The Experts below are selected from a list of 41340 Experts worldwide ranked by ideXlab platform
Per Hellqvist - One of the best experts on this subject based on the ideXlab platform.
-
VTC Fall - Estimation of Uplink WCDMA Load in a Single RBS
2007 IEEE 66th Vehicular Technology Conference, 2007Co-Authors: Torbjorn Wigren, Per HellqvistAbstract:The measurement of uplink load is important for the scheduling of enhanced uplink channels in WCDMA systems. This measurement is particularly difficult since the thermal noise power floor is unobservable when using power measurements in a single base station. The problem is due to the Neighbor Cell interference. The paper proposes a work around, using a novel algorithm for soft Bayesian estimation of a conditional probability distribution of the minimum of filtered power samples, this minimum approximating the thermal noise power floor of the digital receiver. The load can then be estimated from the total wideband power of the Cell and the estimated minimum. The discretized conditional pdf is one-dimensional - hence the algorithm has a low complexity. Details of the implementation are described in the paper, together with measured results.
-
Estimation of Uplink WCDMA Load in a Single RBS
2007 IEEE 66th Vehicular Technology Conference, 2007Co-Authors: Torbjorn Wigren, Per HellqvistAbstract:The measurement of uplink load is important for the scheduling of enhanced uplink channels in WCDMA systems. This measurement is particularly difficult since the thermal noise power floor is unobservable when using power measurements in a single base station. The problem is due to the Neighbor Cell interference. The paper proposes a work around, using a novel algorithm for soft Bayesian estimation of a conditional probability distribution of the minimum of filtered power samples, this minimum approximating the thermal noise power floor of the digital receiver. The load can then be estimated from the total wideband power of the Cell and the estimated minimum. The discretized conditional pdf is one-dimensional - hence the algorithm has a low complexity. Details of the implementation are described in the paper, together with measured results.
Chun Peng Song - One of the best experts on this subject based on the ideXlab platform.
-
bzu2 zmmute controls symmetrical division of guard mother Cell and specifies Neighbor Cell fate in maize
PLOS Genetics, 2019Co-Authors: Hongliang Wang, Xin Qiao, Zuliang Li, Yusen Zhou, Daojie Wang, Pengcheng Wang, David W Galbraith, Chun Peng SongAbstract:InterCellular communication in adjacent Cell layers determines Cell fate and polarity, thus orchestrating tissue specification and differentiation. Here we use the maize stomatal apparatus as a model to investigate Cell fate determination. Mutations in ZmBZU2 (bizui2, bzu2) confer a complete absence of subsidiary Cells (SCs) and normal guard Cells (GCs), leading to failure of formation of mature stomatal complexes. Nuclear polarization and actin accumulation at the interface between subsidiary mother Cells (SMCs) and guard mother Cells (GMCs), an essential pre-requisite for asymmetric Cell division, did not occur in Zmbzu2 mutants. ZmBZU2 encodes a basic helix-loop-helix (bHLH) transcription factor, which is an ortholog of AtMUTE in Arabidopsis (BZU2/ZmMUTE). We found that a number of genes implicated in stomatal development are transcriptionally regulated by BZU2/ZmMUTE. In particular, BZU2/ZmMUTE directly binds to the promoters of PAN1 and PAN2, two early regulators of protodermal Cell fate and SMC polarization, consistent with the low levels of transcription of these genes observed in bzu2-1 mutants. BZU2/ZmMUTE has the Cell-to-Cell mobility characteristic similar to that of BdMUTE in Brachypodium distachyon. Unexpectedly, BZU2/ZmMUTE is expressed in GMC from the asymmetric division stage to the GMC division stage, and especially in the SMC establishment stage. Taken together, these data imply that BZU2/ZmMUTE is required for early events in SMC polarization and differentiation as well as for the last symmetrical division of GMCs to produce the two GCs, and is a master determinant of the Cell fate of its Neighbors through Cell-to-Cell communication.
David W Galbraith - One of the best experts on this subject based on the ideXlab platform.
-
bzu2 zmmute controls symmetrical division of guard mother Cell and specifies Neighbor Cell fate in maize
PLOS Genetics, 2019Co-Authors: Hongliang Wang, Xin Qiao, Zuliang Li, Yusen Zhou, Daojie Wang, Pengcheng Wang, David W Galbraith, Chun Peng SongAbstract:InterCellular communication in adjacent Cell layers determines Cell fate and polarity, thus orchestrating tissue specification and differentiation. Here we use the maize stomatal apparatus as a model to investigate Cell fate determination. Mutations in ZmBZU2 (bizui2, bzu2) confer a complete absence of subsidiary Cells (SCs) and normal guard Cells (GCs), leading to failure of formation of mature stomatal complexes. Nuclear polarization and actin accumulation at the interface between subsidiary mother Cells (SMCs) and guard mother Cells (GMCs), an essential pre-requisite for asymmetric Cell division, did not occur in Zmbzu2 mutants. ZmBZU2 encodes a basic helix-loop-helix (bHLH) transcription factor, which is an ortholog of AtMUTE in Arabidopsis (BZU2/ZmMUTE). We found that a number of genes implicated in stomatal development are transcriptionally regulated by BZU2/ZmMUTE. In particular, BZU2/ZmMUTE directly binds to the promoters of PAN1 and PAN2, two early regulators of protodermal Cell fate and SMC polarization, consistent with the low levels of transcription of these genes observed in bzu2-1 mutants. BZU2/ZmMUTE has the Cell-to-Cell mobility characteristic similar to that of BdMUTE in Brachypodium distachyon. Unexpectedly, BZU2/ZmMUTE is expressed in GMC from the asymmetric division stage to the GMC division stage, and especially in the SMC establishment stage. Taken together, these data imply that BZU2/ZmMUTE is required for early events in SMC polarization and differentiation as well as for the last symmetrical division of GMCs to produce the two GCs, and is a master determinant of the Cell fate of its Neighbors through Cell-to-Cell communication.
Xin Wang - One of the best experts on this subject based on the ideXlab platform.
-
GLOBECOM - SSS Detection Scheme for Neighbor Cell Search in 3GPP LTE Systems
2011 IEEE Global Telecommunications Conference - GLOBECOM 2011, 2011Co-Authors: Baojin Li, Xin WangAbstract:In this paper, we propose an iterative SSS detection scheme for Neighbor Cell search in 3GPP LTE systems. The proposed scheme contains three stages for each iteration. At the first stage, SSS is detected without channel information and a candidate Cell is selected. Then a coherent detection is utilized with channel response estimated from the candidate's SSCH at the second stage, in which a corresponding decision metric is calculated as well. By comparing the value of this decision metric with a predetermined threshold, the candidate Cell is further confirmed. At the third stage, interference canCellation is performed in order to search another Neighbor Cell with less interference in the next iteration. Simulation results demonstrate that the proposed iterative SSS detection scheme improves the Neighbor Cell search performance significantly.
-
Efficient SSS Detection for Neighbor Cell Search in 3GPP LTE TDD Systems
2011 IEEE International Conference on Communications (ICC), 2011Co-Authors: Baojin Li, Xin WangAbstract:This paper presents a novel SSS detection method for the second step of Neighbor Cell search in 3GPP LTE TDD systems. The proposed method is based on coherent detection and contains two stages. At the first stage, SSS is detected by using estimated channel response at PSCH. Owing to the difference of channels between PSCH and SSCH in TDD mode, the channel response estimated from PSCH does not exactly match the channel response of SSCH and performance degradation is occurred. To mitigate the effect of such channel mismatch problems and improve the Cell search reliability, the candidate Cells selected at the first stage will be further confirmed by a second coherent detection with channel response estimated from SSCH at the second stage. Simulation results demonstrate that the proposed two-stage scheme improves the Neighbor Cell search performance significantly.
-
ICC - Efficient SSS Detection for Neighbor Cell Search in 3GPP LTE TDD Systems
2011 IEEE International Conference on Communications (ICC), 2011Co-Authors: Baojin Li, Xin WangAbstract:This paper presents a novel SSS detection method for the second step of Neighbor Cell search in 3GPP LTE TDD systems. The proposed method is based on coherent detection and contains two stages. At the first stage, SSS is detected by using estimated channel response at PSCH. Owing to the difference of channels between PSCH and SSCH in TDD mode, the channel response estimated from PSCH does not exactly match the channel response of SSCH and performance degradation is occurred. To mitigate the effect of such channel mismatch problems and improve the Cell search reliability, the candidate Cells selected at the first stage will be further confirmed by a second coherent detection with channel response estimated from SSCH at the second stage. Simulation results demonstrate that the proposed two-stage scheme improves the Neighbor Cell search performance significantly.
-
SSS Detection Scheme for Neighbor Cell Search in 3GPP LTE Systems
2011 IEEE Global Telecommunications Conference - GLOBECOM 2011, 2011Co-Authors: Baojin Li, Xin WangAbstract:In this paper, we propose an iterative SSS detection scheme for Neighbor Cell search in 3GPP LTE systems. The proposed scheme contains three stages for each iteration. At the first stage, SSS is detected without channel information and a candidate Cell is selected. Then a coherent detection is utilized with channel response estimated from the candidate's SSCH at the second stage, in which a corresponding decision metric is calculated as well. By comparing the value of this decision metric with a predetermined threshold, the candidate Cell is further confirmed. At the third stage, interference canCellation is performed in order to search another Neighbor Cell with less interference in the next iteration. Simulation results demonstrate that the proposed iterative SSS detection scheme improves the Neighbor Cell search performance significantly.
Michal Vondra - One of the best experts on this subject based on the ideXlab platform.
-
Self-optimizing Neighbor Cell list with dynamic threshold for handover purposes in networks with small Cells
Wireless Communications and Mobile Computing, 2013Co-Authors: Zdenek Becvar, Pavel Mach, Michal VondraAbstract:To select a proper target Cell for handover of mobile users, signal level of Cells in user's Neighborhood is scanned by a user equipment UE. Cells assumed to be scanned are included in the so-called Neighbor Cell list NCL. Conventionally, the NCL is managed according to the probability of handover of users to a target Cell with fixed threshold. Nevertheless, the size of NCL could be significant if this approach is applied to networks with small Cells. In this paper, we exploit knowledge of handover probability among Cells derived from a handover history to reduce the amount of scanned Cells. We introduce dynamic adaptation of the amount of Cells to be scanned according to the quality of signal of a serving Cell, measured by the UE. We also investigate impact of relation between the handover probability and the signal level to maximize efficiency of this approach. Further, the NCL management considering either summarized handover history of all UE or individual history of each user is compared in our evaluations. As the results show, both methods notably reduce the amount of Cells to be scanned, while call drop rate and outage of the users are still negligible as in the conventional way. Copyright © 2013 John Wiley & Sons, Ltd.
-
PIMRC - Self-configured Neighbor Cell List of macro Cells in network with Small Cells
2013 IEEE 24th Annual International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC), 2013Co-Authors: Michal Vondra, Zdenek BecvarAbstract:To ensure faultless handover procedure of mobile users, each Cell in the network must establish a Neighbor Cell List (NCL). The NCL contains adjacent Cells to which handover can be performed. A problem related to the handover from a Macro/Micro Cell (MeNB) appears with the rising density of Cells with the limited coverage, so-called Small Cells (SCeNBs). By using method of the NCL creation described in standards or literature, the number of Neighboring Cells suitable for handover from the MeNB can be extensive. Therefore, we propose an algorithm for automatic creation of the NCL with reduced number of included Cells. The proposed algorithm exploits knowledge of the last visited Cell in combination with the statistical information on performed handovers in the past to determine the possibility of transition to the Neighboring Cells. As the results show, the proposed algorithm significantly reduces the number of Cells in the NCL while the probability of missing handover target Cell in the NCL is kept negligible.
-
PIMRC - Optimization of SINR-based Neighbor Cell List for networks with small Cells
2013 IEEE 24th Annual International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC), 2013Co-Authors: Zdenek Becvar, Pavel Mach, Michal VondraAbstract:In this paper, we propose an optimization of Neighbor Cell List (NCL) management algorithm. The goal is to minimize a number of scanned Cells for handover purposes while a call drop rate is not increased. To that end, the NCL is dynamically optimized according to the SINR observed by a User Equipment (UE) from its serving Cell. If a UE is in the Cell center, only the serving Cell is scanned. Contrary, if the UE moves closer to the Cell edge, also other Cells are inserted to the list of scanned Cells. The Cells are included in the list based on the probability of handover to these Cells. The optimization presented in this paper consists in derivation of the optimal value of the parameters that describes a relation between a handover probability threshold for scanning and SINR measured by the UE. First, we provide analytical analysis of the problem and then we confirm the derived optimal values by means of simulations. The results show the proposed optimization of the NCL management is able to reduce the number of scanned Cells significantly while the call drops due to NCL can be eliminated.
-
Dynamic Optimization of Neighbor Cell List for FemtoCells
2013 IEEE 77th Vehicular Technology Conference (VTC Spring), 2013Co-Authors: Zdenek Becvar, Michal Vondra, Pavel MachAbstract:To select appropriate target Cell for handover if a user is moving, Cells in user's Neighborhood must be scanned and their signal quality must be measured by a User Equipment (UE). The Cells intended to be scanned are listed in a Neighbor Cell List (NCL). The NCL is defined for each Cell in the network and it is distributed to the users. A size of the NCL can be negatively influenced by dense deployment of Cells with small radius, such as femtoCells. In this paper, we investigate potential reduction of an amount of Cells in the NCL to minimize signaling overhead and time required for scanning in networks with femtoCells. Contrary to a conventional management of the NCL, we reduce the NCL for each UE individually. The lower number of Cells in the UEs' NCL is achieved by consideration of mobility patterns of individual user. To avoid situation when a real target Cell is missing in the NCL, we propose a dynamic adaptation of the UE's NCL according to the quality of signal measured by the UE from a serving Cell. As the results show, the proposed approach with dynamic threshold significantly reduces amount of scanned Cells comparing to competitive algorithms. Simultaneously, the outage probability and call drop rates are still kept at minimum level by our proposal.
-
VTC Spring - Dynamic Optimization of Neighbor Cell List for FemtoCells
2013 IEEE 77th Vehicular Technology Conference (VTC Spring), 2013Co-Authors: Zdenek Becvar, Michal Vondra, Pavel MachAbstract:To select appropriate target Cell for handover if a user is moving, Cells in user's Neighborhood must be scanned and their signal quality must be measured by a User Equipment (UE). The Cells intended to be scanned are listed in a Neighbor Cell List (NCL). The NCL is defined for each Cell in the network and it is distributed to the users. A size of the NCL can be negatively influenced by dense deployment of Cells with small radius, such as femtoCells. In this paper, we investigate potential reduction of an amount of Cells in the NCL to minimize signaling overhead and time required for scanning in networks with femtoCells. Contrary to a conventional management of the NCL, we reduce the NCL for each UE individually. The lower number of Cells in the UEs' NCL is achieved by consideration of mobility patterns of individual user. To avoid situation when a real target Cell is missing in the NCL, we propose a dynamic adaptation of the UE's NCL according to the quality of signal measured by the UE from a serving Cell. As the results show, the proposed approach with dynamic threshold significantly reduces amount of scanned Cells comparing to competitive algorithms. Simultaneously, the outage probability and call drop rates are still kept at minimum level by our proposal.
