Pub Date : 2008-03-05DOI: 10.1109/RWS.2008.4463428
M. Hamada, N. Itoh
Scaled CMOS technology has opened the door of CMOS wireless SoC. The bright side is, apparently, high integration level and low cost implementation brought by the huge capacity of standard CMOS. However, as a designer point of view, another side should also be addressed, especially on PVT variation issues of scaled CMOS. In this paper, we will show the issues and their respective countermeasures on a voltage controlled oscillator in the local oscillator, a low noise amplifier and a channel select filter in the receiver, and digital calibration of I/Q mismatch in the transmitter.
{"title":"Robust design of deep Sub-micron CMOS wireless SoC","authors":"M. Hamada, N. Itoh","doi":"10.1109/RWS.2008.4463428","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463428","url":null,"abstract":"Scaled CMOS technology has opened the door of CMOS wireless SoC. The bright side is, apparently, high integration level and low cost implementation brought by the huge capacity of standard CMOS. However, as a designer point of view, another side should also be addressed, especially on PVT variation issues of scaled CMOS. In this paper, we will show the issues and their respective countermeasures on a voltage controlled oscillator in the local oscillator, a low noise amplifier and a channel select filter in the receiver, and digital calibration of I/Q mismatch in the transmitter.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"153 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129152637","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463433
E. R. Srinidhi, R. Ma, A. Z. Markos, G. Kompa
This paper focuses on the optimization of broadband envelope termination for reliable device characterization for future UMTS-LTE systems. Drain bias modulation is suppressed in 8times500 mum GaN HEMT using compensation network overcoming the parasitic effects of the DC feed, generally ignored during broadband measurements. Drain modulation index (DMI) metric is defined for quantifying the extent of drain voltage modulation as a function of carrier spacing and up to 80% reduction in DMI is achieved after drain bias compensation. Further, based on the experimental analysis, a simple bias tee is designed which can overcome improper DC feed conditions. Under 2-carrier CW and W-CDMA excitation, maximum of 19 dB and 18 dB IMD3 suppression together with the minimization of IMD asymmetry, were achieved using in- house bias tee, emphasizing the importance of broadband bias network design.
{"title":"Optimization of broadband drain modulation in GaN HEMT devices","authors":"E. R. Srinidhi, R. Ma, A. Z. Markos, G. Kompa","doi":"10.1109/RWS.2008.4463433","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463433","url":null,"abstract":"This paper focuses on the optimization of broadband envelope termination for reliable device characterization for future UMTS-LTE systems. Drain bias modulation is suppressed in 8times500 mum GaN HEMT using compensation network overcoming the parasitic effects of the DC feed, generally ignored during broadband measurements. Drain modulation index (DMI) metric is defined for quantifying the extent of drain voltage modulation as a function of carrier spacing and up to 80% reduction in DMI is achieved after drain bias compensation. Further, based on the experimental analysis, a simple bias tee is designed which can overcome improper DC feed conditions. Under 2-carrier CW and W-CDMA excitation, maximum of 19 dB and 18 dB IMD3 suppression together with the minimization of IMD asymmetry, were achieved using in- house bias tee, emphasizing the importance of broadband bias network design.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"141 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124463731","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463516
Youngmin Kim, Sang-Sub Song, K. Seo, Y. Kwon
An active single-ended 30 to 60 GHz doubler/power amplifier chain MMIC based on a commercial 0.15 um GaAs pHEMT process has been developed that requires low input drive power and produces high output power with high fundamental suppression without external filter. The maximum conversion gain is 17 dB with -25 dB fundamental signal suppression and saturated output power is 19 dBm at 59 GH output frequency. Packaging and interconnects are discussed and as a alternative to wire bonding, flip-chip mounting test with SNU's MCM-D (multi-chip module) substrate are presented. These test indicate that the presented MMIC and this flip- chip technologies are especially well suited for the 60 GHz wireless communication systems.
基于商用0.15 um GaAs pHEMT工艺，开发了一种有源单端30至60 GHz倍频/功率放大器链MMIC，它需要低输入驱动功率，产生高输出功率，具有高基波抑制，无需外部滤波器。最大转换增益为17 dB，基频抑制为-25 dB，在59gh输出频率下饱和输出功率为19 dBm。讨论了封装和互连，并提出了使用首尔大学的MCM-D(多芯片模块)基板进行倒装芯片安装测试，作为线键合的替代方法。测试结果表明，所提出的MMIC和倒装芯片技术特别适合于60 GHz无线通信系统。
{"title":"60 GHz flip-chip mounted frequency doubler/PA chain MMIC with low input power and high output power","authors":"Youngmin Kim, Sang-Sub Song, K. Seo, Y. Kwon","doi":"10.1109/RWS.2008.4463516","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463516","url":null,"abstract":"An active single-ended 30 to 60 GHz doubler/power amplifier chain MMIC based on a commercial 0.15 um GaAs pHEMT process has been developed that requires low input drive power and produces high output power with high fundamental suppression without external filter. The maximum conversion gain is 17 dB with -25 dB fundamental signal suppression and saturated output power is 19 dBm at 59 GH output frequency. Packaging and interconnects are discussed and as a alternative to wire bonding, flip-chip mounting test with SNU's MCM-D (multi-chip module) substrate are presented. These test indicate that the presented MMIC and this flip- chip technologies are especially well suited for the 60 GHz wireless communication systems.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"321 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124537570","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463446
M. Mjeku, Nathan J. Gomes
A burst transmission mechanism has been defined in the IEEE 802.11e medium access control extension in order to reduce the overheads in protocol operation and improve efficiency. In this paper, we analyze the throughput and delay performance when this mechanism is used with the immediate acknowledgment policy in a fiber-fed wireless LAN (WLAN). It is shown that the extra propagation delay caused by the optical distribution network in the system affects the burst transmission operation in the presence or otherwise of channel errors and affects the optimum thresholds for switching between the basic access and the request-to-send/clear-to-send (RTS/CTS) modes. It is also shown that significant throughput and media access delay improvements can be gained by the use of burst transmission in contention based 802.11e fiber-fed WLANs, regardless of the load in the network.
{"title":"Performance analysis of 802.11e transmission bursting in fiberfed networks","authors":"M. Mjeku, Nathan J. Gomes","doi":"10.1109/RWS.2008.4463446","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463446","url":null,"abstract":"A burst transmission mechanism has been defined in the IEEE 802.11e medium access control extension in order to reduce the overheads in protocol operation and improve efficiency. In this paper, we analyze the throughput and delay performance when this mechanism is used with the immediate acknowledgment policy in a fiber-fed wireless LAN (WLAN). It is shown that the extra propagation delay caused by the optical distribution network in the system affects the burst transmission operation in the presence or otherwise of channel errors and affects the optimum thresholds for switching between the basic access and the request-to-send/clear-to-send (RTS/CTS) modes. It is also shown that significant throughput and media access delay improvements can be gained by the use of burst transmission in contention based 802.11e fiber-fed WLANs, regardless of the load in the network.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124148086","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463415
U. Rohde, A. Poddar
Frequency reference standards are essential to achieving frequency accuracy and phase stability in electronic systems. Such reference standards require the chief characteristics of low phase noise and good frequency stability. The best oscillator performance can be expensive. The novel approach (noise-feedback and mode-coupling mechanism) reported in this paper optimizes the performance of voltage-controlled crystal oscillators (VCXOs), even those with relative low Q resonators, for low phase noise and good frequency stability. The typical measured phase noise for 120 MHz VCXO is typically -138 dBc/Hz at 100 Hz offset from the carrier, and to author knowledge, this is the best phase noise performance for this class of VCXO so far reported.
{"title":"Dynamic noise-feedback and mode-coupling mechanism silences the VCXOS phase noise","authors":"U. Rohde, A. Poddar","doi":"10.1109/RWS.2008.4463415","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463415","url":null,"abstract":"Frequency reference standards are essential to achieving frequency accuracy and phase stability in electronic systems. Such reference standards require the chief characteristics of low phase noise and good frequency stability. The best oscillator performance can be expensive. The novel approach (noise-feedback and mode-coupling mechanism) reported in this paper optimizes the performance of voltage-controlled crystal oscillators (VCXOs), even those with relative low Q resonators, for low phase noise and good frequency stability. The typical measured phase noise for 120 MHz VCXO is typically -138 dBc/Hz at 100 Hz offset from the carrier, and to author knowledge, this is the best phase noise performance for this class of VCXO so far reported.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"55 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125987657","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463418
S. Sen, R. Senguttuvan, A. Chatterjee
High peak-to-average ratio (PAR) of OFDM signals is a major bottleneck in the implementation of power efficient transmitters since the efficiency of a linear RF power amplifier reduce drastically due to backoff requirements. In this paper, a concurrent approach that uses adaptive baseband companding/ expanding of the OFDM signal along with dynamic PA biasing to achieve significant power savings in the transmitters is proposed. While using existing channel estimation techniques to drive the dynamic PAR adaptation, the proposed approach achieves a PAR reduction as high as 7.25 dB and power savings of 5.27X when channel conditions are good.
{"title":"Concurrent PAR and power amplifier adaptation for power efficient operation of WiMAX OFDM transmitters","authors":"S. Sen, R. Senguttuvan, A. Chatterjee","doi":"10.1109/RWS.2008.4463418","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463418","url":null,"abstract":"High peak-to-average ratio (PAR) of OFDM signals is a major bottleneck in the implementation of power efficient transmitters since the efficiency of a linear RF power amplifier reduce drastically due to backoff requirements. In this paper, a concurrent approach that uses adaptive baseband companding/ expanding of the OFDM signal along with dynamic PA biasing to achieve significant power savings in the transmitters is proposed. While using existing channel estimation techniques to drive the dynamic PAR adaptation, the proposed approach achieves a PAR reduction as high as 7.25 dB and power savings of 5.27X when channel conditions are good.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127923536","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463611
H. Ueda, K. Nakajima, G. Kanazawa, M. Shimozawa, J. Koide, M. Uesugi, R. Takeuchi, N. Suematsu, Y. Isota, S. Kameda, H. Nakase, T. Takagi, K. Tsubouchi
A 5 GHz-band SiGe-MMIC transceiver for 324 Mbps transmission is developed. The broadband transceiver characteristics are obtained by utilizing a 5 GHz- band Q-MOD with a circular polyphase filter in the transmitter, and a broadband IFVGA and Q-MIX in the receiver. A developed SiGe-MMIC performs EVM of 3.3%rms and EVM of 5.9%rms in the transmitter and the receiver, respectively using 64-QAM OFDM signal with 120 MHz bandwidth, which corresponds to the data rate of 324 Mbps. Utilizing the developed SiGe-MMIC, the Hi-Vision streaming video data is transmitted without interruption, and is clearly projected onto the TV.
{"title":"A 5GHz-band SiGe-MMIC transceiver for 324Mbps transmission","authors":"H. Ueda, K. Nakajima, G. Kanazawa, M. Shimozawa, J. Koide, M. Uesugi, R. Takeuchi, N. Suematsu, Y. Isota, S. Kameda, H. Nakase, T. Takagi, K. Tsubouchi","doi":"10.1109/RWS.2008.4463611","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463611","url":null,"abstract":"A 5 GHz-band SiGe-MMIC transceiver for 324 Mbps transmission is developed. The broadband transceiver characteristics are obtained by utilizing a 5 GHz- band Q-MOD with a circular polyphase filter in the transmitter, and a broadband IFVGA and Q-MIX in the receiver. A developed SiGe-MMIC performs EVM of 3.3%rms and EVM of 5.9%rms in the transmitter and the receiver, respectively using 64-QAM OFDM signal with 120 MHz bandwidth, which corresponds to the data rate of 324 Mbps. Utilizing the developed SiGe-MMIC, the Hi-Vision streaming video data is transmitted without interruption, and is clearly projected onto the TV.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"93 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131918993","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463417
C. Snow, L. Lampe, R. Schober
We consider the ECMA-368 Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) standard for high rate Ultra Wideband (UWB) wireless communication in the 3.1- 10.6 GHz band. The performance of MB-OFDM is impacted by interference from IEEE 802.16 WiMAX systems operating in the licensed 3.5 GHz band. Motivated by recent work showing the approximately Gaussian nature of the WiMAX interference to MB-OFDM, we propose a simple two-stage interference mitigation technique for coded MB-OFDM transmissions according to the ECMA-368 standard, consisting of interference spectrum estimation during silent periods followed by appropriate bit metric weighting during Viterbi decoding. We compare parametric and non-parametric spectrum estimation techniques for coded MB-OFDM transmissions and WiMAX interference for various scenarios of interest. The proposed two-stage interference mitigation technique is shown to be highly effective at mitigating the impact of WiMAX interference.
{"title":"Interference mitigation for coded MB-OFDM UWB","authors":"C. Snow, L. Lampe, R. Schober","doi":"10.1109/RWS.2008.4463417","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463417","url":null,"abstract":"We consider the ECMA-368 Multiband Orthogonal Frequency Division Multiplexing (MB-OFDM) standard for high rate Ultra Wideband (UWB) wireless communication in the 3.1- 10.6 GHz band. The performance of MB-OFDM is impacted by interference from IEEE 802.16 WiMAX systems operating in the licensed 3.5 GHz band. Motivated by recent work showing the approximately Gaussian nature of the WiMAX interference to MB-OFDM, we propose a simple two-stage interference mitigation technique for coded MB-OFDM transmissions according to the ECMA-368 standard, consisting of interference spectrum estimation during silent periods followed by appropriate bit metric weighting during Viterbi decoding. We compare parametric and non-parametric spectrum estimation techniques for coded MB-OFDM transmissions and WiMAX interference for various scenarios of interest. The proposed two-stage interference mitigation technique is shown to be highly effective at mitigating the impact of WiMAX interference.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132382973","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463527
M. Anis, S. Tontisirin, R. Tielert, N. Wehn
This paper presents the ultra-wide-bandpass super- regenerative filter of 1 GHz bandwith. The super-regenerative bandpass filter (SR-BPF) with synchronization loop is designed to extract UWB impulses. The DC-free on-off keying modulated data pattern is required to synchronize the filter response with high sensitivity. The super-regenerative bandpass filter, tuned at 7 GHz, is sensitive to -90 dBm signals of 1 GHz bandwidth. The test structure of SR-BPF has been implemented in 0.18 mum CMOS technology. The data exchange rate of 100Mb/s is achieved with power consumption of 3 mW at 1.5 V.
提出了一种1ghz频段的超宽带通超再生滤波器。设计了带同步环的超再生带通滤波器(SR-BPF)来提取超宽带脉冲。需要无直流开关键控调制数据模式来同步高灵敏度的滤波器响应。超再生带通滤波器，调谐频率为7 GHz，对带宽为1 GHz的-90 dBm信号敏感。SR-BPF的测试结构已在0.18 μ m CMOS技术上实现。数据交换速率为100Mb/s，功耗为3mw，电压为1.5 V。
{"title":"A 3mW 1GHz ultra-wide-bandpass super-regenerative filter","authors":"M. Anis, S. Tontisirin, R. Tielert, N. Wehn","doi":"10.1109/RWS.2008.4463527","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463527","url":null,"abstract":"This paper presents the ultra-wide-bandpass super- regenerative filter of 1 GHz bandwith. The super-regenerative bandpass filter (SR-BPF) with synchronization loop is designed to extract UWB impulses. The DC-free on-off keying modulated data pattern is required to synchronize the filter response with high sensitivity. The super-regenerative bandpass filter, tuned at 7 GHz, is sensitive to -90 dBm signals of 1 GHz bandwidth. The test structure of SR-BPF has been implemented in 0.18 mum CMOS technology. The data exchange rate of 100Mb/s is achieved with power consumption of 3 mW at 1.5 V.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"43 9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130474929","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 : 2008-03-05DOI: 10.1109/RWS.2008.4463459
A. Maxim
The aim of this paper is to explore existing process, radio architecture and system partition choices for modern broadcast receivers and describe the recent developments and future trends in their integration path. Design challenges and circuit/system solutions are presented for both SoC and SiP receivers.
{"title":"Notice of Violation of IEEE Publication PrinciplesTrends in broadcast receiver integration: SoC versus SiP","authors":"A. Maxim","doi":"10.1109/RWS.2008.4463459","DOIUrl":"https://doi.org/10.1109/RWS.2008.4463459","url":null,"abstract":"The aim of this paper is to explore existing process, radio architecture and system partition choices for modern broadcast receivers and describe the recent developments and future trends in their integration path. Design challenges and circuit/system solutions are presented for both SoC and SiP receivers.","PeriodicalId":431471,"journal":{"name":"2008 IEEE Radio and Wireless Symposium","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134225835","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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