Pub Date : 2005-12-01DOI: 10.1109/GLOCOM.2005.1578068
R. Cavalcante, M. Yukawa, I. Yamada
This paper presents a family of multiple access interference (MAI) suppression receivers based on the adaptive projected subgradient method. The proposed scheme can be applied to many different channel models and modulations in a unified manner. Moreover, it is suitable for both blind and nonblind receivers. The adaptive projected subgradient method realizes excellent convergence to a set including an optimal solution with high probability by asymptotically minimizing a sequence of nonnegative convex functions. Simulation results show much better (variable) tradeoff between speed and performance at steady-state as compared to existing techniques
{"title":"Set-theoretic DS/CDMA receivers for fading channels by adaptive projected subgradient method","authors":"R. Cavalcante, M. Yukawa, I. Yamada","doi":"10.1109/GLOCOM.2005.1578068","DOIUrl":"https://doi.org/10.1109/GLOCOM.2005.1578068","url":null,"abstract":"This paper presents a family of multiple access interference (MAI) suppression receivers based on the adaptive projected subgradient method. The proposed scheme can be applied to many different channel models and modulations in a unified manner. Moreover, it is suitable for both blind and nonblind receivers. The adaptive projected subgradient method realizes excellent convergence to a set including an optimal solution with high probability by asymptotically minimizing a sequence of nonnegative convex functions. Simulation results show much better (variable) tradeoff between speed and performance at steady-state as compared to existing techniques","PeriodicalId":319736,"journal":{"name":"GLOBECOM '05. IEEE Global Telecommunications Conference, 2005.","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124776652","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 : 2005-12-01DOI: 10.1109/GLOCOM.2005.1577738
Chia-Jen Hsu, Chien Chen, Chun-Yuan Lin
In order to support Internet security, virtual private networks, QoS, etc., Internet routers need to classify incoming packets quickly into flows. A packet classifier uses information contained in the packet header and a predefined rule table in the routers to classify the packets. This paper presents a novel packet classification algorithm, called the bit compression algorithm. Like the previously best known algorithm, bitmap intersection, bit compression is based on the multiple dimensional range lookup approach. Since the bit vectors of the bitmap intersection contain lots of '0' bits, the bit vectors could be compressed. We compress the bit vectors by preserving useful information but removing the redundant '0' bits of the bit vectors. Additionally, the wildcard rules also enable more extensive improvement. Comparing with the bitmap intersection algorithm, the bit compression algorithm reduces the storage complexity in the average-case from thetas (dN2) to thetas (dN-logN), where d denotes the number of dimensions and N represents the number of rules. By exploring the memory hierarchy, we show that bit compression algorithm requires much less memory access than bitmap intersection algorithm on Intel IXP1200 network processor. Since memory access dominates the lookup time, even though extra decompression time is required for bit compression scheme, the bit compression scheme in the average still outperforms bitmap intersection scheme on the classification performance
{"title":"Fast packet classification using bit compression","authors":"Chia-Jen Hsu, Chien Chen, Chun-Yuan Lin","doi":"10.1109/GLOCOM.2005.1577738","DOIUrl":"https://doi.org/10.1109/GLOCOM.2005.1577738","url":null,"abstract":"In order to support Internet security, virtual private networks, QoS, etc., Internet routers need to classify incoming packets quickly into flows. A packet classifier uses information contained in the packet header and a predefined rule table in the routers to classify the packets. This paper presents a novel packet classification algorithm, called the bit compression algorithm. Like the previously best known algorithm, bitmap intersection, bit compression is based on the multiple dimensional range lookup approach. Since the bit vectors of the bitmap intersection contain lots of '0' bits, the bit vectors could be compressed. We compress the bit vectors by preserving useful information but removing the redundant '0' bits of the bit vectors. Additionally, the wildcard rules also enable more extensive improvement. Comparing with the bitmap intersection algorithm, the bit compression algorithm reduces the storage complexity in the average-case from thetas (dN2) to thetas (dN-logN), where d denotes the number of dimensions and N represents the number of rules. By exploring the memory hierarchy, we show that bit compression algorithm requires much less memory access than bitmap intersection algorithm on Intel IXP1200 network processor. Since memory access dominates the lookup time, even though extra decompression time is required for bit compression scheme, the bit compression scheme in the average still outperforms bitmap intersection scheme on the classification performance","PeriodicalId":319736,"journal":{"name":"GLOBECOM '05. IEEE Global Telecommunications Conference, 2005.","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123169073","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 : 2005-12-01DOI: 10.1109/GLOCOM.2005.1578022
Shing-Jeh Jiang, H. J. Chao
Optical cell switching (OCS) is a new flexible all-optical switching paradigm. An OCS consists of cell edge routers (CER) and core switches (OCX). The CER is the interface between the electrical domain and the optical domain, while the OCX is the all optical packet switch without opto-electro-optical (OEO) conversion. In our previous research we have proposed a low complexity and highly scalable switch architecture for the OCX with several high performance scheduling algorithms. In this paper, we focus on the design of the CER. To maximize the optical bandwidth utilization and minimize the packet delay within the OCS, most of OCS intelligence and functionalities are build in the CER. To ensure the performance and the quality of the OCS network, we propose two practical and scalable switch architectures and corresponding efficient scheduling algorithms for ingress and egress CERs accordingly. We show by simulations that with the proposed scheduling algorithms both CERs can achieve ~100% throughput. Additionally, the complexity of both scheduling algorithms at two routers is only O(log(N))
{"title":"Designs of cell edge routers in the optical cell switching (OCS) network","authors":"Shing-Jeh Jiang, H. J. Chao","doi":"10.1109/GLOCOM.2005.1578022","DOIUrl":"https://doi.org/10.1109/GLOCOM.2005.1578022","url":null,"abstract":"Optical cell switching (OCS) is a new flexible all-optical switching paradigm. An OCS consists of cell edge routers (CER) and core switches (OCX). The CER is the interface between the electrical domain and the optical domain, while the OCX is the all optical packet switch without opto-electro-optical (OEO) conversion. In our previous research we have proposed a low complexity and highly scalable switch architecture for the OCX with several high performance scheduling algorithms. In this paper, we focus on the design of the CER. To maximize the optical bandwidth utilization and minimize the packet delay within the OCS, most of OCS intelligence and functionalities are build in the CER. To ensure the performance and the quality of the OCS network, we propose two practical and scalable switch architectures and corresponding efficient scheduling algorithms for ingress and egress CERs accordingly. We show by simulations that with the proposed scheduling algorithms both CERs can achieve ~100% throughput. Additionally, the complexity of both scheduling algorithms at two routers is only O(log(N))","PeriodicalId":319736,"journal":{"name":"GLOBECOM '05. IEEE Global Telecommunications Conference, 2005.","volume":"125 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126262645","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 : 2005-12-01DOI: 10.1109/GLOCOM.2005.1578315
M. Janani, Aria Nosratinia
It is well-known that diversity, despite being widely used as a design criterion, may not be enough to ensure good performance of a wireless system, because the diversity factor may "kick in" at unrealistically high values of SNR. This paper proposes a new class of layered space-time codes with a new design criterion that works well in moderate SNR's. Specifically, we propose to relax some of the constraints of threaded algebraic space-time (TAST) codes, leading to a class of codes with better error performance, which we call relaxed threaded space time (RTST) codes. We also propose a modified design criterion, the average union bound (AUB), which ensures good performance at medium SNR. For a 2 times 2 system operating at 6 b/s/Hz, improvements of more than 1.5 dB have been observed
{"title":"Relaxed threaded space-time codes","authors":"M. Janani, Aria Nosratinia","doi":"10.1109/GLOCOM.2005.1578315","DOIUrl":"https://doi.org/10.1109/GLOCOM.2005.1578315","url":null,"abstract":"It is well-known that diversity, despite being widely used as a design criterion, may not be enough to ensure good performance of a wireless system, because the diversity factor may \"kick in\" at unrealistically high values of SNR. This paper proposes a new class of layered space-time codes with a new design criterion that works well in moderate SNR's. Specifically, we propose to relax some of the constraints of threaded algebraic space-time (TAST) codes, leading to a class of codes with better error performance, which we call relaxed threaded space time (RTST) codes. We also propose a modified design criterion, the average union bound (AUB), which ensures good performance at medium SNR. For a 2 times 2 system operating at 6 b/s/Hz, improvements of more than 1.5 dB have been observed","PeriodicalId":319736,"journal":{"name":"GLOBECOM '05. IEEE Global Telecommunications Conference, 2005.","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134160592","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 : 2005-12-01DOI: 10.1109/GLOCOM.2005.1577963
Xi Zhang, D. Saha, Hsiao-Hwa Chen
Viruses spreading over the Internet can cause significant damage and the loss of network security. On the other hand, the anti-virus process also plays an important part affecting the dynamics of the virus spreading. The spreading dynamics of most viruses depend on the underlying network topology. While much research attention has been paid in developing the anti-virus software/tools, the dynamics and propagating model of the virus and anti-virus spreading in the topology-aware networks is neither well understood, nor thoroughly studied. To remedy this deficiency, we model and analyze the spreading characteristics of viruses as coexisting with the anti-virus spreading process in the two-layer small-world topology. Applying the fluid analysis, we derive the analytical solutions to the two-layer model. The simulations experiments confirm the validity of our fluid analyses in characterizing both virus and anti-virus spreading dynamics.
{"title":"Analysis of virus and anti-virus spreading dynamics","authors":"Xi Zhang, D. Saha, Hsiao-Hwa Chen","doi":"10.1109/GLOCOM.2005.1577963","DOIUrl":"https://doi.org/10.1109/GLOCOM.2005.1577963","url":null,"abstract":"Viruses spreading over the Internet can cause significant damage and the loss of network security. On the other hand, the anti-virus process also plays an important part affecting the dynamics of the virus spreading. The spreading dynamics of most viruses depend on the underlying network topology. While much research attention has been paid in developing the anti-virus software/tools, the dynamics and propagating model of the virus and anti-virus spreading in the topology-aware networks is neither well understood, nor thoroughly studied. To remedy this deficiency, we model and analyze the spreading characteristics of viruses as coexisting with the anti-virus spreading process in the two-layer small-world topology. Applying the fluid analysis, we derive the analytical solutions to the two-layer model. The simulations experiments confirm the validity of our fluid analyses in characterizing both virus and anti-virus spreading dynamics.","PeriodicalId":319736,"journal":{"name":"GLOBECOM '05. IEEE Global Telecommunications Conference, 2005.","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132687483","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 : 2005-12-01DOI: 10.1109/GLOCOM.2005.1577904
Yakun Sun, M. Honig
The performance of a wireless channel with multiple antennas benefits from channel knowledge at the receiver, which is typically unknown a priori. We study the capacity of a block fading multiple-input/multiple-output (MIMO) channel with a linear receiver, which is estimated from a training sequence via a least squares (LS) algorithm. Given a fixed block size, the amount of training overhead plays a key role in balancing the quality of the receiver estimate and the data transmission time. Here we study the optimal training length, which maximizes the large system MIMO capacity, i.e., the number of transmit and receive antennas go to infinity with fixed ratio. In order to obtain a meaningful limit, the training length and packet length also increase in fixed proportion to the number of antennas. We show that the optimal amount of training grows as the square root of the block size, as the block size becomes large. Furthermore, only a slight benefit is obtained from optimizing the allocation of power across training and data symbols. Numerical results show that for a fixed block length, the capacity can be increased somewhat by adding a properly chosen diagonal loading factor to the LS algorithm.
{"title":"Large system capacity of MIMO block channels with least squares linear adaptive receivers","authors":"Yakun Sun, M. Honig","doi":"10.1109/GLOCOM.2005.1577904","DOIUrl":"https://doi.org/10.1109/GLOCOM.2005.1577904","url":null,"abstract":"The performance of a wireless channel with multiple antennas benefits from channel knowledge at the receiver, which is typically unknown a priori. We study the capacity of a block fading multiple-input/multiple-output (MIMO) channel with a linear receiver, which is estimated from a training sequence via a least squares (LS) algorithm. Given a fixed block size, the amount of training overhead plays a key role in balancing the quality of the receiver estimate and the data transmission time. Here we study the optimal training length, which maximizes the large system MIMO capacity, i.e., the number of transmit and receive antennas go to infinity with fixed ratio. In order to obtain a meaningful limit, the training length and packet length also increase in fixed proportion to the number of antennas. We show that the optimal amount of training grows as the square root of the block size, as the block size becomes large. Furthermore, only a slight benefit is obtained from optimizing the allocation of power across training and data symbols. Numerical results show that for a fixed block length, the capacity can be increased somewhat by adding a properly chosen diagonal loading factor to the LS algorithm.","PeriodicalId":319736,"journal":{"name":"GLOBECOM '05. IEEE Global Telecommunications Conference, 2005.","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132594441","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 : 2005-12-01DOI: 10.1109/GLOCOM.2005.1578094
Fu-Hsuan Chiu, Sau-Hsuan Wu, C.-C. Jay Kuo
An expectation maximization (EM) algorithm for joint channel tracking and symbol detection in a multi-input multi-output (MIMO) time-varying frequency-selective fading environment is proposed in this research. Based on the recursive EM procedure in conjunction with soft decoding, we develop an iterative algorithm that performs the minimum mean squared error (MMSE) channel estimation and the maximum a posterior (MAP) probability symbol detection jointly. Two soft decoders are examined; namely, the BCJR algorithm and the soft sphere decoder. The performance of the proposed algorithm is evaluated via simulation and compared with that of Kalman filtering with hard decision feedback. It is demonstrated by numerical simulation that the proposed algorithm has robust performance in the presence of a severe channel model mismatch
{"title":"Joint MIMO channel tracking and symbol detection with EM algorithm and soft decoding","authors":"Fu-Hsuan Chiu, Sau-Hsuan Wu, C.-C. Jay Kuo","doi":"10.1109/GLOCOM.2005.1578094","DOIUrl":"https://doi.org/10.1109/GLOCOM.2005.1578094","url":null,"abstract":"An expectation maximization (EM) algorithm for joint channel tracking and symbol detection in a multi-input multi-output (MIMO) time-varying frequency-selective fading environment is proposed in this research. Based on the recursive EM procedure in conjunction with soft decoding, we develop an iterative algorithm that performs the minimum mean squared error (MMSE) channel estimation and the maximum a posterior (MAP) probability symbol detection jointly. Two soft decoders are examined; namely, the BCJR algorithm and the soft sphere decoder. The performance of the proposed algorithm is evaluated via simulation and compared with that of Kalman filtering with hard decision feedback. It is demonstrated by numerical simulation that the proposed algorithm has robust performance in the presence of a severe channel model mismatch","PeriodicalId":319736,"journal":{"name":"GLOBECOM '05. IEEE Global Telecommunications Conference, 2005.","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133143179","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 : 2005-12-01DOI: 10.1109/GLOCOM.2005.1577890
Feng-Tsun Chien, C.-C. Jay Kuo
A blind recursive algorithm to effectively update the carrier frequency offset (CFO) vector in a multicarrier code-division multiple-access (MC-CDMA) system is studied in this research. The recursive relation is developed based on the expectation maximization (EM) algorithm with a quadratic constraint. This new perspective enables the use of linear estimation theory to deal with the blind CFO estimation problem, leading to an analytic CFO estimate in closed-form. The multiple access interference (MAI) is mitigated using the second order statistics of the interference-plus-noise vector, which can also be updated in a recursive manner under the EM formulation. Finally, we verify the effectiveness of the proposed algorithm with computer simulation.
{"title":"Blind recursive tracking of carrier frequency offsets in MC-CDMA systems","authors":"Feng-Tsun Chien, C.-C. Jay Kuo","doi":"10.1109/GLOCOM.2005.1577890","DOIUrl":"https://doi.org/10.1109/GLOCOM.2005.1577890","url":null,"abstract":"A blind recursive algorithm to effectively update the carrier frequency offset (CFO) vector in a multicarrier code-division multiple-access (MC-CDMA) system is studied in this research. The recursive relation is developed based on the expectation maximization (EM) algorithm with a quadratic constraint. This new perspective enables the use of linear estimation theory to deal with the blind CFO estimation problem, leading to an analytic CFO estimate in closed-form. The multiple access interference (MAI) is mitigated using the second order statistics of the interference-plus-noise vector, which can also be updated in a recursive manner under the EM formulation. Finally, we verify the effectiveness of the proposed algorithm with computer simulation.","PeriodicalId":319736,"journal":{"name":"GLOBECOM '05. IEEE Global Telecommunications Conference, 2005.","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115139918","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 : 2005-12-01DOI: 10.1109/GLOCOM.2005.1578012
Qiong Zhang, V. Vokkarane, Yuke Wang, J. Jue
Due to the bufferless nature of OBS networks, random burst losses may occur, even at low traffic loads. For optical burst-switched (OBS) networks in which TCP is implemented at a higher layer, these random burst losses may be mistakenly interpreted by the TCP layer as congestion in the network, leading to serious degradation of the TCP performance. In this paper, we reduce random burst losses by a burst retransmission scheme in which the bursts lost due to contention in the OBS network are retransmitted at the OBS layer. The OBS retransmission scheme can then reduce the probability that the TCP layer falsely detects congestion, thereby improving the TCP throughput. We analyze the TCP throughput when OBS networks employ the burst retransmission scheme and develop a simulation model to validate the analytical results. Based on our simulation results, we show that an OBS layer with burst retransmission provides an improvement of up to ten times the TCP throughput over an OBS layer without burst retransmission. This significant improvement is primarily because the TCP layer triggers fewer time-out based retransmissions when the OBS retransmission scheme is used
{"title":"Analysis of TCP over optical burst-switched networks with burst retransmission","authors":"Qiong Zhang, V. Vokkarane, Yuke Wang, J. Jue","doi":"10.1109/GLOCOM.2005.1578012","DOIUrl":"https://doi.org/10.1109/GLOCOM.2005.1578012","url":null,"abstract":"Due to the bufferless nature of OBS networks, random burst losses may occur, even at low traffic loads. For optical burst-switched (OBS) networks in which TCP is implemented at a higher layer, these random burst losses may be mistakenly interpreted by the TCP layer as congestion in the network, leading to serious degradation of the TCP performance. In this paper, we reduce random burst losses by a burst retransmission scheme in which the bursts lost due to contention in the OBS network are retransmitted at the OBS layer. The OBS retransmission scheme can then reduce the probability that the TCP layer falsely detects congestion, thereby improving the TCP throughput. We analyze the TCP throughput when OBS networks employ the burst retransmission scheme and develop a simulation model to validate the analytical results. Based on our simulation results, we show that an OBS layer with burst retransmission provides an improvement of up to ten times the TCP throughput over an OBS layer without burst retransmission. This significant improvement is primarily because the TCP layer triggers fewer time-out based retransmissions when the OBS retransmission scheme is used","PeriodicalId":319736,"journal":{"name":"GLOBECOM '05. IEEE Global Telecommunications Conference, 2005.","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129327911","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 : 2005-12-01DOI: 10.1109/GLOCOM.2005.1577463
A. Schmid, A. Neubauer, C. Günther
Location based services with Galileo/GPS satellite receivers integrated in mobile phones are expected to experience a substantial market growth. Satellite signals are usually received on the earth surface with very low signal energy. Attenuation, shadowing, and multipath fading in urban canyons and moderate indoor environments impose challenging acquisition conditions for the state-of-the-art enhanced sensitivity mobile satellite receivers. Residual frequency deviations between the down-conversion frequency and the received signal frequency due to unknown Doppler frequency shifts significantly reduce the signal acquisition sensitivity of current satellite receivers. This paper shows how the residual frequency deviation can be reduced incrementally towards zero much faster than the CDMA code synchronization be detected with sufficient probability. This paper furthermore derives the probability density functions for the signal detection using the adaptive frequency correction method and illustrates the acquisition sensitivity gain of around 4 dB for different Galileo and GPS satellite receiver configurations.
{"title":"Adaptive frequency correction method for enhanced sensitivity CDMA acquisition","authors":"A. Schmid, A. Neubauer, C. Günther","doi":"10.1109/GLOCOM.2005.1577463","DOIUrl":"https://doi.org/10.1109/GLOCOM.2005.1577463","url":null,"abstract":"Location based services with Galileo/GPS satellite receivers integrated in mobile phones are expected to experience a substantial market growth. Satellite signals are usually received on the earth surface with very low signal energy. Attenuation, shadowing, and multipath fading in urban canyons and moderate indoor environments impose challenging acquisition conditions for the state-of-the-art enhanced sensitivity mobile satellite receivers. Residual frequency deviations between the down-conversion frequency and the received signal frequency due to unknown Doppler frequency shifts significantly reduce the signal acquisition sensitivity of current satellite receivers. This paper shows how the residual frequency deviation can be reduced incrementally towards zero much faster than the CDMA code synchronization be detected with sufficient probability. This paper furthermore derives the probability density functions for the signal detection using the adaptive frequency correction method and illustrates the acquisition sensitivity gain of around 4 dB for different Galileo and GPS satellite receiver configurations.","PeriodicalId":319736,"journal":{"name":"GLOBECOM '05. IEEE Global Telecommunications Conference, 2005.","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123969892","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}