Jonas Medbo

Propagation Characteristics of Polarized Radio Waves in Cellular Communications

Narrowband and wideband measurements of the radio channel using different combinations of transmit and receive polarization have been performed. The measurements cover a range of scenarios including urban, suburban and open terrain, as well as both outdoor and indoor terminals. The vertical-to-vertical (V-V) and horizontal-to-horizontal (H-H) polarization combinations are found to provide equal received power on average, while the cross-polarized combinations (V-H) and (H-V) typically provide 5-15 dB weaker received power due to the limited amount of cross-polarization scattering in the radio channel. Fast fading variations are further found to be uncorrelated between different combinations of transmit and receive polarization.

Propagation channel impact on LTE positioning accuracy: A study based on real measurements of observed time difference of arrival

The goal with this work is to evaluate the performance of the observed time difference of arrival (OTDOA) positioning method using real measured channel data in a macro-cellular urban LTE scenario. This has been made possible using a highly accurate channel sounder developed within Ericsson Research. A wideband (20 MHz bandwidth) measurement campaign at 2.66 GHz was performed using three separate base station sites in a realistic deployment. One main conclusion is that the measured channel allows a positioning accuracy of 20 m and 63 m at the median and 95% level respectively. This is a very encouraging result since the FCC requirements are fulfilled with a safe margin in this urban scenario.

Carrier Frequency Effects on Path Loss

To study the carrier frequency effects on path loss, measurements have been conducted at four discrete frequencies in the range 460-5100 MHz. The transmitter was placed on the roof of a 36 meters tall building and the receive antennas were placed on the roof of a van. Both urban and suburban areas were included in the measurement campaign. The results show that there is a frequency dependency, in addition to the well known free-space dependency 20 log10(f), in most of the areas included in the measurements. In non line of sight conditions, the excess path loss is clearly larger at the higher frequencies than at the lower. A model capturing these effects is presented

Temporal radio channel variations with stationary terminal

In wireless communications, stationary terminal scenarios are becoming increasingly important as bitrates goes up. Consequently, the need to improve the knowledge about the channel behavior and to develop realistic channel models for these scenarios is also increasing. The present work comprises both measurements and modeling of the radio channel when the terminal is stationary. The measurements were performed at 5 GHz in indoor scenarios using a vector network analyzer. The measured channel was essentially static most of the time. Only about 1% of the time did it show substantial channel variations. An important finding is that the dominant cause for temporal channel variations in the measurements was the movement of persons in the vicinity of either antenna. This is also supported by a simple model, based on a single moving scatterer, which shows good agreement with measurements.

Waveform and Numerology to Support 5G Services and Requirements

The standardization of the next generation 5G radio access technology has just started in 3GPP with the ambition of making it commercially available by 2020. There are a number of features that are unique for 5G radio access compared to the previous generations such as a wide range of carrier frequencies and deployment options, diverse use cases with very different user requirements, small-size base stations, self-backhaul, massive MIMO, and large channel bandwidths. In this article, we propose a flexible physical layer for the NR to meet the 5G requirements. A symmetric physical layer design with OFDM is proposed for all link types, including uplink, downlink, device-to-device, and backhaul. A scalable OFDM waveform is proposed to handle the wide range of carrier frequencies and deployments.

Measurements and analysis of a MIMO macrocell outdoor-indoor scenario at 1947 MHz

Narrowband MIMO channel measurements at 1947 MHz have been performed in an urban macrocellular outdoor-indoor scenario. The spatial characteristics of the channel have been analyzed, showing an angular spread of 5-10/spl deg/ at the base station and 30-60/spl deg/ at the mobile station. The maximum theoretical capacity that the channel can support has been evaluated for various antenna spacings and number of antenna array elements. Only about 50% of ideal gain, relative to capacity with fully correlated antenna array elements, was obtained with a 2/spl lambda/ antenna spacing at the base station. However, measured Ricean K factors indicate that the gain would be about 90% for sufficiently large antenna spacing.

15 GHz propagation properties assessed with 5G radio access prototype

This paper presents coverage and penetration loss measurements in an urban environment at 15 GHz to provide insight into the design and deployment of future 5G systems in higher frequency bands. The measurements are performed using a 5G radio access prototype including two transmission points (TPs) and a mobile terminal over a 200 MHz bandwidth. The TPs and the mobile terminal each consists of multiple antennas, enabling spatial multiplexing of multiple data streams. Coverage measurements are performed for both outdoor and outdoor-to-indoor scenarios. Penetration losses are measured for human body, normal and coated windows, a metallic white board, and a concrete pillar. Outdoor microcellular coverage in line-of-sight (LOS) and lightly shadowed areas is shown to be possible with similar antenna directivities as in the existing cellular networks. Transitions into non-line-of-sight (NLOS) bring additional losses in the order of 20 dB, thereby making the NLOS coverage challenging. Outdoor-to-indoor coverage seems to be limited to areas that are in almost LOS with the outdoor TP. Moreover, the penetration loss of indoor blocking objects seems to further restrict the indoor coverage. Potentials of beamforming as a means to improve the coverage are also evaluated via simulations.

Single and Multi-User Cooperative MIMO in a Measured Urban Macrocellular Environment

We study the potential benefits of cooperative multiple-input multiple-output signaling from multiple coherent base stations with one or more mobile stations in an urban macrocellular environment at 2.66 GHz. The analysis uses fully-coherent measurements of the channel from three base stations to a single mobile station equipped with four antennas. The observed channels are used to explore the gains in capacity enabled by cooperative base station signaling for point-to-point and multi-user communications. The analysis shows that for point-to-point links, the average capacity for cooperative signaling is 53% higher than that achieved for a single base station. For downlink and uplink communication with three mobile users, cooperative signaling yields average sum rate increases of 91% and 63%, respectively.

Leaky coaxial cable MIMO performance in an indoor office environment

This study has been performed in order to improve the understanding of the performance of leaky feeders used in MIMO radio access deployments. In order to achieve this, a measurement campaign has been conducted in an indoor office environment at 2.4 GHz. Several configurations of leaky feeders as well as dipole antennas (as a reference case) have been investigated. The corresponding MIMO channel performance has been evaluated. The main findings are that leaky feeders provide as good performance as well separated dipole antennas. The measured performance is very close the performance of the favorable i.i.d. (full MIMO richness) channel. Even taping two leaky feeders together does not degrade the performance significantly. The advantage with the leaky feeders is that they provide much more uniform signal strength over the coverage area.

Correlation Properties of Large Scale Parameters from 2.66 GHz Multi-Site Macro Cell Measurements

Multi-site measurements for urban macro cells at 2.66 GHz are performed with three base stations and one mobile station. In order to analyze the correlation properties of large scale parameters, we split up the routes into subsets, where it can be assumed that wide-sense stationarity (WSS) applies. The autocorrelation distance and correlation properties of large scale parameters for each link are analyzed. By comparing these properties with the corresponding parameters from the COST 2100 and WINNER II models, we can see that the measured autocorrelation distance of the shadow fading as well the autocorrelation distance of delay spread have similar properties as in the two models. The shadow fading and delay spread from the same link are negatively correlated and match the two models well. Based on the WSS subsets, we can see that large scale parameters for different links can be correlated, also when two BSs are far away from each other. In those cases the correlation of different links tends to be positively correlated when both base stations are in the same direction compared to the movement of the MS, otherwise the two links are usually negatively correlated.