Pub Date : 2009-12-01DOI: 10.1109/VETECF.2009.5378863
Jeng-Ji Huang, Yeh-Horng Chen, Che-Yu Chang
Variable bit rate (VBR) traffic may have a wide range of packet sizes and generation intervals. While the former can be handled in the IEEE 802.11e uplink scheduling, e.g., by adapting transmission opportunity (TXOP) durations according to backlogged traffic reports, the latter may cause packet losses if service intervals of the scheduling do not fit the generation intervals. In this paper, a scheduler that employs adaptive maximum service interval (MSI) is proposed to fix this problem, while attempting to minimize scheduling overheads.
{"title":"An MSI-Based Scheduler for IEEE 802.11e HCCA","authors":"Jeng-Ji Huang, Yeh-Horng Chen, Che-Yu Chang","doi":"10.1109/VETECF.2009.5378863","DOIUrl":"https://doi.org/10.1109/VETECF.2009.5378863","url":null,"abstract":"Variable bit rate (VBR) traffic may have a wide range of packet sizes and generation intervals. While the former can be handled in the IEEE 802.11e uplink scheduling, e.g., by adapting transmission opportunity (TXOP) durations according to backlogged traffic reports, the latter may cause packet losses if service intervals of the scheduling do not fit the generation intervals. In this paper, a scheduler that employs adaptive maximum service interval (MSI) is proposed to fix this problem, while attempting to minimize scheduling overheads.","PeriodicalId":316671,"journal":{"name":"2009 IEEE 70th Vehicular Technology Conference Fall","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131376185","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 : 2009-12-01DOI: 10.1109/VETECF.2009.5378988
H. Higuchi, Y. Sanada
Through fractional sampling (FS) it is possible to separate multipath components and achieve path diversity. However, if no path component whose delay corresponds to the sampling point, FS cannot obtain diversity gain. In this paper, a novel scheme to improve the performance with FS over a sparse multipath channel is proposed. The proposed scheme uses multiple transmit antennas and sends multiple signals with fractional delays. The performance improvement with the proposed scheme is confirmed through computer simulation. It is shown that the proposed scheme increases the capacity of a MIMO-OFDM system by a factor of 1.5 to 2 and improves the BER performance on the sparse multipath channels.
{"title":"Path Diversity with Fractional Delay Transmission for Fractional Sampling-MIMO-OFDM System","authors":"H. Higuchi, Y. Sanada","doi":"10.1109/VETECF.2009.5378988","DOIUrl":"https://doi.org/10.1109/VETECF.2009.5378988","url":null,"abstract":"Through fractional sampling (FS) it is possible to separate multipath components and achieve path diversity. However, if no path component whose delay corresponds to the sampling point, FS cannot obtain diversity gain. In this paper, a novel scheme to improve the performance with FS over a sparse multipath channel is proposed. The proposed scheme uses multiple transmit antennas and sends multiple signals with fractional delays. The performance improvement with the proposed scheme is confirmed through computer simulation. It is shown that the proposed scheme increases the capacity of a MIMO-OFDM system by a factor of 1.5 to 2 and improves the BER performance on the sparse multipath channels.","PeriodicalId":316671,"journal":{"name":"2009 IEEE 70th Vehicular Technology Conference Fall","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121634681","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 : 2009-12-01DOI: 10.1109/VETECF.2009.5379028
C. Comaniciu, N. Mandayam, H. Poor
In this paper, an auctioning strategy is proposed for cellular networks that ensures net energy savings. The pricing scheme, in conjunction with the two dimensional bid structure, incentivizes cooperation at the terminal nodes for better interference management at receivers and for cooperative relaying. It is shown that, for the proposed auctioning strategy, network operators are guaranteed revenue gains, mobile nodes' dominant strategy is to bid their true valuation of their energy resources, and overall effective energy gains occur under the assumption of a reserve price for bidding.
{"title":"Radio Resource Management for Green Wireless Networks","authors":"C. Comaniciu, N. Mandayam, H. Poor","doi":"10.1109/VETECF.2009.5379028","DOIUrl":"https://doi.org/10.1109/VETECF.2009.5379028","url":null,"abstract":"In this paper, an auctioning strategy is proposed for cellular networks that ensures net energy savings. The pricing scheme, in conjunction with the two dimensional bid structure, incentivizes cooperation at the terminal nodes for better interference management at receivers and for cooperative relaying. It is shown that, for the proposed auctioning strategy, network operators are guaranteed revenue gains, mobile nodes' dominant strategy is to bid their true valuation of their energy resources, and overall effective energy gains occur under the assumption of a reserve price for bidding.","PeriodicalId":316671,"journal":{"name":"2009 IEEE 70th Vehicular Technology Conference Fall","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126253595","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 : 2009-12-01DOI: 10.1109/VETECF.2009.5378747
M. Inamori, Takashi Kawai, Tatsuya Kobayashi, H. Nishimura, Y. Sanada
In this paper, a metric weighting scheme on a coded fractional sampling orthogonal frequency division multiplexing (FS OFDM) system is investigated. FS achieves path diversity with a single antenna through oversampling and subcarrier-based maximal ratio combining (MRC). Though the oversampling increases diversity order, correlation among noise components may deteriorate bit error rate (BER) performance. To clarify the relationship between the impulse response of the pulse shaping filter and the BER performance, five different pulse shaping filters are evaluated in the coded FS OFDM system. Numerical results obtained through computer simulation show that the metric weighting based on the Frobenius norm improves BER performance of the coded FS OFDM system.
{"title":"Metric Weighting Scheme on a Coded Fractional Sampling OFDM System","authors":"M. Inamori, Takashi Kawai, Tatsuya Kobayashi, H. Nishimura, Y. Sanada","doi":"10.1109/VETECF.2009.5378747","DOIUrl":"https://doi.org/10.1109/VETECF.2009.5378747","url":null,"abstract":"In this paper, a metric weighting scheme on a coded fractional sampling orthogonal frequency division multiplexing (FS OFDM) system is investigated. FS achieves path diversity with a single antenna through oversampling and subcarrier-based maximal ratio combining (MRC). Though the oversampling increases diversity order, correlation among noise components may deteriorate bit error rate (BER) performance. To clarify the relationship between the impulse response of the pulse shaping filter and the BER performance, five different pulse shaping filters are evaluated in the coded FS OFDM system. Numerical results obtained through computer simulation show that the metric weighting based on the Frobenius norm improves BER performance of the coded FS OFDM system.","PeriodicalId":316671,"journal":{"name":"2009 IEEE 70th Vehicular Technology Conference Fall","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123733770","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 : 2009-12-01DOI: 10.1109/VETECF.2009.5378855
M. Iki, M. Tanahashi, H. Ochiai
The authors have recently proposed a novel trellis shaping (TS) approach for peak power reduction of single- carrier signals. In this paper, we propose the use of M algorithm as well as sequential decoding with stack algorithm for the purpose of complexity reduction. Our comparative studies with the Viterbi algorithm (VA) show that the TS with these low- complexity algorithms can still offer substantial peak power reduction capabilities that are comparable to the VA. I. INTRODUCTION In many wireless and mobile communication systems, band- width and power efficiencies are the two most important factors. In order to enhance bandwidth efficiency, the use of linear modulations such as pulse-shaped PSK and QAM is necessary, and even higher efficiency can be achieved by using a pulse shaping filter with a narrow roll-off band or by combining QAM with orthogonal frequency-division multiplexing (OFDM). The OFDM signals, however, tend to
{"title":"Peak Power Reduction of Single-Carrier Signals Using Trellis Shaping with M and Stack Algorithms","authors":"M. Iki, M. Tanahashi, H. Ochiai","doi":"10.1109/VETECF.2009.5378855","DOIUrl":"https://doi.org/10.1109/VETECF.2009.5378855","url":null,"abstract":"The authors have recently proposed a novel trellis shaping (TS) approach for peak power reduction of single- carrier signals. In this paper, we propose the use of M algorithm as well as sequential decoding with stack algorithm for the purpose of complexity reduction. Our comparative studies with the Viterbi algorithm (VA) show that the TS with these low- complexity algorithms can still offer substantial peak power reduction capabilities that are comparable to the VA. I. INTRODUCTION In many wireless and mobile communication systems, band- width and power efficiencies are the two most important factors. In order to enhance bandwidth efficiency, the use of linear modulations such as pulse-shaped PSK and QAM is necessary, and even higher efficiency can be achieved by using a pulse shaping filter with a narrow roll-off band or by combining QAM with orthogonal frequency-division multiplexing (OFDM). The OFDM signals, however, tend to","PeriodicalId":316671,"journal":{"name":"2009 IEEE 70th Vehicular Technology Conference Fall","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123816676","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 : 2009-09-26DOI: 10.1109/VETECF.2009.5379056
M. Afgani, H. Haas
An information theoretic approach to detecting unusual events in radio signals is presented. Anomalies are detected through a measure of the events' information content. Clustering is utilised to reduce false-positives while allowing a lower discrimination threshold to be used for improved anomaly detection. Experiments with a real wireless local area network test signal shows that it is possible to achieve 100% detection rates while maintaining very low false discovery rate of 1%.
{"title":"Information Content Analysis and Clustering for Signal Anomaly Detection","authors":"M. Afgani, H. Haas","doi":"10.1109/VETECF.2009.5379056","DOIUrl":"https://doi.org/10.1109/VETECF.2009.5379056","url":null,"abstract":"An information theoretic approach to detecting unusual events in radio signals is presented. Anomalies are detected through a measure of the events' information content. Clustering is utilised to reduce false-positives while allowing a lower discrimination threshold to be used for improved anomaly detection. Experiments with a real wireless local area network test signal shows that it is possible to achieve 100% detection rates while maintaining very low false discovery rate of 1%.","PeriodicalId":316671,"journal":{"name":"2009 IEEE 70th Vehicular Technology Conference Fall","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115128463","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 : 2009-09-24DOI: 10.1109/VETECF.2009.5379025
S. Videv, G. Auer, H. Haas
This paper presents the integration of power control and the busy burst (BB) technique for a TDD OFDMA (time division duplex orthogonal frequency division multiple access) system in an urban Manhattan grid type of environment. The objective is to combine power control with the BB protocol to develop a power efficient interference-avoidance technique. Previous work has demonstrated that the time multiplexed BB can be used to achieve interference aware medium access. It has also been demonstrated in other work that the implicit feedback mechanism of BB can be exploited to achieve Pareto optimal SINR-based (signal-to-interference-plus-noise ratio) power con- trol. However, these two applications are not compatible - the former depends on fixed signal powers across users, while the latter makes use of variable signal power to achieve optimum power control. This paper proposes an amendment to the BB technique that allows the two approaches to co-exist by exploiting the frequency granularity of OFDMA to frequency multiplex two BBs - one with variable and one with fixed power. The resulting control protocol exhibits an eight-fold reduction at the 50th percentile of used energy with no additional overhead as compared to the single BB protocol.
{"title":"Power Control and Interference Awareness Using Busy Bursts","authors":"S. Videv, G. Auer, H. Haas","doi":"10.1109/VETECF.2009.5379025","DOIUrl":"https://doi.org/10.1109/VETECF.2009.5379025","url":null,"abstract":"This paper presents the integration of power control and the busy burst (BB) technique for a TDD OFDMA (time division duplex orthogonal frequency division multiple access) system in an urban Manhattan grid type of environment. The objective is to combine power control with the BB protocol to develop a power efficient interference-avoidance technique. Previous work has demonstrated that the time multiplexed BB can be used to achieve interference aware medium access. It has also been demonstrated in other work that the implicit feedback mechanism of BB can be exploited to achieve Pareto optimal SINR-based (signal-to-interference-plus-noise ratio) power con- trol. However, these two applications are not compatible - the former depends on fixed signal powers across users, while the latter makes use of variable signal power to achieve optimum power control. This paper proposes an amendment to the BB technique that allows the two approaches to co-exist by exploiting the frequency granularity of OFDMA to frequency multiplex two BBs - one with variable and one with fixed power. The resulting control protocol exhibits an eight-fold reduction at the 50th percentile of used energy with no additional overhead as compared to the single BB protocol.","PeriodicalId":316671,"journal":{"name":"2009 IEEE 70th Vehicular Technology Conference Fall","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132584158","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 : 2009-09-23DOI: 10.1109/VETECF.2009.5379032
Rui Wang, J. Thompson, H. Haas
In this paper, we discuss resource management in modern wireless communications with the objective of minimizing power consumption, and carry out an analysis of simultaneous transmission and orthogonal transmission schemes in an FDMA (Frequency Division Multiple Access) framework. Based on a two-link line model with path-loss only, the performance of these two schemes for network power minimization under the specified rate constraints is investigated. It is found that ST (Simultaneous Transmission) consumes less power than OT (Orthogonal Transmission) close to the base station, but much more power in the cell-edge area. This illustrates that the ST/OT selection criterion for sum power minimization is location- dependent. Further, numerical results suggest that the ST/OT selection margins are generally dominated by their network rate constraints rather than the rate proportions between the two links. New definitions of power-utility and fairness metrics are further proposed, following by the design of weighted resource allocation approaches based on efficiency-fairness tradeoffs. I. Introduction With the expansion of the global population and the preva- lence of wireless devices, interference among multiple active links is becoming a dominant problem, causing serious QoS degradation for future wireless communications (1). Although various interference mitigation techniques are designed to im- prove QoS, these methods generally require high-complexity transceiver devices. Meanwhile, wireless resources are often wasted during the mutually-interfered transmission processes. Taking these issues into consideration, modern communication industries have shifted their interests to looking for economical system-design strategies rather than simply improving QoS with more advanced radio techniques (2). 'Economical design' takes into account both the network operation requirements and the requirement to minimize en- ergy consumption for environmental reasons, which could be interpreted together with geographic demographics. In high- density city areas, huge energy consumption may reach system energy constraints, causing serious interference and excessive CO2 emissions (3) (4). The energy loss due to enabling and maintaining communications takes a great portion of the total energy consumption compared with the required RF (Radio Frequency) energy. Recently, the concept of 'green radio' is proposed, aiming at the 'economical and environmental design' of wireless communication systems (5). Regarding implementations, intelligent resource allocation and scheduling algorithms are needed under the definition of power-efficiency metrics. Compared with the throughput maximization problem which employs capacity as an effective measure, designing new power-efficient resource allocation strategies is still an open problem. In this paper, several power-efficiency metrics are suggested. One simple form is to minimize the sum power consumption in the network. In this paper
{"title":"A New Framework for Designing Power-Efficient Resource Allocation under Rate Constraints","authors":"Rui Wang, J. Thompson, H. Haas","doi":"10.1109/VETECF.2009.5379032","DOIUrl":"https://doi.org/10.1109/VETECF.2009.5379032","url":null,"abstract":"In this paper, we discuss resource management in modern wireless communications with the objective of minimizing power consumption, and carry out an analysis of simultaneous transmission and orthogonal transmission schemes in an FDMA (Frequency Division Multiple Access) framework. Based on a two-link line model with path-loss only, the performance of these two schemes for network power minimization under the specified rate constraints is investigated. It is found that ST (Simultaneous Transmission) consumes less power than OT (Orthogonal Transmission) close to the base station, but much more power in the cell-edge area. This illustrates that the ST/OT selection criterion for sum power minimization is location- dependent. Further, numerical results suggest that the ST/OT selection margins are generally dominated by their network rate constraints rather than the rate proportions between the two links. New definitions of power-utility and fairness metrics are further proposed, following by the design of weighted resource allocation approaches based on efficiency-fairness tradeoffs. I. Introduction With the expansion of the global population and the preva- lence of wireless devices, interference among multiple active links is becoming a dominant problem, causing serious QoS degradation for future wireless communications (1). Although various interference mitigation techniques are designed to im- prove QoS, these methods generally require high-complexity transceiver devices. Meanwhile, wireless resources are often wasted during the mutually-interfered transmission processes. Taking these issues into consideration, modern communication industries have shifted their interests to looking for economical system-design strategies rather than simply improving QoS with more advanced radio techniques (2). 'Economical design' takes into account both the network operation requirements and the requirement to minimize en- ergy consumption for environmental reasons, which could be interpreted together with geographic demographics. In high- density city areas, huge energy consumption may reach system energy constraints, causing serious interference and excessive CO2 emissions (3) (4). The energy loss due to enabling and maintaining communications takes a great portion of the total energy consumption compared with the required RF (Radio Frequency) energy. Recently, the concept of 'green radio' is proposed, aiming at the 'economical and environmental design' of wireless communication systems (5). Regarding implementations, intelligent resource allocation and scheduling algorithms are needed under the definition of power-efficiency metrics. Compared with the throughput maximization problem which employs capacity as an effective measure, designing new power-efficient resource allocation strategies is still an open problem. In this paper, several power-efficiency metrics are suggested. One simple form is to minimize the sum power consumption in the network. In this paper","PeriodicalId":316671,"journal":{"name":"2009 IEEE 70th Vehicular Technology Conference Fall","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129032738","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 : 2009-09-20DOI: 10.1109/VETECF.2009.5378760
Jiayi Zhang, Lie-liang Yang, L. Hanzo
This paper characterises two single-relay assisted single- carrier frequency-division multiple-access (SC-FDMA) amplify-and- forward (AF) based cooperative strategies employed for multiuser uplink transmissions over multipath fading channels. For the sake of exploiting the benefits of cooperative diversity, we investigate both single-dedicated- relaying (SDR) as well as single-shared-relaying (SSR), and propose a frequency-domain (FD) subband-based AF scheme combined with subband remapping, which is benchmarked against conventional time- domain (TD) AF in the context of both of the above-mentioned relaying topologies. Our simulation results show that cooperative diversity is beneficial for both SDR and SSR, both in the absence and in the presence of multipath diversity. More importantly, the proposed FD-AF scheme is capable of attaining a multiuser performance, which is better than that of the conventional single-user TD-AF protocol operating in a multipath environment, because of the subband-based AF and noise suppression capability of the relay. I. INTRODUCTION Wireless cooperative communications and relaying have attracted substantial research attention over the past decade as a benefit of their spatial diversity gain attained in a virtual multiple-input multiple-output (V-MIMO) scenario created by the distributed single- antenna terminals by sharing resources with their cooperative part- ners. This cooperation allows the system to mitigate the radio channel's fading by jointly exploiting the benefits of frequency- , time- and spatial-diversity. Furthermore, the cooperative strategy nal subcarrier mapping in order to support multiple users without con- tamination by MUI. Furthermore, our single-relay assisted SC-FDMA system allows user cooperation to achieve a diversity gain without imposing MUI by the cooperating sources and relays upon the UL- receiver at the basestation (BS). It is worth noting that SC-FDMA is capable of exploiting the benefits of multipath diversity for transmis- sion over broadband channels, while in orthogonal frequency-division multiplexing (OFDM) (12) each subcarrier experiences a single-path channel, hence no multipath diversity gain is achieved. It has been indicated in (13) that SC-FDMA attains a similar overall performance as orthogonal frequency division multiple access (OFDMA), but it is more suitable for uplink transmission due to its lower peak-to- average power ratio (PAPR), which is typically high in multicarrier systems (12). Additionally, the combination of based modulation with the discrete Fourier transform and inverse discrete Fourier transform (DFT/IDFT) SC-FDMA transmitter can be adaptively reconfigured in order to mitigate the effects of time-variant channels. The system is also available to cooperative communications. Hence, our novel contribution is that we achieve cooperative diversity by utilising a sophisticated SC-FDMA scheme, which exploits the benefits of AF based single-relay assisted user co
{"title":"Multi-User Performance of the Amplify-and-Forward Single-Relay Assisted SC-FDMA Uplink","authors":"Jiayi Zhang, Lie-liang Yang, L. Hanzo","doi":"10.1109/VETECF.2009.5378760","DOIUrl":"https://doi.org/10.1109/VETECF.2009.5378760","url":null,"abstract":"This paper characterises two single-relay assisted single- carrier frequency-division multiple-access (SC-FDMA) amplify-and- forward (AF) based cooperative strategies employed for multiuser uplink transmissions over multipath fading channels. For the sake of exploiting the benefits of cooperative diversity, we investigate both single-dedicated- relaying (SDR) as well as single-shared-relaying (SSR), and propose a frequency-domain (FD) subband-based AF scheme combined with subband remapping, which is benchmarked against conventional time- domain (TD) AF in the context of both of the above-mentioned relaying topologies. Our simulation results show that cooperative diversity is beneficial for both SDR and SSR, both in the absence and in the presence of multipath diversity. More importantly, the proposed FD-AF scheme is capable of attaining a multiuser performance, which is better than that of the conventional single-user TD-AF protocol operating in a multipath environment, because of the subband-based AF and noise suppression capability of the relay. I. INTRODUCTION Wireless cooperative communications and relaying have attracted substantial research attention over the past decade as a benefit of their spatial diversity gain attained in a virtual multiple-input multiple-output (V-MIMO) scenario created by the distributed single- antenna terminals by sharing resources with their cooperative part- ners. This cooperation allows the system to mitigate the radio channel's fading by jointly exploiting the benefits of frequency- , time- and spatial-diversity. Furthermore, the cooperative strategy nal subcarrier mapping in order to support multiple users without con- tamination by MUI. Furthermore, our single-relay assisted SC-FDMA system allows user cooperation to achieve a diversity gain without imposing MUI by the cooperating sources and relays upon the UL- receiver at the basestation (BS). It is worth noting that SC-FDMA is capable of exploiting the benefits of multipath diversity for transmis- sion over broadband channels, while in orthogonal frequency-division multiplexing (OFDM) (12) each subcarrier experiences a single-path channel, hence no multipath diversity gain is achieved. It has been indicated in (13) that SC-FDMA attains a similar overall performance as orthogonal frequency division multiple access (OFDMA), but it is more suitable for uplink transmission due to its lower peak-to- average power ratio (PAPR), which is typically high in multicarrier systems (12). Additionally, the combination of based modulation with the discrete Fourier transform and inverse discrete Fourier transform (DFT/IDFT) SC-FDMA transmitter can be adaptively reconfigured in order to mitigate the effects of time-variant channels. The system is also available to cooperative communications. Hence, our novel contribution is that we achieve cooperative diversity by utilising a sophisticated SC-FDMA scheme, which exploits the benefits of AF based single-relay assisted user co","PeriodicalId":316671,"journal":{"name":"2009 IEEE 70th Vehicular Technology Conference Fall","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2009-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125659658","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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