i.e., the bits per... more This paper presents an analytical approach to quantify energy efficiency (EE), i.e., the bits per Joule performance of a large scale interference limited random wireless ad hoc network. Energy consumption is investigated at physical, medium access control (MAC) and routing layers. Communication between a user and its destination is facilitated by multihop relaying and Slotted ALOHA based MAC protocol. Energy consumption of user's communication hardware platform is analyzed considering the transceiver architecture. Geometry of the forwarding areas resulting from two different long hop routing protocols is explicitly considered in the analysis. The link model is formulated to cater for user's desired QoS while considering the network interference and the spatial/channel uncertainties. EE performance of the network is quantified from single-hop forward progress, node isolation and hop statistics. Optimal MAP which maximizes the network EE is also investigated. Analytical results are supported by Monte Carlo simulations. It is shown that several hypothesis established in existing literature which ignores network interference and fading do not hold in large scale interference limited ad hoc network.
In a recent letter, Lichte et al. proposed a closed form approximation of the expected aggregate ... more In a recent letter, Lichte et al. proposed a closed form approximation of the expected aggregate interference caused by a random network of interferers. Modeling the positions of the latter by a Poisson point process with density and assuming a guard disc of radius g around the receiver, the authors derived the expected interference as 2P=((2)g2), where is the path loss exponent and P is the transmit power of each interferer. In this letter, we demonstrate that this result can be obtained by applying the well-known Campbell’s theorem in a straight-forward manner. We also point out that the Laplace transform of the aggregate interference is well known in the literature, and hence moments of the interference can be easily obtained from existing results.
In this paper, we consider a 802.22 type cognitive radio network. We assume that, the communicati... more In this paper, we consider a 802.22 type cognitive radio network. We assume that, the communication in such a network is subjected to the small scale fading, modeled by Rayleigh distribution. Considering the deterministic network geometry we develop the analytical framework to characterize the interference and outage of the primary network.
A new generic statistical fading model for wireless ad hoc networks is proposed. Besides small sc... more A new generic statistical fading model for wireless ad hoc networks is proposed. Besides small scale fading, our proposed model incorporates the variations due to geometry, i.e. the statistical distribution of transmission and reception distances. The geometry-inclusive fading model presented here can also be considered as a generalization of several prior studies. Consequently, it is valid for any arbitrary but realistic numeric value of parameters. We assume that nodes are distributed according to a Poisson point process, while small scale fading is modeled using a Rayleigh distribution. Under these assumptions, we formulate a statistical framework to determine the probability density function (PDF) and the cumulative density function (CDF) of fading coefficients. Several applications of this fading model are highlighted. Lastly, we employ the developed analytical machinery to show that the fading in ad hoc networks can not be characterized alone by the statistical distribution of the multipath impairment process. Rather, the distribution of the link distances is also required to accurately model the overall random wireless impairment process. Besides link distances, the intensity/density of nodes in a region and path loss exponent determined by the enviornment, also plays a vital role in accurate characterization
A solution to the coverage problem in wireless sensor networks provides the total number of senso... more A solution to the coverage problem in wireless sensor networks provides the total number of sensors that are required to cover a given area of deployment. While prior studies have proposed different formulations and solutions to this problem, these studies have not addressed the problem of
minimum cost coverage in which full coverage is achieved by using the minimum number of sensor nodes for an arbitrary geometric shape region. In this paper, we present a geometric solution to the minimum cost coverage problem under a deterministic deployment. Furthermore, we present a probabilistic coverage solution which provides a relationship between the probability of coverage and the number of Randomly deployed sensors in an arbitrarily-shaped region. We
demonstrate that for virtually 100% probability of coverage, random deployment needs approximately seven times more sensors as compared to a deterministic setup.
One of the fundamental problems in the wireless sensor networks is the coverage problem. The cove... more One of the fundamental problems in the wireless sensor networks is the coverage problem. The coverage problem fundamentally address the quality of service (surveillance or monitoring) provided in the desired area. In past, several studies have proposed different formulation and solutions to this problem. Nevertheless none of them has addressed minimum cost solution to the coverage problem. In this paper we consider minimum cost wireless sensor network which provides full coverage to any arbitrary geometric profile under deterministic/random deployment. We then formulate probabilistic coverage model which provides k -coverage probability for minimum cost wireless sensor
networks.
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minimum cost coverage in which full coverage is achieved by using the minimum number of sensor nodes for an arbitrary geometric shape region. In this paper, we present a geometric solution to the minimum cost coverage problem under a deterministic deployment. Furthermore, we present a probabilistic coverage solution which provides a relationship between the probability of coverage and the number of Randomly deployed sensors in an arbitrarily-shaped region. We
demonstrate that for virtually 100% probability of coverage, random deployment needs approximately seven times more sensors as compared to a deterministic setup.
networks.
minimum cost coverage in which full coverage is achieved by using the minimum number of sensor nodes for an arbitrary geometric shape region. In this paper, we present a geometric solution to the minimum cost coverage problem under a deterministic deployment. Furthermore, we present a probabilistic coverage solution which provides a relationship between the probability of coverage and the number of Randomly deployed sensors in an arbitrarily-shaped region. We
demonstrate that for virtually 100% probability of coverage, random deployment needs approximately seven times more sensors as compared to a deterministic setup.
networks.