Pub Date : 2005-09-11DOI: 10.1109/PIMRC.2005.1651887
S. Jeng, C. Tsung
In smart antenna systems, the DOA (direction of arrival) based beamforming algorithms use the information of users DOAs to detect the desired user's signals and suppress other interference. However, in the real wireless environment, the subspace based high resolution DOA estimation algorithms will fail to estimate the correct DOA because of the loss of rank caused by the correlation between the received signals. This paper proposes a new smoothing algorithm associated with OFDM technique to solve the problem of loss of rank. In the simulation, the proposed algorithm with TLS ESPRIT is used to estimate the DOAs. The simulation results showed that this algorithm can really solve the problem of loss of rank in the multipath channel and accurately estimate DOAs of the signals
{"title":"Multipath direction finding with frequency allocation subspace smoothing for an OFDM wireless communication system","authors":"S. Jeng, C. Tsung","doi":"10.1109/PIMRC.2005.1651887","DOIUrl":"https://doi.org/10.1109/PIMRC.2005.1651887","url":null,"abstract":"In smart antenna systems, the DOA (direction of arrival) based beamforming algorithms use the information of users DOAs to detect the desired user's signals and suppress other interference. However, in the real wireless environment, the subspace based high resolution DOA estimation algorithms will fail to estimate the correct DOA because of the loss of rank caused by the correlation between the received signals. This paper proposes a new smoothing algorithm associated with OFDM technique to solve the problem of loss of rank. In the simulation, the proposed algorithm with TLS ESPRIT is used to estimate the DOAs. The simulation results showed that this algorithm can really solve the problem of loss of rank in the multipath channel and accurately estimate DOAs of the signals","PeriodicalId":248766,"journal":{"name":"2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"81 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116342786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-09-11DOI: 10.1109/PIMRC.2005.1651717
A. Negi, Suresh Singh
This paper discusses various approaches to save power in relay-based cellular networks. We introduce an optimization method based on the Hungarian assignment problem to globally minimize the power-based allocation of relays. We compare this approach with the greedy approach of choosing a relay. We introduce another approach based on the concept of intelligent relays. Here, based on the expected power values of mobiles at the relay's location, the relay chooses to carry call for a mobile. We show that this approach introduces less intra-cell interference
{"title":"Power saving approaches in 2-hop relaying cellular networks","authors":"A. Negi, Suresh Singh","doi":"10.1109/PIMRC.2005.1651717","DOIUrl":"https://doi.org/10.1109/PIMRC.2005.1651717","url":null,"abstract":"This paper discusses various approaches to save power in relay-based cellular networks. We introduce an optimization method based on the Hungarian assignment problem to globally minimize the power-based allocation of relays. We compare this approach with the greedy approach of choosing a relay. We introduce another approach based on the concept of intelligent relays. Here, based on the expected power values of mobiles at the relay's location, the relay chooses to carry call for a mobile. We show that this approach introduces less intra-cell interference","PeriodicalId":248766,"journal":{"name":"2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123478857","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-09-11DOI: 10.1109/PIMRC.2005.1651824
Guocong Song, Geoffrey Y. Li
Channel-aware packet scheduling is investigated in this paper. Based on extreme value theory, we propose asymptotic analyses for average throughput and delay in both single-carrier and multicarrier networks. Those analyses provide accurate results and have concise expressions, which explicitly show the multiuser diversity gain inherent in channel-aware scheduling. Although multicarrier networks with channel-aware scheduling have the same throughput as single-carrier networks, multicarrier networks can provide better delay performance than single-carrier networks
{"title":"Throughput and delay performance comparison for single-carrier and multicarrier networks with multiuser diversity","authors":"Guocong Song, Geoffrey Y. Li","doi":"10.1109/PIMRC.2005.1651824","DOIUrl":"https://doi.org/10.1109/PIMRC.2005.1651824","url":null,"abstract":"Channel-aware packet scheduling is investigated in this paper. Based on extreme value theory, we propose asymptotic analyses for average throughput and delay in both single-carrier and multicarrier networks. Those analyses provide accurate results and have concise expressions, which explicitly show the multiuser diversity gain inherent in channel-aware scheduling. Although multicarrier networks with channel-aware scheduling have the same throughput as single-carrier networks, multicarrier networks can provide better delay performance than single-carrier networks","PeriodicalId":248766,"journal":{"name":"2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117241200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-09-11DOI: 10.1109/PIMRC.2005.1651795
F. González-Castaño, F. Gil-Castiñeira, Jaime García-Reinoso
A practical real-time mobile auction system must fulfill diverse constraints. In Rodriguez-Hernandez P.S. et al. (2002), we described a mobile auction system implemented with 433 MHz band modems. Nowadays, that system has become a standard in the Galician fish markets, which include the most important fishing port in Europe, Vigo (Spain). Although our system has been performing satisfactorily for four years, it is obvious that new technologies such as Bluetooth and IEEE 802.11 have shaped the wireless market and deserve our attention. In this paper, we evaluate Bluetooth in the context of real-time mobile auctions. As a result, we propose a novel approach to implement mobile auction systems by exploiting the park mode in Bluetooth specifications, which may also be useful for other remote-command applications with hard real-time constraints
一个实用的实时移动拍卖系统必须满足多种约束条件。在Rodriguez-Hernandez P.S. et al.(2002)中，我们描述了一个使用433 MHz频段调制解调器实现的移动拍卖系统。如今，该系统已成为加利西亚鱼市场的标准，其中包括欧洲最重要的渔港维戈(西班牙)。虽然我们的系统四年来表现令人满意，但很明显，蓝牙和IEEE 802.11等新技术已经塑造了无线市场，值得我们关注。在本文中，我们在实时移动拍卖的背景下评估蓝牙。因此，我们提出了一种利用蓝牙规范中的停车模式来实现移动拍卖系统的新方法，这也可能对其他具有硬实时限制的远程命令应用程序有用
{"title":"Bluetooth real-time mobile auctions","authors":"F. González-Castaño, F. Gil-Castiñeira, Jaime García-Reinoso","doi":"10.1109/PIMRC.2005.1651795","DOIUrl":"https://doi.org/10.1109/PIMRC.2005.1651795","url":null,"abstract":"A practical real-time mobile auction system must fulfill diverse constraints. In Rodriguez-Hernandez P.S. et al. (2002), we described a mobile auction system implemented with 433 MHz band modems. Nowadays, that system has become a standard in the Galician fish markets, which include the most important fishing port in Europe, Vigo (Spain). Although our system has been performing satisfactorily for four years, it is obvious that new technologies such as Bluetooth and IEEE 802.11 have shaped the wireless market and deserve our attention. In this paper, we evaluate Bluetooth in the context of real-time mobile auctions. As a result, we propose a novel approach to implement mobile auction systems by exploiting the park mode in Bluetooth specifications, which may also be useful for other remote-command applications with hard real-time constraints","PeriodicalId":248766,"journal":{"name":"2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"732 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120861980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-09-11DOI: 10.1109/PIMRC.2005.1651535
T. Clevorn, J. Brauers, M. Adrat, P. Vary
Turbo decodulation is the combination of iterative demodulation and iterative source-channel decoding to a single multiple turbo process. The receiver structures of bit-interleaved coded modulation with iterative decoding (BICM-ID), iterative source-channel decoding (ISCD), and iterative source coded modulation (ISCM) are merged to one novel turbo system, in which in two iterative loops reliability information is exchanged between the three single components, demodulator, channel decoder, and (softbit) source decoder. Simulations show quality improvements compared to the different previously known systems, which use iterative processing only for two components of the receiver. We propose the enhancement to turbo decodulation by an additional link for a direct supply of reliabilities from the softbit source decoder to the demodulator. We will demonstrate that using three-dimensional EXIT charts a convergence analysis of turbo decodulation similar to single turbo processes is possible
{"title":"EXIT chart analysis of turbo decodulation","authors":"T. Clevorn, J. Brauers, M. Adrat, P. Vary","doi":"10.1109/PIMRC.2005.1651535","DOIUrl":"https://doi.org/10.1109/PIMRC.2005.1651535","url":null,"abstract":"Turbo decodulation is the combination of iterative demodulation and iterative source-channel decoding to a single multiple turbo process. The receiver structures of bit-interleaved coded modulation with iterative decoding (BICM-ID), iterative source-channel decoding (ISCD), and iterative source coded modulation (ISCM) are merged to one novel turbo system, in which in two iterative loops reliability information is exchanged between the three single components, demodulator, channel decoder, and (softbit) source decoder. Simulations show quality improvements compared to the different previously known systems, which use iterative processing only for two components of the receiver. We propose the enhancement to turbo decodulation by an additional link for a direct supply of reliabilities from the softbit source decoder to the demodulator. We will demonstrate that using three-dimensional EXIT charts a convergence analysis of turbo decodulation similar to single turbo processes is possible","PeriodicalId":248766,"journal":{"name":"2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129587517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-09-11DOI: 10.1109/PIMRC.2005.1651406
R. Alihemmati, A. A. Shishegar, N. Hojjat, G. Dadashzadeh, B. Boghrati, A. Mehrtash
The smart antenna technique as a method of improving the physical layer performance of OFDM WLANs is studied. For this purpose, a comparison of the smart antenna architectures for IEEE 802.11a WLAN system using pre-FFT and post-FFT array processing with different parameters is represented. Simulations are performed on a new Simulink model for IEEE802.11a system using a spatio-temporal channel modeling which is based on the measured wideband channels in the 5 GHz band. Raw bit-error-rate performance for QPSK/16QAM modulations at LOS and NLOS channel scenarios are evaluated and compared
{"title":"Comparison of the Smart Antenna Architectures for OFDM-WLAN Systems in a Rich Multipath Environment based on a Spatio-Temporal Channel Model","authors":"R. Alihemmati, A. A. Shishegar, N. Hojjat, G. Dadashzadeh, B. Boghrati, A. Mehrtash","doi":"10.1109/PIMRC.2005.1651406","DOIUrl":"https://doi.org/10.1109/PIMRC.2005.1651406","url":null,"abstract":"The smart antenna technique as a method of improving the physical layer performance of OFDM WLANs is studied. For this purpose, a comparison of the smart antenna architectures for IEEE 802.11a WLAN system using pre-FFT and post-FFT array processing with different parameters is represented. Simulations are performed on a new Simulink model for IEEE802.11a system using a spatio-temporal channel modeling which is based on the measured wideband channels in the 5 GHz band. Raw bit-error-rate performance for QPSK/16QAM modulations at LOS and NLOS channel scenarios are evaluated and compared","PeriodicalId":248766,"journal":{"name":"2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127134088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-09-11DOI: 10.1109/PIMRC.2005.1651548
C. Moy, A. Bisiaux, S. Paquelet
This paper describes how cognitive radio (CR) could benefit from software-defined radio (SDR) compatible ultra-wide band (UWB) systems. It introduces the notion of umbilical cord that can keep a CR device connected to its surrounding world, thanks to sensing and low speed over-the-air reconfiguration (OTAR) means provided by low-data rate (LDR) systems, and to fast OTAR downloading facilities based on high-data rate (HDR) hot spots. A particular UWB architecture supporting SDR-compatible technological constraints is proposed as candidate to realize this promising combination of capabilities
{"title":"An ultra-wide band umbilical cord for cognitive radio systems","authors":"C. Moy, A. Bisiaux, S. Paquelet","doi":"10.1109/PIMRC.2005.1651548","DOIUrl":"https://doi.org/10.1109/PIMRC.2005.1651548","url":null,"abstract":"This paper describes how cognitive radio (CR) could benefit from software-defined radio (SDR) compatible ultra-wide band (UWB) systems. It introduces the notion of umbilical cord that can keep a CR device connected to its surrounding world, thanks to sensing and low speed over-the-air reconfiguration (OTAR) means provided by low-data rate (LDR) systems, and to fast OTAR downloading facilities based on high-data rate (HDR) hot spots. A particular UWB architecture supporting SDR-compatible technological constraints is proposed as candidate to realize this promising combination of capabilities","PeriodicalId":248766,"journal":{"name":"2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127161042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-09-11DOI: 10.1109/PIMRC.2005.1651490
S. C. Thompson, J. Proakis, J. Zeidler
A noncoherent constant envelope orthogonal frequency-division multiplexing (CE-OFDM) receiver is proposed. It is shown that CE-OFDM is naturally noncoherent since the effect of an unknown phase shift at the receiver is eliminated by the matched-filter bank following the front-end phase demodulator. The noncoherent receiver demodulates continuous phase CE-OFDM signals - which produce less adjacent channel interference - with no added complexity. Performance is evaluated in flat fading channels having both Rayleigh and Ricean statistics. Simulation results are compared to analytical approximations
{"title":"Noncoherent Reception of Constant Envelope OFDM in Flat Fading Channels","authors":"S. C. Thompson, J. Proakis, J. Zeidler","doi":"10.1109/PIMRC.2005.1651490","DOIUrl":"https://doi.org/10.1109/PIMRC.2005.1651490","url":null,"abstract":"A noncoherent constant envelope orthogonal frequency-division multiplexing (CE-OFDM) receiver is proposed. It is shown that CE-OFDM is naturally noncoherent since the effect of an unknown phase shift at the receiver is eliminated by the matched-filter bank following the front-end phase demodulator. The noncoherent receiver demodulates continuous phase CE-OFDM signals - which produce less adjacent channel interference - with no added complexity. Performance is evaluated in flat fading channels having both Rayleigh and Ricean statistics. Simulation results are compared to analytical approximations","PeriodicalId":248766,"journal":{"name":"2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127459771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-09-11DOI: 10.1109/PIMRC.2005.1651876
C. Teekapakvisit, Yonghui Li, V. Pham, B. Vucetic
It is well known that an adaptive frequency domain receiver can dramatically reduce the detection computation complexity of a communication system compared to standard time domain receiver. In this paper, we propose a new low complexity frequency domain adaptive and iterative receiver for a layered space-time coded CDMA (LSTC-CDMA) system with no knowledge of channel state information (CSI), spreading sequences, and the fading coefficients, except a training sequence for each user. The proposed low complexity receiver consists of a normalized LMS feed forward filter and a feedback iterative parallel interference canceller in frequency domain. The proposed frequency domain receiver has a significant reduction in computation complexity and achieves the same performance compared to a time domain receiver. Our simulation results exhibit that the proposed adaptive iterative receiver can also approach the interference-free single user performance for a certain range of the signal to noise ratio (SNR)
{"title":"Low complexity adaptive iterative receiver for layered space-time coding CDMA systems","authors":"C. Teekapakvisit, Yonghui Li, V. Pham, B. Vucetic","doi":"10.1109/PIMRC.2005.1651876","DOIUrl":"https://doi.org/10.1109/PIMRC.2005.1651876","url":null,"abstract":"It is well known that an adaptive frequency domain receiver can dramatically reduce the detection computation complexity of a communication system compared to standard time domain receiver. In this paper, we propose a new low complexity frequency domain adaptive and iterative receiver for a layered space-time coded CDMA (LSTC-CDMA) system with no knowledge of channel state information (CSI), spreading sequences, and the fading coefficients, except a training sequence for each user. The proposed low complexity receiver consists of a normalized LMS feed forward filter and a feedback iterative parallel interference canceller in frequency domain. The proposed frequency domain receiver has a significant reduction in computation complexity and achieves the same performance compared to a time domain receiver. Our simulation results exhibit that the proposed adaptive iterative receiver can also approach the interference-free single user performance for a certain range of the signal to noise ratio (SNR)","PeriodicalId":248766,"journal":{"name":"2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130209402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-09-11DOI: 10.1109/PIMRC.2005.1651829
A. Dekorsy
This paper addresses the evaluation of cross-layer metrics for wireless access systems employing hybrid automatic retransmission request (HARQ) processing combined with multiple input multiple output (MIMO) data transmission. The proposed metrics can be utilized by resource management algorithms to control resources in next generation networks. The objective is twofold. First, we evaluate a reliable throughput performance metric encompassing MIMO as well as HARQ protocol parameters in a single expression. In particular, we perform an information theoretic consideration by employing the conditional cutoff rate for MIMO transmission while the HARQ process is described by the renewal-theory. In a second step, we illustrate the flexibility of the metric evaluation approach by its application to two transmission schemes. Both schemes employ V-BLAST transmission but differ in HARQ processing. Results given for all schemes clearly indicate the suitability of the proposed metrics. With the metrics introduced we also get hints on designing wireless transmission schemes with multi antenna technologies and HARQ processing while avoiding intensive simulation studies
{"title":"A cutoff rate based cross-layer metric for MIMO-HARQ transmission","authors":"A. Dekorsy","doi":"10.1109/PIMRC.2005.1651829","DOIUrl":"https://doi.org/10.1109/PIMRC.2005.1651829","url":null,"abstract":"This paper addresses the evaluation of cross-layer metrics for wireless access systems employing hybrid automatic retransmission request (HARQ) processing combined with multiple input multiple output (MIMO) data transmission. The proposed metrics can be utilized by resource management algorithms to control resources in next generation networks. The objective is twofold. First, we evaluate a reliable throughput performance metric encompassing MIMO as well as HARQ protocol parameters in a single expression. In particular, we perform an information theoretic consideration by employing the conditional cutoff rate for MIMO transmission while the HARQ process is described by the renewal-theory. In a second step, we illustrate the flexibility of the metric evaluation approach by its application to two transmission schemes. Both schemes employ V-BLAST transmission but differ in HARQ processing. Results given for all schemes clearly indicate the suitability of the proposed metrics. With the metrics introduced we also get hints on designing wireless transmission schemes with multi antenna technologies and HARQ processing while avoiding intensive simulation studies","PeriodicalId":248766,"journal":{"name":"2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications","volume":"225 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130638910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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