We consider a bidirectional communication between two terminals with the help of a relay. The transmissions of the three nodes are divided in time and there is no direct link between the terminals. The allocation of the transmission time and of the rates in both directions can be asymmetric. We first derive a closed form expression of the optimal time allocation for a given ratio of the rates in both directions and for given signal-to-noise ratios of all channels. Then, we derive a closed form expression of the optimal rate ratio such that the sum-rate is maximized under the assumption that the time allocation is optimally chosen. This also leads to a condition based on the channel SNRs, when to communicate with or without network coding in order to maximize the sum-rate. Then, we consider the design of the network code and compare several code designs by simulation whereas we assume that a turbo code is used as channel code. It turns out that efficient asymmetric two-way communication requires to perform network coding at the physical layer and can be realized by network-encoding the channel-encoded bits.
{"title":"Optimal time and rate allocation for a network-coded bidirectional two-hop communication","authors":"C. Hausl, O. Iscan, F. Rossetto","doi":"10.1109/EW.2010.5483533","DOIUrl":"https://doi.org/10.1109/EW.2010.5483533","url":null,"abstract":"We consider a bidirectional communication between two terminals with the help of a relay. The transmissions of the three nodes are divided in time and there is no direct link between the terminals. The allocation of the transmission time and of the rates in both directions can be asymmetric. We first derive a closed form expression of the optimal time allocation for a given ratio of the rates in both directions and for given signal-to-noise ratios of all channels. Then, we derive a closed form expression of the optimal rate ratio such that the sum-rate is maximized under the assumption that the time allocation is optimally chosen. This also leads to a condition based on the channel SNRs, when to communicate with or without network coding in order to maximize the sum-rate. Then, we consider the design of the network code and compare several code designs by simulation whereas we assume that a turbo code is used as channel code. It turns out that efficient asymmetric two-way communication requires to perform network coding at the physical layer and can be realized by network-encoding the channel-encoded bits.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123998408","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, we analyze spectrum occupancy of the 2.36–2.4 GHz band. Interest in this band has risen recently, as secondary allocation of this radio spectrum is being considered for body sensor network operation to offer wireless healthcare services. We present spectrum measurements conducted in the Eindhoven area, in the Netherlands, where the 2.36–2.4 GHz band is currently used for land mobile and amateur radio services. Our objective is to show the spectrum usage in this band, provide statistics for the received power of active transmissions and obtain their occupation time.
{"title":"Spectrum occupancy in the 2.36–2.4 GHZ band: Measurements and analysis","authors":"R. de Francisco, A. Pandharipande","doi":"10.1109/EW.2010.5483422","DOIUrl":"https://doi.org/10.1109/EW.2010.5483422","url":null,"abstract":"In this paper, we analyze spectrum occupancy of the 2.36–2.4 GHz band. Interest in this band has risen recently, as secondary allocation of this radio spectrum is being considered for body sensor network operation to offer wireless healthcare services. We present spectrum measurements conducted in the Eindhoven area, in the Netherlands, where the 2.36–2.4 GHz band is currently used for land mobile and amateur radio services. Our objective is to show the spectrum usage in this band, provide statistics for the received power of active transmissions and obtain their occupation time.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124113853","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}
Jan Ellenbeck, M. Hammoud, B. Lazarov, C. Hartmann
Cellular systems like Long Term Evolution Advanced (LTE-Advanced) aim at reusing the whole spectrum in each cell which leads to high inter-cell interference and thus low signal to interference and noise ratio (SINR) conditions for users at the cell edge. One way to utilize multiple antennas at the base station is to perform downlink transmit beamforming which besides increasing the received power at the mobile also has the potential to reduce interference when collisions of beams from different base stations are avoided. To this end we propose an autonomous coordination mechanism that allows cells to coordinate their beams in the frequency domain. In addition to increasing the SINR, it reduces interference fluctuations (the “flash light” effect) due to uncoordinated scheduling in neighbor cells thus making the interference situation more predictable. This further boosts the throughput potential. The proposed scheme is based on feedback from mobiles to their serving base station but does not require inter-cell signaling. By means of system level simulations we show that our autonomous approach converges after few iterations and yields significant cell mean and cell-edge throughput improvements.
{"title":"Autonomous beam coordination for the downlink of an IMT-Advanced cellular system","authors":"Jan Ellenbeck, M. Hammoud, B. Lazarov, C. Hartmann","doi":"10.1109/EW.2010.5483472","DOIUrl":"https://doi.org/10.1109/EW.2010.5483472","url":null,"abstract":"Cellular systems like Long Term Evolution Advanced (LTE-Advanced) aim at reusing the whole spectrum in each cell which leads to high inter-cell interference and thus low signal to interference and noise ratio (SINR) conditions for users at the cell edge. One way to utilize multiple antennas at the base station is to perform downlink transmit beamforming which besides increasing the received power at the mobile also has the potential to reduce interference when collisions of beams from different base stations are avoided. To this end we propose an autonomous coordination mechanism that allows cells to coordinate their beams in the frequency domain. In addition to increasing the SINR, it reduces interference fluctuations (the “flash light” effect) due to uncoordinated scheduling in neighbor cells thus making the interference situation more predictable. This further boosts the throughput potential. The proposed scheme is based on feedback from mobiles to their serving base station but does not require inter-cell signaling. By means of system level simulations we show that our autonomous approach converges after few iterations and yields significant cell mean and cell-edge throughput improvements.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"152 5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120947461","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 generalization of the concept of crystallized rate regions for MIMO/OFDM transmission is introduced. The extension from the SISO to MIMO case of the timesharing convex hull is discussed and a new definition of the cost function for the game is derived. Finally, a new game definition is provided followed by the simulation results for the MIMO case. Moreover, the OFDM transmission case is investigated, which can be treated as the special case of the MIMO system, when the channel transfer matrices are diagonal.
{"title":"MIMO crystallized rate regions","authors":"Adrian Kliks, P. Sroka, M. Debbah","doi":"10.1109/EW.2010.5483430","DOIUrl":"https://doi.org/10.1109/EW.2010.5483430","url":null,"abstract":"In this paper the generalization of the concept of crystallized rate regions for MIMO/OFDM transmission is introduced. The extension from the SISO to MIMO case of the timesharing convex hull is discussed and a new definition of the cost function for the game is derived. Finally, a new game definition is provided followed by the simulation results for the MIMO case. Moreover, the OFDM transmission case is investigated, which can be treated as the special case of the MIMO system, when the channel transfer matrices are diagonal.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121598045","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}
E. Ben Salem, Roberto López-Valcarce, Hichem Besbes, S. Cherif
This paper considers time-domain equalization of fading channels for multicarrier systems with channels whose delay spread exceeds the length of the cyclic prefix. We propose to apply Regalia's Finite Interval Constant Modulus Algorithm, which directly minimizes the constant modulus criterion for finite data sets, to the output of a single sub-carrier. This results in a blind adaptive channel shortening technique which is used to design a time-domain finite impulse response equalizer or channel shortener, whose goal is to compress the overall channel impulse response to within the length of the cyclic prefix. Simulation results are provided in terms of bit error rate (BER) in the context of wireless systems.
{"title":"A finite interval constant modulus criterion for multicarrier channel shortening","authors":"E. Ben Salem, Roberto López-Valcarce, Hichem Besbes, S. Cherif","doi":"10.1109/EW.2010.5483478","DOIUrl":"https://doi.org/10.1109/EW.2010.5483478","url":null,"abstract":"This paper considers time-domain equalization of fading channels for multicarrier systems with channels whose delay spread exceeds the length of the cyclic prefix. We propose to apply Regalia's Finite Interval Constant Modulus Algorithm, which directly minimizes the constant modulus criterion for finite data sets, to the output of a single sub-carrier. This results in a blind adaptive channel shortening technique which is used to design a time-domain finite impulse response equalizer or channel shortener, whose goal is to compress the overall channel impulse response to within the length of the cyclic prefix. Simulation results are provided in terms of bit error rate (BER) in the context of wireless systems.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"103 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127641930","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}
Francesco De Pellegrini, D. Miorandi, Iacopo Carreras
In this work we deal with the problem of dynamic decentralized self-optimization of forwarding protocols in delay-tolerant networks. We consider the two-hop forwarding protocol and we model the routing problem as an optimization one. We describe, under mild assumptions on the contact process among mobile nodes, the connection between the number of copies of a message and the cumulative probability distribution function of the message delay. We show that, despite the possible presence of a plurality of optimal policies, there always exists a threshold policy that is optimal. We also show that such an optimal strategy can be achieved at run-time by probing the network and with minimal message overhead. The approach is validated by implementing a self-optimizing algorithm in a network simulator; the performance of our solution is analyzed in the case of various real-world contact traces.
{"title":"Optimal two-hop routing in delay-tolerant networks","authors":"Francesco De Pellegrini, D. Miorandi, Iacopo Carreras","doi":"10.1109/EW.2010.5483532","DOIUrl":"https://doi.org/10.1109/EW.2010.5483532","url":null,"abstract":"In this work we deal with the problem of dynamic decentralized self-optimization of forwarding protocols in delay-tolerant networks. We consider the two-hop forwarding protocol and we model the routing problem as an optimization one. We describe, under mild assumptions on the contact process among mobile nodes, the connection between the number of copies of a message and the cumulative probability distribution function of the message delay. We show that, despite the possible presence of a plurality of optimal policies, there always exists a threshold policy that is optimal. We also show that such an optimal strategy can be achieved at run-time by probing the network and with minimal message overhead. The approach is validated by implementing a self-optimizing algorithm in a network simulator; the performance of our solution is analyzed in the case of various real-world contact traces.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134217686","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}
This paper aims at investigating some simple cooperative relaying strategies which rely on the exploitation of the Delay Diversity (DD) technique in a DVB-SH compliant hybrid satellite/terrestrial network. In particular the combination of the proposed cooperative system with the Cyclic Left Sample-Shift of the received signal is adopted in order to simplify the channel estimation process. The opposite effects of the Cooperative Delay Diversity technique and the Cyclic Left Sample-Shift on the equivalent channel transfer function are analysed: particularly, the two algorithms can coexist without any mutual impingement. Simulation results confirm the effectiveness of the proposed schemes in the mitigation of the Non-Line-Of-Sight (NLOS) propagation drawbacks and in the simplification of the channel estimation: the first positive effect is caused by the increase of the frequency selectivity of the equivalent channel perceived by the receiver (Cooperative DD technique) whereas the second result is due to the reduction of the frequency selectivity of the channel transfer function, which is used in the equalization process (Cyclic Left Sample-Shift).
{"title":"Cooperative Delay Diversity scheme with low complexity channel estimation in integrated satellite/terrestrial systems","authors":"S. Morosi, S. Jayousi, E. Del Re","doi":"10.1109/EW.2010.5483488","DOIUrl":"https://doi.org/10.1109/EW.2010.5483488","url":null,"abstract":"This paper aims at investigating some simple cooperative relaying strategies which rely on the exploitation of the Delay Diversity (DD) technique in a DVB-SH compliant hybrid satellite/terrestrial network. In particular the combination of the proposed cooperative system with the Cyclic Left Sample-Shift of the received signal is adopted in order to simplify the channel estimation process. The opposite effects of the Cooperative Delay Diversity technique and the Cyclic Left Sample-Shift on the equivalent channel transfer function are analysed: particularly, the two algorithms can coexist without any mutual impingement. Simulation results confirm the effectiveness of the proposed schemes in the mitigation of the Non-Line-Of-Sight (NLOS) propagation drawbacks and in the simplification of the channel estimation: the first positive effect is caused by the increase of the frequency selectivity of the equivalent channel perceived by the receiver (Cooperative DD technique) whereas the second result is due to the reduction of the frequency selectivity of the channel transfer function, which is used in the equalization process (Cyclic Left Sample-Shift).","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133997456","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}
This paper gives an overview of some outcomes produced in the FP7 project PHYDYAS — PHYsical layer for DYnamic AccesS and cognitive radio. The main concern of the project is to analyze and propose a new physical layer succeeding OFDM, i.e. a multi carrier system applying filter banks omitting the severe out-of-band leakage of OFDM. The new physical layer was investigated within two different scenarios. On the one side a cognitive radio scenario exploiting the stronger frequency containment for improved dynamic spectrum access. On the other side a cellular basestation ruled network harvesting the increased spectral efficiency. Within this paper we concentrate on the latter. We compare a conventional OFDM based system to its modified version applying the filter bank in terms of complexity, performance and compatibility. Additionally we propose a smooth evolution path ensuring legacy support.
{"title":"Filterbank based multi carrier transmission (FBMC) — evolving OFDM: FBMC in the context of WiMAX","authors":"F. Schaich","doi":"10.1109/EW.2010.5483518","DOIUrl":"https://doi.org/10.1109/EW.2010.5483518","url":null,"abstract":"This paper gives an overview of some outcomes produced in the FP7 project PHYDYAS — PHYsical layer for DYnamic AccesS and cognitive radio. The main concern of the project is to analyze and propose a new physical layer succeeding OFDM, i.e. a multi carrier system applying filter banks omitting the severe out-of-band leakage of OFDM. The new physical layer was investigated within two different scenarios. On the one side a cognitive radio scenario exploiting the stronger frequency containment for improved dynamic spectrum access. On the other side a cellular basestation ruled network harvesting the increased spectral efficiency. Within this paper we concentrate on the latter. We compare a conventional OFDM based system to its modified version applying the filter bank in terms of complexity, performance and compatibility. Additionally we propose a smooth evolution path ensuring legacy support.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132933102","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 rates of change of a wide variety of MIMO metrics are evaluated by differentiating the relevant random processes. Moments, distributions and simplified representations are derived where possible for the resulting derivatives. Fundamental metrics such as the channel coefficients, channel correlation matrices and eigenvalues are considered in addition to performance metrics such as bit-error-rate and the condition number. The analysis presents a comprehensive framework for studying the time-varying nature of MIMO systems in independent Rayleigh fading and leads to insights into the relative rates of change of the various metrics. For example, we show that there is a difference of several orders of magnitude between the moderate rates of change of channel elements and eigenvalues and the extremely rapid variations of the channel condition number. The channel eigenvectors are also shown to experience rapid fluctuations.
{"title":"Random matrix processes: Quantifying rates of change in MIMO systems","authors":"Peter J. Smith, M. Mckay, A. Giorgetti, M. Chiani","doi":"10.1109/EW.2010.5483415","DOIUrl":"https://doi.org/10.1109/EW.2010.5483415","url":null,"abstract":"The rates of change of a wide variety of MIMO metrics are evaluated by differentiating the relevant random processes. Moments, distributions and simplified representations are derived where possible for the resulting derivatives. Fundamental metrics such as the channel coefficients, channel correlation matrices and eigenvalues are considered in addition to performance metrics such as bit-error-rate and the condition number. The analysis presents a comprehensive framework for studying the time-varying nature of MIMO systems in independent Rayleigh fading and leads to insights into the relative rates of change of the various metrics. For example, we show that there is a difference of several orders of magnitude between the moderate rates of change of channel elements and eigenvalues and the extremely rapid variations of the channel condition number. The channel eigenvectors are also shown to experience rapid fluctuations.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114609104","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}
I. Stupia, F. Giannetti, V. Lottici, L. Vandendorpe
This paper develops cross-layer adaptive modulation and coding as an efficient method for bit interleaved coded OFDM packet transmission. As objective function, we adopt the goodput, or the number of data bits delivered without error per unit of time. After the formalization of the optimization problem through an accurate modeling on the link performance, an iterative solution is derived based on the framework of greedy algorithms. Simulation results show that the proposed method improves upon the performance of static transmission and uniform bit allocation by 2–4 dB.
{"title":"A greedy algorithm for goodput-based adaptive modulation and coding in BIC-OFDM systems","authors":"I. Stupia, F. Giannetti, V. Lottici, L. Vandendorpe","doi":"10.1109/EW.2010.5483466","DOIUrl":"https://doi.org/10.1109/EW.2010.5483466","url":null,"abstract":"This paper develops cross-layer adaptive modulation and coding as an efficient method for bit interleaved coded OFDM packet transmission. As objective function, we adopt the goodput, or the number of data bits delivered without error per unit of time. After the formalization of the optimization problem through an accurate modeling on the link performance, an iterative solution is derived based on the framework of greedy algorithms. Simulation results show that the proposed method improves upon the performance of static transmission and uniform bit allocation by 2–4 dB.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2010-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123626302","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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