Pub Date : 2011-05-17DOI: 10.1109/CWIT.2011.5872141
S. Lampoudi, J. Brevik, M. O'Sullivan
We examine various algebraic/combinatorial properties of Low-Density Parity-Check codes as predictors for the performance of the sum-product algorithm on the AWGN channel in the error floor region. We consider three families of check matrices, two algebraically constructed and one sampled from an ensemble, expurgated to remove short cycles. The three families have similar properties, all are (3; 6)-regular, have girth 8, and have code length roughly 280. The best predictors are small trapping sets, and the predictive value is much higher for the algebraically constructed families than the random ones.
{"title":"Combinatorial Properties as Predictors for the Performance of the Sum-Product Algorithm","authors":"S. Lampoudi, J. Brevik, M. O'Sullivan","doi":"10.1109/CWIT.2011.5872141","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872141","url":null,"abstract":"We examine various algebraic/combinatorial properties of Low-Density Parity-Check codes as predictors for the performance of the sum-product algorithm on the AWGN channel in the error floor region. We consider three families of check matrices, two algebraically constructed and one sampled from an ensemble, expurgated to remove short cycles. The three families have similar properties, all are (3; 6)-regular, have girth 8, and have code length roughly 280. The best predictors are small trapping sets, and the predictive value is much higher for the algebraically constructed families than the random ones.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126239580","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872123
Lin Zheng, E. Yang
Causal video coding is a coding paradigm where video source frames are encoded in a frame by frame manner, the encoder for each frame can use all previous frames and all previous encoded frames, and the corresponding decoder can use only all previous encoded frames. In this paper, the design of causal video coding is considered from an information theoretic perspective by modeling each frame as a stationary information source. We first put forth a concept called causal scalar quantization. By extending the classic Lloyd-Max algorithm for a single source to this multiple sources case, we then propose an algorithm for designing optimum fixed-rate causal scalar quantizers for causal video coding to minimize the total distortion among all sources. The proposed algorithm converges in the sense that the total distortion cost is monotonically decreasing until a stationary point is reached. Simulation results show that in comparison with fixed-rate predictive scalar quantization, fixed-rate causal scalar quantization offers as large as 16% quality improvement (distortion reduction).
{"title":"On optimum fixed-rate causal scalar quantization design for causal video coding","authors":"Lin Zheng, E. Yang","doi":"10.1109/CWIT.2011.5872123","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872123","url":null,"abstract":"Causal video coding is a coding paradigm where video source frames are encoded in a frame by frame manner, the encoder for each frame can use all previous frames and all previous encoded frames, and the corresponding decoder can use only all previous encoded frames. In this paper, the design of causal video coding is considered from an information theoretic perspective by modeling each frame as a stationary information source. We first put forth a concept called causal scalar quantization. By extending the classic Lloyd-Max algorithm for a single source to this multiple sources case, we then propose an algorithm for designing optimum fixed-rate causal scalar quantizers for causal video coding to minimize the total distortion among all sources. The proposed algorithm converges in the sense that the total distortion cost is monotonically decreasing until a stationary point is reached. Simulation results show that in comparison with fixed-rate predictive scalar quantization, fixed-rate causal scalar quantization offers as large as 16% quality improvement (distortion reduction).","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127243713","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872154
Gongpu Wang, F. Gao, C. Tellambura
This paper utilizes a general superimposed training based transmission scheme that includes superimposed training and pilot symbol assisted modulation (PSAM) as special cases. The channel estimator of the scheme is the linear minimum mean square error (LMMSE) estimator. By taking into account errors of this method, we derive the closed-form lower bound of the data throughput under the constraint of limited amplitude for each symbol. Our study shows that with the constraint of total amplitude for each symbol, the conventional PSAM performs better in the high signal-to-noise ratio (SNR) region while at low SNR, the superimposed scheme performs better.
{"title":"Channel estimation with amplitude constraint: Superimposed training or conventional training ?","authors":"Gongpu Wang, F. Gao, C. Tellambura","doi":"10.1109/CWIT.2011.5872154","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872154","url":null,"abstract":"This paper utilizes a general superimposed training based transmission scheme that includes superimposed training and pilot symbol assisted modulation (PSAM) as special cases. The channel estimator of the scheme is the linear minimum mean square error (LMMSE) estimator. By taking into account errors of this method, we derive the closed-form lower bound of the data throughput under the constraint of limited amplitude for each symbol. Our study shows that with the constraint of total amplitude for each symbol, the conventional PSAM performs better in the high signal-to-noise ratio (SNR) region while at low SNR, the superimposed scheme performs better.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125504231","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872159
S. C. Jha, Umesh Phuyal, V. Bhargava
In multi-hop distributed cognitive radio network, link layer resource allocation must consider the information about number of hops packets have already traveled in the network in order to optimize the overall resource utilization. The loss of a packet after traveling some hops results in waste of all the resources allocated to it in previous hops. The existing resource allocation schemes may not provide optimal resource utilization in such network as this issue has been greatly ignored. Therefore, in this paper, we propose a scheme to allocate transmit power to different packets favoring those which have traveled more hops before reaching a particular node. We present a cross-layer approach in which link layer gets the hop-count information from network layer module. Distributed implementation is possible with the proposed scheme because each node can access this information. We formulate the power allocation problem as a convex optimization problem and obtain its analytical solution by using Lagrangian duality. Simulation results show that the proposed scheme is capable of minimizing wastage of network resources used by packets in their previous hops without any degradation in throughput and outage performance.
{"title":"Cross-layer resource allocation approach for multi-hop distributed cognitive radio network","authors":"S. C. Jha, Umesh Phuyal, V. Bhargava","doi":"10.1109/CWIT.2011.5872159","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872159","url":null,"abstract":"In multi-hop distributed cognitive radio network, link layer resource allocation must consider the information about number of hops packets have already traveled in the network in order to optimize the overall resource utilization. The loss of a packet after traveling some hops results in waste of all the resources allocated to it in previous hops. The existing resource allocation schemes may not provide optimal resource utilization in such network as this issue has been greatly ignored. Therefore, in this paper, we propose a scheme to allocate transmit power to different packets favoring those which have traveled more hops before reaching a particular node. We present a cross-layer approach in which link layer gets the hop-count information from network layer module. Distributed implementation is possible with the proposed scheme because each node can access this information. We formulate the power allocation problem as a convex optimization problem and obtain its analytical solution by using Lagrangian duality. Simulation results show that the proposed scheme is capable of minimizing wastage of network resources used by packets in their previous hops without any degradation in throughput and outage performance.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124435989","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872116
A. Chaaban, A. Sezgin
A network consisting of a point-to-point (P2P) link and a multiple access channel (MAC) sharing the same medium is considered. The resulting interference network, with three transmitters and two receivers is studied from degrees of freedom (DoF) perspective, with and without cognition. Several cognition variants are examined. Namely, the setup is studied with (1) no cognitive transmitters, (2) a cognitive P2P transmitter, (3) one cognitive MAC transmitter, and (4) with two cognitive MAC transmitters. It is shown that having a cognitive P2P transmitter does not bring any DoF gain to the network. This is obtained by showing that the DoF of the two former cases (1) and (2) is 1. However, it is shown that a cognitive MAC transmitter is more beneficial since the latter two cases (3) and (4) have 3/2 DoF. The achievability of 3/2 DoF is guaranteed by using a combination of interference neutralization and interference alignment.
{"title":"Interference alignment and neutralization in a cognitive 3-user MAC-interference channel: degrees of freedom","authors":"A. Chaaban, A. Sezgin","doi":"10.1109/CWIT.2011.5872116","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872116","url":null,"abstract":"A network consisting of a point-to-point (P2P) link and a multiple access channel (MAC) sharing the same medium is considered. The resulting interference network, with three transmitters and two receivers is studied from degrees of freedom (DoF) perspective, with and without cognition. Several cognition variants are examined. Namely, the setup is studied with (1) no cognitive transmitters, (2) a cognitive P2P transmitter, (3) one cognitive MAC transmitter, and (4) with two cognitive MAC transmitters. It is shown that having a cognitive P2P transmitter does not bring any DoF gain to the network. This is obtained by showing that the DoF of the two former cases (1) and (2) is 1. However, it is shown that a cognitive MAC transmitter is more beneficial since the latter two cases (3) and (4) have 3/2 DoF. The achievability of 3/2 DoF is guaranteed by using a combination of interference neutralization and interference alignment.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"62 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126412608","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872158
Umesh Phuyal, S. C. Jha, V. Bhargava
Relay-based cooperative transmission in cellular network has been an area of tremendous research recently. Transmission via relays introduces power consumption at both the source and relay stations which may lead to less efficient system in terms of power consumption. Because of increasing energy cost for cellular systems and concern over environmental issues, an energy efficient design of resource allocation scheme in cooperative cellular network is of prime importance. In this paper, we propose a novel resource allocation scheme in order to maximize the energy aware system performance. The proposed low-complexity scheme allocates powers for base station and relay by using a strategy that minimizes required transmit power per unit achieved throughput and at the same time guarantees a predefined quality of service (QoS) which is specified in terms of minimum end-to-end data rate required by each user. Simulation results show that proposed scheme outperforms existing power allocation schemes by decreasing required power to guarantee the QoS without increasing system outage penalty, which is essential for green communication systems.
{"title":"Green resource allocation with QoS provisioning for cooperative cellular network","authors":"Umesh Phuyal, S. C. Jha, V. Bhargava","doi":"10.1109/CWIT.2011.5872158","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872158","url":null,"abstract":"Relay-based cooperative transmission in cellular network has been an area of tremendous research recently. Transmission via relays introduces power consumption at both the source and relay stations which may lead to less efficient system in terms of power consumption. Because of increasing energy cost for cellular systems and concern over environmental issues, an energy efficient design of resource allocation scheme in cooperative cellular network is of prime importance. In this paper, we propose a novel resource allocation scheme in order to maximize the energy aware system performance. The proposed low-complexity scheme allocates powers for base station and relay by using a strategy that minimizes required transmit power per unit achieved throughput and at the same time guarantees a predefined quality of service (QoS) which is specified in terms of minimum end-to-end data rate required by each user. Simulation results show that proposed scheme outperforms existing power allocation schemes by decreasing required power to guarantee the QoS without increasing system outage penalty, which is essential for green communication systems.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130334419","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872137
Ahmad Abu Al Haija, M. Vu
We propose a half-duplex cooperative scheme for a discrete memoryless channel (DMC) consisting of two users communicating with one destination. The half-duplex constraint is satisfied by performing the communication over 3 time slots with variable durations in each code block. Each user alternatively transmits and receives during the first 2 time slots, then both of them transmit during the last one. Different from [1], here we use joint typicality instead of maximum likelihood (ML) decoding to derive the rate region. The main contribution is in the joint decoding and proof techniques that concurrently combine code segments of different lengths.
{"title":"Joint typicality analysis for half-duplex cooperative communication","authors":"Ahmad Abu Al Haija, M. Vu","doi":"10.1109/CWIT.2011.5872137","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872137","url":null,"abstract":"We propose a half-duplex cooperative scheme for a discrete memoryless channel (DMC) consisting of two users communicating with one destination. The half-duplex constraint is satisfied by performing the communication over 3 time slots with variable durations in each code block. Each user alternatively transmits and receives during the first 2 time slots, then both of them transmit during the last one. Different from [1], here we use joint typicality instead of maximum likelihood (ML) decoding to derive the rate region. The main contribution is in the joint decoding and proof techniques that concurrently combine code segments of different lengths.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129518766","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872119
Lin Dong, N. Yu
Golay complementary sequences are a good solution to reduce the high peak-to-average power ratio (PAPR) of multicarrier communication systems. In this paper, we present a simple but novel technique to develop theoretical PAPR bounds of downlink MC-CDMA system using Golay complementary sequences for spreading and coding. The developed PAPR bounds are independent of the spreading factor in uncoded MC-CDMA. Furthermore, they have no dependency on the number of spreading processes as well as the spreading factor in coded MC-CDMA. Simulation results demonstrate that the theoretical bounds are well followed by 99.9% PAPRs which are also independent of spreading factors (for uncoded and coded cases), and the number of spreading processes (for coded case only). Practically, the independency gives us a useful insight for peak power control in MC-CDMA employing Golay complementary sequences.
{"title":"Peak power analysis of MC-CDMA employing Golay complementary sequences","authors":"Lin Dong, N. Yu","doi":"10.1109/CWIT.2011.5872119","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872119","url":null,"abstract":"Golay complementary sequences are a good solution to reduce the high peak-to-average power ratio (PAPR) of multicarrier communication systems. In this paper, we present a simple but novel technique to develop theoretical PAPR bounds of downlink MC-CDMA system using Golay complementary sequences for spreading and coding. The developed PAPR bounds are independent of the spreading factor in uncoded MC-CDMA. Furthermore, they have no dependency on the number of spreading processes as well as the spreading factor in coded MC-CDMA. Simulation results demonstrate that the theoretical bounds are well followed by 99.9% PAPRs which are also independent of spreading factors (for uncoded and coded cases), and the number of spreading processes (for coded case only). Practically, the independency gives us a useful insight for peak power control in MC-CDMA employing Golay complementary sequences.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132916889","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872110
Yong Jin Daniel Kim, J. Bajcsy
Faster than Nyquist (FTN) signaling has been studied as an alternative transmission technology in communication systems when information carrying symbols are sent faster than the Nyquist rate determined by the physical channel bandwidth. This paper presents analysis of the information rates of cyclostationary FTN signaling on AWGN and selected ISI channels. It also presents related numerical capacity results and discusses potential merits to the FTN signaling.
{"title":"Information rates of cyclostationary faster-than-nyquist signaling","authors":"Yong Jin Daniel Kim, J. Bajcsy","doi":"10.1109/CWIT.2011.5872110","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872110","url":null,"abstract":"Faster than Nyquist (FTN) signaling has been studied as an alternative transmission technology in communication systems when information carrying symbols are sent faster than the Nyquist rate determined by the physical channel bandwidth. This paper presents analysis of the information rates of cyclostationary FTN signaling on AWGN and selected ISI channels. It also presents related numerical capacity results and discusses potential merits to the FTN signaling.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116300103","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 : 2011-05-17DOI: 10.1109/CWIT.2011.5872115
Sang Joon Kim, S. Ghassemzadeh, Robert R. Miller, V. Tarokh
Reducing interference induced by secondary users is one of the most challenging problems in spectrum sharing. In this paper, we derive the optimum transmission strategy that minimizes the average interference power created by cognitive radios at a given point of space i.e. the location of a primary receiver. Surprisingly, this is not given by the water-filling solution.
{"title":"Optimum cognitive radio transmission scheme for reducing average interference power","authors":"Sang Joon Kim, S. Ghassemzadeh, Robert R. Miller, V. Tarokh","doi":"10.1109/CWIT.2011.5872115","DOIUrl":"https://doi.org/10.1109/CWIT.2011.5872115","url":null,"abstract":"Reducing interference induced by secondary users is one of the most challenging problems in spectrum sharing. In this paper, we derive the optimum transmission strategy that minimizes the average interference power created by cognitive radios at a given point of space i.e. the location of a primary receiver. Surprisingly, this is not given by the water-filling solution.","PeriodicalId":250626,"journal":{"name":"2011 12th Canadian Workshop on Information Theory","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-05-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132432141","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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