Seppo Hämäläinen

System level analysis of vertical sectorization for 3GPP LTE

The aim of this paper is to evaluate the impact of a novel method for advanced antenna technologies for the downlink performance of the 3GPP Long Term Evolution (LTE) networks. The network performance impact of 3 × 2 vertical sectorization in different macro-cellular network scenarios for various combinations of antenna parameter configurations have been studied in terms of Signal to Interference plus Noise Ratio (SINR) and throughput performance. Simulation studies are performed for uniform UE distribution and full-buffer traffic by using LTE snap-shot simulator and three dimensional propagation modeling.

Performance of hybrid ARQ techniques for WCDMA high data rates

Hybrid ARQ is being considered as a potential method for improving the performance of WCDMA in UMTS. We compare different hybrid ARQ techniques, namely the incremental redundancy type II hybrid ARQ schemes and type I hybrid ARQ schemes with and without soft combining. The emphasis is at high data rates and downlink shared channel (DSCH). Both link and system simulations are used for comparison. The hybrid ARQ schemes are shown to achieve higher throughput and capacity than the conventional ARQ schemes currently specified in the 3GPP WCDMA standard. Also, the combining of packets can cut the tail of the delay distribution which reduces the required maximum number of transmissions. However, the complexity increase due to physical layer buffering in the mobile station is too high if the round trip delay is large.

Analysis of CDMA downlink capacity enhancements

The CDMA downlink capacity obtained by a system simulator is considered. Capacity improvements with macro-diversity, reception antenna diversity and with interference reduction techniques are analyzed. A cellular system simulator is utilized in assessing the achievable capacity gains with these techniques. Interference reduction can be achieved with, for example, interference canceling or with appropriate spreading code design. Algorithms for canceling interference are not described in this paper nor are antenna hardware requirements considered but the possible capacity gains are evaluated. Urban macro- and micro-cell environments are studied. The intra-cell interference cancellation is found to be important for the macro-cell environment, where as for micro-cell environment macro- or antenna-diversity means are seen as essential.

Comparison of Remote Electrical and Mechanical Antenna Downtilt Performance for 3GPP LTE

The aim of this paper is to evaluate and compare impacts of mechanical and electrical downtilt angles of antenna systems to the downlink performance of the 3GPP Long Term Evolution (LTE) networks. Cell coverage and capacity in different macro-cellular network scenarios for various combinations of antenna parameter configurations have been studied in terms of signal to interference plus noise ratio (SINR) performance. Simulation studies are performed for uniform UE distribution and full-buffer traffic by using LTE snap-shot simulator modeling electrical and mechanical antenna tilt in details and propagation in three dimensions.

Capacity evaluation of a cellular CDMA uplink with multiuser detection

The performance of a cellular CDMA uplink together with multiuser detection is evaluated. A system level simulator is built to utilise the link level simulation results and to derive the actual network capacity. A semistatic approach is chosen for the network simulator to model the special features in a CDMA system. The work is currently continued within the European Union ACTS program in the FRAMES project.

Analysis of Antenna Parameter Optimization Space for 3GPP LTE

The aim of this paper is to evaluate the impact of various antenna parameters to the down-link performance of the 3GPP Long Term Evolution (LTE) networks. The network performance impacts of horizontal and vertical half-power beamwidths (HPBW) as well as downtilt angle of antenna systems are investigated. Cell coverage and capacity in different macro-cellular network scenarios for various combinations of antenna parameter configurations have been studied in terms of signal to interference plus noise ratio (SINR) performance and cell throughput. Simulation studies are performed for uniform UE distribution and full-buffer traffic by using LTE snap-shot simulator where propagation is modeled in three dimensions. Keywords; LTE, Remote Electrical Antenna Tilt, Antenna Modeling, Adaptive Antenna Solutions.

Performance of a CDMA based hierarchical cell structure network

The link and system level performance of a cellular hierarchical cell structure (HCS) network utilising DS-CDMA and multi-user detection is evaluated. The adjacent channel interference (ACI) attenuation masks for the system level simulations were generated by using the characteristics of a measured power amplifier IC. The capacity of hierarchical cell structure network is evaluated. In this paper, both uplink and downlink are considered.

Self-healing framework for LTE networks

Fault management is an important part of the operations and maintenance subsystem (OSS) of cellular mobile networks. Perhaps the most important reason is to reduce the number of outages and duration of outages in the network in order to meet the operators requirements such as network availability, robustness, coverage and capacity etc. Increasing complexity of the cellular networks has significant impact on the operations and maintenance of the network. Automation is necessary to protect the operational as well as capital expenses of the cellular network. The aim of this paper is to present a self-healing framework developed for 3GPP Long Term Evolution (LTE) networks and to provide a platform where the detection and compensation of cell outages are evaluated in realistic environment. The impact of early fault detection and timely execution of compensation tasks are shown in terms of radio link failures and number of connected users.

Self-optimization of random access channel in 3rd Generation Partnership Project Long Term Evolution

The long term evolution (LTE) is being designed to enhance third generation radio access technologies, and it represents a major step towards high-performance mobile data networks that are fully optimized for packet-switched connections. In an initial access, the LTE user equipment executes the random access (RA) procedure while searching for serving base station and initiating services. For a good cell coverage to be obtained, feasible uplink data rate and low delays in, for example, call setup, the optimal random access channel (RACH) performance is essential. Although manual tuning of procedures can be very costly, it is important to design self-organizing network (SON) algorithms that optimize procedures such as RA. In this paper, a mathematical framework for the RACH modeling in LTE technology is presented on the basis of probability theory and statistics. A self-optimization algorithm for RACH preamble sequence allocation and preamble split is then examined using the deduced mathematical framework and system-level simulations. Performance analysis is semi-analytical: First, RACH performance results are produced using analytical model, and second, outputs are fed into a dynamic LTE network simulator. Results show that the proposed optimization approach clearly improves uplink performance and ensures a certain success rate at the first RA attempt so that shorter handover durations and call setup delays can be achieved. Copyright

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.