Pub Date : 2008-12-30DOI: 10.1109/ISWCS.2008.4726006
Johannes Georg Klotz, C. Huppert, M. Bossert
In this paper a heuristic resource allocation algorithm for sum rate maximization is presented. We consider an orthogonal frequency division multiplexing channel with multiple antennas at the base station as well as at the mobile stations. Our algorithm uses eigen-beamforming and dirty paper coding. The user interference is estimated and the eigenvalues of the affected beams are updated. Our algorithm is compared to the optimal but more complex solution. It is shown that the performance of the suggested algorithm is very close to the optimum.
{"title":"Heuristic resource allocation for sum rate optimization in MIMO-OFDM systems using eigenvalue updates","authors":"Johannes Georg Klotz, C. Huppert, M. Bossert","doi":"10.1109/ISWCS.2008.4726006","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726006","url":null,"abstract":"In this paper a heuristic resource allocation algorithm for sum rate maximization is presented. We consider an orthogonal frequency division multiplexing channel with multiple antennas at the base station as well as at the mobile stations. Our algorithm uses eigen-beamforming and dirty paper coding. The user interference is estimated and the eigenvalues of the affected beams are updated. Our algorithm is compared to the optimal but more complex solution. It is shown that the performance of the suggested algorithm is very close to the optimum.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121116497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-12-30DOI: 10.1109/ISWCS.2008.4726045
Hussein Hijazi, L. Ros
The on-line Bayesian Cramer-Rao (BCRB) lower bound for the dynamic estimation of a time-varying multi-path Rayleigh channel in 4-QAM OFDM system is considered. In case of negligible channel variation within one symbol and delay related information, true BCRB for data-aided (DA) context, and two closed-form expressions for non-data aided (NDA) context are derived.
{"title":"On-line Bayesian Cramer-Rao Bounds for OFDM slowly varying rayleigh multi-path channel estimation","authors":"Hussein Hijazi, L. Ros","doi":"10.1109/ISWCS.2008.4726045","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726045","url":null,"abstract":"The on-line Bayesian Cramer-Rao (BCRB) lower bound for the dynamic estimation of a time-varying multi-path Rayleigh channel in 4-QAM OFDM system is considered. In case of negligible channel variation within one symbol and delay related information, true BCRB for data-aided (DA) context, and two closed-form expressions for non-data aided (NDA) context are derived.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123741137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-12-30DOI: 10.1109/ISWCS.2008.4726135
C. Both, Eliane Gobetti de Camargo, Rafael Kunst
The increasing development of mobile applications has changed the traditional demands of computer networks, which must now provide ubiquitous broadband wireless communication. In this context, IEEE 802.16 standardizes the physical and medium access control layers of the technology, aiming to allow network access in both nomadic and mobile scenarios. In this work we analyze the impact caused by overhead on the bandwidth allocation mechanism of WiMAX networks. Our main focus is to evaluate the number of SSs that can be served, and the influence of adaptive modulation and coding configuration. Finally, we discuss the importance of considering physical impairments in the process of designing a broadband wireless access network.
{"title":"Analysis of WiMAX bandwidth allocation mechanism considering physical conditions","authors":"C. Both, Eliane Gobetti de Camargo, Rafael Kunst","doi":"10.1109/ISWCS.2008.4726135","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726135","url":null,"abstract":"The increasing development of mobile applications has changed the traditional demands of computer networks, which must now provide ubiquitous broadband wireless communication. In this context, IEEE 802.16 standardizes the physical and medium access control layers of the technology, aiming to allow network access in both nomadic and mobile scenarios. In this work we analyze the impact caused by overhead on the bandwidth allocation mechanism of WiMAX networks. Our main focus is to evaluate the number of SSs that can be served, and the influence of adaptive modulation and coding configuration. Finally, we discuss the importance of considering physical impairments in the process of designing a broadband wireless access network.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122588175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-12-30DOI: 10.1109/ISWCS.2008.4726107
H. Luecken, T. Zasowski, A. Wittneben
Ultra-wide band (UWB) communication shows great potential for low-power communication for wireless sensor or body area network (BAN) applications. In particular, noncoherent receivers can be implemented with very low complexity. However, impulse radio and low duty cycle signaling involve stringent requirements on timing recovery. Standard synchronization algorithms might not be applicable due to constraints on memory capacity, clock accuracy and the sampling frequency of the receiver. Therefore, we present a scheme for burst detection and joint frame and symbol synchronization where both transmitter and receiver respect the low-duty cycle requirements. Furthermore, a subsampling analog-to-digital converter with a free running clock is assumed to meet low-power constraints. Burst detection is based on correlation with a known synchronization sequence. For symbol synchronization digital reconstruction of the symbol timing is applied, based on an FIR interpolation filter. Finally, it can be seen from performance results with real measured BAN channels that the presented synchronization algorithm is very well suited for the use in such applications.
{"title":"Synchronization scheme for low duty cycle UWB impulse radio receiver","authors":"H. Luecken, T. Zasowski, A. Wittneben","doi":"10.1109/ISWCS.2008.4726107","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726107","url":null,"abstract":"Ultra-wide band (UWB) communication shows great potential for low-power communication for wireless sensor or body area network (BAN) applications. In particular, noncoherent receivers can be implemented with very low complexity. However, impulse radio and low duty cycle signaling involve stringent requirements on timing recovery. Standard synchronization algorithms might not be applicable due to constraints on memory capacity, clock accuracy and the sampling frequency of the receiver. Therefore, we present a scheme for burst detection and joint frame and symbol synchronization where both transmitter and receiver respect the low-duty cycle requirements. Furthermore, a subsampling analog-to-digital converter with a free running clock is assumed to meet low-power constraints. Burst detection is based on correlation with a known synchronization sequence. For symbol synchronization digital reconstruction of the symbol timing is applied, based on an FIR interpolation filter. Finally, it can be seen from performance results with real measured BAN channels that the presented synchronization algorithm is very well suited for the use in such applications.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117018613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-12-30DOI: 10.1109/ISWCS.2008.4726018
Rodolfo Oliveira, Luís Bernardo, Paulo Pinto
This work presents a novel approach to select a packet from a set of packets that are waiting to be transmitted to different destinations. This approach aims to achieve proportional throughput for each different destination, taking the channel quality and prior successful transmissions into account.
{"title":"Achieving proportional fair throughput in multi-rate random access wireless networks","authors":"Rodolfo Oliveira, Luís Bernardo, Paulo Pinto","doi":"10.1109/ISWCS.2008.4726018","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726018","url":null,"abstract":"This work presents a novel approach to select a packet from a set of packets that are waiting to be transmitted to different destinations. This approach aims to achieve proportional throughput for each different destination, taking the channel quality and prior successful transmissions into account.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129722225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-12-30DOI: 10.1109/ISWCS.2008.4726042
G. Egeland, P. Engelstad
When planning the structure of a backhaul mesh network for public access, it is common to introduce redundant nodes in the mesh network. These are called redundant, because they do not increase the network capacity under normal operation, due to the shortest-path metric of the routing protocol. Instead, their sole purpose is to increase the network reliability by providing failover links when a link in the shortest-path fails. This paper shows how to estimate the additional network reliability that results from introducing a redundant node. The best location of a redundant node, i.e. where to locate the node in order to maximise the additional network reliability, can also be found.
{"title":"The reliability and availability of wireless backhaul mesh networks","authors":"G. Egeland, P. Engelstad","doi":"10.1109/ISWCS.2008.4726042","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726042","url":null,"abstract":"When planning the structure of a backhaul mesh network for public access, it is common to introduce redundant nodes in the mesh network. These are called redundant, because they do not increase the network capacity under normal operation, due to the shortest-path metric of the routing protocol. Instead, their sole purpose is to increase the network reliability by providing failover links when a link in the shortest-path fails. This paper shows how to estimate the additional network reliability that results from introducing a redundant node. The best location of a redundant node, i.e. where to locate the node in order to maximise the additional network reliability, can also be found.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128435968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-12-30DOI: 10.1109/ISWCS.2008.4726143
Jiwon Park, S. Moh, I. Chung
This paper proposes a multipath routing protocol called cross-layered multipath AODV (CM-AODV), which selects multiple routes on demand based on the signal-to-interference plus noise ratio (SINR) measured at the physical layer. Note that AODV (ad hoc on-demand distance vector) is one of the most popular routing protocols for mobile ad hoc networks. Each time a route request (RREQ) message is forwarded hop by hop, each forwarding node updates the route quality which is defined as the minimum SINR of serialized links in a route and contained in the RREQ header. Compared to the conventional multipath version of AODV protocol (which is called AOMDV), CM-AODV assigns the construction of multiple paths to the destination node and makes it algorithmically simple, resulting in the improved performance of packet delivery and the less overhead incurred at intermediate nodes. Our performance study shows that CMAODV significantly outperforms AOMDV in terms of packet delivery ratio and average end-to-end delay, but results in up to 45 percent less routing overhead.
{"title":"A multipath AODV routing protocol in mobile ad hoc networks with SINR-based route selection","authors":"Jiwon Park, S. Moh, I. Chung","doi":"10.1109/ISWCS.2008.4726143","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726143","url":null,"abstract":"This paper proposes a multipath routing protocol called cross-layered multipath AODV (CM-AODV), which selects multiple routes on demand based on the signal-to-interference plus noise ratio (SINR) measured at the physical layer. Note that AODV (ad hoc on-demand distance vector) is one of the most popular routing protocols for mobile ad hoc networks. Each time a route request (RREQ) message is forwarded hop by hop, each forwarding node updates the route quality which is defined as the minimum SINR of serialized links in a route and contained in the RREQ header. Compared to the conventional multipath version of AODV protocol (which is called AOMDV), CM-AODV assigns the construction of multiple paths to the destination node and makes it algorithmically simple, resulting in the improved performance of packet delivery and the less overhead incurred at intermediate nodes. Our performance study shows that CMAODV significantly outperforms AOMDV in terms of packet delivery ratio and average end-to-end delay, but results in up to 45 percent less routing overhead.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124781222","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-12-30DOI: 10.1109/ISWCS.2008.4726088
Rodolfo Oliveira, Luís Bernardo, Paulo Pinto, I. Koutsopoulos
This work presents a simple method to estimate IEEE 802.11 distributed coordination function (DCF) service time. This is the total amount of time needed to transmit a given frame, which is defined as the duration from the instant a node starts the transmission, until the instant when the transmission task effectively finishes. We are motivated by the fact that IEEE 802.11 DCF does not provide time-bounded transmissions. Thus, it is important to have an estimate of the service time because most of the times a physical connection between two nodes exists, but it is misinterpreted by the upper layers due to the long waiting time to obtain a response from a node. In this case, the estimate of the service time can be used by the upper layer protocols to solve some problems caused by IEEE 802.11, such as routing failures due to timeouts or even TCP connection failures. The congestion time in IEEE 802.11 before each (re)transmission, which is due to the random access mechanism employed in the CSMA/CA, makes it more difficult for service time to be estimated. Our approach needs only local information available at each node and considers a realistic scenario where the traffic sources may have different data generation rates (heterogeneous traffic). The applied methodology is described and we present simulation results to assess its accuracy.
{"title":"On service time estimation in 802.11 WLANs with heterogeneous traffic sources","authors":"Rodolfo Oliveira, Luís Bernardo, Paulo Pinto, I. Koutsopoulos","doi":"10.1109/ISWCS.2008.4726088","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726088","url":null,"abstract":"This work presents a simple method to estimate IEEE 802.11 distributed coordination function (DCF) service time. This is the total amount of time needed to transmit a given frame, which is defined as the duration from the instant a node starts the transmission, until the instant when the transmission task effectively finishes. We are motivated by the fact that IEEE 802.11 DCF does not provide time-bounded transmissions. Thus, it is important to have an estimate of the service time because most of the times a physical connection between two nodes exists, but it is misinterpreted by the upper layers due to the long waiting time to obtain a response from a node. In this case, the estimate of the service time can be used by the upper layer protocols to solve some problems caused by IEEE 802.11, such as routing failures due to timeouts or even TCP connection failures. The congestion time in IEEE 802.11 before each (re)transmission, which is due to the random access mechanism employed in the CSMA/CA, makes it more difficult for service time to be estimated. Our approach needs only local information available at each node and considers a realistic scenario where the traffic sources may have different data generation rates (heterogeneous traffic). The applied methodology is described and we present simulation results to assess its accuracy.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129199658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-12-30DOI: 10.1109/ISWCS.2008.4726109
Amir Minayi Jalil, H. Amindavar, J. Cances
In this paper we propose and analyze an approach to improve the convergence rate of blind equalizers for nonstationary signals using wavelet transformation. Transform domain adaptive filters are famous for their improved convergence rate over the conventional least mean square (LMS) algorithm and also facilities for noise reduction without giving much increase in the computational cost; on the other hand, blind equalizers suffer from the poor convergence rate. We propose a wavelet domain (WD) equalization method to improve the convergence rate and discuss its advantage over other transform domain adaptive filters. This discussion is performed on two important categories of blind equalization; the stochastic gradient descent approach and cyclostationary based approach that is used in the case of blind fractionally spaced equalization (FSE) of channels.
{"title":"Blind equalization in wavelet domain","authors":"Amir Minayi Jalil, H. Amindavar, J. Cances","doi":"10.1109/ISWCS.2008.4726109","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726109","url":null,"abstract":"In this paper we propose and analyze an approach to improve the convergence rate of blind equalizers for nonstationary signals using wavelet transformation. Transform domain adaptive filters are famous for their improved convergence rate over the conventional least mean square (LMS) algorithm and also facilities for noise reduction without giving much increase in the computational cost; on the other hand, blind equalizers suffer from the poor convergence rate. We propose a wavelet domain (WD) equalization method to improve the convergence rate and discuss its advantage over other transform domain adaptive filters. This discussion is performed on two important categories of blind equalization; the stochastic gradient descent approach and cyclostationary based approach that is used in the case of blind fractionally spaced equalization (FSE) of channels.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124200699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-12-30DOI: 10.1109/ISWCS.2008.4726022
Yong Fan, Petteri Lundén, M. Kuusela, M. Valkama
The emerging evolved UTRA radio system is generally envisioned to support a large number of VoIP users. This is basically enabled by efficient frequency domain packet scheduling together with accurate channel quality feedback information. In this paper, we investigate the performance of VoIP on EUTRA downlink assuming that only limited channel quality feedback information is available. System level simulation results show that by increasing the CQI measurement frequency window to 2 PRBs and using average best-4 CQI reporting scheme, the achieved VoIP capacities for no packet bundling case and packet bundling case are 201 users/sector and 353 users/sector respectively with 6 control channels. Compared with the ideal CQI measurement frequency window of 1 PRB and full CQI reporting scheme, the relative loss of VoIP capacity is negligible for no bundling case and about 9% for bundling case. On the other hand, the reported CQI wordsize in uplink can be significantly decreased by 84% from 126 bits to 20 bits.
{"title":"Performance of VoIP on EUTRA downlink with limited channel feedback","authors":"Yong Fan, Petteri Lundén, M. Kuusela, M. Valkama","doi":"10.1109/ISWCS.2008.4726022","DOIUrl":"https://doi.org/10.1109/ISWCS.2008.4726022","url":null,"abstract":"The emerging evolved UTRA radio system is generally envisioned to support a large number of VoIP users. This is basically enabled by efficient frequency domain packet scheduling together with accurate channel quality feedback information. In this paper, we investigate the performance of VoIP on EUTRA downlink assuming that only limited channel quality feedback information is available. System level simulation results show that by increasing the CQI measurement frequency window to 2 PRBs and using average best-4 CQI reporting scheme, the achieved VoIP capacities for no packet bundling case and packet bundling case are 201 users/sector and 353 users/sector respectively with 6 control channels. Compared with the ideal CQI measurement frequency window of 1 PRB and full CQI reporting scheme, the relative loss of VoIP capacity is negligible for no bundling case and about 9% for bundling case. On the other hand, the reported CQI wordsize in uplink can be significantly decreased by 84% from 126 bits to 20 bits.","PeriodicalId":158650,"journal":{"name":"2008 IEEE International Symposium on Wireless Communication Systems","volume":"490 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2008-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116193567","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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