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Showing papers by "Preben Mogensen published in 2003"


01 Jan 2003
TL;DR: The HSDPA concept facilitates peak data rates exceeding 2 Mbps, and the cell throughput gain over previous UTRA-FDD releases has been evaluated to be in the order of 50-100% or even more, highly dependent on factors such as the radio environment and the service provision strategy of the network operator.
Abstract: This article gives an overview of the high speed downlink packet access (HSDPA) concept; a new feature which is coming to the Release 5 specifications of the 3GPP WCDMA/UTRA-FDD standard. To support an evolution towards more sophisticated network and multimedia services, the main target of HSDPA is to increase user peak data rates, quality of service, and to generally improve spectral efficiency for downlink asymmetrical and bursty packet data services. This is accomplished by introducing a fast and complex channel control mechanism based on a short and fixed packet transmission time interval (TTI), adaptive modulation and coding (AMC), and fast physical layer (L1) hybrid ARQ. To facilitate fast scheduling with a per-TTI resolution in coherence with the instantaneous air interface load, the HSDPA-related MAC functionality is moved to the Node-B. The HSDPA concept facilitates peak data rates exceeding 2 Mbps (theoretically up to and exceeding 10 Mbps), and the cell throughput gain over previous UTRA-FDD releases has been evaluated to be in the order of 50-100% or even more, highly dependent on factors such as the radio environment and the service provision strategy of the network operator.

126 citations


Journal ArticleDOI
TL;DR: The presented results show that beamforming within logical cells is an effective enabler for higher system capacity, while the use of beamforming for creation of many logical Cells is less attractive due to significantly larger soft handover overhead and somewhat reduced capacity gain.
Abstract: The opportunities and constraints for application of beamforming techniques in UMTS are reviewed and compared by means of extensive dynamic network-level simulations. We start by reviewing the physical layer specifications for UMTS in order to clarify which channels are allowed to use beamforming. Second, radio resource management for cells with beamforming capabilities are addressed from a standardization and algorithmic point of view. The exchange of beamforming specific measurement reports between the base station (Node-B) and the radio network controller is discussed as well as beam switching mechanisms, directional power-based admission control, and more. In addition to implementation of beamforming within logical cells, options for exploiting the antenna array to synthesize independent sector beams are also investigated (i.e., higher order sectorization via beamforming). The presented results show that beamforming within logical cells is an effective enabler for higher system capacity, while the use of beamforming for creation of many logical cells is less attractive due to significantly larger soft handover overhead and somewhat reduced capacity gain.

75 citations


Proceedings ArticleDOI
22 Apr 2003
TL;DR: Comparing the performance of the different transmit diversity schemes to single-antenna transmission, conditioned on proportional fair scheduling, it is found that the closed-loop schemes provide a benefit over a wide range of terminal speeds, whereas open-loop space-time block coding exhibits limited performance and in some cases even a loss.
Abstract: In evolving 3G systems, the proportional fair packet scheduling algorithm promises an attractive trade-off between average cell capacity and user fairness by exploiting multi-user selection diversity in time-shared channels. However, in these systems the option of antenna transmit diversity already exist, whose performance benefit is dependent on the considered scheduling strategy. This study focuses on the interaction between proportional fair packet scheduling and open or closed-loop transmit diversity techniques. The basic interaction is studied by using an analytical model. Additionally, Monte Carlo simulations are conducted to study the effect of scheduling delays. In the low mobility Rayleigh fading case, the potential average cell capacity gain with proportional fair scheduling, compared to a simple round robin in time approach, is on the order of 60% for single-antenna transmission. It reduces, however, to around 35% when dual antenna transmit diversity is additionally deployed. Comparing the performance of the different transmit diversity schemes to single-antenna transmission, conditioned on proportional fair scheduling, it is found that the closed-loop schemes provide a benefit over a wide range of terminal speeds, whereas open-loop space-time block coding exhibits limited performance and in some cases even a loss.

47 citations


Proceedings ArticleDOI
22 Apr 2003
TL;DR: In this paper, the performance of the high speed downlink packet access (HSDPA) concept when transmit and/or receive antenna diversity techniques are used is analyzed for round robin and proportional fair packet scheduling.
Abstract: This study addresses the performance of the high speed downlink packet access (HSDPA) concept when transmit and/or receive antenna diversity techniques are used. Two branch space-time transmit diversity (STTD), closed loop mode-1 transmit diversity (CLTD), dual RAKE receivers at the user equipment (UE), and the combination of dual RAKE and CLTD are analyzed for round robin and proportional fair packet scheduling. These schemes are compared against a reference scenario with single antenna transmission and reception. In pedestrian-A channels at 3 km/h, the combination of CLTD and dual RAKE receivers results in a cell capacity gain of 123% for round robin, while the gain is reduced to 38% for proportional fair. For round robin, the throughput gain per UE is found to be significantly larger for UEs at the cell edge (up to 320%), compared to UEs close to the base station. The equivalent throughput gain per UE for proportional fair equals 115%.

39 citations


Patent
15 Oct 2003
TL;DR: In this paper, a link adaptation for a transmission of data from a sender to a receiver through a communication channel to a variation of a transmission condition of said communication channel is provided.
Abstract: According to the invention a method is provided for a link adaptation for a transmission of data from a sender to a receiver through a communication channel to a variation of a transmission condition of said communication channel. The method comprises the steps of ascertaining at least one current value of at least a first quantity indicative of said transmission condition, comparing said current value with a first target value of said first quantity, modifying the ratio between said first target value and said current value of said first quantity in dependence on the result of said comparing step, and selecting a modulation and coding scheme for said data transmission from a predetermined number of modulation and coding schemes in dependence on the result of said comparing step and on the result of said modifying step. According to the method of the invention, in addition to an inner loop adaptation of the MCS a further adaptation of the first target value is performed. That is, there is a second, outer loop control mechanism for an ongoing transmission. This way, a better link adaptation may be obtained.

25 citations


Proceedings ArticleDOI
01 Jan 2003
TL;DR: The application and performance of WCDMA HSPDA in a beamforming environment is studied under channelization code constraints, using a blind and an intelligent packet scheduler, where it is found that more scrambling codes and less beams are typically required when using intelligent scheduling, compared to blind scheduling.
Abstract: The application and performance of WCDMA HSPDA (high speed downlink packet access) in a beamforming environment is studied under channelization code constraints, using a blind and an intelligent packet scheduler. Results for the optimal number of beams and scrambling codes per cell are presented, where it is found that more scrambling codes and less beams are typically required when using intelligent scheduling, compared to blind scheduling. The cell capacity over single antenna transmission is observed to be larger for radio channels with low temporal dispersion, compared to scenarios with high temporal dispersion. Mainly because an additional code-efficiency gain is obtained over single antenna transmission for environments with low temporal dispersion. The code-efficiency gain originates from a lower selection probability of the higher modulation and coding schemes, when beamforming and multiple scrambling codes are used.

19 citations


Proceedings ArticleDOI
22 Apr 2003
TL;DR: The results concentrate on the uplink noise rise (NR) behavior for different settings of PS related timers and show that a reduction of some of these timers to allow faster scheduling can increase the network capacity, but this potential capacity gain is achievable only for bursty and high user equipment (UE) source data rate.
Abstract: In this paper, we study the operation of release'99 packet scheduler of the UMTS system. We focus on the uplink direction of data transmission. The aim is to investigate the performance of the packet scheduler data scheduling on dedicated transport channels. We emphasize in particular a power based packet scheduler (PS) with fair resource sharing. The PS performance has been evaluated in a time-dynamic network simulator with packet data users characterized by a bursty source traffic model. We shortly describe the source traffic model and the network simulator. The results concentrate on the uplink noise rise (NR) behavior for different settings of PS related timers and show that a reduction of some of these timers to allow faster scheduling can increase the network capacity. However, the results also demonstrate that this potential capacity gain is achievable only for bursty and high user equipment (UE) source data rate.

14 citations


Patent
05 Sep 2003
TL;DR: In this article, a scheduling method and device for scheduling data transmission, usually over a plurality of channels in a data network, where a utilization of an allocated maximum channel capacity in a received data stream of at least one of the plurality channels is typically monitored, and future allocation of the maximum capacity is then normally controlled in response to the monitoring result.
Abstract: A scheduling method and device for scheduling data transmission, usually over a plurality of channels in a data network, wherein a utilization of an allocated maximum channel capacity in a received data stream of at least one of the plurality of channels is typically monitored, and future allocation of the maximum channel capacity is then normally controlled in response to the monitoring result. Thereby, data transmissions may be scheduled according to their often near instantaneous transmission capacity requirements, usually without requiring any explicit uplink signaling.

12 citations