Pub Date : 2010-04-29DOI: 10.1109/WSA.2010.5456439
I. Olabarrieta, J. Ser
In this paper we consider a network of distributed sensors which simultaneously measure a physical parameter of interest, subject to a certain probability of sensing error. The sensed information at each of such nodes is channel-encoded and forwarded to a central receiver through parallel independent AWGN channels. In this scenario, several recent contributions have shown that the end-to-end Bit Error Rate (BER) performance can be dramatically improved if the decoders associated to each received signal and the data fusion stage exchange soft information in an iterative Turbo-like fashion. In order to achieve optimum performance, the probability of sensing error must be known (or estimated) at the receiver. In this work we describe a novel method for estimating such sensing error probability by properly weighting likelihoods output from the Soft-Input Soft-Output decoders (SISO), which is shown to outperform other estimation methods based in hard-decision comparisons, specially in the low SNR regime.
{"title":"Enhanced sensing error probability estimation for iterative data fusion in the low SNR regime","authors":"I. Olabarrieta, J. Ser","doi":"10.1109/WSA.2010.5456439","DOIUrl":"https://doi.org/10.1109/WSA.2010.5456439","url":null,"abstract":"In this paper we consider a network of distributed sensors which simultaneously measure a physical parameter of interest, subject to a certain probability of sensing error. The sensed information at each of such nodes is channel-encoded and forwarded to a central receiver through parallel independent AWGN channels. In this scenario, several recent contributions have shown that the end-to-end Bit Error Rate (BER) performance can be dramatically improved if the decoders associated to each received signal and the data fusion stage exchange soft information in an iterative Turbo-like fashion. In order to achieve optimum performance, the probability of sensing error must be known (or estimated) at the receiver. In this work we describe a novel method for estimating such sensing error probability by properly weighting likelihoods output from the Soft-Input Soft-Output decoders (SISO), which is shown to outperform other estimation methods based in hard-decision comparisons, specially in the low SNR regime.","PeriodicalId":311394,"journal":{"name":"2010 International ITG Workshop on Smart Antennas (WSA)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130546009","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 : 2010-04-29DOI: 10.1109/WSA.2010.5456441
T. Lang, A. Mezghani, J. Nossek
We present iterative algorithms which efficiently compute an optimized subset of equiprobable input symbols that achieves near-capacity on a large asymmetric discrete memoryless channel (DMC). The optimized subset defines a delay-free channel-adapted inner code which can be combined with a standard code. The introduction of a dense data structure renders it possible to apply channel-adaptive coding to 2-bit quantized MIMO systems, which exhibit a very large output set. The coding approach is shown to be robust to imperfect channel state information (CSI). Finally, we present a binary index switching algorithm that minimizes the BER by optimizing the mapping from code bits to input symbols.
{"title":"Channel-adaptive coding for coarsely quantized MIMO systems","authors":"T. Lang, A. Mezghani, J. Nossek","doi":"10.1109/WSA.2010.5456441","DOIUrl":"https://doi.org/10.1109/WSA.2010.5456441","url":null,"abstract":"We present iterative algorithms which efficiently compute an optimized subset of equiprobable input symbols that achieves near-capacity on a large asymmetric discrete memoryless channel (DMC). The optimized subset defines a delay-free channel-adapted inner code which can be combined with a standard code. The introduction of a dense data structure renders it possible to apply channel-adaptive coding to 2-bit quantized MIMO systems, which exhibit a very large output set. The coding approach is shown to be robust to imperfect channel state information (CSI). Finally, we present a binary index switching algorithm that minimizes the BER by optimizing the mapping from code bits to input symbols.","PeriodicalId":311394,"journal":{"name":"2010 International ITG Workshop on Smart Antennas (WSA)","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131844335","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 : 2010-04-29DOI: 10.1109/WSA.2010.5456390
Jörg Holfeld, Vincent Kotzsch, G. Fettweis
This paper describes an order-recursive algorithm to calculate the Wiener transmit filter for coherent coordinated multi-point transmissions between several decentralized base stations to several decentralized mobile terminals in cellular radio networks. State of the art implementations do not offer the flexibility to handle multiple transmission setups as required for multi-user precoding in conjunction with the proposed reduced complexity. A discussion of all signal processing steps shows how algebraic observations are mapped to physical parameters and how they reflect the spatial eigenmodes. These observations can be integrated into a spatial scheduling process to extend the precoding coefficients recursively with additional spatial streams. Finally, experimental resultqs with a hardware platform for cellular field trials are presented that compare the proposed multiuser interference cancelation technique with a non-cooperative transmission.
{"title":"Order-recursive precoding for cooperative multi-point transmission","authors":"Jörg Holfeld, Vincent Kotzsch, G. Fettweis","doi":"10.1109/WSA.2010.5456390","DOIUrl":"https://doi.org/10.1109/WSA.2010.5456390","url":null,"abstract":"This paper describes an order-recursive algorithm to calculate the Wiener transmit filter for coherent coordinated multi-point transmissions between several decentralized base stations to several decentralized mobile terminals in cellular radio networks. State of the art implementations do not offer the flexibility to handle multiple transmission setups as required for multi-user precoding in conjunction with the proposed reduced complexity. A discussion of all signal processing steps shows how algebraic observations are mapped to physical parameters and how they reflect the spatial eigenmodes. These observations can be integrated into a spatial scheduling process to extend the precoding coefficients recursively with additional spatial streams. Finally, experimental resultqs with a hardware platform for cellular field trials are presented that compare the proposed multiuser interference cancelation technique with a non-cooperative transmission.","PeriodicalId":311394,"journal":{"name":"2010 International ITG Workshop on Smart Antennas (WSA)","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114484175","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 : 2010-04-29DOI: 10.1109/WSA.2010.5456449
Wenyao Xue, T. Wiegand, S. Paul
Iterative tree search algorithms like K-Best or sphere decoder algorithms are promising candidates for the upcoming wireless communications systems. In this paper a square root and division free Givens rotation (SDFG) algorithm is merged into a common sphere decoder algorithm to decrease the entire complexity. Furthermore, the algorithm is speeded up due to parallelizing the computation by taking the orthogonality of the real and imaginary parts of the complex transmit symbols into account.
{"title":"Implementation of an SDFG based parallel depth-first complex sphere decoding algorithm","authors":"Wenyao Xue, T. Wiegand, S. Paul","doi":"10.1109/WSA.2010.5456449","DOIUrl":"https://doi.org/10.1109/WSA.2010.5456449","url":null,"abstract":"Iterative tree search algorithms like K-Best or sphere decoder algorithms are promising candidates for the upcoming wireless communications systems. In this paper a square root and division free Givens rotation (SDFG) algorithm is merged into a common sphere decoder algorithm to decrease the entire complexity. Furthermore, the algorithm is speeded up due to parallelizing the computation by taking the orthogonality of the real and imaginary parts of the complex transmit symbols into account.","PeriodicalId":311394,"journal":{"name":"2010 International ITG Workshop on Smart Antennas (WSA)","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121338028","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 : 2010-04-29DOI: 10.1109/WSA.2010.5456420
M. Joham, R. Hunger
Based on recent results for the vector broadcast channel (BC), the feasibility of the quality of service (QoS) optimization in the multiple-input multiple-output (MIMO) BC with linear precoders and linear equalizers is investigated. Based on the observation that only single data stream transmission must be considered for feasibility, we find that the test for feasibility is the comparison of the sum of the transformed rate requirements with a bound given by the difference of the number of users and the degrees of freedom available at the BC transmitter, as long as the channel realization fulfills some regularity condition.
{"title":"Feasible rate region of the MIMO broadcast channel with linear transceivers","authors":"M. Joham, R. Hunger","doi":"10.1109/WSA.2010.5456420","DOIUrl":"https://doi.org/10.1109/WSA.2010.5456420","url":null,"abstract":"Based on recent results for the vector broadcast channel (BC), the feasibility of the quality of service (QoS) optimization in the multiple-input multiple-output (MIMO) BC with linear precoders and linear equalizers is investigated. Based on the observation that only single data stream transmission must be considered for feasibility, we find that the test for feasibility is the comparison of the sum of the transformed rate requirements with a bound given by the difference of the number of users and the degrees of freedom available at the BC transmitter, as long as the channel realization fulfills some regularity condition.","PeriodicalId":311394,"journal":{"name":"2010 International ITG Workshop on Smart Antennas (WSA)","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132823466","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 : 2010-04-29DOI: 10.1109/WSA.2010.5456431
M. Lieberei, U. Zölzer
Questions of providing MIMO infrastructure rise with continued standardization of multiple-input multiple-output (MIMO) radio techniques. Depending on the environment, the usage of special antennas might be advantageous. In aircraft cabins so called leaky lines are installed for usage with mobile phones according to the GSM standard. When establishing a point-to-point-link, antennas which exhibit a directional characteristic might be useful. When providing a MIMO setup in a room or office with no predictable placement of terminals, omnidirectional antennas are the best choice. In this paper measurement campaigns are presented, in which an experimental MIMO system is used with different types of antennas on transmitter side, in an office-like environment and in an aircraft cabin, to evaluate the influence of the usage of different types of antennas on the measured MIMO channel in those environments, in terms of capacity, spatial correlation and delay spread. It is found that neither different antenna types nor the aircraft cabin heavily affect the measured MIMO channel capacity.
{"title":"MIMO channel measurements with different antennas in different environments","authors":"M. Lieberei, U. Zölzer","doi":"10.1109/WSA.2010.5456431","DOIUrl":"https://doi.org/10.1109/WSA.2010.5456431","url":null,"abstract":"Questions of providing MIMO infrastructure rise with continued standardization of multiple-input multiple-output (MIMO) radio techniques. Depending on the environment, the usage of special antennas might be advantageous. In aircraft cabins so called leaky lines are installed for usage with mobile phones according to the GSM standard. When establishing a point-to-point-link, antennas which exhibit a directional characteristic might be useful. When providing a MIMO setup in a room or office with no predictable placement of terminals, omnidirectional antennas are the best choice. In this paper measurement campaigns are presented, in which an experimental MIMO system is used with different types of antennas on transmitter side, in an office-like environment and in an aircraft cabin, to evaluate the influence of the usage of different types of antennas on the measured MIMO channel in those environments, in terms of capacity, spatial correlation and delay spread. It is found that neither different antenna types nor the aircraft cabin heavily affect the measured MIMO channel capacity.","PeriodicalId":311394,"journal":{"name":"2010 International ITG Workshop on Smart Antennas (WSA)","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120952462","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 : 2010-04-29DOI: 10.1109/WSA.2010.5456426
H. Schulze
We apply the Monte-Carlo simulation model to a frequency selective fading channel including space-variance. This model is suited to simulate the performance of a multi-antenna system for a moving receiver (or transmitter). It takes into account that the time-variance of the channel due to this motion has its origin in the space-variance. We emphasize that for such a channel, time and frequency correlations cannot be separated.
{"title":"A simulation model for space-time-frequency variant fading channels","authors":"H. Schulze","doi":"10.1109/WSA.2010.5456426","DOIUrl":"https://doi.org/10.1109/WSA.2010.5456426","url":null,"abstract":"We apply the Monte-Carlo simulation model to a frequency selective fading channel including space-variance. This model is suited to simulate the performance of a multi-antenna system for a moving receiver (or transmitter). It takes into account that the time-variance of the channel due to this motion has its origin in the space-variance. We emphasize that for such a channel, time and frequency correlations cannot be separated.","PeriodicalId":311394,"journal":{"name":"2010 International ITG Workshop on Smart Antennas (WSA)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130416174","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 : 2010-04-29DOI: 10.1109/WSA.2010.5456456
Meng Wu, P. Weitkemper, D. Wübben, K. Kammeyer
In order to approach the theoretical limit of the decode-and-forward strategy for the half-duplex relay channel, distributed LDPC coding schemes have been proposed. In these schemes, the code applied at the source should be decodable at the relay to yield correct parity bits. With the help of the parity bits the destination should also be able to estimate the transmitted information correctly. For successful decoding the distributed coding scheme has to be designed jointly, requiring a high design complexity. As an alternative a distributed LDPC scheme based on puncturing is investigated, which requires only the design of one mother code. In this paper we compare three different approaches for designing distributed LDPC codes with respect to their performance and their design complexity.
{"title":"Comparison of distributed LDPC coding schemes for decode-and-forward relay channels","authors":"Meng Wu, P. Weitkemper, D. Wübben, K. Kammeyer","doi":"10.1109/WSA.2010.5456456","DOIUrl":"https://doi.org/10.1109/WSA.2010.5456456","url":null,"abstract":"In order to approach the theoretical limit of the decode-and-forward strategy for the half-duplex relay channel, distributed LDPC coding schemes have been proposed. In these schemes, the code applied at the source should be decodable at the relay to yield correct parity bits. With the help of the parity bits the destination should also be able to estimate the transmitted information correctly. For successful decoding the distributed coding scheme has to be designed jointly, requiring a high design complexity. As an alternative a distributed LDPC scheme based on puncturing is investigated, which requires only the design of one mother code. In this paper we compare three different approaches for designing distributed LDPC codes with respect to their performance and their design complexity.","PeriodicalId":311394,"journal":{"name":"2010 International ITG Workshop on Smart Antennas (WSA)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130073736","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 : 2010-04-29DOI: 10.1109/WSA.2010.5456376
Tarik Akbudak, A. Czylwik
In this paper, the downlink power control problem in decentralized orthogonal frequency division multiple access (OFDMA) networks is addressed. First, the optimization problem which minimizes the overall transmission power subject to individual rate and power constraints in a decentralized network is considered. An optimal solution requires global link information. However, obtaining such information is almost impossible. This paper introduces a power control and scheduling algorithm which can be implemented in a distributed manner. This algorithm delivers suboptimal solutions, since it is based on local information. However, simulation results show that the suboptimal solutions obtained through this algorithm are close to the global optimum, as long as it exists. Furthermore, it is shown that the obtained solutions are very similar to the ones obtained through a central controller.
{"title":"Distributed power control and scheduling for decentralized OFDMA networks","authors":"Tarik Akbudak, A. Czylwik","doi":"10.1109/WSA.2010.5456376","DOIUrl":"https://doi.org/10.1109/WSA.2010.5456376","url":null,"abstract":"In this paper, the downlink power control problem in decentralized orthogonal frequency division multiple access (OFDMA) networks is addressed. First, the optimization problem which minimizes the overall transmission power subject to individual rate and power constraints in a decentralized network is considered. An optimal solution requires global link information. However, obtaining such information is almost impossible. This paper introduces a power control and scheduling algorithm which can be implemented in a distributed manner. This algorithm delivers suboptimal solutions, since it is based on local information. However, simulation results show that the suboptimal solutions obtained through this algorithm are close to the global optimum, as long as it exists. Furthermore, it is shown that the obtained solutions are very similar to the ones obtained through a central controller.","PeriodicalId":311394,"journal":{"name":"2010 International ITG Workshop on Smart Antennas (WSA)","volume":"181 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122568752","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 : 2010-04-29DOI: 10.1109/WSA.2010.5456399
R. Mehmood, J. Wallace
Reconfigurable aperture (RECAP) antennas consist of a regular array of reconfigurable elements confined to an aperture, representing a generalization of the reconfigurable antenna concept. RECAPs have the potential of supporting operations like beamforming, null steering, interference suppression, adaptive matching, and frequency and bandwidth agility in a single aperture. Although very complex RECAP structures theoretically have performance that is only limited by the physical extent of the aperture, high complexity is impractical due to increased loss, biasing difficulties, and system cost. This work reviews the RECAP antenna concept and focuses on the role of performance bounds imposed by limited complexity in practical RECAP structures. This initial effort studies empirical bounds on beamforming performance observed from detailed simulation of two idealized RECAP structures: (i) a 5×5 parasitic dipole array, and (ii) a 8×8 planar configuration of reactively connected patches. Performance bounds for limited complexity are identified, indicating the number of elements per wavelength and the states per reconfigurable element that are needed to capture most of the available performance.
{"title":"Exploring beamforming performance versus complexity in reconfigurable aperture antennas","authors":"R. Mehmood, J. Wallace","doi":"10.1109/WSA.2010.5456399","DOIUrl":"https://doi.org/10.1109/WSA.2010.5456399","url":null,"abstract":"Reconfigurable aperture (RECAP) antennas consist of a regular array of reconfigurable elements confined to an aperture, representing a generalization of the reconfigurable antenna concept. RECAPs have the potential of supporting operations like beamforming, null steering, interference suppression, adaptive matching, and frequency and bandwidth agility in a single aperture. Although very complex RECAP structures theoretically have performance that is only limited by the physical extent of the aperture, high complexity is impractical due to increased loss, biasing difficulties, and system cost. This work reviews the RECAP antenna concept and focuses on the role of performance bounds imposed by limited complexity in practical RECAP structures. This initial effort studies empirical bounds on beamforming performance observed from detailed simulation of two idealized RECAP structures: (i) a 5×5 parasitic dipole array, and (ii) a 8×8 planar configuration of reactively connected patches. Performance bounds for limited complexity are identified, indicating the number of elements per wavelength and the states per reconfigurable element that are needed to capture most of the available performance.","PeriodicalId":311394,"journal":{"name":"2010 International ITG Workshop on Smart Antennas (WSA)","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115904364","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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