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.2010.5456385
J. Baumgarten, J. Robert, N. Muhammad, L. Stadelmeier
The application of space-time/frequency coding is an interesting means to mitigate fading effects in terrestrial channels. Therefore, the well-known Alamouti scheme was introduced to the DVB-T2 standard. However, there have not been any measurements so far analysing the achievable gains using MIMO-schemes for broadcasting in UHF channels. Thus, extensive measurements have been performed. The obtained data was then used to feed a simulation chain for simulating the potential benefits of Alamouti coding in the measured channel. The created simulation results show significant gain for the application of Alamouti in DVB-T2.
{"title":"Performance of Alamouti coding in real measured UHF channels","authors":"J. Baumgarten, J. Robert, N. Muhammad, L. Stadelmeier","doi":"10.1109/WSA.2010.5456385","DOIUrl":"https://doi.org/10.1109/WSA.2010.5456385","url":null,"abstract":"The application of space-time/frequency coding is an interesting means to mitigate fading effects in terrestrial channels. Therefore, the well-known Alamouti scheme was introduced to the DVB-T2 standard. However, there have not been any measurements so far analysing the achievable gains using MIMO-schemes for broadcasting in UHF channels. Thus, extensive measurements have been performed. The obtained data was then used to feed a simulation chain for simulating the potential benefits of Alamouti coding in the measured channel. The created simulation results show significant gain for the application of Alamouti in DVB-T2.","PeriodicalId":311394,"journal":{"name":"2010 International ITG Workshop on Smart Antennas (WSA)","volume":"379 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":"134598354","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.2010.5456390
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.2010.5456420
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.2010.5456399
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}
Pub Date : 2010-04-29DOI: 10.1109/WSA.2010.5456419
M. Stefer, Martin Schneider
The influence of mutual coupling of antenna elements is usually not considered when dealing with MIMO (Multiple Input Multiple Output) communication systems. This is justifiable if mobile subscribers feature only one antenna and base station antenna elements are separated by a distance of several wavelengths. However, regarding pico-cell base stations that consist of multiple antenna elements, the coupling has to be taken into account due to the reduced antenna element spacing. In this paper, the influence of antenna coupling on adaptive MIMO-OFDM (Orthogonal Frequency Division Multiplex) systems is investigated in terms of the attainable signal-to-interference-plus-noise ratio (SINR). The mutual coupling of the antenna elements is calculated for different antenna models based on the ”infinitesimally thin” lambda/2 dipole and the Hertzian dipole. Additionally, a coupling model based on the isotropic radiator is considered. The different results for the SINR stemming from the antenna models when exploiting linear pre-equalization are presented. It is shown that using an isotropic radiator based model is not sufficient for describing the effect of mutual coupling for lambda/2 dipoles.
{"title":"On modeling antenna coupling for adaptive MIMO-OFDM systems","authors":"M. Stefer, Martin Schneider","doi":"10.1109/WSA.2010.5456419","DOIUrl":"https://doi.org/10.1109/WSA.2010.5456419","url":null,"abstract":"The influence of mutual coupling of antenna elements is usually not considered when dealing with MIMO (Multiple Input Multiple Output) communication systems. This is justifiable if mobile subscribers feature only one antenna and base station antenna elements are separated by a distance of several wavelengths. However, regarding pico-cell base stations that consist of multiple antenna elements, the coupling has to be taken into account due to the reduced antenna element spacing. In this paper, the influence of antenna coupling on adaptive MIMO-OFDM (Orthogonal Frequency Division Multiplex) systems is investigated in terms of the attainable signal-to-interference-plus-noise ratio (SINR). The mutual coupling of the antenna elements is calculated for different antenna models based on the ”infinitesimally thin” lambda/2 dipole and the Hertzian dipole. Additionally, a coupling model based on the isotropic radiator is considered. The different results for the SINR stemming from the antenna models when exploiting linear pre-equalization are presented. It is shown that using an isotropic radiator based model is not sufficient for describing the effect of mutual coupling for lambda/2 dipoles.","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":"115920113","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.2010.5456450
Vincent Kotzsch, C. Jandura, W. Rave, G. Fettweis
It is well known that symbol timing offsets larger than the cyclic prefix between transmitter and receiver stations destroy the orthogonality among OFDM subcarriers inducing interblock interference by coupling subsequent OFDM symbols. In conjunction with MIMO transmission over frequency selective channels, this effect on top of multi-user interference strongly degrades performance. In this paper we analyze the timing constraints in cellular MIMO OFDM networks that necessarily occur due to time-of-arrival differences of signals from different locations. We investigate a simple hexagonal model, where three users transmit their data on the same time-frequency resource to three cooperating base stations. Based on a detailed analytical derivation of the transmission model we present results for the post detection SINR in systems with symmetric and uniform user distribution within one cooperative cell.
{"title":"On timing constraints and OFDM parameter design for cooperating basestations","authors":"Vincent Kotzsch, C. Jandura, W. Rave, G. Fettweis","doi":"10.1109/WSA.2010.5456450","DOIUrl":"https://doi.org/10.1109/WSA.2010.5456450","url":null,"abstract":"It is well known that symbol timing offsets larger than the cyclic prefix between transmitter and receiver stations destroy the orthogonality among OFDM subcarriers inducing interblock interference by coupling subsequent OFDM symbols. In conjunction with MIMO transmission over frequency selective channels, this effect on top of multi-user interference strongly degrades performance. In this paper we analyze the timing constraints in cellular MIMO OFDM networks that necessarily occur due to time-of-arrival differences of signals from different locations. We investigate a simple hexagonal model, where three users transmit their data on the same time-frequency resource to three cooperating base stations. Based on a detailed analytical derivation of the transmission model we present results for the post detection SINR in systems with symmetric and uniform user distribution within one cooperative cell.","PeriodicalId":311394,"journal":{"name":"2010 International ITG Workshop on Smart Antennas (WSA)","volume":"200 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":"116149849","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.2010.5456431
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}
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