This paper deals with the performance evaluation of wireless cellular networks serving streaming traffic. In contrast to data traffic, streaming users require predefined transmission rates, which can be maintained at the price of blocking of some arrivals or cutting some existing connections when a network congestion occurs. The fractions of blocked and cut transmissions in the long run of the system, called respectively, blocking and cut probabilities, are the main performance metrics of such networks. In this paper we evaluate the impact of the intra-and extra-cell user mobility on these metrics. Specifically, we assume a spatio-temporal Poisson arrival process of streaming calls, independent Markovian mobility and exponential duration of each call. The dynamics of this free (offered) process is modified each time a congestion-generating transition occurs. We consider two possible modifications, which lead to two different loss models. We study both of them, and in particular, we propose some explicit approximations for the blocking and cut probabilities, which take into account the mean user mobility speed. We illustrate our approach studying UMTS release 99 building upon the scalable admission control schemes developed previously, which allow for an exact representation of the geometry of interference in the network.
{"title":"Impact of mean user speed on blocking and cuts of streaming traffic in cellular networks","authors":"B. Błaszczyszyn, M. Karray","doi":"10.1109/EW.2008.4623911","DOIUrl":"https://doi.org/10.1109/EW.2008.4623911","url":null,"abstract":"This paper deals with the performance evaluation of wireless cellular networks serving streaming traffic. In contrast to data traffic, streaming users require predefined transmission rates, which can be maintained at the price of blocking of some arrivals or cutting some existing connections when a network congestion occurs. The fractions of blocked and cut transmissions in the long run of the system, called respectively, blocking and cut probabilities, are the main performance metrics of such networks. In this paper we evaluate the impact of the intra-and extra-cell user mobility on these metrics. Specifically, we assume a spatio-temporal Poisson arrival process of streaming calls, independent Markovian mobility and exponential duration of each call. The dynamics of this free (offered) process is modified each time a congestion-generating transition occurs. We consider two possible modifications, which lead to two different loss models. We study both of them, and in particular, we propose some explicit approximations for the blocking and cut probabilities, which take into account the mean user mobility speed. We illustrate our approach studying UMTS release 99 building upon the scalable admission control schemes developed previously, which allow for an exact representation of the geometry of interference in the network.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"519 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123123782","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 design of wireless sensor networks (WSNs) should focus on energy efficiency since wireless sensor nodes work on limited batteries, which are difficult or impossible to replace in most situations. However, the performance of WSNs is adversely impacted by fading effects, which requires much energy to combat for a high bit error rate (BER) requirement. On the other hand, since the transmit energy is proportional to transmit distance, energy imbalance is caused by the different distances to the base station (BS). Sensor nodes far from the BS consume much more energy than those close to the BS and may die out quickly, which shortens the lifetime or results in a malfunction of the WSN. Reducing the proportion of transmit energy in total energy consumption helps minimize the differences in transmit energy among sensor nodes. Cooperative transmission has been proven to be an effective way to combat the impacts of fading by obtaining diversity gains and therefore, reduces the transmit energy. In this paper, we first apply cooperative transmission in WSNs, which not only reduces energy consumption but also lessens the differences of energy consumption among sensor nodes. To further balance energy among sensor nodes, we apply different cluster size and simulation results show that unequal cluster size improves energy balancing.
{"title":"Energy balance in cooperative Wireless Sensor Network","authors":"L. Bai, Lian Zhao, Z. Liao","doi":"10.1109/EW.2008.4623879","DOIUrl":"https://doi.org/10.1109/EW.2008.4623879","url":null,"abstract":"The design of wireless sensor networks (WSNs) should focus on energy efficiency since wireless sensor nodes work on limited batteries, which are difficult or impossible to replace in most situations. However, the performance of WSNs is adversely impacted by fading effects, which requires much energy to combat for a high bit error rate (BER) requirement. On the other hand, since the transmit energy is proportional to transmit distance, energy imbalance is caused by the different distances to the base station (BS). Sensor nodes far from the BS consume much more energy than those close to the BS and may die out quickly, which shortens the lifetime or results in a malfunction of the WSN. Reducing the proportion of transmit energy in total energy consumption helps minimize the differences in transmit energy among sensor nodes. Cooperative transmission has been proven to be an effective way to combat the impacts of fading by obtaining diversity gains and therefore, reduces the transmit energy. In this paper, we first apply cooperative transmission in WSNs, which not only reduces energy consumption but also lessens the differences of energy consumption among sensor nodes. To further balance energy among sensor nodes, we apply different cluster size and simulation results show that unequal cluster size improves energy balancing.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114664531","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 provides an overview of the methodology used in the performance assessment of the 64QAM and MIMO HSDPA features in a macro-cellular environment. The paper describes how the geometry experienced by end users could be measured in a live HSPA network, and how this could be used together with link level simulations to perform a first assessment of performance expectation of both MIMO and 64QAM.
{"title":"3G HSDPA evolution: MIMO and 64QAM performance in macrocellular deployments","authors":"S. Tenorio, Yannick Le Pezennec, Manuel Sierra","doi":"10.1109/EW.2008.4623927","DOIUrl":"https://doi.org/10.1109/EW.2008.4623927","url":null,"abstract":"This paper provides an overview of the methodology used in the performance assessment of the 64QAM and MIMO HSDPA features in a macro-cellular environment. The paper describes how the geometry experienced by end users could be measured in a live HSPA network, and how this could be used together with link level simulations to perform a first assessment of performance expectation of both MIMO and 64QAM.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125178532","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 study joint radio resource management (JRRM) in heterogeneous networks and we propose a way of achieving optimality. We consider a micro, pico or femto cell with two co-localized radio access technologies (RAT), e.g. WLAN and HSDPA. RAT are mainly characterized by the data rates they offer at a given distance of the access point (resp. base station). Dual-technology mobile stations (MS) are initiating downlink packet calls in the considered cell. A network controlled joint RRM algorithm is responsible to assign MS to a RAT, while taking into account the joint spatial distribution of already accepted MS, the current load of each RAT, the location of the newly accepted packet call and its influence on the global performance. Two classes of JRRM algorithms are considered. In a study based on the Semi Markov Decision Process (SMDP) theory, we show how to obtain optimal policies for each of these classes. Optimality is here defined through a utility function accounting for user satisfaction and blocking.
{"title":"SMDP approach for JRRM analysis in heterogeneous networks","authors":"M. Coupechoux, J. Kélif, P. Godlewski","doi":"10.1109/EW.2008.4623856","DOIUrl":"https://doi.org/10.1109/EW.2008.4623856","url":null,"abstract":"In this paper, we study joint radio resource management (JRRM) in heterogeneous networks and we propose a way of achieving optimality. We consider a micro, pico or femto cell with two co-localized radio access technologies (RAT), e.g. WLAN and HSDPA. RAT are mainly characterized by the data rates they offer at a given distance of the access point (resp. base station). Dual-technology mobile stations (MS) are initiating downlink packet calls in the considered cell. A network controlled joint RRM algorithm is responsible to assign MS to a RAT, while taking into account the joint spatial distribution of already accepted MS, the current load of each RAT, the location of the newly accepted packet call and its influence on the global performance. Two classes of JRRM algorithms are considered. In a study based on the Semi Markov Decision Process (SMDP) theory, we show how to obtain optimal policies for each of these classes. Optimality is here defined through a utility function accounting for user satisfaction and blocking.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125278893","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 use of multiple antennas for diversity and array gain may require accurate channel state information (CSI) on each subcarrier in orthogonal frequency division multiplexing systems. Such CSI is usually reported from the receiver to the transmitter, causing a significant amount of feedback signaling burden. Recent work can noticeably reduce the feedback signaling burden by exploiting the channel correlation properties in the frequency domain, but it can be applied to the generation of a single beam [1]. In this paper, this idea is extended to the use of multiple beams for spatial multiplexing. Simulation results show that the proposed scheme can improve the performance using the same amount of feedback signaling burden or provide the same performance while noticeably reducing the amount of feedback signaling burden, compared to conventional schemes.
{"title":"Transmit beamforming with reduced channel information in MIMO-OFDM wireless systems","authors":"Seung-Hyeon Yang, J. Ko, Yong-Hwan Lee","doi":"10.1109/EW.2008.4623875","DOIUrl":"https://doi.org/10.1109/EW.2008.4623875","url":null,"abstract":"The use of multiple antennas for diversity and array gain may require accurate channel state information (CSI) on each subcarrier in orthogonal frequency division multiplexing systems. Such CSI is usually reported from the receiver to the transmitter, causing a significant amount of feedback signaling burden. Recent work can noticeably reduce the feedback signaling burden by exploiting the channel correlation properties in the frequency domain, but it can be applied to the generation of a single beam [1]. In this paper, this idea is extended to the use of multiple beams for spatial multiplexing. Simulation results show that the proposed scheme can improve the performance using the same amount of feedback signaling burden or provide the same performance while noticeably reducing the amount of feedback signaling burden, compared to conventional schemes.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"39 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126733465","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}
OFDM systems are very sensitive in phase noise and frequency dispersion. Thus, time and frequency synchronization tasks are very crucial for the proper signal recovery in the receiver. The difficulties and challenges are multiplied if we consider a multiuser OFDM system (OFDMA) where the subcarriers are shared between different users. The receiver has the task to choose optimal sampling instants and to align the subcarrier frequencies of an OFDM symbol that contains signals from multiple users. In this study the use of filter banks is considered in order to reduce Intercarrier interference in such a system and simplify the synchronization procedures that must take place. The proposed schemes are applicable to adjacent subcarrier permutation OFDMA systems where users are separated in bands of adjacent subcarriers. In order to achieve low processing load, techniques of multirate signal processing are adopted. The DFT - polyphase filters are the basic elements of the processing chain. Moreover the filtering procedure is preferred to be divided in multiple stages. The computational workload for each structure is determined and some measures for the reduction of the computational burden are presented.
{"title":"Receiver architectures for OFDMA systems with subband carrier allocation","authors":"K. Maliatsos, A. Adamis, P. Constantinou","doi":"10.1109/EW.2008.4623916","DOIUrl":"https://doi.org/10.1109/EW.2008.4623916","url":null,"abstract":"OFDM systems are very sensitive in phase noise and frequency dispersion. Thus, time and frequency synchronization tasks are very crucial for the proper signal recovery in the receiver. The difficulties and challenges are multiplied if we consider a multiuser OFDM system (OFDMA) where the subcarriers are shared between different users. The receiver has the task to choose optimal sampling instants and to align the subcarrier frequencies of an OFDM symbol that contains signals from multiple users. In this study the use of filter banks is considered in order to reduce Intercarrier interference in such a system and simplify the synchronization procedures that must take place. The proposed schemes are applicable to adjacent subcarrier permutation OFDMA systems where users are separated in bands of adjacent subcarriers. In order to achieve low processing load, techniques of multirate signal processing are adopted. The DFT - polyphase filters are the basic elements of the processing chain. Moreover the filtering procedure is preferred to be divided in multiple stages. The computational workload for each structure is determined and some measures for the reduction of the computational burden are presented.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116094381","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}
M. Chouayakh, A. Knopp, Constant Ahokpossi, B. Lankl
A new MIMO detector for frequency selective indoor channels is proposed. The detector is based on a two-stage detection followed by a decision feedback equalizer (DFE). The first detection stage is assured by a linear equalizer subsequently followed by a decision unit. The second step is a reduced search (RS) around the solution acquired by the linear equalization, which will be performed in an efficient way at the different transmitted data streams. The RS will be adjusted depending on the search probability at each level. The DFE is applied in order to remove the effect of the inter symbol interferences (ISI) caused by the channel dispersion as it has been observed in the indoor measurements. The RS method provides a near ML performance while it demands a fixed computational effort which is determined by the number of operations and limited by the hardware resources. Compared to some of the most important MIMO detectors, such as for example V-BLAST and sphere decoder, in simulations as well as in field measurements our approach exhibits a near ML performance in terms of BER while its computational effort always remains distinctly lower.
{"title":"Low effort MIMO eetector for frequency selective indoor channels","authors":"M. Chouayakh, A. Knopp, Constant Ahokpossi, B. Lankl","doi":"10.1109/EW.2008.4623853","DOIUrl":"https://doi.org/10.1109/EW.2008.4623853","url":null,"abstract":"A new MIMO detector for frequency selective indoor channels is proposed. The detector is based on a two-stage detection followed by a decision feedback equalizer (DFE). The first detection stage is assured by a linear equalizer subsequently followed by a decision unit. The second step is a reduced search (RS) around the solution acquired by the linear equalization, which will be performed in an efficient way at the different transmitted data streams. The RS will be adjusted depending on the search probability at each level. The DFE is applied in order to remove the effect of the inter symbol interferences (ISI) caused by the channel dispersion as it has been observed in the indoor measurements. The RS method provides a near ML performance while it demands a fixed computational effort which is determined by the number of operations and limited by the hardware resources. Compared to some of the most important MIMO detectors, such as for example V-BLAST and sphere decoder, in simulations as well as in field measurements our approach exhibits a near ML performance in terms of BER while its computational effort always remains distinctly lower.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116168947","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 contribution we present the results of a study on satellite to outdoor channel modeling for satellite systems with multiple satellites. Our model for several satellites is based on a first order Markov channel state model for joint processes. The probability density function (PDF) of the signal amplitude within each state is fitted to the Loo distribution. The parameters of our model are based on the simultaneous measurements of the Satellite Digital Audio Radio services (S-DARS) systems XM Radio and Sirius carried out on various locations in the USA and Canada. All channel model parameters are estimated for four different measured environments. We also study the channel state duration, the correlation between two satellite channels, and the channel spatial autocorrelation. The probability density functions of these parameters are approximated with analytical expressions. The correlation properties between two channels and the state duration indicate that significant diversity gains are possible in multiple satellite systems.
{"title":"Measurement based satellite to outdoor channel modeling for multiple satellite systems","authors":"M. Milojević, M. Haardt, A. Heuberger","doi":"10.1109/EW.2008.4623848","DOIUrl":"https://doi.org/10.1109/EW.2008.4623848","url":null,"abstract":"In this contribution we present the results of a study on satellite to outdoor channel modeling for satellite systems with multiple satellites. Our model for several satellites is based on a first order Markov channel state model for joint processes. The probability density function (PDF) of the signal amplitude within each state is fitted to the Loo distribution. The parameters of our model are based on the simultaneous measurements of the Satellite Digital Audio Radio services (S-DARS) systems XM Radio and Sirius carried out on various locations in the USA and Canada. All channel model parameters are estimated for four different measured environments. We also study the channel state duration, the correlation between two satellite channels, and the channel spatial autocorrelation. The probability density functions of these parameters are approximated with analytical expressions. The correlation properties between two channels and the state duration indicate that significant diversity gains are possible in multiple satellite systems.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"25 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122507048","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}
Dongwook Lee, Okkyeong Bang, Sooyeol Im, Hyuckjae Lee
Passive RFID tags, which have no self-battery and just backscatter the energy from a reader, share a common channel. It causes a tag-to-tag collision problem when at least two or more tags communicate to the reader simultaneously. The dynamic frame slotted Aloha (DFS-Aloha) protocol is one of the well-known anti-collision algorithms to solve this problem. To maximize the system performance and enhance the reading speed of Aloha protocols, we propose a frame-size estimator which is a modified version of Q-Algorithm. To maximize the system performance, the optimum bias values of the proposed estimator are searched by using Least Square method from mathematical model of DFS-Aloha. Simulation results show that the proposed estimation algorithm enhances the system performance. The proposed estimation algorithm takes less identification time than DFS-Aloha with the existing Q-Algorithm based on EPC Class 1 Generation 2 protocol.
{"title":"Efficient dual bias Q-Algorithm and optimum weights for EPC Class 1 Generation 2 Protocol","authors":"Dongwook Lee, Okkyeong Bang, Sooyeol Im, Hyuckjae Lee","doi":"10.1109/EW.2008.4623846","DOIUrl":"https://doi.org/10.1109/EW.2008.4623846","url":null,"abstract":"Passive RFID tags, which have no self-battery and just backscatter the energy from a reader, share a common channel. It causes a tag-to-tag collision problem when at least two or more tags communicate to the reader simultaneously. The dynamic frame slotted Aloha (DFS-Aloha) protocol is one of the well-known anti-collision algorithms to solve this problem. To maximize the system performance and enhance the reading speed of Aloha protocols, we propose a frame-size estimator which is a modified version of Q-Algorithm. To maximize the system performance, the optimum bias values of the proposed estimator are searched by using Least Square method from mathematical model of DFS-Aloha. Simulation results show that the proposed estimation algorithm enhances the system performance. The proposed estimation algorithm takes less identification time than DFS-Aloha with the existing Q-Algorithm based on EPC Class 1 Generation 2 protocol.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122184266","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 situation where a transmitter has a batch of packets in its buffers and wants to transmit these in one go and in a semi-reliable fashion to an arbitrary subset of its neighbors over error-prone channels. We design schemes that let the transmitter node control the sleeping activities of the receivers (in order to save energy) and which adapt the sequence in which receivers are addressed to current channel conditions.
{"title":"Batch delivery in wireless sensor networks","authors":"F. Naldi, A. Willig","doi":"10.1109/EW.2008.4623878","DOIUrl":"https://doi.org/10.1109/EW.2008.4623878","url":null,"abstract":"We consider a situation where a transmitter has a batch of packets in its buffers and wants to transmit these in one go and in a semi-reliable fashion to an arbitrary subset of its neighbors over error-prone channels. We design schemes that let the transmitter node control the sleeping activities of the receivers (in order to save energy) and which adapt the sequence in which receivers are addressed to current channel conditions.","PeriodicalId":237850,"journal":{"name":"2008 14th European Wireless Conference","volume":"68 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132457879","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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