Ramon Agusti - Academia.edu (original) (raw)

Papers by Ramon Agusti

Spatial diversity is an attractive technology to cope with the fading channel encountered in mobi... more Spatial diversity is an attractive technology to cope with the fading channel encountered in mobile communications. This paper presents novel closed analytical expressions of the bit-error rate (BER) achievable in a coherent binary phase-shiftkeying (CBPSK) direct-sequence code-division multiple-access (DS/CDMA) system for any power delay profile and for either postdetection selection or maximal ratio combining (MRC). In particular, expressions for the cutoff rate R o and for its related parameter D are also formulated in order to assess the system performance under the consideration of some channel coding schemes. Finally, an exemplary study is carried out in order to illustrate the behavior of a realistic space-diversity code-division multiple-access (CDMA) system according to the analytical expressions that have been derived.

IEEE Communications Letters, 2005

This paper analyzes the performance of a MAC scheme for wireless local area networks (WLANs) that... more This paper analyzes the performance of a MAC scheme for wireless local area networks (WLANs) that makes use of distributed queues to improve radio channel utilization. Analytical values for the maximum throughput performance are derived as a function of the system parameters. The obtained results show that the proposed scheme outperforms the legacy 802.11 MAC protocol in terms of maximum stable throughput. This benefit is obtained from eliminating back-off periods and collisions in data packet transmissions while minimizing the needed control overhead. The proposal also makes performance to be independent of the number of nodes transmitting in the system and provides stability for high load conditions. Index Terms-Distributed queuing, expected effective throughput, IEEE 802.11, MAC, WLAN.

The paper analyses the performance of a novel MAC-PHY scheme for wireless local area networks (WL... more The paper analyses the performance of a novel MAC-PHY scheme for wireless local area networks (WLAN) that makes use of distributed queues and cross-layer concepts to improve radio channel utilisation. Analytical values for the maximum throughput performance are derived as a function of different scenario parameters. The obtained results show that the proposed scheme outperforms throughput bounds achieved when using a legacy 802.11 MAC protocol. The usage of distributed queues and cross-layer information eliminates back-off periods and collisions in data packet transmissions, makes performance to be independent of the number of stations transmitting in the system and provides stability for high load conditions. Furthermore, the cross-layer concept allows the MAC layer to improve its decisions by means of physical layer information knowledge.

IEEE Transactions on Communications, 1989

In this paper, a calculation method for assessing the asynchronous frequency-hopping (FH) spread-... more In this paper, a calculation method for assessing the asynchronous frequency-hopping (FH) spread-spectrum multiple-access performance has been envisaged. The method is based upon a Gauss quadrature rule and for this purpose a moment generation algorithm of the random variables involved has been introduced. False alarm and miss probabilities in a basic FH search acquisition configuration and bit error rate in both slow and fast FH binary frequency-shift keyed have been obtained. Different power levels of the multiuser interference, user activity modeled as a Poisson point process and nonfading as well as nonselective Rayleigh fading channels have been considered. , where he became Full Professor in 1987. He has been working in the field of digital communications with particular emphasis on digital radio, both fixed radio relay and mobile communications. In the last few years he has also been concerned with the performance analysis and development of frequencyhopped spread-spectrum systems. His research interests are in the area of communications theory with current emphasis on spread-spectrum systems, digital radio, and trellis coded modulation.

This paper proposes a new Radio Access Technology (RAT) selection algorithm for multi-service sce... more This paper proposes a new Radio Access Technology (RAT) selection algorithm for multi-service scenarios which allows increasing the capacity of heterogeneous CDMA/TDMA systems by controlling the effective cell radius of the CDMAbased system (i.e. a network-controlled cell-breathing), so that the interference level is reduced. The strategy is evaluated in a scenario including voice and interactive traffic and combined with service-based RAT selection strategies.

The heterogeneous network concept offers a flexible architecture that allows an efficient utiliza... more The heterogeneous network concept offers a flexible architecture that allows an efficient utilization of radio resources by means of Common RRM strategies that ensure a coordinated management of the resource pools in each Radio Access Network. In this context, this paper discusses different strategies for initial RAT selection as one of the key CRRM strategies. A general framework for the definition of policy-based RAT selection strategies is proposed and some specific examples are evaluated by means of simulations.

This paper proposes a new Common Radio Resource Management (CRRM) methodology which allows increa... more This paper proposes a new Common Radio Resource Management (CRRM) methodology which allows increasing the capacity of heterogeneous CDMA/TDMA. This is achieved by controlling the effective cell radius of the CDMAbased system (i.e. a network-controlled cell-breathing) through appropriate initial RAT selection and vertical handover strategies, so that the interference level in the CDMA-based RAT is reduced while at the same time the target coverage area is assured by means of the cooperation of the FDMA/TDMA based RATs. The proposed approach is evaluated by means of system level simulations in a detailed scenario including UTRAN and GERAN as examples of CDMA and FDMA/TDMA-based access technologies. Results reveal that throughput improvements up to 24% can be achieved with respect to other CRRM strategies based on load balancing principles.

Indoor traffic is expected to be key in 3G networks. Nevertheless, the implications of indoor tra... more Indoor traffic is expected to be key in 3G networks. Nevertheless, the implications of indoor traffic in a 3G WCDMA- based network may be significantly different from those already well know in 2G TDMA-based networks. This papers reveals, by means of a simple analytical model that uplink is much more sensitive than downlink in WCDMA in terms of capacity degradation

IEEE Journal on Selected Areas in Communications, 2001

In the context of third-generation (3G) systems a mix of services with different requirements are... more In the context of third-generation (3G) systems a mix of services with different requirements are expected. Consequently, packet scheduling mechanisms for quality of service (QoS) guarantees will play a key role. This paper proposes a new scheduling strategy that makes consistent the target quality in the radio link with the priority level assigned to each user. The performance of such a strategy is assessed by system level simulations and, in order to gain more insight into the difficulties of this optimization problem, it is compared to other alternatives.

IEEE Communications Magazine, 2003

Third-generation mobile communication systems will bring a wide range of new services with differ... more Third-generation mobile communication systems will bring a wide range of new services with different quality of service requirements and will open the ability to exploit radio resource management functions to guarantee a certain target QoS, to maintain the planned coverage area and to offer a high-capacity while using the radio resources in an efficient way. RRM functions impact the overall system efficiency and the operator infrastructure cost, so they will definitively play an important role in a mature 3G scenario. In order to provide some insight into RRM strategies implementation, a range of representative case studies with several innovative algorithms arc presented and supported by simulation results in a realistic UMTS Terrestrial Radio Access Network scenario as devised in the 3GGP standardization forum. In particular, a decentralized uplink transmission ratc selection algorithm in the short term, a congestion control mechanism to cope with overload situations, and downlink scheduling for layered streaming video packets are proposed. 100 0163-6804103/$17.00 0 2003 IEEE IEEE Communications Magazine February 2003

IEEE Journal on Selected Areas in Communications, 2000

This paper presents and analyzes a new near-optimum medium access control (MAC) protocol. The pro... more This paper presents and analyzes a new near-optimum medium access control (MAC) protocol. The proposed access scheme is suitable for a CDMA mobile communication environment, and keeps under control and upper bounded the number of simultaneous transmissions. It has a delay performance approaching that of an ideal optimum M/M/K system, where K is the number of spreading codes being used (maximum number of simultaneous transmissions). The protocol is a free random access protocol when the traffic load is light, and switches smoothly and automatically to a reservation protocol when traffic load becomes heavier. It is based on distributed queues and a collision resolution algorithm. Moreover, a physical receiver structure is proposed and analyzed in order to preserve the robustness of the protocol in a wireless link. The results obtained show that the protocol outperforms other well known medium access protocols in terms of stability and delay, even when taking into account the loss caused by channel propagation conditions.

This paper proposes a new Radio Access Technology (RAT) selection algorithm for multi-service sce... more This paper proposes a new Radio Access Technology (RAT) selection algorithm for multi-service scenarios which allows increasing the capacity of heterogeneous CDMA/TDMA systems by controlling the effective cell radius of the CDMAbased system (i.e. a network-controlled cell-breathing), so that the interference level is reduced. The strategy is evaluated in a scenario including voice and interactive traffic and combined with service-based RAT selection strategies.

IEEE Communications Magazine, 2004

The heterogeneous network concept offers a flexible architecture that allows an efficient utiliza... more The heterogeneous network concept offers a flexible architecture that allows an efficient utilization of radio resources by means of Common RRM strategies that ensure a coordinated management of the resource pools in each Radio Access Network. In this context, this paper discusses different strategies for initial RAT selection as one of the key CRRM strategies. A general framework for the definition of policy-based RAT selection strategies is proposed and some specific examples are evaluated by means of simulations.

This paper proposes a new Common Radio Resource Management (CRRM) methodology which allows increa... more This paper proposes a new Common Radio Resource Management (CRRM) methodology which allows increasing the capacity of heterogeneous CDMA/TDMA. This is achieved by controlling the effective cell radius of the CDMAbased system (i.e. a network-controlled cell-breathing) through appropriate initial RAT selection and vertical handover strategies, so that the interference level in the CDMA-based RAT is reduced while at the same time the target coverage area is assured by means of the cooperation of the FDMA/TDMA based RATs. The proposed approach is evaluated by means of system level simulations in a detailed scenario including UTRAN and GERAN as examples of CDMA and FDMA/TDMA-based access technologies. Results reveal that throughput improvements up to 24% can be achieved with respect to other CRRM strategies based on load balancing principles.

This paper proposes a new Radio Access Technology (RAT) selection algorithm which allows increasi... more This paper proposes a new Radio Access Technology (RAT) selection algorithm which allows increasing the capacity of heterogeneous CDMA/TDMA systems. This is achieved by controlling the effective cell radius of the CDMA-based system (i.e. a network-controlled cell-breathing), so that the interference level in the CDMA-based RAT is reduced while at the same time the target coverage area is assured by

Indoor traffic is expected to be key in 3G networks. Nevertheless, the implications of indoor tra... more Indoor traffic is expected to be key in 3G networks. Nevertheless, the implications of indoor traffic in a 3G WCDMA- based network may be significantly different from those already well know in 2G TDMA-based networks. This papers reveals, by means of a simple analytical model that uplink is much more sensitive than downlink in WCDMA in terms of capacity degradation

... non-satisfaction probability of1% (ie the probability that the allocated bandwidth is below .... more ... non-satisfaction probability of1% (ie the probability that the allocated bandwidth is below ... Jaekel, Friedrich K. Jondral: ,,Auction Sequence as a New Resource Allocation Mechansim'; VTC05 Fall, Dallas, 2005 [2] C. Kloeck, Holger Jaekel, Friedrich K. Jondral: ,,Dynamic an Local ...

IEEE Journal on Selected Areas in Communications, 2001

In the context of third-generation (3G) systems a mix of services with different requirements are... more In the context of third-generation (3G) systems a mix of services with different requirements are expected. Consequently, packet scheduling mechanisms for quality of service (QoS) guarantees will play a key role. This paper proposes a new scheduling strategy that makes consistent the target quality in the radio link with the priority level assigned to each user. The performance of such a strategy is assessed by system level simulations and, in order to gain more insight into the difficulties of this optimization problem, it is compared to other alternatives.

IEEE Communications Magazine, 2003

Third-generation mobile communication systems will bring a wide range of new services with differ... more Third-generation mobile communication systems will bring a wide range of new services with different quality of service requirements and will open the ability to exploit radio resource management functions to guarantee a certain target QoS, to maintain the planned coverage area and to offer a high-capacity while using the radio resources in an efficient way. RRM functions impact the overall system efficiency and the operator infrastructure cost, so they will definitively play an important role in a mature 3G scenario. In order to provide some insight into RRM strategies implementation, a range of representative case studies with several innovative algorithms arc presented and supported by simulation results in a realistic UMTS Terrestrial Radio Access Network scenario as devised in the 3GGP standardization forum. In particular, a decentralized uplink transmission ratc selection algorithm in the short term, a congestion control mechanism to cope with overload situations, and downlink scheduling for layered streaming video packets are proposed. 100 0163-6804103/$17.00 0 2003 IEEE IEEE Communications Magazine February 2003

Spatial diversity is an attractive technology to cope with the fading channel encountered in mobi... more Spatial diversity is an attractive technology to cope with the fading channel encountered in mobile communications. This paper presents novel closed analytical expressions of the bit-error rate (BER) achievable in a coherent binary phase-shiftkeying (CBPSK) direct-sequence code-division multiple-access (DS/CDMA) system for any power delay profile and for either postdetection selection or maximal ratio combining (MRC). In particular, expressions for the cutoff rate R o and for its related parameter D are also formulated in order to assess the system performance under the consideration of some channel coding schemes. Finally, an exemplary study is carried out in order to illustrate the behavior of a realistic space-diversity code-division multiple-access (CDMA) system according to the analytical expressions that have been derived.

IEEE Communications Letters, 2005

This paper analyzes the performance of a MAC scheme for wireless local area networks (WLANs) that... more This paper analyzes the performance of a MAC scheme for wireless local area networks (WLANs) that makes use of distributed queues to improve radio channel utilization. Analytical values for the maximum throughput performance are derived as a function of the system parameters. The obtained results show that the proposed scheme outperforms the legacy 802.11 MAC protocol in terms of maximum stable throughput. This benefit is obtained from eliminating back-off periods and collisions in data packet transmissions while minimizing the needed control overhead. The proposal also makes performance to be independent of the number of nodes transmitting in the system and provides stability for high load conditions. Index Terms-Distributed queuing, expected effective throughput, IEEE 802.11, MAC, WLAN.

The paper analyses the performance of a novel MAC-PHY scheme for wireless local area networks (WL... more The paper analyses the performance of a novel MAC-PHY scheme for wireless local area networks (WLAN) that makes use of distributed queues and cross-layer concepts to improve radio channel utilisation. Analytical values for the maximum throughput performance are derived as a function of different scenario parameters. The obtained results show that the proposed scheme outperforms throughput bounds achieved when using a legacy 802.11 MAC protocol. The usage of distributed queues and cross-layer information eliminates back-off periods and collisions in data packet transmissions, makes performance to be independent of the number of stations transmitting in the system and provides stability for high load conditions. Furthermore, the cross-layer concept allows the MAC layer to improve its decisions by means of physical layer information knowledge.

IEEE Transactions on Communications, 1989

In this paper, a calculation method for assessing the asynchronous frequency-hopping (FH) spread-... more In this paper, a calculation method for assessing the asynchronous frequency-hopping (FH) spread-spectrum multiple-access performance has been envisaged. The method is based upon a Gauss quadrature rule and for this purpose a moment generation algorithm of the random variables involved has been introduced. False alarm and miss probabilities in a basic FH search acquisition configuration and bit error rate in both slow and fast FH binary frequency-shift keyed have been obtained. Different power levels of the multiuser interference, user activity modeled as a Poisson point process and nonfading as well as nonselective Rayleigh fading channels have been considered. , where he became Full Professor in 1987. He has been working in the field of digital communications with particular emphasis on digital radio, both fixed radio relay and mobile communications. In the last few years he has also been concerned with the performance analysis and development of frequencyhopped spread-spectrum systems. His research interests are in the area of communications theory with current emphasis on spread-spectrum systems, digital radio, and trellis coded modulation.

This paper proposes a new Radio Access Technology (RAT) selection algorithm for multi-service sce... more This paper proposes a new Radio Access Technology (RAT) selection algorithm for multi-service scenarios which allows increasing the capacity of heterogeneous CDMA/TDMA systems by controlling the effective cell radius of the CDMAbased system (i.e. a network-controlled cell-breathing), so that the interference level is reduced. The strategy is evaluated in a scenario including voice and interactive traffic and combined with service-based RAT selection strategies.

The heterogeneous network concept offers a flexible architecture that allows an efficient utiliza... more The heterogeneous network concept offers a flexible architecture that allows an efficient utilization of radio resources by means of Common RRM strategies that ensure a coordinated management of the resource pools in each Radio Access Network. In this context, this paper discusses different strategies for initial RAT selection as one of the key CRRM strategies. A general framework for the definition of policy-based RAT selection strategies is proposed and some specific examples are evaluated by means of simulations.

This paper proposes a new Common Radio Resource Management (CRRM) methodology which allows increa... more This paper proposes a new Common Radio Resource Management (CRRM) methodology which allows increasing the capacity of heterogeneous CDMA/TDMA. This is achieved by controlling the effective cell radius of the CDMAbased system (i.e. a network-controlled cell-breathing) through appropriate initial RAT selection and vertical handover strategies, so that the interference level in the CDMA-based RAT is reduced while at the same time the target coverage area is assured by means of the cooperation of the FDMA/TDMA based RATs. The proposed approach is evaluated by means of system level simulations in a detailed scenario including UTRAN and GERAN as examples of CDMA and FDMA/TDMA-based access technologies. Results reveal that throughput improvements up to 24% can be achieved with respect to other CRRM strategies based on load balancing principles.

Indoor traffic is expected to be key in 3G networks. Nevertheless, the implications of indoor tra... more Indoor traffic is expected to be key in 3G networks. Nevertheless, the implications of indoor traffic in a 3G WCDMA- based network may be significantly different from those already well know in 2G TDMA-based networks. This papers reveals, by means of a simple analytical model that uplink is much more sensitive than downlink in WCDMA in terms of capacity degradation

IEEE Journal on Selected Areas in Communications, 2001

In the context of third-generation (3G) systems a mix of services with different requirements are... more In the context of third-generation (3G) systems a mix of services with different requirements are expected. Consequently, packet scheduling mechanisms for quality of service (QoS) guarantees will play a key role. This paper proposes a new scheduling strategy that makes consistent the target quality in the radio link with the priority level assigned to each user. The performance of such a strategy is assessed by system level simulations and, in order to gain more insight into the difficulties of this optimization problem, it is compared to other alternatives.

IEEE Communications Magazine, 2003

Third-generation mobile communication systems will bring a wide range of new services with differ... more Third-generation mobile communication systems will bring a wide range of new services with different quality of service requirements and will open the ability to exploit radio resource management functions to guarantee a certain target QoS, to maintain the planned coverage area and to offer a high-capacity while using the radio resources in an efficient way. RRM functions impact the overall system efficiency and the operator infrastructure cost, so they will definitively play an important role in a mature 3G scenario. In order to provide some insight into RRM strategies implementation, a range of representative case studies with several innovative algorithms arc presented and supported by simulation results in a realistic UMTS Terrestrial Radio Access Network scenario as devised in the 3GGP standardization forum. In particular, a decentralized uplink transmission ratc selection algorithm in the short term, a congestion control mechanism to cope with overload situations, and downlink scheduling for layered streaming video packets are proposed. 100 0163-6804103/$17.00 0 2003 IEEE IEEE Communications Magazine February 2003

IEEE Journal on Selected Areas in Communications, 2000

This paper presents and analyzes a new near-optimum medium access control (MAC) protocol. The pro... more This paper presents and analyzes a new near-optimum medium access control (MAC) protocol. The proposed access scheme is suitable for a CDMA mobile communication environment, and keeps under control and upper bounded the number of simultaneous transmissions. It has a delay performance approaching that of an ideal optimum M/M/K system, where K is the number of spreading codes being used (maximum number of simultaneous transmissions). The protocol is a free random access protocol when the traffic load is light, and switches smoothly and automatically to a reservation protocol when traffic load becomes heavier. It is based on distributed queues and a collision resolution algorithm. Moreover, a physical receiver structure is proposed and analyzed in order to preserve the robustness of the protocol in a wireless link. The results obtained show that the protocol outperforms other well known medium access protocols in terms of stability and delay, even when taking into account the loss caused by channel propagation conditions.

This paper proposes a new Radio Access Technology (RAT) selection algorithm for multi-service sce... more This paper proposes a new Radio Access Technology (RAT) selection algorithm for multi-service scenarios which allows increasing the capacity of heterogeneous CDMA/TDMA systems by controlling the effective cell radius of the CDMAbased system (i.e. a network-controlled cell-breathing), so that the interference level is reduced. The strategy is evaluated in a scenario including voice and interactive traffic and combined with service-based RAT selection strategies.

IEEE Communications Magazine, 2004

The heterogeneous network concept offers a flexible architecture that allows an efficient utiliza... more The heterogeneous network concept offers a flexible architecture that allows an efficient utilization of radio resources by means of Common RRM strategies that ensure a coordinated management of the resource pools in each Radio Access Network. In this context, this paper discusses different strategies for initial RAT selection as one of the key CRRM strategies. A general framework for the definition of policy-based RAT selection strategies is proposed and some specific examples are evaluated by means of simulations.

This paper proposes a new Common Radio Resource Management (CRRM) methodology which allows increa... more This paper proposes a new Common Radio Resource Management (CRRM) methodology which allows increasing the capacity of heterogeneous CDMA/TDMA. This is achieved by controlling the effective cell radius of the CDMAbased system (i.e. a network-controlled cell-breathing) through appropriate initial RAT selection and vertical handover strategies, so that the interference level in the CDMA-based RAT is reduced while at the same time the target coverage area is assured by means of the cooperation of the FDMA/TDMA based RATs. The proposed approach is evaluated by means of system level simulations in a detailed scenario including UTRAN and GERAN as examples of CDMA and FDMA/TDMA-based access technologies. Results reveal that throughput improvements up to 24% can be achieved with respect to other CRRM strategies based on load balancing principles.

This paper proposes a new Radio Access Technology (RAT) selection algorithm which allows increasi... more This paper proposes a new Radio Access Technology (RAT) selection algorithm which allows increasing the capacity of heterogeneous CDMA/TDMA systems. This is achieved by controlling the effective cell radius of the CDMA-based system (i.e. a network-controlled cell-breathing), so that the interference level in the CDMA-based RAT is reduced while at the same time the target coverage area is assured by

Indoor traffic is expected to be key in 3G networks. Nevertheless, the implications of indoor tra... more Indoor traffic is expected to be key in 3G networks. Nevertheless, the implications of indoor traffic in a 3G WCDMA- based network may be significantly different from those already well know in 2G TDMA-based networks. This papers reveals, by means of a simple analytical model that uplink is much more sensitive than downlink in WCDMA in terms of capacity degradation

... non-satisfaction probability of1% (ie the probability that the allocated bandwidth is below .... more ... non-satisfaction probability of1% (ie the probability that the allocated bandwidth is below ... Jaekel, Friedrich K. Jondral: ,,Auction Sequence as a New Resource Allocation Mechansim'; VTC05 Fall, Dallas, 2005 [2] C. Kloeck, Holger Jaekel, Friedrich K. Jondral: ,,Dynamic an Local ...

IEEE Journal on Selected Areas in Communications, 2001

In the context of third-generation (3G) systems a mix of services with different requirements are... more In the context of third-generation (3G) systems a mix of services with different requirements are expected. Consequently, packet scheduling mechanisms for quality of service (QoS) guarantees will play a key role. This paper proposes a new scheduling strategy that makes consistent the target quality in the radio link with the priority level assigned to each user. The performance of such a strategy is assessed by system level simulations and, in order to gain more insight into the difficulties of this optimization problem, it is compared to other alternatives.

IEEE Communications Magazine, 2003

Third-generation mobile communication systems will bring a wide range of new services with differ... more Third-generation mobile communication systems will bring a wide range of new services with different quality of service requirements and will open the ability to exploit radio resource management functions to guarantee a certain target QoS, to maintain the planned coverage area and to offer a high-capacity while using the radio resources in an efficient way. RRM functions impact the overall system efficiency and the operator infrastructure cost, so they will definitively play an important role in a mature 3G scenario. In order to provide some insight into RRM strategies implementation, a range of representative case studies with several innovative algorithms arc presented and supported by simulation results in a realistic UMTS Terrestrial Radio Access Network scenario as devised in the 3GGP standardization forum. In particular, a decentralized uplink transmission ratc selection algorithm in the short term, a congestion control mechanism to cope with overload situations, and downlink scheduling for layered streaming video packets are proposed. 100 0163-6804103/$17.00 0 2003 IEEE IEEE Communications Magazine February 2003