Pub Date : 2011-05-03DOI: 10.1109/MC-SS.2011.5910737
Fengning Xu, T. Fujii
In this paper, frequency sharing with OFDMA (orthogonal frequency division multiple access) is considered to be applied to road to vehicle communication (RVC) and inter-vehicle communication (IVC). However, it is difficult to accomplish perfect frequency and timing synchronization in the autonomous distributed system such as IVC. This will result in multiple access interference with the collapse of orthogonality among OFDMA subcarriers due to carrier frequency and timing offsets of IVC. This paper proposes a frequency sharing scheduling to suppress the interference to RVC by selecting subcarriers and controlling power properly during the period allocating the time slots and the subcarriers of OFDMA to multiple pairs of IVC and RVC, respectively. Furthermore, the proposed scheduling can give the appropriate priority to the short distance IVC pair from the frequencies unutilized by RVC.
{"title":"Frequency sharing scheduling with OFDMA for road to vehicle and inter-vehicle communications","authors":"Fengning Xu, T. Fujii","doi":"10.1109/MC-SS.2011.5910737","DOIUrl":"https://doi.org/10.1109/MC-SS.2011.5910737","url":null,"abstract":"In this paper, frequency sharing with OFDMA (orthogonal frequency division multiple access) is considered to be applied to road to vehicle communication (RVC) and inter-vehicle communication (IVC). However, it is difficult to accomplish perfect frequency and timing synchronization in the autonomous distributed system such as IVC. This will result in multiple access interference with the collapse of orthogonality among OFDMA subcarriers due to carrier frequency and timing offsets of IVC. This paper proposes a frequency sharing scheduling to suppress the interference to RVC by selecting subcarriers and controlling power properly during the period allocating the time slots and the subcarriers of OFDMA to multiple pairs of IVC and RVC, respectively. Furthermore, the proposed scheduling can give the appropriate priority to the short distance IVC pair from the frequencies unutilized by RVC.","PeriodicalId":251147,"journal":{"name":"2011 8th International Workshop on Multi-Carrier Systems & Solutions","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134475492","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 : 2011-05-03DOI: 10.1109/MC-SS.2011.5910701
Tetsuya Yamamoto, Kazuki Takeda, F. Adachi
For achieving very high-speed and high quality packet transmission, the joint use of multi-input multi-output (MIMO) spatial multiplexing and hybrid automatic repeat request (HARQ) is very effective. The HARQ throughput depends on the packet combining scheme. In this paper, we consider a single-carrier (SC) MIMO and propose a maximum likelihood block detection using recursive QR packet combing and M-algorithm called recursive QRM-MLBD. We will show, by computer simulation, the recursive QR packet combing provides a better throughput performance than the conventional bit-level log likelihood ratio (LLR) packet combining. We also compare the achievable throughput performance of proposed recursive QRM-MLBD to that of the frequency-domain detection based on the minimum mean square error criterion (MMSED).
{"title":"HARQ throughput enhancement using maximum likelihood block detection with recursive QR packet combining and M-algorithm for single-carrier MIMO","authors":"Tetsuya Yamamoto, Kazuki Takeda, F. Adachi","doi":"10.1109/MC-SS.2011.5910701","DOIUrl":"https://doi.org/10.1109/MC-SS.2011.5910701","url":null,"abstract":"For achieving very high-speed and high quality packet transmission, the joint use of multi-input multi-output (MIMO) spatial multiplexing and hybrid automatic repeat request (HARQ) is very effective. The HARQ throughput depends on the packet combining scheme. In this paper, we consider a single-carrier (SC) MIMO and propose a maximum likelihood block detection using recursive QR packet combing and M-algorithm called recursive QRM-MLBD. We will show, by computer simulation, the recursive QR packet combing provides a better throughput performance than the conventional bit-level log likelihood ratio (LLR) packet combining. We also compare the achievable throughput performance of proposed recursive QRM-MLBD to that of the frequency-domain detection based on the minimum mean square error criterion (MMSED).","PeriodicalId":251147,"journal":{"name":"2011 8th International Workshop on Multi-Carrier Systems & Solutions","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129050943","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 : 2011-05-03DOI: 10.1109/MC-SS.2011.5910733
C. Langlais, Salim Haddad, Y. Louét, N. Mazouz
By virtue of its simplicity, clipping appears to be one of the most attractive methods to mitigate Peak to Average Power Ratio (PAPR) in OFDM systems. After positioning clipping in a new classification of PAPR reduction methods, this article focuses on the performance of clipped OFDM at low signal to noise ratio, typical of capacity approaching forward error correcting coded systems. A lower bound on the BER performance of clipped coded OFDM is given and shown to be consistent with the genie aided performance of the iterative clipping noise cancellation receiver. Finally, numerical results on the BER performance of a clipped LDPC coded OFDM system are provided.1
{"title":"Clipping noise mitigation with capacity approaching FEC codes for PAPR reduction of OFDM signals","authors":"C. Langlais, Salim Haddad, Y. Louét, N. Mazouz","doi":"10.1109/MC-SS.2011.5910733","DOIUrl":"https://doi.org/10.1109/MC-SS.2011.5910733","url":null,"abstract":"By virtue of its simplicity, clipping appears to be one of the most attractive methods to mitigate Peak to Average Power Ratio (PAPR) in OFDM systems. After positioning clipping in a new classification of PAPR reduction methods, this article focuses on the performance of clipped OFDM at low signal to noise ratio, typical of capacity approaching forward error correcting coded systems. A lower bound on the BER performance of clipped coded OFDM is given and shown to be consistent with the genie aided performance of the iterative clipping noise cancellation receiver. Finally, numerical results on the BER performance of a clipped LDPC coded OFDM system are provided.1","PeriodicalId":251147,"journal":{"name":"2011 8th International Workshop on Multi-Carrier Systems & Solutions","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131348548","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 : 2011-05-03DOI: 10.1109/MC-SS.2011.5910728
Cheol Jeong, Il Kim
We study the multi-carrier decode-and-forward relay communication system, where an eavesdropper exists. The source power and relay power are optimized over all subcarriers to maximize the sum secrecy rate under a total system power constraint. From the power allocation result, an optimal transmission strategy is determined among no transmission, direct transmission, and relay transmission on each subcarrier. In numerical results, the performance of the optimal power allocation is evaluated and compared for various scenarios.
{"title":"Optimal power allocation for secure multi-carrier relay systems","authors":"Cheol Jeong, Il Kim","doi":"10.1109/MC-SS.2011.5910728","DOIUrl":"https://doi.org/10.1109/MC-SS.2011.5910728","url":null,"abstract":"We study the multi-carrier decode-and-forward relay communication system, where an eavesdropper exists. The source power and relay power are optimized over all subcarriers to maximize the sum secrecy rate under a total system power constraint. From the power allocation result, an optimal transmission strategy is determined among no transmission, direct transmission, and relay transmission on each subcarrier. In numerical results, the performance of the optimal power allocation is evaluated and compared for various scenarios.","PeriodicalId":251147,"journal":{"name":"2011 8th International Workshop on Multi-Carrier Systems & Solutions","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123350406","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 : 2011-05-03DOI: 10.1109/MC-SS.2011.5910725
Stephan Saur, H. Halbauer
This paper investigates the properties of a cellular mobile radio system with the capability to dynamically adapt the downtilt at the base station on a per terminal basis. We compare several realization options of this vertical beam steering and explore the impacts of downtilt, vertical half-power beam width (HPBW) and inter-site distance (ISD) on spectral efficiency and cell coverage. We show that our approach improves performance in single-cell environment and can achieve a significant amount of interference avoidance already without any kind of coordination between cells.
{"title":"Exploring the vertical dimension of dynamic beam steering","authors":"Stephan Saur, H. Halbauer","doi":"10.1109/MC-SS.2011.5910725","DOIUrl":"https://doi.org/10.1109/MC-SS.2011.5910725","url":null,"abstract":"This paper investigates the properties of a cellular mobile radio system with the capability to dynamically adapt the downtilt at the base station on a per terminal basis. We compare several realization options of this vertical beam steering and explore the impacts of downtilt, vertical half-power beam width (HPBW) and inter-site distance (ISD) on spectral efficiency and cell coverage. We show that our approach improves performance in single-cell environment and can achieve a significant amount of interference avoidance already without any kind of coordination between cells.","PeriodicalId":251147,"journal":{"name":"2011 8th International Workshop on Multi-Carrier Systems & Solutions","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114723321","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 : 2011-05-03DOI: 10.1109/MC-SS.2011.5910730
Junjie Ma, Nian Geng, L. Ping
In this paper, we investigate the impact of the a priori channel state information (CSI) on the orthogonal frequency-division multiplexing (OFDM) system performance. A joint iterative channel estimation, detection and decoding receiver involving the dual diagonal linear-minimum-mean-square-error (DD-LMMSE) algorithm is employed. We show that the discrepancy between the a priori CSI and true CSI has a relatively benign impact. On the other hand, the position discrepancy can lead to significant performance loss.
{"title":"Impact of the a priori channel state information on the performance of OFDM systems","authors":"Junjie Ma, Nian Geng, L. Ping","doi":"10.1109/MC-SS.2011.5910730","DOIUrl":"https://doi.org/10.1109/MC-SS.2011.5910730","url":null,"abstract":"In this paper, we investigate the impact of the a priori channel state information (CSI) on the orthogonal frequency-division multiplexing (OFDM) system performance. A joint iterative channel estimation, detection and decoding receiver involving the dual diagonal linear-minimum-mean-square-error (DD-LMMSE) algorithm is employed. We show that the discrepancy between the a priori CSI and true CSI has a relatively benign impact. On the other hand, the position discrepancy can lead to significant performance loss.","PeriodicalId":251147,"journal":{"name":"2011 8th International Workshop on Multi-Carrier Systems & Solutions","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125499231","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 : 2011-05-03DOI: 10.1109/MC-SS.2011.5910703
M. Fujii, Yu Watanabe
Ultra-Wide Band (UWB) spectrum causes interference to primary wireless communication systems whose spectra overlap the UWB band because UWB systems make use of huge bandwidth compared with the primary systems. Therefore, we have to implement Detect-And-Avoid (DAA) techniques to detect the primary system and control the signal transmitted from the UWB devices. Although there is the energy detection scheme for detecting the primary signal based on a threshold, it is difficult to find an appropriate threshold. In this paper, we investigate a novel detection scheme for UWB Multi-Band OFDM system. The proposed method detects the presence of the primary system using estimates of the primary signal and the noise variance based on the maximum likelihood criterion. Moreover, we introduce Akaike Information Criterion (AIC) in order to select the most suitable primary signal model out of some possible models. As a result, the proposed method dynamically find the threshold to detect the presence of the primary signal in sharp contrast to the conventional energy detection method which uses a static threshold. By the computer simulations, we show that the proposed method outperforms the conventional method with respect to missed-detection and false-detection probabilities.
超宽带(UWB)频谱对频谱与UWB频带重叠的初级无线通信系统造成干扰，因为UWB系统比初级系统占用更大的带宽。因此，我们必须实现检测和避免(DAA)技术来检测主系统并控制从超宽带设备传输的信号。虽然有基于阈值检测一次信号的能量检测方案，但很难找到合适的阈值。本文研究了一种新的UWB多波段OFDM系统检测方案。该方法利用基于极大似然准则的主信号和噪声方差的估计来检测主系统的存在。此外，我们引入了赤池信息准则(Akaike Information Criterion, AIC)，以便从多种可能的信号模型中选择出最合适的主信号模型。与传统能量检测方法采用静态阈值相比，该方法能够动态地找到阈值来检测主信号的存在。通过计算机仿真，我们证明了该方法在漏检和误检概率方面优于传统方法。
{"title":"A study on interference detection scheme using AIC for UWB MB-OFDM systems","authors":"M. Fujii, Yu Watanabe","doi":"10.1109/MC-SS.2011.5910703","DOIUrl":"https://doi.org/10.1109/MC-SS.2011.5910703","url":null,"abstract":"Ultra-Wide Band (UWB) spectrum causes interference to primary wireless communication systems whose spectra overlap the UWB band because UWB systems make use of huge bandwidth compared with the primary systems. Therefore, we have to implement Detect-And-Avoid (DAA) techniques to detect the primary system and control the signal transmitted from the UWB devices. Although there is the energy detection scheme for detecting the primary signal based on a threshold, it is difficult to find an appropriate threshold. In this paper, we investigate a novel detection scheme for UWB Multi-Band OFDM system. The proposed method detects the presence of the primary system using estimates of the primary signal and the noise variance based on the maximum likelihood criterion. Moreover, we introduce Akaike Information Criterion (AIC) in order to select the most suitable primary signal model out of some possible models. As a result, the proposed method dynamically find the threshold to detect the presence of the primary signal in sharp contrast to the conventional energy detection method which uses a static threshold. By the computer simulations, we show that the proposed method outperforms the conventional method with respect to missed-detection and false-detection probabilities.","PeriodicalId":251147,"journal":{"name":"2011 8th International Workshop on Multi-Carrier Systems & Solutions","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117225265","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 : 2011-05-03DOI: 10.1109/MC-SS.2011.5910736
Guangxia Zhou, G. Bauch, J. Berkmann
In this paper, a downlink multi-cell orthogonal frequency division multiplexing access (OFDMA) system using the same carrier frequency is studied. The multi-cell interference degrades the performance severely. This paper analyzes the interference mitigation performance of the simple Han-Kobayashi rate splitting scheme in a realistic modeling of the multi-cell system. A cooperative rate splitting scheme is proposed and a closed form optimal power allocation solution is derived. Then, we propose a new scheduling strategy to further improve the performance. Simulation results show that the cooperative rate splitting strategy combined the new scheduling algorithm can get a substantial capacity gain.
{"title":"Interference mitigation via cooperative rate splitting and scheduling in tri-sectored OFDMA systems","authors":"Guangxia Zhou, G. Bauch, J. Berkmann","doi":"10.1109/MC-SS.2011.5910736","DOIUrl":"https://doi.org/10.1109/MC-SS.2011.5910736","url":null,"abstract":"In this paper, a downlink multi-cell orthogonal frequency division multiplexing access (OFDMA) system using the same carrier frequency is studied. The multi-cell interference degrades the performance severely. This paper analyzes the interference mitigation performance of the simple Han-Kobayashi rate splitting scheme in a realistic modeling of the multi-cell system. A cooperative rate splitting scheme is proposed and a closed form optimal power allocation solution is derived. Then, we propose a new scheduling strategy to further improve the performance. Simulation results show that the cooperative rate splitting strategy combined the new scheduling algorithm can get a substantial capacity gain.","PeriodicalId":251147,"journal":{"name":"2011 8th International Workshop on Multi-Carrier Systems & Solutions","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126596187","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 : 2011-05-03DOI: 10.1109/MC-SS.2011.5910719
Vincent Kotzsch, G. Fettweis
We consider coordinated multi-point systems where multiple base stations apply a joint signal processing in the uplink and downlink. Large distances between the base stations result in unavoidable differences in time of arrival between the users' signals which in turn lead to inter-symbol interference in OFDM systems if the cyclic prefix length is exceeded. Moreover, carrier frequency offsets which are caused by imperfect oscillators lead to inter-carrier interference and are in particular a problem in the downlink due to the feedback delay of the measured channel state information. In this paper we derive metrics for evaluating the impact of time and frequency asynchronisms in CoMP systems with large base station distances. We compare performance results for CoMP and single user transmission techniques in a selected transmission scenario where we use a 3GPP/LTE baseline system.
{"title":"On synchronization requirements and performance limitations for CoMP systems in large cells","authors":"Vincent Kotzsch, G. Fettweis","doi":"10.1109/MC-SS.2011.5910719","DOIUrl":"https://doi.org/10.1109/MC-SS.2011.5910719","url":null,"abstract":"We consider coordinated multi-point systems where multiple base stations apply a joint signal processing in the uplink and downlink. Large distances between the base stations result in unavoidable differences in time of arrival between the users' signals which in turn lead to inter-symbol interference in OFDM systems if the cyclic prefix length is exceeded. Moreover, carrier frequency offsets which are caused by imperfect oscillators lead to inter-carrier interference and are in particular a problem in the downlink due to the feedback delay of the measured channel state information. In this paper we derive metrics for evaluating the impact of time and frequency asynchronisms in CoMP systems with large base station distances. We compare performance results for CoMP and single user transmission techniques in a selected transmission scenario where we use a 3GPP/LTE baseline system.","PeriodicalId":251147,"journal":{"name":"2011 8th International Workshop on Multi-Carrier Systems & Solutions","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131424800","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 : 2011-05-03DOI: 10.1109/MC-SS.2011.5910702
Adrian Kliks, I. Stupia, V. Lottici, F. Giannetti, F. Bader
In this paper the Generalized Multicarrier (GMC) based transmission has been proposed as a candidate for wireless cognitive applications. It has been proved that by relaxing the constraints typical for OFDM transmission (such as fixed time and frequency distance between the transmit pulses) one can gain not only in terms of spectral efficiency but also in terms of lower out-of-band radiation. Moreover, it has been proposed to solve one of the main problems of the GMC signaling, that is the presence of the so-called residual self-interference by means of iterative interference cancellation (IIC) methods. The performance in terms of BER and averaged transmit power of the GMC system has been compared with OFDM one in the presence of the fading channel. In both cases, the pragmatic bit-and-power loading scheme based on the Campello algorithm have been considered and the IIC based receivers have been tested.
{"title":"Generalized multi-carrier: An efficient platform for cognitive wireless applications","authors":"Adrian Kliks, I. Stupia, V. Lottici, F. Giannetti, F. Bader","doi":"10.1109/MC-SS.2011.5910702","DOIUrl":"https://doi.org/10.1109/MC-SS.2011.5910702","url":null,"abstract":"In this paper the Generalized Multicarrier (GMC) based transmission has been proposed as a candidate for wireless cognitive applications. It has been proved that by relaxing the constraints typical for OFDM transmission (such as fixed time and frequency distance between the transmit pulses) one can gain not only in terms of spectral efficiency but also in terms of lower out-of-band radiation. Moreover, it has been proposed to solve one of the main problems of the GMC signaling, that is the presence of the so-called residual self-interference by means of iterative interference cancellation (IIC) methods. The performance in terms of BER and averaged transmit power of the GMC system has been compared with OFDM one in the presence of the fading channel. In both cases, the pragmatic bit-and-power loading scheme based on the Campello algorithm have been considered and the IIC based receivers have been tested.","PeriodicalId":251147,"journal":{"name":"2011 8th International Workshop on Multi-Carrier Systems & Solutions","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128773447","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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