Pub Date : 2012-04-03DOI: 10.1109/NCC.2012.6176887
S. Chandrasekaran, S. K. Mohammed, A. Chockalingam
In this paper, we study the achievable rate region of two-user Gaussian broadcast channel (GBC) when the messages to be transmitted to both the users take values from finite signal sets and the received signal is quantized at both the users. We refer to this channel as quantized broadcast channel (QBC). We first observe that the capacity region defined for a GBC does not carry over as such to QBC. Also, we show that the optimal decoding scheme for GBC (i.e., high SNR user doing successive decoding and low SNR user decoding its message alone) is not optimal for QBC. We then propose an achievable rate region for QBC based on two different schemes. We present achievable rate region results for the case of uniform quantization at the receivers. We find that rotation of one of the user's input alphabet with respect to the other user's alphabet marginally enlarges the achievable rate region of QBC when almost equal powers are allotted to both the users.
{"title":"Achievable rate region of gaussian broadcast channel with finite input alphabet and quantized output","authors":"S. Chandrasekaran, S. K. Mohammed, A. Chockalingam","doi":"10.1109/NCC.2012.6176887","DOIUrl":"https://doi.org/10.1109/NCC.2012.6176887","url":null,"abstract":"In this paper, we study the achievable rate region of two-user Gaussian broadcast channel (GBC) when the messages to be transmitted to both the users take values from finite signal sets and the received signal is quantized at both the users. We refer to this channel as quantized broadcast channel (QBC). We first observe that the capacity region defined for a GBC does not carry over as such to QBC. Also, we show that the optimal decoding scheme for GBC (i.e., high SNR user doing successive decoding and low SNR user decoding its message alone) is not optimal for QBC. We then propose an achievable rate region for QBC based on two different schemes. We present achievable rate region results for the case of uniform quantization at the receivers. We find that rotation of one of the user's input alphabet with respect to the other user's alphabet marginally enlarges the achievable rate region of QBC when almost equal powers are allotted to both the users.","PeriodicalId":178278,"journal":{"name":"2012 National Conference on Communications (NCC)","volume":"114 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128182400","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 : 2012-04-03DOI: 10.1109/NCC.2012.6176757
M. Harish, B. Srikanth, R. Bhattacharjee
Some of the vital issues that need to be addressed in wireless sensor network (WSN) based applications are improving the network lifetime without replacing the batteries of node and diminution of energy imbalanced hotspots in the network. Many protocols are proposed for energy efficient cluster based sensor network. In this paper, energy efficient Adaptive number of Frames per Round (AFR) protocol is proposed for a WSN where cluster heads are evenly distributed. The proposed AFR protocol combined with the cooperative Multiple Input Single Output (MISO) technique is extended for dual-hop wireless sensor networks to improve the network lifetime. The selection of the cooperative relay then explored so that the unexpected partition in network is avoided. Different cooperative relay positions have been investigated for decreasing and balancing the energy consumption in the network. Comparison is made for AFR protocol with and without dual-hop cooperative MISO scheme as well as with some other existing protocols.
无线传感器网络(WSN)应用中需要解决的一些关键问题是在不更换节点电池的情况下提高网络的使用寿命和减少网络中的能量不平衡热点。为实现高效节能的集群传感器网络，提出了多种协议。针对簇头均匀分布的无线传感器网络，提出了一种节能的AFR (Adaptive number of Frames per Round)协议。将所提出的AFR协议与多输入单输出(MISO)合作技术相结合，扩展到双跳无线传感器网络中，以提高网络的生存时间。探讨了协作中继的选择，避免了网络中的意外分区。为了降低和平衡网络中的能量消耗，研究了不同的协同中继位置。对采用和不采用双跳合作MISO方案的AFR协议进行了比较，并与现有协议进行了比较。
{"title":"An Energy efficient WSN with cooperative relaying technique","authors":"M. Harish, B. Srikanth, R. Bhattacharjee","doi":"10.1109/NCC.2012.6176757","DOIUrl":"https://doi.org/10.1109/NCC.2012.6176757","url":null,"abstract":"Some of the vital issues that need to be addressed in wireless sensor network (WSN) based applications are improving the network lifetime without replacing the batteries of node and diminution of energy imbalanced hotspots in the network. Many protocols are proposed for energy efficient cluster based sensor network. In this paper, energy efficient Adaptive number of Frames per Round (AFR) protocol is proposed for a WSN where cluster heads are evenly distributed. The proposed AFR protocol combined with the cooperative Multiple Input Single Output (MISO) technique is extended for dual-hop wireless sensor networks to improve the network lifetime. The selection of the cooperative relay then explored so that the unexpected partition in network is avoided. Different cooperative relay positions have been investigated for decreasing and balancing the energy consumption in the network. Comparison is made for AFR protocol with and without dual-hop cooperative MISO scheme as well as with some other existing protocols.","PeriodicalId":178278,"journal":{"name":"2012 National Conference on Communications (NCC)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125689761","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 : 2012-04-03DOI: 10.1109/NCC.2012.6176802
A. Deshmukh, P. Baxi, C. Kamdar, B. Vora, K. P. Ray
The dual band microstrip antenna is realized by placing open circuit stub on the edges of the patch. When the stub length is taken to be nearly quarter wave in length, it offers capacitive and inductive impedance around the resonance frequency of the patch and realizes dual frequency response. In this paper, a detail analysis for the effect of stub on the dual band response of rectangular microstrip antenna is presented. The surface current distributions and the resonance curve plots were studied. It was observed that the stub modifies the fundamental and higher order orthogonal mode resonance frequencies of the patch and realizes dual frequency response. With an increase in stub length the directions of surface currents are modified, which gives broadside radiation pattern at the dual frequencies. The formulation of resonant length at dual frequencies in terms of stub dimensions is proposed and they agree within 5% with that of the simulated results.
{"title":"Analysis of stub loaded rectangular microstrip antenna","authors":"A. Deshmukh, P. Baxi, C. Kamdar, B. Vora, K. P. Ray","doi":"10.1109/NCC.2012.6176802","DOIUrl":"https://doi.org/10.1109/NCC.2012.6176802","url":null,"abstract":"The dual band microstrip antenna is realized by placing open circuit stub on the edges of the patch. When the stub length is taken to be nearly quarter wave in length, it offers capacitive and inductive impedance around the resonance frequency of the patch and realizes dual frequency response. In this paper, a detail analysis for the effect of stub on the dual band response of rectangular microstrip antenna is presented. The surface current distributions and the resonance curve plots were studied. It was observed that the stub modifies the fundamental and higher order orthogonal mode resonance frequencies of the patch and realizes dual frequency response. With an increase in stub length the directions of surface currents are modified, which gives broadside radiation pattern at the dual frequencies. The formulation of resonant length at dual frequencies in terms of stub dimensions is proposed and they agree within 5% with that of the simulated results.","PeriodicalId":178278,"journal":{"name":"2012 National Conference on Communications (NCC)","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128925626","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 : 2012-04-03DOI: 10.1109/NCC.2012.6176753
A. Bhadriraju, S. Bhaumik, Y. Lohith, M. Brinda, A. Svr, M. Hegde
6PANview[1] is a Wireless Sensor Network(WSN) monitoring system for 6LoWPAN/RPL networks which we developed as an overlay network for a WSN application. A monitoring system, while performing its operations for maintaining the health of the monitored network, must also be conscious of its impact on the application performance, and must strive to minimize this impact. To this end, we propose a centralized scheduling algorithm within 6PANview which non-intrusively analyzes application traffic arrival patterns at the base station, identifies network idle periods and schedules monitoring activities. The proposed algorithm finds those periodic sequences which are likely to have given rise to the pattern of arrivals seen at the base station. Parts of those sequences are then extended to coarsely predict future traffic and find epochs where low traffic is predicted, in order to schedule monitoring traffic or other activities at these times. We present simulation results for the proposed prediction and scheduling algorithm and its implementation as part of 6PANview. As an enhancement, we briefly talk about using 6PANview's overlay network architecture for distributed scheduling.
{"title":"6PANview: Application performance conscious network monitoring for 6LoWPAN based WSNs","authors":"A. Bhadriraju, S. Bhaumik, Y. Lohith, M. Brinda, A. Svr, M. Hegde","doi":"10.1109/NCC.2012.6176753","DOIUrl":"https://doi.org/10.1109/NCC.2012.6176753","url":null,"abstract":"6PANview[1] is a Wireless Sensor Network(WSN) monitoring system for 6LoWPAN/RPL networks which we developed as an overlay network for a WSN application. A monitoring system, while performing its operations for maintaining the health of the monitored network, must also be conscious of its impact on the application performance, and must strive to minimize this impact. To this end, we propose a centralized scheduling algorithm within 6PANview which non-intrusively analyzes application traffic arrival patterns at the base station, identifies network idle periods and schedules monitoring activities. The proposed algorithm finds those periodic sequences which are likely to have given rise to the pattern of arrivals seen at the base station. Parts of those sequences are then extended to coarsely predict future traffic and find epochs where low traffic is predicted, in order to schedule monitoring traffic or other activities at these times. We present simulation results for the proposed prediction and scheduling algorithm and its implementation as part of 6PANview. As an enhancement, we briefly talk about using 6PANview's overlay network architecture for distributed scheduling.","PeriodicalId":178278,"journal":{"name":"2012 National Conference on Communications (NCC)","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129200292","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 : 2012-04-03DOI: 10.1109/NCC.2012.6176854
M. K. Hati, T. K. Bhattacharyya
This paper gives a brief idea for the use and implementation of ETSI digital Video broadcasting Handheld (DVB-H) Standard in the context of providing an efficient way of carrying multimedia services over digital terrestrial broadcasting networks to handheld devices. In addition, the paper gives a brief review of the new Digital Video Broadcasting-Handheld (DVB-H) standard. This is based on the earlier existence standard Digital Video Broadcasting-Terrestrial (DVB-T), which is used for terrestrial digital TV broadcasting. The new technology not like 3G or 4G, technology brings features that make it possible to receive digital video broadcast type services in handheld, mobile terminals, PDA etc. This paper describes the key technology of the DVB-H, time slicing, and MPE-FEC. It also gives an idea on DVB-SH, DVB-IPDC, DVB-C, IP Datacast, DVB-IPDC, and 4K mode. Finally, it presents a design viewpoint for simplified DVB-H receiver subsystem.
{"title":"Dgital video broadcast services to handheld devices and a simplified DVB-H receiver subsystem","authors":"M. K. Hati, T. K. Bhattacharyya","doi":"10.1109/NCC.2012.6176854","DOIUrl":"https://doi.org/10.1109/NCC.2012.6176854","url":null,"abstract":"This paper gives a brief idea for the use and implementation of ETSI digital Video broadcasting Handheld (DVB-H) Standard in the context of providing an efficient way of carrying multimedia services over digital terrestrial broadcasting networks to handheld devices. In addition, the paper gives a brief review of the new Digital Video Broadcasting-Handheld (DVB-H) standard. This is based on the earlier existence standard Digital Video Broadcasting-Terrestrial (DVB-T), which is used for terrestrial digital TV broadcasting. The new technology not like 3G or 4G, technology brings features that make it possible to receive digital video broadcast type services in handheld, mobile terminals, PDA etc. This paper describes the key technology of the DVB-H, time slicing, and MPE-FEC. It also gives an idea on DVB-SH, DVB-IPDC, DVB-C, IP Datacast, DVB-IPDC, and 4K mode. Finally, it presents a design viewpoint for simplified DVB-H receiver subsystem.","PeriodicalId":178278,"journal":{"name":"2012 National Conference on Communications (NCC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129530732","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 : 2012-04-03DOI: 10.1109/NCC.2012.6176837
N. Shrivastava, A. Trivedi
It has been shown in the literature that capacity region of the Gaussian broadcast channels is achieved by dirty paper coding but due to full channel state information requirement and high complexity, its application is limited. Several multiple-input multiple-output (MIMO) techniques have been proposed for the orthogonal frequency-division multiplexing (OFDM) systems. In this paper, we consider a cellular system employing MIMO-OFDM technique and beamforming with the goal of maximizing the system throughput. We use an approach based on iterative random orthogonal beamforming and correlation between the subcarriers which exploits orthogonality conditions of the scheduled users with reduced feedback. By simulation results, it is observed that this approach improves the throughput of the system with lower complexity.
{"title":"Iterative random beamforming for MIMO-OFDM systems","authors":"N. Shrivastava, A. Trivedi","doi":"10.1109/NCC.2012.6176837","DOIUrl":"https://doi.org/10.1109/NCC.2012.6176837","url":null,"abstract":"It has been shown in the literature that capacity region of the Gaussian broadcast channels is achieved by dirty paper coding but due to full channel state information requirement and high complexity, its application is limited. Several multiple-input multiple-output (MIMO) techniques have been proposed for the orthogonal frequency-division multiplexing (OFDM) systems. In this paper, we consider a cellular system employing MIMO-OFDM technique and beamforming with the goal of maximizing the system throughput. We use an approach based on iterative random orthogonal beamforming and correlation between the subcarriers which exploits orthogonality conditions of the scheduled users with reduced feedback. By simulation results, it is observed that this approach improves the throughput of the system with lower complexity.","PeriodicalId":178278,"journal":{"name":"2012 National Conference on Communications (NCC)","volume":"160 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132835474","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 : 2012-04-03DOI: 10.1109/NCC.2012.6176760
S. Kumar, P. Patel, A. Mittal, A. de
This paper presents the novel rectenna design for Wireless Power Transmission. The design would receive and convert microwave of 2.45GHz to DC. Proposed rectenna is a combination of Microstrip patch antenna, followed by stepped impedance filter and zero biased rectifier. Performance of rectenna is analyzed using Harmonic Balance Analysis. Good agreement between simulated and measured results is observed.
{"title":"Design, analysis and fabrication of rectenna for wireless power transmission - Virtual battery","authors":"S. Kumar, P. Patel, A. Mittal, A. de","doi":"10.1109/NCC.2012.6176760","DOIUrl":"https://doi.org/10.1109/NCC.2012.6176760","url":null,"abstract":"This paper presents the novel rectenna design for Wireless Power Transmission. The design would receive and convert microwave of 2.45GHz to DC. Proposed rectenna is a combination of Microstrip patch antenna, followed by stepped impedance filter and zero biased rectifier. Performance of rectenna is analyzed using Harmonic Balance Analysis. Good agreement between simulated and measured results is observed.","PeriodicalId":178278,"journal":{"name":"2012 National Conference on Communications (NCC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131412325","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 : 2012-04-03DOI: 10.1109/NCC.2012.6176860
M. Jha, P. Rao
The proper pronunciation of lyrics is an important component of vocal music. While automatic vowel classification has been widely studied for speech, a separate investigation of the methods is needed for singing due to the differences in acoustic properties between sung and spoken vowels. Acoustic features combining spectrum envelope and pitch are used with classifiers trained on sung vowels for classification of test vowels segmented from the audio of solo singing. Two different classifiers are tested, viz., Gaussian Mixture Models (GMM) and Linear Regression, and observed to perform well on both male and female sung vowels.
{"title":"Assessing vowel quality for singing evaluation","authors":"M. Jha, P. Rao","doi":"10.1109/NCC.2012.6176860","DOIUrl":"https://doi.org/10.1109/NCC.2012.6176860","url":null,"abstract":"The proper pronunciation of lyrics is an important component of vocal music. While automatic vowel classification has been widely studied for speech, a separate investigation of the methods is needed for singing due to the differences in acoustic properties between sung and spoken vowels. Acoustic features combining spectrum envelope and pitch are used with classifiers trained on sung vowels for classification of test vowels segmented from the audio of solo singing. Two different classifiers are tested, viz., Gaussian Mixture Models (GMM) and Linear Regression, and observed to perform well on both male and female sung vowels.","PeriodicalId":178278,"journal":{"name":"2012 National Conference on Communications (NCC)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134155467","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 : 2012-04-03DOI: 10.1109/NCC.2012.6176825
R. Tripathi, Y. N. Singh, N. Verma
Load on individual cluster head node increases (decreases) if there exist less (more) than the optimum number of cluster head nodes, As we only fix the the number of cluster heads and as the nodes choose the nearest cluster head for data transmission, the number of supported nodes may vary for different cluster head nodes. This leads to uneven load distribution among nodes in a Wireless Sensor Network (WSN). We proposed a new cluster head selection method for LEACH clustering routing protocol. It balances the energy consumption of every sensor node in a sensor network. Simulation results show that the lifetime of sensor network is significantly enhanced compared to the LEACH routing algorithm for the wireless sensor networks.
{"title":"N-LEACH, a balanced cost cluster-heads selection algorithm for Wireless Sensor Network","authors":"R. Tripathi, Y. N. Singh, N. Verma","doi":"10.1109/NCC.2012.6176825","DOIUrl":"https://doi.org/10.1109/NCC.2012.6176825","url":null,"abstract":"Load on individual cluster head node increases (decreases) if there exist less (more) than the optimum number of cluster head nodes, As we only fix the the number of cluster heads and as the nodes choose the nearest cluster head for data transmission, the number of supported nodes may vary for different cluster head nodes. This leads to uneven load distribution among nodes in a Wireless Sensor Network (WSN). We proposed a new cluster head selection method for LEACH clustering routing protocol. It balances the energy consumption of every sensor node in a sensor network. Simulation results show that the lifetime of sensor network is significantly enhanced compared to the LEACH routing algorithm for the wireless sensor networks.","PeriodicalId":178278,"journal":{"name":"2012 National Conference on Communications (NCC)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129973858","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 : 2012-04-03DOI: 10.1109/NCC.2012.6176784
J. Satyanarayana, A. G. Ramakrishnan
Distributed compressed sensing exploits information redundancy, inbuilt in multi-signal ensembles with interas well as intra-signal correlations, to reconstruct undersampled signals. In this paper we revisit this problem, albeit from a different perspective, of taking streaming data, from several correlated sources, as input to a real time system which, without any a priori information, incrementally learns and admits each source into the system.
{"title":"Compressed acquisition of correlated signals","authors":"J. Satyanarayana, A. G. Ramakrishnan","doi":"10.1109/NCC.2012.6176784","DOIUrl":"https://doi.org/10.1109/NCC.2012.6176784","url":null,"abstract":"Distributed compressed sensing exploits information redundancy, inbuilt in multi-signal ensembles with interas well as intra-signal correlations, to reconstruct undersampled signals. In this paper we revisit this problem, albeit from a different perspective, of taking streaming data, from several correlated sources, as input to a real time system which, without any a priori information, incrementally learns and admits each source into the system.","PeriodicalId":178278,"journal":{"name":"2012 National Conference on Communications (NCC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130369539","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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