| 1. |
- Reggiani, Luca, et al.
(författare)
-
Adapting the Ranging Algorithm to the Positioning Technique in UWB Sensor Networks
- 2007
-
Ingår i: Proceedings 4th COST289 workshop.
-
Konferensbidrag (refereegranskat)abstract
- Ultra-Wideband (UWB) is an emerging technology for short-rangewireless communications. Due to the high bandwidth of UWB signals,accurate ranging and positioning is possible, which is one of manyreasons why UWB is a candidate physical layer for another emergingresearch area; that of wireless sensor networks (WSNs). In thiswork, we argue that the ranging algorithm design should be madewith the characteristics of the positioning algorithm in mind. Inconsidering ranging and positioning in parallel, we are able toconstruct an estimator of range that is tailored to thepositioning algorithm, thereby achieving robustness tonon-line-of-sight (NLOS) effects, reasonable overall complexity,and good performance in terms of positioning error. The analysisand simulations in this work are based on the channel modelsadopted by the IEEE 802.15.4a working group, and highlight thebenefits and drawbacks of the proposed approach.
|
|
| 2. |
|
|
| 3. |
- Rydström, Mats, 1978, et al.
(författare)
-
Adapting the Ranging Algorithm to the Positioning Technique in UWB Sensor Networks
- 2008
-
Ingår i: Wireless Personal Communications. - : Springer Science and Business Media LLC. - 1572-834X .- 0929-6212. ; 47:1, s. 27-38
-
Tidskriftsartikel (refereegranskat)abstract
- Ultra-Wideband (UWB) is an emerging technology for short-range wireless communications. Due to the high bandwidth of UWB signals, accurate ranging and positioning is possible, which is one of many reasons why UWB is a candidate physical layer for another emerging research area, that of wireless sensor networks (WSNs). In this work, we argue that the ranging algorithm design should be made with the characteristics of the positioning algorithm in mind. In considering ranging and positioning in parallel, we are able to construct a range estimator that is tailored to the positioning algorithm, thereby achieving robustness to non-line-of-sight (NLOS) effects, reasonable overall complexity, and good performance in terms of positioning error. The analysis and simulations in this work are based on the channel models adopted by the IEEE 802.15.4a working group, and highlight the benefits and drawbacks of the proposed approach.
|
|
| 4. |
- Rydström, Mats, 1978, et al.
(författare)
-
An Algorithm for Locating Point Scatterers Using a Wide-Band Wireless Network
- 2008
-
Ingår i: 4th Management Committee Meeting of COST2100.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A map of the coordinates of the most significant pointscatterersin the environment surrounding a wireless network would be useful in many contexts, e.g., in indoor positioning and mapping applications, for channel estimation, and also for wake-up radio schemes. In this work, we investigate the feasibility of creating such a map based on signal propagation path length data gatheredat a number of wide-band network transceivers. Differently from previous approaches to this problem, we propose to formulate the point scatterer mapping problem as an assignment problem. Computer simulations show that, under a few simplifying assumptions, it is indeed feasible to position point scatterers using the proposed algorithm.
|
|
| 5. |
- Rydström, Mats, 1978, et al.
(författare)
-
An Algorithm for Mapping the Positions of Point Scatterers
- 2008
-
Ingår i: Proceedings Fifth IEEE Sensor Array and Multichannel Signal Processing Workshop, Darmstadt, Germany. - 9781424422418 ; , s. 63-67
-
Konferensbidrag (refereegranskat)abstract
- We investigate the feasibility of mapping point scatterers basedonly on multipath signal component delay estimates, i.e., no angleof-arrival information is assumed to be available. In this work wefocus on the generation of input data to a point scatterer mappingalgorithm that was recently proposed in [1]. In an effort to makethe mapping problem computationally tractable in ultra-wide bandnetworks, we first propose a mechanism that detects the presenceof new point scatterers in an environment, and reduces the numberof unwanted signal components due to other scattering objects inthe environment. We also propose to group signal components intoclusters, and base delay estimates on the cluster arrival times, insteadof on individual signal components. Computer simulationsof an ultra-wide band network indicate that reasonably accuratepoint scatterer mapping should indeed be feasible in some scenariosusing only estimates of signal component delay.
|
|
| 6. |
- Rydström, Mats, 1978, et al.
(författare)
-
An Algorithm for Positioning Relays and Point Scatterers in Wireless Systems
- 2008
-
Ingår i: IEEE Signal Processing Letters. - 1070-9908 .- 1558-2361. ; Vol. 15, s. 381-384
-
Tidskriftsartikel (refereegranskat)abstract
- In this letter, we discuss the problem of positioningan unknown number of amplify-and-forward relays or point scatterersusing a wireless network of wideband transceivers.We proposeto model this positioning problem as an assignment problem.In doing so, we avoid the problems associated with an exhaustivegridsearch approach, which has recently been proposed to solve theproblem. Numerical simulations showpromising results in terms ofperformance and robustness.
|
|
| 7. |
- Rydström, Mats, 1978, et al.
(författare)
-
An Approach to Positioning Road-Users in a Telematics Network
- 2007
-
Ingår i: Proceedings IEEE International Symposium on Autonomous Decentralized Systems, Sedona, Arizona, USA. - 076952804X ; , s. 335-343
-
Konferensbidrag (refereegranskat)abstract
- In this invited paper, we discuss positioning of road-users in a traffic environment. Once accurate and reliable position information can be made available, many interesting and innovative telematics applications may be realized. Some of the problems facing radio-frequency (RF) based positioning systems today include blocked RF channels and multipath propagation, complicating distance estimation between network members and between network members and the infrastructure. In this work, we propose a novel estimator of range operating on an ultra-wideband(UWB) physical layer. This distance estimator has been designedspecifically with a novel type of positioning algorithm in mind,based on the method of projections onto convex sets. Also, weinvestigate the feasibility of positioning users that are notmembers of the telematics network based on arbitrary transmittedRF signals. Numerical simulations, using channel models recentlyadopted by the IEEE 802.15.4a working group, confirm therobustness and accuracy of the proposed approach in the presenceof both non-line-of-sight (NLOS) channels, and severe multipathpropagation.
|
|
| 8. |
- Rydström, Mats, 1978, et al.
(författare)
-
Autonomous Positioning Techniques Based on Cramer-Rao Lower Bound Analysis
- 2006
-
Ingår i: Eurasip Journal on Applied Signal Processing. - 1110-8657 .- 1687-0433. ; 2006, s. 1-10
-
Tidskriftsartikel (refereegranskat)abstract
- We consider the problem of autonomously locating a number ofasynchronous sensor nodes in a wireless network. A strong focuslies on reducing the processing resources needed to solve therelative positioning problem, an issue of great interest inresource-constrained wireless sensor networks. In the first partof the paper, based on a well-known derivation of the Cramér-Raolower bound for the asynchronous sensor positioning problem, weare able to construct optimal preprocessing methods for sensorclock-offset cancellation. A cancellation of unknown clock-offsetsfrom the asynchronous positioning problem reduces processingrequirements, and, under certain reasonable assumptions, allowsfor statistically efficient distributed positioning algorithms. Cramér-Rao lower bound theory may also be used for estimatingthe performance of a positioning algorithm. In the second part ofthis paper, we exploit this property in developing a distributedalgorithm, where the global positioning problem is solvedsuboptimally, using a divide-and-conquer approach of lowcomplexity. The performance of this suboptimal algorithm isevaluated through computer simulation, and compared to previouslypublished algorithms. Copyright © 2006 Hindawai Publication Corporation. All rights reserved.
|
|
| 9. |
- Rydström, Mats, 1978, et al.
(författare)
-
Clock-offset Cancellation Methods for Positioning in Asynchronous Sensor Networks
- 2005
-
Ingår i: Proceedings IEEE WirelessCom, Hawaii, USA. - 0780393058 ; 2, s. 981-986
-
Konferensbidrag (refereegranskat)abstract
- For most applications of wireless sensor networks, knowledge about the position of sensors relative to other sensors in the network, or to some global coordinate system, is a key ingredient to successful operation of the network. Estimation of relative node coordinates, based on measured time-of-flight between neighbouring nodes, has been suggested as a means to provide position-awareness in sensor networks where satellite based systems are not available. However, to directly measure the inter-node distances, based on RF or ultra-sound propagation delay, requires the nodes to be tightly synchronized in time. This is an assumption that is not easily justified in sensor networks operating under complexity, latency, power consumption or bandwidth constraints. Joint ML estimation of clock-offsets and node coordinates has been suggested, but, although this approach shows great promise in terms of coordinate estimation accuracy, it does not scale well as sensor networks grow in size. In this paper, we present two linear preprocessing operations that cancels the effect of unknown clock-offsets from the estimation problem. For both operations, we show that the Fisher information on node coordinates in the original data-set remains unchanged after preprocessing. Novel ML estimators of relative node coordinates are proposed, that are of significantly lower complexity, while their performance equals that of the joint ML estimator. © 2005 IEEE.
|
|
| 10. |
|
|
