Multimedia Broadcast Multicast Service (MBMS) epitomizes the increasing popularity of enhanced end-user experience in Universal Mobile Telecommunications System (UMTS), since it allows the economical delivery of multimedia services to a large number of users. MBMS multicast supports both Point-to-Point (PTP) and Point-to-Multipoint (PTM) modes in order to confront the strict resource limitations in wireless environments and improve efficiency during data transmission. The aim of this paper is to highlight the performance enhancements of MBMS multicasting over the High Speed Downlink Packet Access (HSDPA) and underline the need for its integration in MBMS specifications. HSDPA can play an instrumental role in positioning MBMS services as a key enabler for true Mobile Broadband. Under this prism, we investigate the provision of MBMS services over HSDPA, through a direct comparison between HSDPA and Release ’99 bearers. Since downlink transmission power is the most limited resource in UMTS networks, the evaluation is performed via an analytical dimensioning of the MBMS transmission power both in macrocells and microcells. Simulation results reveal that HSDPA can significantly optimize MBMS power allocation, bring more capacity and, consequently, enable the mass-market delivery of rich multimedia services in mobile networks.
{"title":"Optimizing MBMS Power Allocation through HSDPA Transmissions","authors":"A. Alexiou, C. Bouras, Evangelos Rekkas","doi":"10.1109/AICT.2009.63","DOIUrl":"https://doi.org/10.1109/AICT.2009.63","url":null,"abstract":"Multimedia Broadcast Multicast Service (MBMS) epitomizes the increasing popularity of enhanced end-user experience in Universal Mobile Telecommunications System (UMTS), since it allows the economical delivery of multimedia services to a large number of users. MBMS multicast supports both Point-to-Point (PTP) and Point-to-Multipoint (PTM) modes in order to confront the strict resource limitations in wireless environments and improve efficiency during data transmission. The aim of this paper is to highlight the performance enhancements of MBMS multicasting over the High Speed Downlink Packet Access (HSDPA) and underline the need for its integration in MBMS specifications. HSDPA can play an instrumental role in positioning MBMS services as a key enabler for true Mobile Broadband. Under this prism, we investigate the provision of MBMS services over HSDPA, through a direct comparison between HSDPA and Release ’99 bearers. Since downlink transmission power is the most limited resource in UMTS networks, the evaluation is performed via an analytical dimensioning of the MBMS transmission power both in macrocells and microcells. Simulation results reveal that HSDPA can significantly optimize MBMS power allocation, bring more capacity and, consequently, enable the mass-market delivery of rich multimedia services in mobile networks.","PeriodicalId":409336,"journal":{"name":"2009 Fifth Advanced International Conference on Telecommunications","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124949857","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}
We consider iteratively decoded bit-interleaved coded modulation (BICM-ID) for bandwidth-efficient transmission over AWGN channel, where the bit error rate is reduced through iterations between a demapper and a channel decoder. In this paper, we conduct a comparative study, using intensive set of simulations, to examine the different parameters which affect the performance of BICM-ID in term of convergence and BER error floor. More specifically the following parameters are considered: the effect of convolutional code constraint, interleaver size and mapping schemes. In this comparative study, these mapping schemes were used: set partitioning (SP), modified set partitioning (MSP), Schreckenbach, M16 and maximum squared Euclidean weight (MSEW).
{"title":"Comparative Study for Bit-Interleaved Coded Modulation with Iterative Decoding","authors":"S. S. Al-Samahi, S. L. Goff, B. Sharif","doi":"10.1109/AICT.2009.61","DOIUrl":"https://doi.org/10.1109/AICT.2009.61","url":null,"abstract":"We consider iteratively decoded bit-interleaved coded modulation (BICM-ID) for bandwidth-efficient transmission over AWGN channel, where the bit error rate is reduced through iterations between a demapper and a channel decoder. In this paper, we conduct a comparative study, using intensive set of simulations, to examine the different parameters which affect the performance of BICM-ID in term of convergence and BER error floor. More specifically the following parameters are considered: the effect of convolutional code constraint, interleaver size and mapping schemes. In this comparative study, these mapping schemes were used: set partitioning (SP), modified set partitioning (MSP), Schreckenbach, M16 and maximum squared Euclidean weight (MSEW).","PeriodicalId":409336,"journal":{"name":"2009 Fifth Advanced International Conference on Telecommunications","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114121690","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}
The paper presents an approximate method for modeling of the WCDMA interface in the UMTS network in which the mobile operator introduces priorities and user differentiation. In our considerations we use a model of the full-availability group servicing multi-rate traffic with priorities for services. In the proposed model we assume that user priorities and the priorities for classes of services are introduced into the network. The proposed scheme is applicable for cost-effective WCDMA resource management in 3G mobile networks and can be easily applied to network capacity calculations.
{"title":"Analytical Model of the WCDMA Radio Interface in UMTS Network with User Differentiation","authors":"M. Stasiak, P. Zwierzykowski, J. Wiewióra","doi":"10.1109/AICT.2009.20","DOIUrl":"https://doi.org/10.1109/AICT.2009.20","url":null,"abstract":"The paper presents an approximate method for modeling of the WCDMA interface in the UMTS network in which the mobile operator introduces priorities and user differentiation. In our considerations we use a model of the full-availability group servicing multi-rate traffic with priorities for services. In the proposed model we assume that user priorities and the priorities for classes of services are introduced into the network. The proposed scheme is applicable for cost-effective WCDMA resource management in 3G mobile networks and can be easily applied to network capacity calculations.","PeriodicalId":409336,"journal":{"name":"2009 Fifth Advanced International Conference on Telecommunications","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127870234","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}
We propose a novel family of low-density parity-check (LDPC) codes that can be obtained as the serial concatenation of very simple components. Codes designed through the proposed approach exhibit very good performance and have a number of benefits, as high flexibility in length and rate and low complexity encoding. In addition, the systematic form of the component codes ensures rate compatibility, so the proposed codes are suitable for application in type-II hybrid automatic repeat request schemes. We analyze their properties through theoretical arguments and give design examples in order to assess their performance.
{"title":"New LDPC Codes Based on Serial Concatenation","authors":"M. Baldi, G. Cancellieri, F. Chiaraluce","doi":"10.1109/AICT.2009.60","DOIUrl":"https://doi.org/10.1109/AICT.2009.60","url":null,"abstract":"We propose a novel family of low-density parity-check (LDPC) codes that can be obtained as the serial concatenation of very simple components. Codes designed through the proposed approach exhibit very good performance and have a number of benefits, as high flexibility in length and rate and low complexity encoding. In addition, the systematic form of the component codes ensures rate compatibility, so the proposed codes are suitable for application in type-II hybrid automatic repeat request schemes. We analyze their properties through theoretical arguments and give design examples in order to assess their performance.","PeriodicalId":409336,"journal":{"name":"2009 Fifth Advanced International Conference on Telecommunications","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114704729","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}
The third generation network which is vigorous nowadays will be followed by an all-IP infrastructure referred to as Next Generation Networks (NGN) in the near future. More specifically, the IP Multimedia Subsystem (IMS) is the only standardized way to offer IP based services that are enabled by one common core and all types of access networks and devices. The heterogeneity and mobility of the IMS raises many challenges as to the quality and pertinence of information required for device management. Therefore, we have to focus on the information required in this new environment and propose to evolve today’s Home Subscriber Server (HSS) and Domain Name System (DNS). Indeed, an IMS session must be adaptable to all mobility and meet the Service Level Agreement (SLA) of the user. The proposed solution is based on the user data model and the pertinence of information able to meet the QoS needs of the user in any time. Moreover, a solution which can allow a subscriber to register with one or more operator(s) is also presented.
{"title":"Required Information for Device Management Quality in IP Multimedia Subsystem","authors":"I. Elloumi, T. Desprats, M. Sibilla, S. Tabbanne","doi":"10.1109/AICT.2009.26","DOIUrl":"https://doi.org/10.1109/AICT.2009.26","url":null,"abstract":"The third generation network which is vigorous nowadays will be followed by an all-IP infrastructure referred to as Next Generation Networks (NGN) in the near future. More specifically, the IP Multimedia Subsystem (IMS) is the only standardized way to offer IP based services that are enabled by one common core and all types of access networks and devices. The heterogeneity and mobility of the IMS raises many challenges as to the quality and pertinence of information required for device management. Therefore, we have to focus on the information required in this new environment and propose to evolve today’s Home Subscriber Server (HSS) and Domain Name System (DNS). Indeed, an IMS session must be adaptable to all mobility and meet the Service Level Agreement (SLA) of the user. The proposed solution is based on the user data model and the pertinence of information able to meet the QoS needs of the user in any time. Moreover, a solution which can allow a subscriber to register with one or more operator(s) is also presented.","PeriodicalId":409336,"journal":{"name":"2009 Fifth Advanced International Conference on Telecommunications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129867752","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}
M. Aydin, T. Atmaca, O. C. Turna, A. Zaim, T. Eido
In this study, a wavelength grouping approach has been proposed for core nodes in OBS in order to control byte drop rates for different classes of traffic. Preemptive Channel Scheduling Algorithm (PCSA) has been used for channel scheduling in OBS. In terms of performance criteria, loss rate in bytes is considered. A 2-state MMPP (Markov Modulated Poisson Process) traffic generator on a 14-node mesh network topology illustrating NSFNET is designed as the testbed. NS2 Network Simulation tool is used for our tests. In OBS algorithms, bursts are created using a hybrid model that takes into account both timeout and maximum length threshold mechanisms. In nodes, in order to satisfy QoS requirements, priority based queuing and Regulative Wavelength Grouping (RWG) are used. In priority based queuing, packets (bursts) are sent according to their priority order. RWG mechanism, where the number of wavelengths for each traffic class is arranged for adjusting the packet drop probability of different classes of client traffic under a specific threshold value, is used for providing priority levels. According to the simulation studies, RWG algorithm gives better results in OBS for high priority traffic performance.
{"title":"Regulative Wavelength Grouping Approach for QoS in OBS Networks","authors":"M. Aydin, T. Atmaca, O. C. Turna, A. Zaim, T. Eido","doi":"10.1109/AICT.2009.50","DOIUrl":"https://doi.org/10.1109/AICT.2009.50","url":null,"abstract":"In this study, a wavelength grouping approach has been proposed for core nodes in OBS in order to control byte drop rates for different classes of traffic. Preemptive Channel Scheduling Algorithm (PCSA) has been used for channel scheduling in OBS. In terms of performance criteria, loss rate in bytes is considered. A 2-state MMPP (Markov Modulated Poisson Process) traffic generator on a 14-node mesh network topology illustrating NSFNET is designed as the testbed. NS2 Network Simulation tool is used for our tests. In OBS algorithms, bursts are created using a hybrid model that takes into account both timeout and maximum length threshold mechanisms. In nodes, in order to satisfy QoS requirements, priority based queuing and Regulative Wavelength Grouping (RWG) are used. In priority based queuing, packets (bursts) are sent according to their priority order. RWG mechanism, where the number of wavelengths for each traffic class is arranged for adjusting the packet drop probability of different classes of client traffic under a specific threshold value, is used for providing priority levels. According to the simulation studies, RWG algorithm gives better results in OBS for high priority traffic performance.","PeriodicalId":409336,"journal":{"name":"2009 Fifth Advanced International Conference on Telecommunications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129673659","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}
To cut down the hardware implementation cost this paper presents an efficient method to construct large girth Quasi-Cyclic low density parity check (QC-LDPC) codes. The row groups are paired two times the row weight, which has the complexity as compared to the connection of individual columns and rows. The complexity of directing within groups estimates on the transposition employed to connect rows and columns between groups. The newly obtained codes are incorporated with diversity techniques and are employed as a forward error correction codes to cater for some anti-jamming (AJ) competences in the presence of partial band noise jamming (PBNJ). The robustness of two girth-twelve QC-LDPC codes is evidenced by comparing it with randomly constructed LDPC codes and QC-LDPC codes proposed in [14].
{"title":"Row Division Method to Generate QC-LDPC Codes","authors":"A. Yahya, O. Sidek, M. Salleh, F. Ghani","doi":"10.1109/AICT.2009.38","DOIUrl":"https://doi.org/10.1109/AICT.2009.38","url":null,"abstract":"To cut down the hardware implementation cost this paper presents an efficient method to construct large girth Quasi-Cyclic low density parity check (QC-LDPC) codes. The row groups are paired two times the row weight, which has the complexity as compared to the connection of individual columns and rows. The complexity of directing within groups estimates on the transposition employed to connect rows and columns between groups. The newly obtained codes are incorporated with diversity techniques and are employed as a forward error correction codes to cater for some anti-jamming (AJ) competences in the presence of partial band noise jamming (PBNJ). The robustness of two girth-twelve QC-LDPC codes is evidenced by comparing it with randomly constructed LDPC codes and QC-LDPC codes proposed in [14].","PeriodicalId":409336,"journal":{"name":"2009 Fifth Advanced International Conference on Telecommunications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129988289","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}
Yooseung Song, Jeeyon Choi, Yunjoo Kim, Hyungu Park, Sok-Kyu Lee
In this paper, high performance MAC is designed and implemented to support multi-gigabit physical layer. New algorithms and Control channels are introduced for low MAC latency and high MAC throughput. The new multi-gigabit nomadic/local area wireless access, called NoLA, is implemented using the proposed MAC. NoLA demonstrated the multi-gigabit service with full HD video streams where the proposed high performance MAC supports the 84 full HD video streams in real time. The implemented NoLA system shows near 1.8Gbps MAC throughput, which can meet the requirements of the gigabit IMT-Advanced wireless nomadic access. It is proved that the proposed high performance MAC used in NoLA can be one of the promising solutions for the future multi-gigabit wireless communication systems.
{"title":"Multi-Gbps MAC Design and Real-Time Experiment for IMT-Advanced Wireless Nomadic Access","authors":"Yooseung Song, Jeeyon Choi, Yunjoo Kim, Hyungu Park, Sok-Kyu Lee","doi":"10.1109/AICT.2009.84","DOIUrl":"https://doi.org/10.1109/AICT.2009.84","url":null,"abstract":"In this paper, high performance MAC is designed and implemented to support multi-gigabit physical layer. New algorithms and Control channels are introduced for low MAC latency and high MAC throughput. The new multi-gigabit nomadic/local area wireless access, called NoLA, is implemented using the proposed MAC. NoLA demonstrated the multi-gigabit service with full HD video streams where the proposed high performance MAC supports the 84 full HD video streams in real time. The implemented NoLA system shows near 1.8Gbps MAC throughput, which can meet the requirements of the gigabit IMT-Advanced wireless nomadic access. It is proved that the proposed high performance MAC used in NoLA can be one of the promising solutions for the future multi-gigabit wireless communication systems.","PeriodicalId":409336,"journal":{"name":"2009 Fifth Advanced International Conference on Telecommunications","volume":"535 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116221829","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}
M. Z. Alam, Charles Chittaranjan Patra, Colin Patra, M. Sobhan
The next generation broadband wireless communication offers all types of services at very low cost at any time and at any where basis using Orthogonal Frequency Division Multiplexing and Worldwide Interoperability for Microwave Access Technology. The transmitted signal is distorted by channel noise and interference from other sources causing bit error. Diversity is a technology to reduce both the effects of channel noise and interference. The diversity technique is used in the two previously mentioned techniques to send data through a fading channel at a high symbol rate. Beamforming technique is used to direct a signal to a particular direction. Recently, it is used in the aforementioned second technique to transmit data at a very high rate with low bit error probability. In this paper, we propose an alternative beamforming algorithm in this second technique to obtain better bit error rate performance for a multi-path fading channel, compared to results reported in earlier work The simulation results of the proposed algorithm also show expected performance.
{"title":"An Efficient Beamforming Technique in WiMAX","authors":"M. Z. Alam, Charles Chittaranjan Patra, Colin Patra, M. Sobhan","doi":"10.1109/AICT.2009.66","DOIUrl":"https://doi.org/10.1109/AICT.2009.66","url":null,"abstract":"The next generation broadband wireless communication offers all types of services at very low cost at any time and at any where basis using Orthogonal Frequency Division Multiplexing and Worldwide Interoperability for Microwave Access Technology. The transmitted signal is distorted by channel noise and interference from other sources causing bit error. Diversity is a technology to reduce both the effects of channel noise and interference. The diversity technique is used in the two previously mentioned techniques to send data through a fading channel at a high symbol rate. Beamforming technique is used to direct a signal to a particular direction. Recently, it is used in the aforementioned second technique to transmit data at a very high rate with low bit error probability. In this paper, we propose an alternative beamforming algorithm in this second technique to obtain better bit error rate performance for a multi-path fading channel, compared to results reported in earlier work The simulation results of the proposed algorithm also show expected performance.","PeriodicalId":409336,"journal":{"name":"2009 Fifth Advanced International Conference on Telecommunications","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124850534","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}
In this paper, the analytical modeling of a time-threshold based multi-guard bandwidth allocation scheme is presented using a two-dimensional markov chain. The main idea of the scheme is based on monitoring the elapsed real time of handoff calls and according to a time threshold (te), a handoff call is either slightly-prioritized or fully-prioritized. A slightly-prioritized handoff call has higher priority than a new call and lower priority than a fully-prioritized handoff call. Also in this paper, the numerical results obtained from two dimensional markov chain analysis are compared with the numerical results which are obtained using one-dimensional markov chain analysis and simulation ones. The simulation and analytical results agree well. The performances of different bandwidth allocation schemes are measured using a crucial general performance metric Z. Z, which is a performance/cost ratio, is a function of the new call blocking probability, handoff call dropping probability and system utilization all together. The results indicate that our scheme outperforms other traditional schemes.
{"title":"Analytical Modeling of a Time-Threshold Based Multi-guard Bandwidth Allocation Scheme for Cellular Networks","authors":"I. Candan, M. Salamah","doi":"10.1109/AICT.2009.12","DOIUrl":"https://doi.org/10.1109/AICT.2009.12","url":null,"abstract":"In this paper, the analytical modeling of a time-threshold based multi-guard bandwidth allocation scheme is presented using a two-dimensional markov chain. The main idea of the scheme is based on monitoring the elapsed real time of handoff calls and according to a time threshold (te), a handoff call is either slightly-prioritized or fully-prioritized. A slightly-prioritized handoff call has higher priority than a new call and lower priority than a fully-prioritized handoff call. Also in this paper, the numerical results obtained from two dimensional markov chain analysis are compared with the numerical results which are obtained using one-dimensional markov chain analysis and simulation ones. The simulation and analytical results agree well. The performances of different bandwidth allocation schemes are measured using a crucial general performance metric Z. Z, which is a performance/cost ratio, is a function of the new call blocking probability, handoff call dropping probability and system utilization all together. The results indicate that our scheme outperforms other traditional schemes.","PeriodicalId":409336,"journal":{"name":"2009 Fifth Advanced International Conference on Telecommunications","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116555021","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：