This paper addresses the question whether decode-and-forward relaying protocols can beat transmit diversity with respect to ε-outage capacity. We derive expressions of ε-outage capacity for transmit diversity, decode-and-forward, selective decode-and-forward, and incremental decode-and-forward. We demonstrate that the relaying protocols outperform transmit diversity in certain regions. Decode-and-forward is beneficial over transmit diversity when the relay is located close to the source. For selective decode-and-forward to beat transmit diversity, the relay should be placed between the source and the destination, but not too close to the source. The best performance is achieved by incremental decode-and-forward. The region in which this scheme is beneficial over transmit diversity is large. Moreover, as the region becomes smaller, the outage probability for the source-destination link becomes larger.
{"title":"Do decode-and-forward relaying protocols beat transmit diversity?","authors":"T. Renk, H. Jaekel, F. Jondral, A. Goldsmith","doi":"10.1109/EW.2010.5483434","DOIUrl":"https://doi.org/10.1109/EW.2010.5483434","url":null,"abstract":"This paper addresses the question whether decode-and-forward relaying protocols can beat transmit diversity with respect to ε-outage capacity. We derive expressions of ε-outage capacity for transmit diversity, decode-and-forward, selective decode-and-forward, and incremental decode-and-forward. We demonstrate that the relaying protocols outperform transmit diversity in certain regions. Decode-and-forward is beneficial over transmit diversity when the relay is located close to the source. For selective decode-and-forward to beat transmit diversity, the relay should be placed between the source and the destination, but not too close to the source. The best performance is achieved by incremental decode-and-forward. The region in which this scheme is beneficial over transmit diversity is large. Moreover, as the region becomes smaller, the outage probability for the source-destination link becomes larger.","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":"133602423","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}
New advanced transmission protocols are required to fulfill the cost-efficiency objective of next generation mobile communications systems. This paper presents the study and performance evaluation of a two-relay assisted cooperative transmission protocol which could make a good candidate technique to improve the capacity and the quality of service of future cellular networks. Simulation results obtained in a realistic radio environment confirm the superior efficiency of this protocol over both its non-cooperative counterpart and conventional direct transmission, provided that the relays' positions are adequately chosen and that an interference cancellation mechanism is implemented in one of the two relays.
{"title":"Performance analysis of a two-relay assisted transmission scheme","authors":"Pascale Fouillot, I. Icart, C. L. Le Martret","doi":"10.1109/EW.2010.5483404","DOIUrl":"https://doi.org/10.1109/EW.2010.5483404","url":null,"abstract":"New advanced transmission protocols are required to fulfill the cost-efficiency objective of next generation mobile communications systems. This paper presents the study and performance evaluation of a two-relay assisted cooperative transmission protocol which could make a good candidate technique to improve the capacity and the quality of service of future cellular networks. Simulation results obtained in a realistic radio environment confirm the superior efficiency of this protocol over both its non-cooperative counterpart and conventional direct transmission, provided that the relays' positions are adequately chosen and that an interference cancellation mechanism is implemented in one of the two relays.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"42 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":"134182123","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}
Graphic Processing Units (GPUs) have evolved to provide a massive computational power. In contrast to Central Processing Units, GPUs are so-called many-core processors with hundreds of cores capable of running thousands of threads in parallel. This parallel processing power can accelerate the simulation of communication systems. In this work, we utilize NVIDIA's Compute Unified Device Architecture (CUDA) to execute two different sphere decoders on a graphic card. Both flat fading and frequency selective channels are considered. We find that the execution of the soft-sphere decoder can be accelerated by factors of 6-8, and the fixed-complexity sphere decoder even by a factor of 50.
{"title":"Boosting sphere decoding speed through Graphic Processing Units","authors":"M. S. Khairy, C. Mehlführer, M. Rupp","doi":"10.1109/EW.2010.5483399","DOIUrl":"https://doi.org/10.1109/EW.2010.5483399","url":null,"abstract":"Graphic Processing Units (GPUs) have evolved to provide a massive computational power. In contrast to Central Processing Units, GPUs are so-called many-core processors with hundreds of cores capable of running thousands of threads in parallel. This parallel processing power can accelerate the simulation of communication systems. In this work, we utilize NVIDIA's Compute Unified Device Architecture (CUDA) to execute two different sphere decoders on a graphic card. Both flat fading and frequency selective channels are considered. We find that the execution of the soft-sphere decoder can be accelerated by factors of 6-8, and the fixed-complexity sphere decoder even by a factor of 50.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"1 2 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":"134467224","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 article, we have studied the statistical properties of the capacity of Nakagami-m channels when spatial diversity combining, such as maximal ratio combining (MRC) and equal gain combining (EGC), is employed at the receiver. The presented results provide insight into the statistical properties of the channel capacity under a wide range of fading conditions in wireless links using L-branch diversity combining techniques. We have derived closed-form analytical expressions for the probability density function (PDF), cumulative distribution function (CDF), level-crossing rate (LCR), and average duration of fades (ADF) of the channel capacity. The statistical properties of the capacity are studied for different values of the number of diversity branches and for different severity levels of fading. The analytical results are verified with the help of simulations. It is observed that increasing the number of diversity branches increases the mean channel capacity, while the variance and ADF of the channel capacity decreases. Moreover, systems in which the fading in diversity branches is less severe (as compared to Rayleigh fading) have a higher mean channel capacity. The presented results are very helpful to optimize the design of the receiver of wireless communication systems that employ spatial diversity combining.
{"title":"The influence of severity of fading on the statistical properties of the capacity of Nakagami-m channels with MRC and EGC","authors":"G. Rafiq, V. Kontorovich, M. Patzold","doi":"10.1109/EW.2010.5483507","DOIUrl":"https://doi.org/10.1109/EW.2010.5483507","url":null,"abstract":"In this article, we have studied the statistical properties of the capacity of Nakagami-m channels when spatial diversity combining, such as maximal ratio combining (MRC) and equal gain combining (EGC), is employed at the receiver. The presented results provide insight into the statistical properties of the channel capacity under a wide range of fading conditions in wireless links using L-branch diversity combining techniques. We have derived closed-form analytical expressions for the probability density function (PDF), cumulative distribution function (CDF), level-crossing rate (LCR), and average duration of fades (ADF) of the channel capacity. The statistical properties of the capacity are studied for different values of the number of diversity branches and for different severity levels of fading. The analytical results are verified with the help of simulations. It is observed that increasing the number of diversity branches increases the mean channel capacity, while the variance and ADF of the channel capacity decreases. Moreover, systems in which the fading in diversity branches is less severe (as compared to Rayleigh fading) have a higher mean channel capacity. The presented results are very helpful to optimize the design of the receiver of wireless communication systems that employ spatial diversity combining.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"77 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":"115712232","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 explore the possibility of exploiting underutilized channels in the GSM bands. The secondary (unlicensed) users of the spectrum are the nodes of an overlay cognitive ad-hoc network, which opportunistically transmits in data channels left unused by the primary (licensed) system. The fundamental constraints for the secondary system are: 1) it uses the time slots/frequency channels (i.e. data channels) unused by the primary GSM system, 2) its operation does not degrade the performances of the primary system, 3) there is no exchange of signalling information between the primary and the secondary system to facilitate the secondary usage of spectrum, that is, the primary users are not cognitive aware. The focus is on the feasibility of the proposed approach, so that we consider a system level simulator based on a realistic GSM network deployed in the city of Bologna. In this context we evaluate the impact that the operation of the secondary users has on the performances of the primary system. In addition, we study the performances that can be obtained by the secondary system under the condition of marginal interference to the primary system. We will show that an appropriate choice of the frequency channel, makes the secondary usage of spectrum a valid approach to increase the operator's spectrum efficiency.
{"title":"Evaluation of spectrum opportunities in the GSM band","authors":"Andrea Carniani, L. Giupponi, R. Verdone","doi":"10.1109/EW.2010.5483438","DOIUrl":"https://doi.org/10.1109/EW.2010.5483438","url":null,"abstract":"In this paper we explore the possibility of exploiting underutilized channels in the GSM bands. The secondary (unlicensed) users of the spectrum are the nodes of an overlay cognitive ad-hoc network, which opportunistically transmits in data channels left unused by the primary (licensed) system. The fundamental constraints for the secondary system are: 1) it uses the time slots/frequency channels (i.e. data channels) unused by the primary GSM system, 2) its operation does not degrade the performances of the primary system, 3) there is no exchange of signalling information between the primary and the secondary system to facilitate the secondary usage of spectrum, that is, the primary users are not cognitive aware. The focus is on the feasibility of the proposed approach, so that we consider a system level simulator based on a realistic GSM network deployed in the city of Bologna. In this context we evaluate the impact that the operation of the secondary users has on the performances of the primary system. In addition, we study the performances that can be obtained by the secondary system under the condition of marginal interference to the primary system. We will show that an appropriate choice of the frequency channel, makes the secondary usage of spectrum a valid approach to increase the operator's spectrum efficiency.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"267 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":"114458942","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}
Ramon S. Schwartz, R. Barbosa, N. Meratnia, G. Heijenk, H. Scholten
Several promising applications for Vehicular Ad-hoc Networks (VANETs) exist. For most of these applications, the communication among vehicles is envisioned to be based on the broadcasting of messages. This is due to the inherent highly mobile environment and importance of these messages to vehicles nearby. To deal with broadcast communication, dissemination protocols must be defined in such a way as to (i) prevent the so-called broadcast storm problem in dense networks and (ii) deal with disconnected networks in sparse topologies. In this paper, we present a Simple and Robust Dissemination (SRD) protocol that deals with these requirements in both sparse and dense networks. Its novelty lies in its simplicity and robustness. Simplicity is achieved by considering only two states (cluster tail and non-tail) for a vehicle. Robustness is achieved by assigning message delivery responsibility to multiple vehicles in sparse networks. Our simulation results show that SRD achieves high delivery ratio and low end-to-end delay under diverse traffic conditions.
{"title":"A Simple and Robust Dissemination protocol for VANETs","authors":"Ramon S. Schwartz, R. Barbosa, N. Meratnia, G. Heijenk, H. Scholten","doi":"10.1109/EW.2010.5483419","DOIUrl":"https://doi.org/10.1109/EW.2010.5483419","url":null,"abstract":"Several promising applications for Vehicular Ad-hoc Networks (VANETs) exist. For most of these applications, the communication among vehicles is envisioned to be based on the broadcasting of messages. This is due to the inherent highly mobile environment and importance of these messages to vehicles nearby. To deal with broadcast communication, dissemination protocols must be defined in such a way as to (i) prevent the so-called broadcast storm problem in dense networks and (ii) deal with disconnected networks in sparse topologies. In this paper, we present a Simple and Robust Dissemination (SRD) protocol that deals with these requirements in both sparse and dense networks. Its novelty lies in its simplicity and robustness. Simplicity is achieved by considering only two states (cluster tail and non-tail) for a vehicle. Robustness is achieved by assigning message delivery responsibility to multiple vehicles in sparse networks. Our simulation results show that SRD achieves high delivery ratio and low end-to-end delay under diverse traffic conditions.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"8 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":"114524830","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 a wireless ad hoc network, an opportunistic routing strategy is a strategy where there is no predefined rule for choosing the next node to destination (as it is the case in conventional schemes such as OLSR, DSR or even Geo-Routing). Rather, an intermediate node en route acts in an impromptu fashion and takes a decision that is based solely on current circumstances. A popular example of opportunistic routing is the “delay tolerant” forwarding to “data mules” when a direct path to destination does not exist. Conventional routing in this case would just “drop” the packet. With opportunistic routing, a node acts upon the available information: it seeks the neighbor best qualified to “carry” the packet to destination. If none is available, it will await the right opportunity. This procedure is also known as “data muling” or Delay Tolerant Network (DTN) routing. The Vehicular Ad Hoc Networks (VANET), because of its intrinsic intermittent connectivity (during off peak hours and at night) is an ideal “playground” for opportunistic routing/multicast. In this paper we will examine two examples of VANET opportunistic routing: Delay Tolerant geo-inspired routing and real time video stream multicast of emergency/accident multimedia reports to vehicles in disconnected platoons using network coding.
{"title":"Opportunistic vehicular routing","authors":"Kevin C. Lee, M. Gerla","doi":"10.1109/EW.2010.5483530","DOIUrl":"https://doi.org/10.1109/EW.2010.5483530","url":null,"abstract":"In a wireless ad hoc network, an opportunistic routing strategy is a strategy where there is no predefined rule for choosing the next node to destination (as it is the case in conventional schemes such as OLSR, DSR or even Geo-Routing). Rather, an intermediate node en route acts in an impromptu fashion and takes a decision that is based solely on current circumstances. A popular example of opportunistic routing is the “delay tolerant” forwarding to “data mules” when a direct path to destination does not exist. Conventional routing in this case would just “drop” the packet. With opportunistic routing, a node acts upon the available information: it seeks the neighbor best qualified to “carry” the packet to destination. If none is available, it will await the right opportunity. This procedure is also known as “data muling” or Delay Tolerant Network (DTN) routing. The Vehicular Ad Hoc Networks (VANET), because of its intrinsic intermittent connectivity (during off peak hours and at night) is an ideal “playground” for opportunistic routing/multicast. In this paper we will examine two examples of VANET opportunistic routing: Delay Tolerant geo-inspired routing and real time video stream multicast of emergency/accident multimedia reports to vehicles in disconnected platoons using network coding.","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":"122939099","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 a MIMO radar system with widely-spaced transmit/receive antennas and study the problem of designing the signal waveforms transmitted by each source node so as to maximize the detection probability for a fixed false alarm rate under correlated Gaussian clutter. The proposed design procedure relies on a stochastic-gradient search and is general enough to be applied to any statistical target model. Examples are provided to compare the performance of the proposed codes with other known coding schemes.
{"title":"A stochastic-gradient method to design optimal space-time codes for MIMO radar detection","authors":"L. Venturino, Ke Dong, Xiaodong Wang, M. Lops","doi":"10.1109/EW.2010.5483418","DOIUrl":"https://doi.org/10.1109/EW.2010.5483418","url":null,"abstract":"We consider a MIMO radar system with widely-spaced transmit/receive antennas and study the problem of designing the signal waveforms transmitted by each source node so as to maximize the detection probability for a fixed false alarm rate under correlated Gaussian clutter. The proposed design procedure relies on a stochastic-gradient search and is general enough to be applied to any statistical target model. Examples are provided to compare the performance of the proposed codes with other known coding schemes.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"10 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":"123612347","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}
A mobile sink is widely considered to facilitate the data collection from energy constrained sensor fields, by having the sink come close to the sensors and conserving precious sensor node energy. The effectiveness of such a data collection approach can be measured in terms of the sensor energy conserved and the time required to collect the sensor data from the field (or, equivalently, the length of the trajectory implemented by the mobile sink). In this paper we explore two important dimensions in the design of mobile sink-based data collection schemes. One dimension refers to how close to the sensor nodes the sink moves to, to collect the data, which impacts on the transmission energy expenditure by the sensor node. The other dimension refers to the way the sink moves through the sensor field, to collect the data, which impacts on the delay in collecting the data. To capture the first dimension, the 0-hop and 1-hop data collection schemes are considered and studied; at the same time, two ”extreme” approaches to the sink mobility process are considered: a (topology unaware) random walk-based sink mobility scheme and a (topology aware, optimal) deterministic sink mobility scheme. Through the analytic and simulative study presented in this paper, an understanding of the level of the trade-offs involved between the energy spent by the sensor nodes and the delay in completing the data collection process is obtained.
{"title":"Sink mobility schemes for data extraction in large scale WSNs under single or zero hop data forwarding","authors":"Leonidas Tzevelekas, I. Stavrakakis","doi":"10.1109/EW.2010.5483528","DOIUrl":"https://doi.org/10.1109/EW.2010.5483528","url":null,"abstract":"A mobile sink is widely considered to facilitate the data collection from energy constrained sensor fields, by having the sink come close to the sensors and conserving precious sensor node energy. The effectiveness of such a data collection approach can be measured in terms of the sensor energy conserved and the time required to collect the sensor data from the field (or, equivalently, the length of the trajectory implemented by the mobile sink). In this paper we explore two important dimensions in the design of mobile sink-based data collection schemes. One dimension refers to how close to the sensor nodes the sink moves to, to collect the data, which impacts on the transmission energy expenditure by the sensor node. The other dimension refers to the way the sink moves through the sensor field, to collect the data, which impacts on the delay in collecting the data. To capture the first dimension, the 0-hop and 1-hop data collection schemes are considered and studied; at the same time, two ”extreme” approaches to the sink mobility process are considered: a (topology unaware) random walk-based sink mobility scheme and a (topology aware, optimal) deterministic sink mobility scheme. Through the analytic and simulative study presented in this paper, an understanding of the level of the trade-offs involved between the energy spent by the sensor nodes and the delay in completing the data collection process is obtained.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"19 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":"123702762","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}
Requirements for LTE-Advanced were defined in June 2008 and since then it has been developed and evaluated in 3GPP RAN Working Groups. LTE-Advanced Study Item is to be completed in March 2010 and several LTE Release 10 Work Items have already been kicked off. This paper addresses the state of LTE-Advanced standardization, performance and network deployments in February 2010.
{"title":"LTE-Advanced: The mainstream in mobile broadband evolution","authors":"Matti Kiiski","doi":"10.1109/EW.2010.5483512","DOIUrl":"https://doi.org/10.1109/EW.2010.5483512","url":null,"abstract":"Requirements for LTE-Advanced were defined in June 2008 and since then it has been developed and evaluated in 3GPP RAN Working Groups. LTE-Advanced Study Item is to be completed in March 2010 and several LTE Release 10 Work Items have already been kicked off. This paper addresses the state of LTE-Advanced standardization, performance and network deployments in February 2010.","PeriodicalId":232165,"journal":{"name":"2010 European Wireless Conference (EW)","volume":"19 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":"121851025","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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