Jaana Laiho-Steffens

Estimation of capacity and required transmission power of WCDMA downlink based on a downlink pole equation

A simple method is derived for estimating the downlink capacity and required base station transmission power in a WCDMA system. This is based on a downlink pole equation which is mostly similar with the well known CDMA uplink pole equation. It is shown that the total downlink transmission power is composed of two terms. The first term is equal to what would be needed in the absence of interference and the second one shows the increase due to multiple access interference which is inversely proportional to 1-/spl eta//sub DL/ where /spl eta//sub DL/ is called the downlink loading. The method can be used in radio network dimensioning where extensive simulations can not be run. Usage of the method is demonstrated by some examples.

The performance of polarization diversity schemes at a base station in small/micro cells at 1800 MHz

The aim of this paper is to evaluate experimentally the relationships between cross-polarization discrimination (XPD), signal cross correlation, and polarization diversity gain with horizontally/vertically (HV) polarized reception at the base-station (BS) end at 1800 MHz. The performance of the horizontal/vertical polarization diversity scheme was also compared with a diversity scheme with /spl plusmn/45/spl deg/ slanted polarizations and horizontal space diversity at 1800 MHz in a personal communication system (PCS) mobile network. A measurement campaign was conducted in small/micro cells in different types of areas, taking into account the influence of mobile antenna inclination. According to the measurements, XPD values for horizontal/vertical polarizations vary between 5-15 dB, depending on the environment. Furthermore, XPD values depend highly on the radio propagation path between the BS and mobile station (MS) due to line-of-sight (LOS) and nonline-of-sight (NLOS) situations. Signal cross correlations of horizontal and vertical polarizations in both LOS and NLOS situations were clearly below 0.7, which is the generally accepted value to have a reasonable improvement at the receiving end with diversity. Finally, the results showed that almost equal diversity gain and system performance in a PCS network at 1800 MHz can be achieved in small/micro cells in different environments with /spl plusmn/45/spl deg/ slanted polarizations at the BS end when comparing results with horizontal space diversity. The performance of horizontal/vertical polarization diversity scheme was approximately 1 dB worse than horizontal space diversity.

Static simulator for studying WCDMA radio network planning issues

A static radio network simulator for studying various topics of 3rd generation WCDMA radio network planning is presented. The simulator allows analyzing coverage, capacity and quality of service related issues. Input to the simulator is the network scenario and the user information as a mobile station map. The uplink and downlink are separately analyzed and the outputs are presented in form of maps of best server, number of users, served traffic, SHO areas, AS size, SHO statistics for the area and for the users, Perch C/I plots. In the analysis, impact of the 3rd generations fast power control and soft(er) handover (SHO) possibility are taken into account by importing link level simulations into the analyses. The whole simulator is entirely based on Matlab(R) software.

The impact of the base station sectorisation on WCDMA radio network performance

The third-generation cellular systems will offer services with higher bit rates compared to todays networks and therefore for an operator it is of the utmost importance to exploit all possible resources to improve the capacity of the radio network. One attractive possibility, already used in most of the second-generation networks, is to increase the sectorisation at the base stations, i.e., using 3 or even up to 6 sectors per site. In this paper we demonstrate with simulations and some theoretical derivation how the sectorisation of the base stations influences the performance (capacity and quality of service) of a WCDMA radio network. In addition the simulator and the modelling of the third generations fast power control and soft handover are presented.

Modeling the impact of the fast power control on the WCDMA uplink

The behavior and consequences of the uplink closed loop power control in the uplink of a WCDMA system are analyzed with help of theory and link level simulations. Firstly, the impact of the fast transmit power control (TPC) on the uplink required E/sub b//Io and average transmit power levels are discussed. Furthermore, it is shown how TPC effects can be modeled in network level calculations and an example of TPC corrected capacity numbers is presented. Secondly, the impact of the TPC on the cell range is discussed.

Experimental results of cross polarization discrimination and signal correlation values for a polarization diversity scheme

The paper evaluates experimentally the cross polarization discrimination (XPD) and signal correlation values of a polarization diversity scheme at the base station end. Two orthogonally polarized signals, horizontal and vertical, are received simultaneously. The particular motivation of this study is to find out the performance of polarization diversity technique in a small cell or microcellular environment. The performance can be evaluated based on both of the above mentioned parameters. Two separate polarization diversity measurement campaigns were conducted. First, cross polarization discrimination values were measured at 2 GHz in different type of areas including a microcellular environment. Next, cross polarization discrimination and signal cross-correlation values were measured in the same microcellular environment at both appropriate frequency bands for mobile communications, i.e. 900 MHz and 2 GHz. According to the measurements, cross polarization discrimination values vary between 5-15 dB depending on the environment and frequency. Cross polarization discrimination values depend highly on the radio propagation path between base station and mobile station due to line-of-sight (LOS) and non-line-of-sight (NLOS) situations. Signal cross-correlation values of horizontal and vertical polarizations in measured locations are in both LOS and NLOS situations clearly below 0.7 which is generally accepted value to have a reasonable improvement at the receiving end.

The impact of the radio network planning and site configuration on the WCDMA network capacity and quality of service

The 3/sup rd/ generation cellular systems will offer services with higher bit rates compared to todays networks and therefore for an operator it is of utmost importance to exploit all possible resources to improve the capacity and quality of service of the radio network. The scope of this paper is to demonstrate with simulations how careful radio network planning can improve the network capacity and quality of service (QoS). Furthermore, it is demonstrated how the site configuration expansions can support the network capacity growth. Example results of omni-, three-, four- and six sectored site configuration simulations are presented including four different antennas and various different tilts. Furthermore a test case is shown to demonstrate the effect of a mast head amplifier (MHA) in the WCDMA uplink.

The impact of the subscriber profile on WCDMA radio network performance

The third-generation cellular systems will offer services well beyond the capabilities of todays networks. For an operator to provide the maximum capacity of the network supporting multiple traffic mixes more advanced analysis methods are required. The scope of this paper is to demonstrate with simulations how the subscriber profile (mobile station speed and the used service) impact on the network capacity and quality of service. Furthermore, the simulator used in the study is described, the uplink and downlink iterations and the fast power control and soft handover modeling are briefly introduced.

Comparison of three diversity handover algorithms by using measured propagation data

A diversity handover simulator using measured propagation data is introduced. Furthermore, three different diversity handover algorithms are compared and the comparison results are introduced in this paper. The algorithms used in the study were the basic cdmaOne algorithm, modified cdmaOne algorithm and an algorithm with a threshold relative to the strongest received pilot channel Ec/Io. The most stable performance in terms of diversity handover (DHO) probability can be achieved with the slope algorithm. The basic cdmaOne algorithm tends to be very sensitive to the interference situation. The algorithm, which makes the decision based on the relative differences of the received pilot Ec/Io levels, rather than on absolute thresholds, shows moderate change in both the active set update period and in the DHO probability in changing interference conditions.

Experimental evaluation of the two-dimensional mobile propagation environment at 2 GHz

The paper evaluates experimentally the most important parameters of the two-dimensional (2D) propagation environment. For this purpose, measurements with both fixed and rotating base station (BS) antenna arrays were performed. With a fixed array installation, environmental parameters, such as effective side lobe level (ESL) and cross polarisation discrimination (XPD) were evaluated. With the rotating BS antenna path angular spread (PAS), total angular spread values and the two-dimensional channel impulse responses (2D-CIR) were recorded. Two BS sites were used. With the measured data a simple beam pointing algorithm was tested and the number of receiving beams needed in different measured locations for optimum reception was estimated. With the measured 2D data simple 2D-RAKE allocation routines were done related to a CDMA-SDMA application.