{"title":"Construction of high-rate QC-LDPC codes","authors":"Xu Chen, F. Lau","doi":"10.1109/ATC.2011.6027427","DOIUrl":"https://doi.org/10.1109/ATC.2011.6027427","url":null,"abstract":"In this paper, we construct high-rate quasi-cyclic low-density parity-check (QC-LDPC) codes with girth-10 based on shortened array codes. First, we derive analytic results on the maximum number of columns for shortened array codes of different girths. A code construction method inspired by the analysis is proposed for column-weight-three codes and is compared with the conventional greedy construction algorithm. We show that the proposed method is more effective than the conventional greedy algorithm in the sense that the minimum length of the codes constructed using our proposed method to achieve different code rates is comparative or much shorter than those constructed using the greedy construction.","PeriodicalId":221905,"journal":{"name":"The 2011 International Conference on Advanced Technologies for Communications (ATC 2011)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127149300","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}
{"title":"Assignment problem-based approach for solving permutation ambiguity in frequency domain convolutive source separation","authors":"H. N. Vuong, Quoc Nguyen, H. L. Tran","doi":"10.1109/ATC.2011.6027488","DOIUrl":"https://doi.org/10.1109/ATC.2011.6027488","url":null,"abstract":"In this paper, we propose an effective method for blind source separation of convolutive mixtures in the frequency domain. The main difficulty in a frequency approach is the permutation problem. In the proposed method, we use the Assignment Problem (AP) approach to solve permutation ambiguity in the frequency domain. In our work, we apply different algorithms to solve the AP to find the optimal solution. Furthermore, by using a simple check procedure, the algorithm has to only solve the permutation problem in a few frequency bins instead of all. This method has been proven more efficient on computation than the previous methods using the AP approach. Computer simulation experiments with speech data are presented to illustrate the proposed method.","PeriodicalId":221905,"journal":{"name":"The 2011 International Conference on Advanced Technologies for Communications (ATC 2011)","volume":"123 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126147528","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}
N. Vo, Quoc-Cuong Le, Quang Phu Le, D. T. Tran, T. Nguyen, Minh Trung Lam
{"title":"Vietnam spectrum occupancy measurements and analysis for cognitive radio applications","authors":"N. Vo, Quoc-Cuong Le, Quang Phu Le, D. T. Tran, T. Nguyen, Minh Trung Lam","doi":"10.1109/ATC.2011.6027452","DOIUrl":"https://doi.org/10.1109/ATC.2011.6027452","url":null,"abstract":"The rapid growth of demand for wireless transmission has placed great pressure on the scarce radio spectrum due to the fixed spectrum allocation policy and cognitive radio (CR) is considered as a promising solution to such the problem. The main idea behind a cognitive radio network is for the unlicensed users (also called secondary users) to exploit opportunistically the underutilized spectrum licensed to a licensed network (referred to as a primary network). Before investigating the technical and political implications of CR, it is important to know to what extent the licensed bands are temporally unoccupied. In this paper, for the first time, we investigate the spectrum usage pattern in Vietnam in the frequency bands ranging from 20 MHz to 3000 MHz in Ho Chi Minh City and Long An province. The purpose of the measurement is to find how the scarce radio spectrum allocated to different services is utilized in Vietnam and identify the bands that could be accessed for future opportunistic use due to their low or no active utilization. These analyses indicate that, on average, the actual spectral usage in all bands is 13.74% and 11.19% for Ho Chi Minh City and Long An province, respectively. The experiment results also show that the spectrum band assigned for analog television (470–806) is the highest occupancy band with 58%.","PeriodicalId":221905,"journal":{"name":"The 2011 International Conference on Advanced Technologies for Communications (ATC 2011)","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121870384","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}
{"title":"Novel reconfigurable 8 - shape PIFA antenna using PIN diode","authors":"Trong Duc Nguyen, Y. Duroc, V. Y. Vu, T. Vuong","doi":"10.1109/ATC.2011.6027483","DOIUrl":"https://doi.org/10.1109/ATC.2011.6027483","url":null,"abstract":"A frequency reconfigurable Planar Inverted-F Antenna (RPIFA) antenna is proposed. From an initial 8-shape patch antenna by connecting or disconnecting one or more PIN diode, ten different structures are obtained. Corresponding to ten different geometries such as I-shape patch, U-shape patch, E-shape patch, etc, the antenna can be tuned in two frequency bands from 2GHz to 3GHz and from 4GHz to 7GHz. The novel RPIFA antenna is designed and optimized using Genetic Algorithm (GA) and then it is implemented on FR4 substrate. The simulation and measurement results of antenna parameters are compared to show the performance of the developed antenna.","PeriodicalId":221905,"journal":{"name":"The 2011 International Conference on Advanced Technologies for Communications (ATC 2011)","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116485558","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}