This study considers the design of efficient low-complexity algorithms for dynamic allocation of subcarriers to users in a multiuser transmitter using Orthogonal Frequency Division. The effects upon throughput and delay performances of several canonical algorithms of varying the number of users, the number of subcarriers, and the statistical characteristics of incoming packets are investigated. Consequently, a subcarrier allocation algorithm with low computational complexity and satisfactory performance in almost all cases of interest is developed. The significance of channel v.s. queue state information with respect to various statistical properties of packet arrival processes is explored through extensive simulations. The results carry implications for the amount of channel estimation and feedback necessary. Finally, a new experimental method is proposed and applied for obtaining the stability regions of the algorithms in consideration.
{"title":"Subcarrier allocation in OFDMA with time varying channel and packet arrivals","authors":"Engin Toktas, E. Uysal-Biyikoglu, A. O. Yılmaz","doi":"10.1109/EW.2009.5357997","DOIUrl":"https://doi.org/10.1109/EW.2009.5357997","url":null,"abstract":"This study considers the design of efficient low-complexity algorithms for dynamic allocation of subcarriers to users in a multiuser transmitter using Orthogonal Frequency Division. The effects upon throughput and delay performances of several canonical algorithms of varying the number of users, the number of subcarriers, and the statistical characteristics of incoming packets are investigated. Consequently, a subcarrier allocation algorithm with low computational complexity and satisfactory performance in almost all cases of interest is developed. The significance of channel v.s. queue state information with respect to various statistical properties of packet arrival processes is explored through extensive simulations. The results carry implications for the amount of channel estimation and feedback necessary. Finally, a new experimental method is proposed and applied for obtaining the stability regions of the algorithms in consideration.","PeriodicalId":412079,"journal":{"name":"2009 European Wireless Conference","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129429370","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}
S. Kameda, H. Oguma, T. Takagi, K. Tsubouchi, N. Izuka, Y. Asano, Y. Yamazaki
In this paper, we report on a mobile broadband wireless access (MBWA) system field trial with Fast Low-latency Access with Seamless Handoff Orthogonal Frequency Division Multiplexing (FLASH-OFDM), which was carried out at Sendai city in Japan. This paper discusses the feasibility of downlink transmission with the maximum modulation level of 256 quadrature amplitude modulation (QAM), using the received signal level and throughput under the measurement condition of the maximum modulation level of 64 QAM. The feasibility study results show that 256 QAM yields a higher downlink throughput than 64 QAM within coverage of 1.2 km when the base-station antenna height is 84 m. The results are validated by evaluating the downlink throughput performance in the field trial under the measurement condition of the maximum modulation level of 256 QAM. It is considered that 256 QAM is feasible to provide a mobile broadband data communication service to subscribers in an urban area.
{"title":"Feasibility study of downlink transmission with 256 QAM based on results of MBWA system field trial","authors":"S. Kameda, H. Oguma, T. Takagi, K. Tsubouchi, N. Izuka, Y. Asano, Y. Yamazaki","doi":"10.1109/EW.2009.5357999","DOIUrl":"https://doi.org/10.1109/EW.2009.5357999","url":null,"abstract":"In this paper, we report on a mobile broadband wireless access (MBWA) system field trial with Fast Low-latency Access with Seamless Handoff Orthogonal Frequency Division Multiplexing (FLASH-OFDM), which was carried out at Sendai city in Japan. This paper discusses the feasibility of downlink transmission with the maximum modulation level of 256 quadrature amplitude modulation (QAM), using the received signal level and throughput under the measurement condition of the maximum modulation level of 64 QAM. The feasibility study results show that 256 QAM yields a higher downlink throughput than 64 QAM within coverage of 1.2 km when the base-station antenna height is 84 m. The results are validated by evaluating the downlink throughput performance in the field trial under the measurement condition of the maximum modulation level of 256 QAM. It is considered that 256 QAM is feasible to provide a mobile broadband data communication service to subscribers in an urban area.","PeriodicalId":412079,"journal":{"name":"2009 European Wireless Conference","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131411462","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 the performance of an innovative Frequency Domain (FD) receiver for IEEE 802.15.4a short-range communications. The proposed system takes benefit of the guard intervals which are introduced in the standard between the symbols, so avoiding the need of the cyclic prefix introduction at the transmitter. The proposed receiver strategy is based on the Minimum Mean Square Error (MMSE) criterion and is compared with the classical rake, considering a scenario where a coordinator communicates with several devices in a short range environment. The channel model, which is characterized by severe multipath propagation, has been derived according to the IEEE 802.15.4a recommendations.
{"title":"Frequency Domain receivers for IEEE 802.15.4a short range communication systems","authors":"S. Morosi, T. Bianchi, Francesco Gei","doi":"10.1109/EW.2009.5357998","DOIUrl":"https://doi.org/10.1109/EW.2009.5357998","url":null,"abstract":"In this paper we study the performance of an innovative Frequency Domain (FD) receiver for IEEE 802.15.4a short-range communications. The proposed system takes benefit of the guard intervals which are introduced in the standard between the symbols, so avoiding the need of the cyclic prefix introduction at the transmitter. The proposed receiver strategy is based on the Minimum Mean Square Error (MMSE) criterion and is compared with the classical rake, considering a scenario where a coordinator communicates with several devices in a short range environment. The channel model, which is characterized by severe multipath propagation, has been derived according to the IEEE 802.15.4a recommendations.","PeriodicalId":412079,"journal":{"name":"2009 European Wireless Conference","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114745896","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}
Multipath is one of the dominant error sources in satellite-based positioning. It is a well known fact that the conventional code tracking loop suffers from performance degradation due to the presence of multipath. In past years, several advanced signal processing techniques have been devised to mitigate the multipath induced errors. One particular class of these signal processing techniques is the multi-correlator based feed-forward approach. The multipath performance of these feed-forward techniques has been extensively studied in open loop configuration by the authors in [1], [9]. The goal of this paper is to analyze the performance of these multi-correlator based feed-forward techniques in closed loop configuration, i.e., in the presence of an NCO and a loop filter, in multipath channels. Additionally, the delay tracking methods previously studied for BPSK and Sine BOC signals are also studied here with the newly proposed Multiplexed BOC modulation.
{"title":"Multipath mitigation performance of multi-correlator based code tracking algorithms in closed and open loop model","authors":"M. Z. H. Bhuiyan, Xuan Hu, E. Lohan, M. Renfors","doi":"10.1109/EW.2009.5357986","DOIUrl":"https://doi.org/10.1109/EW.2009.5357986","url":null,"abstract":"Multipath is one of the dominant error sources in satellite-based positioning. It is a well known fact that the conventional code tracking loop suffers from performance degradation due to the presence of multipath. In past years, several advanced signal processing techniques have been devised to mitigate the multipath induced errors. One particular class of these signal processing techniques is the multi-correlator based feed-forward approach. The multipath performance of these feed-forward techniques has been extensively studied in open loop configuration by the authors in [1], [9]. The goal of this paper is to analyze the performance of these multi-correlator based feed-forward techniques in closed loop configuration, i.e., in the presence of an NCO and a loop filter, in multipath channels. Additionally, the delay tracking methods previously studied for BPSK and Sine BOC signals are also studied here with the newly proposed Multiplexed BOC modulation.","PeriodicalId":412079,"journal":{"name":"2009 European Wireless Conference","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121398227","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 integration of satellite and terrestrial systems in a hybrid network permits to benefit from both systems, overcoming the drawbacks of a Non-Line-Of-Sight (NLOS) propagation. The purpose of this paper is to study simple cooperative relaying strategies which rely on the introduction of the Delay Diversity (DD) technique in a DVB-SH compliant hybrid satellite/terrestrial network with the aim of improving the performance of the network. The application of this strategy represents a promising solution to guarantee communication also in public emergency situations, such as the ones caused by fire, earthquake, flood or explosion. We investigated the pros and cons of the proposed scheme, comparing the assumptions which are required and the simulation results with respect to the satellite-only and the terrestrial-only systems.
{"title":"Hybrid satellite/terrestrial cooperative relaying strategies for DVB-SH based communication systems","authors":"S. Morosi, E. Del Re, S. Jayousi, R. Suffritti","doi":"10.1109/EW.2009.5357991","DOIUrl":"https://doi.org/10.1109/EW.2009.5357991","url":null,"abstract":"The integration of satellite and terrestrial systems in a hybrid network permits to benefit from both systems, overcoming the drawbacks of a Non-Line-Of-Sight (NLOS) propagation. The purpose of this paper is to study simple cooperative relaying strategies which rely on the introduction of the Delay Diversity (DD) technique in a DVB-SH compliant hybrid satellite/terrestrial network with the aim of improving the performance of the network. The application of this strategy represents a promising solution to guarantee communication also in public emergency situations, such as the ones caused by fire, earthquake, flood or explosion. We investigated the pros and cons of the proposed scheme, comparing the assumptions which are required and the simulation results with respect to the satellite-only and the terrestrial-only systems.","PeriodicalId":412079,"journal":{"name":"2009 European Wireless Conference","volume":"89 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121711688","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 probability density function and the cumulative distribution function of the product of shifted exponential variates are obtained in terms of the generalized upper incomplete Fox's H function. Using these new results, the exact outage capacity of multi carrier transmission through a slow Rayleigh fading channel is presented. Moreover, it is shown that analytical and simulation results are in perfect agreement.
{"title":"Product of shifted exponential variates and outage capacity of multicarrier systems","authors":"F. Yilmaz, Mohamed-Slim Alouini","doi":"10.1109/EW.2009.5357980","DOIUrl":"https://doi.org/10.1109/EW.2009.5357980","url":null,"abstract":"The probability density function and the cumulative distribution function of the product of shifted exponential variates are obtained in terms of the generalized upper incomplete Fox's H function. Using these new results, the exact outage capacity of multi carrier transmission through a slow Rayleigh fading channel is presented. Moreover, it is shown that analytical and simulation results are in perfect agreement.","PeriodicalId":412079,"journal":{"name":"2009 European Wireless Conference","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123750407","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}
Cognitive radio is a highly promising technology to efficiently solve the spectrum scarcity challenge and harmonize the networks heterogeneity. Through component spectrum sharing, secondary users (SUs) are able to opportunistically access licensed spectrum shared with the primary system. In the literature, spectrum sharing is normally investigated on the basis of the assumption that the spectrum sensing is perfect. However, in reality, the spectrum sensing can not be ideal, as demonstrated by two non-zero metrics, probability of misdetection and the probability of false alarm. In this paper, we focus on the interaction between spectrum sensing and spectrum sharing. In particular, we will study the optimization of cooperative spectrum sensing for achieving maximum spectrum utilization in cognitive radio networks. A new percentage rule is proposed for the spectrum sensing cooperation, which is more generic than quantity-based rules and is applicable in both sparse and dense sensing scenarios. An analytical model is presented to analyze the spectrum sharing performance. Numerical examples are presented to show the optimal percentage of cooperating sensors in achieving maximum utilization, which simultaneously achieve minimum blocking probabilities. Results are also shown to explore the impact of key system parameters on the performance metrics.
{"title":"Optimal sensing cooperation for spectrum sharing in cognitive radio networks","authors":"Yan Zhang, J. Xiang, Qin Xin, G. Oien","doi":"10.1109/EW.2009.5357760","DOIUrl":"https://doi.org/10.1109/EW.2009.5357760","url":null,"abstract":"Cognitive radio is a highly promising technology to efficiently solve the spectrum scarcity challenge and harmonize the networks heterogeneity. Through component spectrum sharing, secondary users (SUs) are able to opportunistically access licensed spectrum shared with the primary system. In the literature, spectrum sharing is normally investigated on the basis of the assumption that the spectrum sensing is perfect. However, in reality, the spectrum sensing can not be ideal, as demonstrated by two non-zero metrics, probability of misdetection and the probability of false alarm. In this paper, we focus on the interaction between spectrum sensing and spectrum sharing. In particular, we will study the optimization of cooperative spectrum sensing for achieving maximum spectrum utilization in cognitive radio networks. A new percentage rule is proposed for the spectrum sensing cooperation, which is more generic than quantity-based rules and is applicable in both sparse and dense sensing scenarios. An analytical model is presented to analyze the spectrum sharing performance. Numerical examples are presented to show the optimal percentage of cooperating sensors in achieving maximum utilization, which simultaneously achieve minimum blocking probabilities. Results are also shown to explore the impact of key system parameters on the performance metrics.","PeriodicalId":412079,"journal":{"name":"2009 European Wireless Conference","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131242299","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 work, a new closed form physical channel fading model, which we term m-n distribution, is introduced. The m-n distribution includes many distributions known in literature as special cases such as Rayleigh, Weibull, Nakagami-m, generalized gamma distributions, etc and their reciprocal distributions. Its statistical properties such as Laplace, Mellin moment generating functions and fractional moments are obtained. In addition, symbol error rate performance of M-ary modulations is derived and the results are given for binary differential phase shift keying.
{"title":"The m-n distribution - A new closed-form physical channel fading model and performance of M-ary modulations","authors":"F. Yilmaz, O. Kucur","doi":"10.1109/EW.2009.5357970","DOIUrl":"https://doi.org/10.1109/EW.2009.5357970","url":null,"abstract":"In this work, a new closed form physical channel fading model, which we term m-n distribution, is introduced. The m-n distribution includes many distributions known in literature as special cases such as Rayleigh, Weibull, Nakagami-m, generalized gamma distributions, etc and their reciprocal distributions. Its statistical properties such as Laplace, Mellin moment generating functions and fractional moments are obtained. In addition, symbol error rate performance of M-ary modulations is derived and the results are given for binary differential phase shift keying.","PeriodicalId":412079,"journal":{"name":"2009 European Wireless Conference","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127670576","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 many applications in wireless sensor network source nodes generate and send periodic traffic to the sink through a number of forwarder nodes. In such a multihop network forwarders have forwarding duties but should, on the other hand, to spend as much time as possible in an energy-saving deep-sleep mode. In this work we explore decentralized approach to organize the wake-up process of the forwarders with the aim to let them wakeup at “just the right time” to catch an incoming packet, forward it and go quickly back to sleep mode. A key assumption for this work is that the forwarders do not know the traffic period beforehand, but they have to estimate the period and maintain their estimate over time. A key difficulty is that the period estimation and the scheduling of wakeup times will have to deal with jitter in the packet inter-arrival times. If a packet arrives before the forwarder wakes up, it is lost. This opens up a tradeoff between loss rates and the sleeping activities of the forwarder: when the forwarder wakes up “early”, the packet loss rate will be low but the forwarder spends more energy, and vice versa. The main contributions of this report are the following ones: (a) we design and implement local estimators for traffic period and jitter; (b) we design and implement a scheduling scheme by which a forwarder locally decides when to sleep and when to wakeup; and (c) we adjoin mechanisms to this scheme that allow to update the period and jitter estimates and to react to changes in the locally observed loss rate. We use measurements and simulation to evaluate our proposed algorithms.
{"title":"Distributed wakeup scheduling scheme for supporting periodic traffic in wsns","authors":"Osama Khader, A. Willig, A. Wolisz","doi":"10.1109/EW.2009.5357978","DOIUrl":"https://doi.org/10.1109/EW.2009.5357978","url":null,"abstract":"In many applications in wireless sensor network source nodes generate and send periodic traffic to the sink through a number of forwarder nodes. In such a multihop network forwarders have forwarding duties but should, on the other hand, to spend as much time as possible in an energy-saving deep-sleep mode. In this work we explore decentralized approach to organize the wake-up process of the forwarders with the aim to let them wakeup at “just the right time” to catch an incoming packet, forward it and go quickly back to sleep mode. A key assumption for this work is that the forwarders do not know the traffic period beforehand, but they have to estimate the period and maintain their estimate over time. A key difficulty is that the period estimation and the scheduling of wakeup times will have to deal with jitter in the packet inter-arrival times. If a packet arrives before the forwarder wakes up, it is lost. This opens up a tradeoff between loss rates and the sleeping activities of the forwarder: when the forwarder wakes up “early”, the packet loss rate will be low but the forwarder spends more energy, and vice versa. The main contributions of this report are the following ones: (a) we design and implement local estimators for traffic period and jitter; (b) we design and implement a scheduling scheme by which a forwarder locally decides when to sleep and when to wakeup; and (c) we adjoin mechanisms to this scheme that allow to update the period and jitter estimates and to react to changes in the locally observed loss rate. We use measurements and simulation to evaluate our proposed algorithms.","PeriodicalId":412079,"journal":{"name":"2009 European Wireless Conference","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125584827","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}
Fundamental limitations in link budgets for wireless indoor networks are considered for millimeter and THz frequencies. Single small antennas at those frequencies are a bottle neck due to the small absorption areas and the ensuing path loss. Although different for LOS links and links in diffuse surroundings, there are no theoretical limitations, if complexity is ignored. Complexity and power consumption may be reduced by using analog solutions where possible, and in the paper we focus on phase conjugation methods, specifically in retrodirective arrays. Considering power solutions only, mimicking optical networks, we call attention to an array of rectennas.
{"title":"Overview of antenna problems and solutions for multi-Gb/s links","authors":"J. Andersen, G. Pedersen","doi":"10.1109/EW.2009.5357759","DOIUrl":"https://doi.org/10.1109/EW.2009.5357759","url":null,"abstract":"Fundamental limitations in link budgets for wireless indoor networks are considered for millimeter and THz frequencies. Single small antennas at those frequencies are a bottle neck due to the small absorption areas and the ensuing path loss. Although different for LOS links and links in diffuse surroundings, there are no theoretical limitations, if complexity is ignored. Complexity and power consumption may be reduced by using analog solutions where possible, and in the paper we focus on phase conjugation methods, specifically in retrodirective arrays. Considering power solutions only, mimicking optical networks, we call attention to an array of rectennas.","PeriodicalId":412079,"journal":{"name":"2009 European Wireless Conference","volume":" 10","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132124523","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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