Janne Kurjenniemi

Uplink power control in UTRA TDD

This paper discusses uplink power control in UTRA TDD, that is, the TDD (time division duplex) mode of the third generation mobile radio system UTRA (UMTS Terrestrial Radio Access), and presents system simulations made for it. The current UTRA TDD uplink power control contains several measurements that involve A considerably amount of error. Also THE power set by power control may involve error. In this paper the effect of power control error on the performance of the UTRA TDD network is studied by the means of a system level simulator.

System Level Performance of Multimedia Broadcast Multicast Service (MBMS) with Macro Diversity

The aim of this paper is to evaluate the system level performance of multimedia broadcast multicast service (MBMS) in WCDMA networks. To enhance coverage and data rates of MBMS users, two macro diversity concepts were introduced in 3GPP release 6: soft and selective combining. Prior work on the evaluation of MBMS with macro diversity schemes has been restricted to link level studies or to very limited scenarios in system level studies. This paper examines the concepts in more detail with dynamic system level tool in which e.g. mobility of users and interactions of the radio resource management functionalities are explicitly taken into account. The evaluation of combining set size and data rates with different thresholds and delays in the combining procedures are especially emphasized. Considering point-to-multipoint (p-t-m) mode of MBMS, the studies indicated clear performance improvements to be gained with macro diversity. In addition, the impact of delays in combining set update procedures was observed to be rather small.

WCDMA HSDPA network performance with receive diversity and LMMSE chip equalization

More advanced receiver structures than the conventional single antenna Rake can be used to improve the signal-to-noise (SNR) ratios, which is especially beneficial in order to utilize the high bit rates provided by the HSDPA concept in WCDMA network. In WCDMA system, orthogonal Walsh-Hadamard sequences are used as channelization codes. In frequency-selective fading channels the orthogonality of channelization codes disappears and intra-cell multiple access interference (MAI) arises. In order to mitigate the effect of MAI, a chip-level equalization has shown to be a simple and effective solution. The effectiveness of chip equalization, however, degrades at the cell borders where the inter-cell interference dominates rather than MAI. Dual antenna is a straight-forward solution to mitigate that performance drop. In this paper we consider receivers equipped with dual antenna and linear minimum mean squared error (LMMSE) chip-level equalizers and present an analysts of the expected gains over conventional single and dual antenna rake receivers in realistic situations by using a dynamic WCDMA system-level tool

Convergence of UTRA TDD uplink power control

In this article convergence of UTRA TDD uplink dedicated physical channel (DPCH) power control is studied. Current uplink power control is based on several measurements, which involve both random and systematic errors. Outer loop power control is used to compensate the systematic error. Since the amount of systematic error is unknown in the beginning of a call and after each handover, the outer loop power control should adapt to the current conditions as fast as possible. In this paper the effect of the convergence speed of the outer loop power control to the UTRA TDD system performance is analyzed by the means of dynamic system level simulator.

Downlink power control of dedicated channels in UTRA TDD

This paper discusses downlink power control of dedicated channels in UTRA TDD. The current UTRA TDD downlink power control is similar to the one in UTRA FDD mode, that comprises of closed inner loop and quality based outer loop. However, due to the time division feature and associated flexibility with asymmetry of TDD, the inner loop can not operate as fast as in FDD and it is affected by rapid changes in environment. Therefore, the effect of downlink power control of dedicated channel inner loop algorithm to the performance of UTRA TDD network is studied in this paper. A dynamic system level simulator is used for this purpose.

Signaled step size for downlink power control of dedicated channels in UTRA TDD

This paper discusses downlink inner loop power control in UTRA TDD. The current UTRA TDD downlink power control is similar to one in UTRA FDD mode, but due to the time division feature of TDD it can not operate as fast as in FDD and it is affected by rapid changes in environment. In this paper an improvement for the downlink inner loop power control algorithm is presented in which the power control step size is based on the difference between UE measured SIR and target SIR. This difference is then signaled from UE to UTRAN. Since the effectiveness of this algorithm depends on available signaling bandwidth that is used, dynamic system simulations are carried out to find out how many bits are needed for the signaling and how this algorithm is affected by signaling and measurement errors.

Improving UTRA TDD downlink power control with asymmetrical steps

This paper discusses downlink power control of dedicated channels in UTRA TDD. The current UTRA TDD downlink power control is similar to the one in UTRA FDD mode, that comprises of closed inner loop and quality based outer loop. However, due to the time division feature and associated flexibility with asymmetry of TDD, the inner loop can not react as fast as in FDD and it is affected by rapid changes in environment. Therefore, the effect of the inner loop algorithm to the performance of UTRA TDD network is studied in this paper. Especially, the use of asymmetrical step sizes in power adjustment is proposed, and the achieved gains are highlighted by the means of dynamic system simulations.

Frame configuration impact to the performance of UTRA TDD system

In this paper we consider the performance of a UTRA TDD system with various slot configurations. UTRA TDD supports flexible and dynamic channel allocations thus it can he configured to different service needs. Uplink and downlink transmissions have different characteristics and in this study we are concentrating on the requirements for symmetrical services in dedicated channels. Effect of number of beacon channels per radio frame and effect of different uplink and downlink partitioning to TDD system capacity are analyzed with dynamic system level simulator. Although this study is limited to circuit-switched data service these findings can be used as a starting point when building up mixed traffic scenarios with asymmetrical services.

Handover and Uplink Power Control Performance in the 3.84 Mcps TDD mode of UTRA Network

In this article we consider the performance of the 3.84 Mcpstime-division duplex (TDD) mode of UTRA (Universal TerrestrialRadio Access) network. We emphasize two of the radio resourcemanagement algorithms, handover and uplink power control, whoserole in the overall system performance is studied extensively.First, a handover algorithm used in WCDMA (Wideband Code DivisionMultiple Access) standard is considered in a TDD-mode operation.This gives rise to a careful setting of different handoverparameters, and the evaluation of the effects to the systemperformance. Secondly, the specified uplink power controlalgorithm is considered. Since it is based on several user-mademeasurements which may involve both random and systematic errors acareful study about the suitability of the power control scheme iscarried out.

A Packet Level Simulator for Future Satellite Communications Research

High Throughput Satellites (HTS) provide many times the throughput of the conventional satellites for the same amount of allocated orbital spectrum. Increased capacity can be provided due to multiple spot beams and frequency re-use whereas conventional satellites use single broad beam or a few beams. These kind of multi-beam systems can also use more advanced Radio Resource Management (RRM) algorithms to control interference levels between beams. System level simulations have increased importance in system design as well as in standardization support due to the ability to provide faster feedback on technological solutions without the need for early-stage test-bed and real systems development. However, there is a need for modular open-source satellite system simulator which would adopt the latest Digital Video Broadcasting (DVB) satellite standards. DVB organisation has published a bluebook for the 2 generation of satellite return link specification, DVB-RCS2. Also, the evolution of DVB-S2, called DVB-S2x, has been standardized by DVB organization in March 2014. Current simulators owned by satellite vendors, operators and research organizations may be proprietary, generally tailored for special purposes and/or may be based on commercial licenses. In this paper we present an overview of a satellite model developed on top of an open-source system/packet level simulator Network Simulator 3 (NS-3) and we are concentrating on the packet acquisition modelling including Signal-to-Noise-and-Interference (SINR) calculation and interference modelling. Simulator module is developed to be highly modular and flexible to be able to match the future R&D needs of satellite system vendors, operators, research organizations, as well as scientific community.