Quality-of-service (QoS) guarantees in networks are increasingly based on per-flow queueing and sophisticated scheduling. Most advanced scheduling algorithms rely on a common computational primitive: priority queues. Large priority queues are built using calendar queue or heap data structures. To support advanced scheduling at OC-192 (10 Gbps) rates and above, pipelined management of the priority queue is needed. We present a pipelined heap manager that we have designed as a core integratable into ASICs, in synthesizable Verilog form. We discuss how to use it in switches and routers, its advantages over calendar queues, and we present cost-performance tradeoffs. Our design can be configured to any heap size. We have verified and synthesized our design and present cost and performance analysis information.
{"title":"Pipelined heap (priority queue) management for advanced scheduling in high-speed networks","authors":"Aggelos D. Ioannou, M. Katevenis","doi":"10.1109/ICC.2001.936948","DOIUrl":"https://doi.org/10.1109/ICC.2001.936948","url":null,"abstract":"Quality-of-service (QoS) guarantees in networks are increasingly based on per-flow queueing and sophisticated scheduling. Most advanced scheduling algorithms rely on a common computational primitive: priority queues. Large priority queues are built using calendar queue or heap data structures. To support advanced scheduling at OC-192 (10 Gbps) rates and above, pipelined management of the priority queue is needed. We present a pipelined heap manager that we have designed as a core integratable into ASICs, in synthesizable Verilog form. We discuss how to use it in switches and routers, its advantages over calendar queues, and we present cost-performance tradeoffs. Our design can be configured to any heap size. We have verified and synthesized our design and present cost and performance analysis information.","PeriodicalId":203874,"journal":{"name":"ICC 2001. IEEE International Conference on Communications. Conference Record (Cat. No.01CH37240)","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122456522","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}
A new suboptimal turbo receiver for coded CDMA is presented. The user-separating front-end of this receiver has been thought of as the extension of linear multiuser detectors to an iterative structure. The complexity of this receiver is shown to be O(K), where K is the number of users. Simulations show that, for sufficiently high signal-to-noise ratios, the linear-US receiver tends to single-user performance.
{"title":"A linear front end for iterative soft interference cancellation and decoding in coded CDMA","authors":"A. Tarable, G. Montorsi, S. Benedetto","doi":"10.1109/ICC.2001.936261","DOIUrl":"https://doi.org/10.1109/ICC.2001.936261","url":null,"abstract":"A new suboptimal turbo receiver for coded CDMA is presented. The user-separating front-end of this receiver has been thought of as the extension of linear multiuser detectors to an iterative structure. The complexity of this receiver is shown to be O(K), where K is the number of users. Simulations show that, for sufficiently high signal-to-noise ratios, the linear-US receiver tends to single-user performance.","PeriodicalId":203874,"journal":{"name":"ICC 2001. IEEE International Conference on Communications. Conference Record (Cat. No.01CH37240)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116572235","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}
Code-constrained super-exponential algorithms (SEA) are presented for blind detection of asynchronous short-code DS-CDMA (direct sequence code division multiple access) signals over multipath channels. Only the spreading code of the desired user is assumed to be known; its transmission delay may be unknown. By exploiting the fact that the equalizer always lies in a subspace associated with the desired user's code sequence, a projection operator is imposed at every iteration so that the algorithm can extract the desired user. The results are further improved by following the constrained SEA by unconstrained SEA. An illustrative simulation example is provided.
{"title":"Super-exponential methods for blind detection of asynchronous CDMA signals over multipath channels","authors":"Tongtong Li, Jitendra Tugnait","doi":"10.1109/ICC.2001.937352","DOIUrl":"https://doi.org/10.1109/ICC.2001.937352","url":null,"abstract":"Code-constrained super-exponential algorithms (SEA) are presented for blind detection of asynchronous short-code DS-CDMA (direct sequence code division multiple access) signals over multipath channels. Only the spreading code of the desired user is assumed to be known; its transmission delay may be unknown. By exploiting the fact that the equalizer always lies in a subspace associated with the desired user's code sequence, a projection operator is imposed at every iteration so that the algorithm can extract the desired user. The results are further improved by following the constrained SEA by unconstrained SEA. An illustrative simulation example is provided.","PeriodicalId":203874,"journal":{"name":"ICC 2001. IEEE International Conference on Communications. Conference Record (Cat. No.01CH37240)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2004-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128741991","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}
This paper proposes a new multicast protocol for mobile ad hoc networks, called the multicast routing protocol based on zone routing (MZR). MZR is a source-initiated on-demand protocol, in which a multicast delivery tree is created using a concept called the zone routing mechanism. It is a source tree based protocol and does not depend on any underlying unicast protocol. The protocol's reaction to topological changes can be restricted to a node's neighborhood instead of propagating it throughout the network. A detailed simulation and performance analysis of MZR is presented.
{"title":"MZR: a multicast protocol for mobile ad hoc networks","authors":"V. Devarapalli, D. Sidhu","doi":"10.1109/ICC.2001.937365","DOIUrl":"https://doi.org/10.1109/ICC.2001.937365","url":null,"abstract":"This paper proposes a new multicast protocol for mobile ad hoc networks, called the multicast routing protocol based on zone routing (MZR). MZR is a source-initiated on-demand protocol, in which a multicast delivery tree is created using a concept called the zone routing mechanism. It is a source tree based protocol and does not depend on any underlying unicast protocol. The protocol's reaction to topological changes can be restricted to a node's neighborhood instead of propagating it throughout the network. A detailed simulation and performance analysis of MZR is presented.","PeriodicalId":203874,"journal":{"name":"ICC 2001. IEEE International Conference on Communications. Conference Record (Cat. No.01CH37240)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134584688","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}
This paper proposes a media synchronization scheme with adaptive /spl Delta/-causality control for networked multimedia applications in which the temporal and causal relationships exist among media streams such as computer data, voice, and video. In the scheme, the adaptive /spl Delta/-causality control, which varies the value of /spl Delta/ of the /spl Delta/-causality control according to the network load, is performed for causality, and the virtual-time rendering (VTR) algorithm, which the authors previously proposed, is used for media synchronization. The scheme also performs group (or inter-destination) synchronization control, which adjusts the output timing among terminals for preservation of the fairness among them, as well as error control and traffic control. We demonstrate the effectiveness of the scheme by carrying out an experiment of a networked shooting game.
{"title":"Adaptive causality and media synchronization control for networked multimedia applications","authors":"Y. Ishibashi, S. Tasaka, Yoshiro Tachibana","doi":"10.1109/ICC.2001.937378","DOIUrl":"https://doi.org/10.1109/ICC.2001.937378","url":null,"abstract":"This paper proposes a media synchronization scheme with adaptive /spl Delta/-causality control for networked multimedia applications in which the temporal and causal relationships exist among media streams such as computer data, voice, and video. In the scheme, the adaptive /spl Delta/-causality control, which varies the value of /spl Delta/ of the /spl Delta/-causality control according to the network load, is performed for causality, and the virtual-time rendering (VTR) algorithm, which the authors previously proposed, is used for media synchronization. The scheme also performs group (or inter-destination) synchronization control, which adjusts the output timing among terminals for preservation of the fairness among them, as well as error control and traffic control. We demonstrate the effectiveness of the scheme by carrying out an experiment of a networked shooting game.","PeriodicalId":203874,"journal":{"name":"ICC 2001. IEEE International Conference on Communications. Conference Record (Cat. No.01CH37240)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115169330","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}
We introduce a forest whose nodes represent orthogonal variable spreading factor (OVSF) code sequences of different lengths used for multi-rate CDMA. These code sequences have properties that facilitate symbol rate adaptation and blind rate detection, which can be used in a fast time-varying environment such as mobile communication systems. The properties of these codes also makes flexible the assignment of code sequences of different lengths to different users who communicates at different constant symbol rates. In particular, certain lineages in the forest have a property that the set of code sequences represented by such a lineage are cyclic orthogonal to each other with unit length being that of the shortest sequence in the set. We present the forest-structured generation of the code sequences and their properties. Then, we present a symbol rate adaptation protocol and a blind rate detection algorithm that use the code properties.
{"title":"Symbol rate adaptation and blind rate detection using FOSSIL (forest for OVSF-sequence-set-inducing lineages)","authors":"L. Tsaur, D. Lee","doi":"10.1109/ICC.2001.937094","DOIUrl":"https://doi.org/10.1109/ICC.2001.937094","url":null,"abstract":"We introduce a forest whose nodes represent orthogonal variable spreading factor (OVSF) code sequences of different lengths used for multi-rate CDMA. These code sequences have properties that facilitate symbol rate adaptation and blind rate detection, which can be used in a fast time-varying environment such as mobile communication systems. The properties of these codes also makes flexible the assignment of code sequences of different lengths to different users who communicates at different constant symbol rates. In particular, certain lineages in the forest have a property that the set of code sequences represented by such a lineage are cyclic orthogonal to each other with unit length being that of the shortest sequence in the set. We present the forest-structured generation of the code sequences and their properties. Then, we present a symbol rate adaptation protocol and a blind rate detection algorithm that use the code properties.","PeriodicalId":203874,"journal":{"name":"ICC 2001. IEEE International Conference on Communications. Conference Record (Cat. No.01CH37240)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115739257","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}
This paper presents a new soft-input soft-output multistage partial parallel interference cancellation (PPIC) detector for direct-sequence code-division multiple-access (DS-CDMA) systems. The proposed detector has a similar simple structure to the conventional PPIC scheme presented by Divsalar et al. (1998). A new way of reliability iterating is derived based on the single-user maximum a posteriori (MAP) criterion. At each stage, extrinsic information is extracted and then used as the a priori information for the next stage. Extensive computer simulations have shown that the proposed approach is capable of offering a good performance gain over the conventional PPIC scheme and some other well-known multiuser detectors, especially when the system load is heavy.
{"title":"Soft-input soft-output partial parallel interference cancellation for DS-CDMA systems","authors":"Kuo-Ming Wu, Chin-Liang Wang","doi":"10.1109/ICC.2001.936859","DOIUrl":"https://doi.org/10.1109/ICC.2001.936859","url":null,"abstract":"This paper presents a new soft-input soft-output multistage partial parallel interference cancellation (PPIC) detector for direct-sequence code-division multiple-access (DS-CDMA) systems. The proposed detector has a similar simple structure to the conventional PPIC scheme presented by Divsalar et al. (1998). A new way of reliability iterating is derived based on the single-user maximum a posteriori (MAP) criterion. At each stage, extrinsic information is extracted and then used as the a priori information for the next stage. Extensive computer simulations have shown that the proposed approach is capable of offering a good performance gain over the conventional PPIC scheme and some other well-known multiuser detectors, especially when the system load is heavy.","PeriodicalId":203874,"journal":{"name":"ICC 2001. IEEE International Conference on Communications. Conference Record (Cat. No.01CH37240)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124264466","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}
The characteristics of spreading sequences significantly affect the performance of the forward link DS-CDMA system in a fading channel. The bit error rate (BER) is a function of the signal-to-interference ratio (SIR) which has different characteristics depending upon the spreading sequence. In this paper, the SIR is analyzed when orthogonal codes and pseudo random codes are used as the spreading sequence. The BER performance is analyzed with and without the use of convolutional codes. The use of orthogonal codes can cancel out the interference signals having the same path delay, but the use of random codes cannot, resulting in significant performance degradation. As a result, the BER performance of the orthogonal spreading system is much better than that of the random spreading system. Even in the case of many multipaths, the number of users achieving a fixed BER value in the orthogonal spreading system is twice larger than that in the random spreading system. The analytical results are verified by computer simulation.
{"title":"Performance analysis of forward link DS-CDMA systems using random and orthogonal spreading sequences","authors":"Jihoon Choi, Yong-Hwan Lee, Yong-Ho Kim","doi":"10.1109/ICC.2001.937160","DOIUrl":"https://doi.org/10.1109/ICC.2001.937160","url":null,"abstract":"The characteristics of spreading sequences significantly affect the performance of the forward link DS-CDMA system in a fading channel. The bit error rate (BER) is a function of the signal-to-interference ratio (SIR) which has different characteristics depending upon the spreading sequence. In this paper, the SIR is analyzed when orthogonal codes and pseudo random codes are used as the spreading sequence. The BER performance is analyzed with and without the use of convolutional codes. The use of orthogonal codes can cancel out the interference signals having the same path delay, but the use of random codes cannot, resulting in significant performance degradation. As a result, the BER performance of the orthogonal spreading system is much better than that of the random spreading system. Even in the case of many multipaths, the number of users achieving a fixed BER value in the orthogonal spreading system is twice larger than that in the random spreading system. The analytical results are verified by computer simulation.","PeriodicalId":203874,"journal":{"name":"ICC 2001. IEEE International Conference on Communications. Conference Record (Cat. No.01CH37240)","volume":"93 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116952359","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}
Ad hoc networks are deployed in situations where no base station is available and a network has to be built impromptu. Since there is no wired backbone, each host is a router and a packet forwarder. Each node may be mobile, and topology changes frequently and unpredictably. Routing protocol development has received much attention because mobility management and efficient bandwidth and power usage are critical in ad hoc networks. No existing protocol however, considers the load as the main route selection criteria. This routing philosophy can lead to network congestion and create bottlenecks. We present dynamic load-aware routing (DLAR) protocol that considers intermediate node routing loads as the primary route selection metric. The protocol also monitors the congestion status of active routes and reconstructs the path when nodes of the route have their interface queue overloaded. We describe three DLAR algorithms and show their effectiveness by presenting and comparing simulation results with an ad hoc routing protocol that uses the shortest paths.
{"title":"Dynamic load-aware routing in ad hoc networks","authors":"Sung-Ju Lee, M. Gerla","doi":"10.1109/ICC.2001.937263","DOIUrl":"https://doi.org/10.1109/ICC.2001.937263","url":null,"abstract":"Ad hoc networks are deployed in situations where no base station is available and a network has to be built impromptu. Since there is no wired backbone, each host is a router and a packet forwarder. Each node may be mobile, and topology changes frequently and unpredictably. Routing protocol development has received much attention because mobility management and efficient bandwidth and power usage are critical in ad hoc networks. No existing protocol however, considers the load as the main route selection criteria. This routing philosophy can lead to network congestion and create bottlenecks. We present dynamic load-aware routing (DLAR) protocol that considers intermediate node routing loads as the primary route selection metric. The protocol also monitors the congestion status of active routes and reconstructs the path when nodes of the route have their interface queue overloaded. We describe three DLAR algorithms and show their effectiveness by presenting and comparing simulation results with an ad hoc routing protocol that uses the shortest paths.","PeriodicalId":203874,"journal":{"name":"ICC 2001. IEEE International Conference on Communications. Conference Record (Cat. No.01CH37240)","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117168095","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}
The analysis, modeling and simulation of time-varying multipath wireless fading channels is usually done through input-output descriptions of the channel. In this paper, we introduce the concept of the state of the channel which is the solution of stochastic differential equations driven by white-noise (Brownian motion). In particular, we show that the dynamics of the instantaneous power associated with each path can be modeled using mean-reverting Ornstein-Uhlenbeck processes, and higher order models. These models are easy to analyze, implement and simulate, and therefore are important in the design and operation of wireless communication systems. The densities of these state processes are given by generalizations of the standard Rayleigh, Ricean, Nakagami-m densities.
{"title":"A state-space approach in modeling multipath fading channels via stochastic differential equations","authors":"C. Charalambous, N. Menemenlis","doi":"10.1109/ICC.2001.937056","DOIUrl":"https://doi.org/10.1109/ICC.2001.937056","url":null,"abstract":"The analysis, modeling and simulation of time-varying multipath wireless fading channels is usually done through input-output descriptions of the channel. In this paper, we introduce the concept of the state of the channel which is the solution of stochastic differential equations driven by white-noise (Brownian motion). In particular, we show that the dynamics of the instantaneous power associated with each path can be modeled using mean-reverting Ornstein-Uhlenbeck processes, and higher order models. These models are easy to analyze, implement and simulate, and therefore are important in the design and operation of wireless communication systems. The densities of these state processes are given by generalizations of the standard Rayleigh, Ricean, Nakagami-m densities.","PeriodicalId":203874,"journal":{"name":"ICC 2001. IEEE International Conference on Communications. Conference Record (Cat. No.01CH37240)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2001-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117187216","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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