ABSTRACT The presence of undetected direct path (UDP) conditions presents significant challenges ... more ABSTRACT The presence of undetected direct path (UDP) conditions presents significant challenges for TOA-based indoor geolocation, since it introduces major errors into distance measurements. Therefore, it is critical to characterize the performance of indoor geolocation systems in the presence of UDP conditions. Until now, however, there has been no standard method of performance benchmarking for such cases. Towards that end, we present an analysis tool, known as the MSE profile, that can aid in this task. We use the MSE profile to analyze the performance of two TOA-based geolocation algorithms and show how the MSE profile can be used to gain insight into their performance, in the presence of distance measurement error (DME) models derived from Ultra-Wideband (UWB) measurements.
2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications, 2007
Abstract Ultra-wideband (UWB) indoor positioning systems based on time of arrival (TOA) technique... more Abstract Ultra-wideband (UWB) indoor positioning systems based on time of arrival (TOA) techniques are considered to be the high precision alternatives to those employing received signal strength (RSS) or angle of arrival (AOA) due to their superior time-domain ...
2010 IEEE 21st International Symposium on Personal, Indoor and Mobile Radio Communications Workshops, 2010
... 2(a) & 2(b), UWB-Only in Figs.3(a) & 3(b), Hybrid WiFi-UWB in Figs. 4(a) & 4(b) a... more ... 2(a) & 2(b), UWB-Only in Figs.3(a) & 3(b), Hybrid WiFi-UWB in Figs. 4(a) & 4(b) and finally overall performance for hybrid and WiFi-Only in Figs. 5 & 6. In all our simulation runs, we have used thirty two equally distanced locations across the route for all robots. For all ...
2009 IEEE International Conference on Ultra-Wideband, 2009
This paper describes the results of frequencydomain dynamic channel sounding in a typical office ... more This paper describes the results of frequencydomain dynamic channel sounding in a typical office environment for studying the spatio-temporal channel behavior pertinent to indoor geolocation. It consists of detailed characterization of complex frequency responses of ultra-wideband (UWB) signals having a nominal center frequency of 5.5GHz and bandwidth of 5GHz. The effects of distance, threshold for picking paths, bandwidth, and occurrence of none-line-of-sight (NLOS) on multipath parameters such as number of multipath-components (MPCs) and path persistency are presented. Furthermore, a novel model for the dynamic behavior of number of MPCs is proposed.
ABSTRACT The presence of undetected direct path (UDP) conditions presents significant challenges ... more ABSTRACT The presence of undetected direct path (UDP) conditions presents significant challenges for TOA-based indoor geolocation, since it introduces major errors into distance measurements. Therefore, it is critical to characterize the performance of indoor geolocation systems in the presence of UDP conditions. Until now, however, there has been no standard method of performance benchmarking for such cases. Towards that end, we present an analysis tool, known as the MSE profile, that can aid in this task. We use the MSE profile to analyze the performance of two TOA-based geolocation algorithms and show how the MSE profile can be used to gain insight into their performance, in the presence of distance measurement error (DME) models derived from Ultra-Wideband (UWB) measurements.
MILCOM 2007 - IEEE Military Communications Conference, 2007
... Ferit Ozan Akgiil, Kaveh Pahlavan Center for Wireless Information Network Studies, Worcester ... more ... Ferit Ozan Akgiil, Kaveh Pahlavan Center for Wireless Information Network Studies, Worcester Polytechnic Institute Worcester, MA, 01609, USA {ferit, kaveh ... When we consider a certain path, we might say this particular path has a certain reflection/transmission pat-tern inside ...
A novel statistical angle-of-arrival (AOA) model for indoor geolocation applications is presented... more A novel statistical angle-of-arrival (AOA) model for indoor geolocation applications is presented. The modeling approach focuses on the arrivals of the multipath components with respect to the line-of-sight (LOS) path which is an important component especially when indoor geolocation applications are considered. The model is particularly important for indoor applications where AOA information could be utilized for tracking indirect paths to aid in precise ranging in harsh and dense multipath environments where LOS path might be blocked due to obstructions. The results have been obtained by a measurement calibrated ray-tracing (RT) tool.
Severe multipath in indoor areas causes undetected direct path (UDP) conditions, which pose a ser... more Severe multipath in indoor areas causes undetected direct path (UDP) conditions, which pose a serious challenge to the design of robust precision indoor geolocation systems. Based on a scenario on the third floor of the Atwater Kent Laboratory at the Worcester Polytechnic Institute, we explain the reason for frequent absence of direct path, and introduce and analyze the effectiveness of two novel approaches to mitigating the large ranging errors caused by UDP conditions. The first technique exploits nondirect paths for ranging, while the second approach relies on cooperative localization for wireless sensor and ad hoc networks.
-- Recently wireless positioning using existing network infrastructure has become an attractive v... more -- Recently wireless positioning using existing network infrastructure has become an attractive value added application in campus and local area networks. However, many complexities, intrinsic to indoor radio propagation create technical challenges for the ...
In this paper we propose the use of statistical QoS guarantees for transmission over the wireless... more In this paper we propose the use of statistical QoS guarantees for transmission over the wireless channel. Here, instead of QoS assurances, we propose to guarantee the percentage of time the QoS requirements are satisfied. We present an associated scheduling algorithm for the opportunistic multiple access system. We compare the proposed scheduler with popular schedulers from the literature. We observe that the statistical QoS guarantee is an attractive alternative to the assured QoS service for the wireless platform, since such strict QoS assurances decrease the wireless system performance significantly. Index Terms-Wireless packet data provisioning, resource allo- cation, scheduling, QoS, 3G, 1xEV-DO.
The third generation wireless networks and wireless local networks possess complementary characte... more The third generation wireless networks and wireless local networks possess complementary characteristics. Recently, there has been significant interest in providing algorithms and specifications that enable their inter-operability. In this paper we propose a novel cross-network, cross-layer algorithm that jointly performs 3G resource allocation and ad-hoc mode WLAN routing towards effectively increasing the performance of the 3G system. The metrics used in this joint design ensures that multi-user diversity is exploited without causing user starvation in the 3G system and the WLAN assistance does not cause an unfair treatment to any of the mobiles from a battery usage point of view. Furthermore, the design attempts to select the WLAN route so that the assistance does not become a major part of the internal WLAN traffic.
2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications, 2006
ABSTRACT The performance of ultra-wideband (UWB) indoor positioning systems based on time of arri... more ABSTRACT The performance of ultra-wideband (UWB) indoor positioning systems based on time of arrival (TOA) techniques is generally affected by the density of reference points (RPs), as well as undetected direct path (UDP) conditions. For a fixed number of reference points (RPs), the performance of some indoor positioning algorithms tends to degrade as the size of the area is increased, i.e. the RP density is decreased. In this paper, we evaluate the effects of RP density on the performance of different positioning algorithms in the presence of empirical distance measurement error (DME) models derived from UWB measurements in typical indoor environments. We then present functional relationships between RP density and positioning mean-square error (MSE) for these algorithms. These relationships can be used for more effective indoor positioning system design and deployment. Finally, we investigate the effects of bandwidth with respect to improving the performance of these algorithms
The third generation wireless networks and wireless local networks possess complementary characte... more The third generation wireless networks and wireless local networks possess complementary characteristics. Recently, there has been significant interest in providing algorithms and specifications that enable their inter-operability. In this paper we propose a novel cross-network, cross-layer algorithm that jointly performs 3G resource allocation and ad-hoc mode WLAN routing towards effectively increasing the performance of the 3G system. The metrics used in this joint design ensures that multi-user diversity is exploited without causing user starvation in the 3G system and the WLAN assistance does not cause an unfair treatment to any of the mobiles from a battery usage point of view. Furthermore, the design attempts to select the WLAN route so that the assistance does not become a major part of the internal WLAN traffic.
2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications, 2007
Ultra-wideband (UWB) indoor positioning systems based on time of arrival (ToA) techniques are con... more Ultra-wideband (UWB) indoor positioning systems based on time of arrival (ToA) techniques are considered to be the high precision alternatives to those employing received signal strength (RSS) or angle of arrival (AoA) due to their superior time-domain resolution. However, the performance of such systems may easily be degraded by the blockage of the direct path (DP) and occurrence of undetected direct path (UDP) condition. By erroneous detection of the other multipath components (MPCs) as DP, which is the indicator of the true distance between the transmitter and the receiver, substantial localization errors will be introduced into the system. Hence, detection of DP categorizes the receiver locations into two main classes of detected direct path (DDP) and undetected direct path (UDP). The real challenge is to be able to identify the class of the receiver location; therefore, to remedy the ranging measurement in UDP condition. In this paper we propose a methodology to identify and mitigate the UDP conditions, which can substantially improve the overall indoor positioning accuracy.
ABSTRACT The presence of undetected direct path (UDP) conditions presents significant challenges ... more ABSTRACT The presence of undetected direct path (UDP) conditions presents significant challenges for TOA-based indoor geolocation, since it introduces major errors into distance measurements. Therefore, it is critical to characterize the performance of indoor geolocation systems in the presence of UDP conditions. Until now, however, there has been no standard method of performance benchmarking for such cases. Towards that end, we present an analysis tool, known as the MSE profile, that can aid in this task. We use the MSE profile to analyze the performance of two TOA-based geolocation algorithms and show how the MSE profile can be used to gain insight into their performance, in the presence of distance measurement error (DME) models derived from Ultra-Wideband (UWB) measurements.
2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications, 2007
Abstract Ultra-wideband (UWB) indoor positioning systems based on time of arrival (TOA) technique... more Abstract Ultra-wideband (UWB) indoor positioning systems based on time of arrival (TOA) techniques are considered to be the high precision alternatives to those employing received signal strength (RSS) or angle of arrival (AOA) due to their superior time-domain ...
2010 IEEE 21st International Symposium on Personal, Indoor and Mobile Radio Communications Workshops, 2010
... 2(a) & 2(b), UWB-Only in Figs.3(a) & 3(b), Hybrid WiFi-UWB in Figs. 4(a) & 4(b) a... more ... 2(a) & 2(b), UWB-Only in Figs.3(a) & 3(b), Hybrid WiFi-UWB in Figs. 4(a) & 4(b) and finally overall performance for hybrid and WiFi-Only in Figs. 5 & 6. In all our simulation runs, we have used thirty two equally distanced locations across the route for all robots. For all ...
2009 IEEE International Conference on Ultra-Wideband, 2009
This paper describes the results of frequencydomain dynamic channel sounding in a typical office ... more This paper describes the results of frequencydomain dynamic channel sounding in a typical office environment for studying the spatio-temporal channel behavior pertinent to indoor geolocation. It consists of detailed characterization of complex frequency responses of ultra-wideband (UWB) signals having a nominal center frequency of 5.5GHz and bandwidth of 5GHz. The effects of distance, threshold for picking paths, bandwidth, and occurrence of none-line-of-sight (NLOS) on multipath parameters such as number of multipath-components (MPCs) and path persistency are presented. Furthermore, a novel model for the dynamic behavior of number of MPCs is proposed.
ABSTRACT The presence of undetected direct path (UDP) conditions presents significant challenges ... more ABSTRACT The presence of undetected direct path (UDP) conditions presents significant challenges for TOA-based indoor geolocation, since it introduces major errors into distance measurements. Therefore, it is critical to characterize the performance of indoor geolocation systems in the presence of UDP conditions. Until now, however, there has been no standard method of performance benchmarking for such cases. Towards that end, we present an analysis tool, known as the MSE profile, that can aid in this task. We use the MSE profile to analyze the performance of two TOA-based geolocation algorithms and show how the MSE profile can be used to gain insight into their performance, in the presence of distance measurement error (DME) models derived from Ultra-Wideband (UWB) measurements.
MILCOM 2007 - IEEE Military Communications Conference, 2007
... Ferit Ozan Akgiil, Kaveh Pahlavan Center for Wireless Information Network Studies, Worcester ... more ... Ferit Ozan Akgiil, Kaveh Pahlavan Center for Wireless Information Network Studies, Worcester Polytechnic Institute Worcester, MA, 01609, USA {ferit, kaveh ... When we consider a certain path, we might say this particular path has a certain reflection/transmission pat-tern inside ...
A novel statistical angle-of-arrival (AOA) model for indoor geolocation applications is presented... more A novel statistical angle-of-arrival (AOA) model for indoor geolocation applications is presented. The modeling approach focuses on the arrivals of the multipath components with respect to the line-of-sight (LOS) path which is an important component especially when indoor geolocation applications are considered. The model is particularly important for indoor applications where AOA information could be utilized for tracking indirect paths to aid in precise ranging in harsh and dense multipath environments where LOS path might be blocked due to obstructions. The results have been obtained by a measurement calibrated ray-tracing (RT) tool.
Severe multipath in indoor areas causes undetected direct path (UDP) conditions, which pose a ser... more Severe multipath in indoor areas causes undetected direct path (UDP) conditions, which pose a serious challenge to the design of robust precision indoor geolocation systems. Based on a scenario on the third floor of the Atwater Kent Laboratory at the Worcester Polytechnic Institute, we explain the reason for frequent absence of direct path, and introduce and analyze the effectiveness of two novel approaches to mitigating the large ranging errors caused by UDP conditions. The first technique exploits nondirect paths for ranging, while the second approach relies on cooperative localization for wireless sensor and ad hoc networks.
-- Recently wireless positioning using existing network infrastructure has become an attractive v... more -- Recently wireless positioning using existing network infrastructure has become an attractive value added application in campus and local area networks. However, many complexities, intrinsic to indoor radio propagation create technical challenges for the ...
In this paper we propose the use of statistical QoS guarantees for transmission over the wireless... more In this paper we propose the use of statistical QoS guarantees for transmission over the wireless channel. Here, instead of QoS assurances, we propose to guarantee the percentage of time the QoS requirements are satisfied. We present an associated scheduling algorithm for the opportunistic multiple access system. We compare the proposed scheduler with popular schedulers from the literature. We observe that the statistical QoS guarantee is an attractive alternative to the assured QoS service for the wireless platform, since such strict QoS assurances decrease the wireless system performance significantly. Index Terms-Wireless packet data provisioning, resource allo- cation, scheduling, QoS, 3G, 1xEV-DO.
The third generation wireless networks and wireless local networks possess complementary characte... more The third generation wireless networks and wireless local networks possess complementary characteristics. Recently, there has been significant interest in providing algorithms and specifications that enable their inter-operability. In this paper we propose a novel cross-network, cross-layer algorithm that jointly performs 3G resource allocation and ad-hoc mode WLAN routing towards effectively increasing the performance of the 3G system. The metrics used in this joint design ensures that multi-user diversity is exploited without causing user starvation in the 3G system and the WLAN assistance does not cause an unfair treatment to any of the mobiles from a battery usage point of view. Furthermore, the design attempts to select the WLAN route so that the assistance does not become a major part of the internal WLAN traffic.
2006 IEEE 17th International Symposium on Personal, Indoor and Mobile Radio Communications, 2006
ABSTRACT The performance of ultra-wideband (UWB) indoor positioning systems based on time of arri... more ABSTRACT The performance of ultra-wideband (UWB) indoor positioning systems based on time of arrival (TOA) techniques is generally affected by the density of reference points (RPs), as well as undetected direct path (UDP) conditions. For a fixed number of reference points (RPs), the performance of some indoor positioning algorithms tends to degrade as the size of the area is increased, i.e. the RP density is decreased. In this paper, we evaluate the effects of RP density on the performance of different positioning algorithms in the presence of empirical distance measurement error (DME) models derived from UWB measurements in typical indoor environments. We then present functional relationships between RP density and positioning mean-square error (MSE) for these algorithms. These relationships can be used for more effective indoor positioning system design and deployment. Finally, we investigate the effects of bandwidth with respect to improving the performance of these algorithms
The third generation wireless networks and wireless local networks possess complementary characte... more The third generation wireless networks and wireless local networks possess complementary characteristics. Recently, there has been significant interest in providing algorithms and specifications that enable their inter-operability. In this paper we propose a novel cross-network, cross-layer algorithm that jointly performs 3G resource allocation and ad-hoc mode WLAN routing towards effectively increasing the performance of the 3G system. The metrics used in this joint design ensures that multi-user diversity is exploited without causing user starvation in the 3G system and the WLAN assistance does not cause an unfair treatment to any of the mobiles from a battery usage point of view. Furthermore, the design attempts to select the WLAN route so that the assistance does not become a major part of the internal WLAN traffic.
2007 IEEE 18th International Symposium on Personal, Indoor and Mobile Radio Communications, 2007
Ultra-wideband (UWB) indoor positioning systems based on time of arrival (ToA) techniques are con... more Ultra-wideband (UWB) indoor positioning systems based on time of arrival (ToA) techniques are considered to be the high precision alternatives to those employing received signal strength (RSS) or angle of arrival (AoA) due to their superior time-domain resolution. However, the performance of such systems may easily be degraded by the blockage of the direct path (DP) and occurrence of undetected direct path (UDP) condition. By erroneous detection of the other multipath components (MPCs) as DP, which is the indicator of the true distance between the transmitter and the receiver, substantial localization errors will be introduced into the system. Hence, detection of DP categorizes the receiver locations into two main classes of detected direct path (DDP) and undetected direct path (UDP). The real challenge is to be able to identify the class of the receiver location; therefore, to remedy the ranging measurement in UDP condition. In this paper we propose a methodology to identify and mitigate the UDP conditions, which can substantially improve the overall indoor positioning accuracy.
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