Christina Larsson

Non-line-of-sight small cell backhauling using microwave technology

In this article we discuss different technology alternatives for small cell backhaul, and we present high-frequency microwave technology as a very interesting alternative for wireless backhauling of small cells. In fact, we demonstrate that high-frequency microwave technology can be used for NLOS wireless backhauling of small cells, which opens up new applications for microwave technology. We discuss urban NLOS channel propagation at high frequencies, and we show both measurement and simulation results to validate the use of high-frequency microwave technology for NLOS small cell backhaul.

Angular Resolved Pathloss Measurements in Urban Macrocell Scenarios at 28 GHz

This paper presents angular resolved measurements in two urban macro scenarios at 28 GHz. The result confirms that the propagation at this relatively high frequency is mainly driven by line-of-sight (LOS) and reflections/scattering. The majority of the energy was contained either in a LOS path or in specular reflections or reflections off smaller objects such as scaffolding, drain pipes, light poles, bikes, and balconies. At all 200 randomly chosen receiver locations up to 350 meters from the transmitter a detectable signal was received in both scenarios and an excess loss of up to 55 dB was measured.

Experimental demonstration of joint-polarization phase recovery algorithms for dual-polarization 16-QAM transmission

The concept of joint-polarization phase estimation is experimentally demonstrated in a dual-polarization 7-Gbaud 16-QAM system. Performance improvement using a distributed feedback laser with 2-MHz linewidth as well as narrow linewidth lasers are presented.

Joint-Polarization and Joint-Subchannel Carrier Phase Estimation for 16-QAM Optical Systems

Carrier phase estimation using information from multiple subchannels and orthogonal polarization channels is proposed and experimentally verified. The concept is evaluated with a 112 Gb/s dual-channel DP-16-QAM system, but may find applications in next generation Terabit systems utilizing superchannels and containing densely packed subchannels originating from the same laser. The new technique requires an accurate carrier frequency estimation algorithm, implemented in the paper using a decision-directed method. The algorithms are tested with a narrow (100 kHz) and a broad (2 MHz) linewidth laser in the coherent receiver.

Angular Resolved Site Characterization of Non-Line-of-Sight Wireless Links

A method and equipment for characterization of wireless paths to potential radio sites are presented. In particular, a measurement set- up is presented and experimentally verified that characterizes possible propagation paths between a hub site and a remote site that can be either in line-of-sight or non-line-of-sight. The characterization includes finding the best possible paths in terms of propagation loss, estimate the microwave path distances, and providing photo documentation of the detected paths. Such measurement can be automated and performed for a large number of possible sites before actual deployment. By using the characterization equipment presented here, an angular path direction resolution of amp;#177;2amp;#x000B0; and a path distance accuracy of better than amp;#177;5 meter can be obtained. A full scan and path characterization can be performed in less than 15 minutes per site. The method is demonstrated at 28 GHz in two different scenarios.

Angular Resolved Pathloss Measurements in a US Suburban Scenario at 28 GHz

This paper presents angular resolved path loss measurements conducted along the streets in a typical US suburban scenario at 28 GHz. It was observed that all Rx location up to 150 meters from the Tx had a detectable signal with path loss under 145 dB and all Rx location up to 200 meters had a detectable signal with path loss under 155 dB. It was also concluded that the LOS direction was the clearly dominating peak power direction even for locations with more than 30 dB excess loss. The angular spread was unexpectedly low, below 10 degrees for half of the locations, which indicate only one or very few closely spaced dominating paths. Finally, the impact of the AP height on the coverage was investigated and for this scenario very little improvements could be noticed increasing the access point height from 6 to 9 or 15 meters. This is likely due to the height of the trees often exceeding 15 m in the measured scenario.