Optimized Codebook Based Hybrid Beamforming

Abstract

In this thesis we research beamforming capabilities of the UEs equipped with several antennas in a 5G scenario.
We define a system model based on the use of phase codebooks that allow to change the radiation patterns of the arrays of antennas installed in the UE. Within this system model, we obtain optimized codebooks in terms of two metrics, which we consider to be of interest in this scenario, employing two different optimization approaches. We use these results to analyze, through simulations, the estimation performance in an AoA estimation scenario. We also analyze the detection performance in receiving the signal that can allow us to estimate the AoA.
So as to gain more insight into how the selection of the optimum codebook affects the detection performance, we define a simpler scenario and we analyze it theoretically and draw conclusions that relate to the simulations obtained.

Popular Abstract

When you think about mobile phones nowadays, no one thinks about the old devices with small screens that you may still keep in a drawer full of dust in the basement of your home. Those devices could be used to make phone calls, maybe they could even send SMSs, and, if you were lucky, you could even use them to play some simple games, such as "Snake" or "Tetris", that required no internet connection. They were the only mobile phones available around 20 years ago. Nowadays, however, one cannot think of a mobile phone without internet connection to use social media or stream videos or music.

If we think about the original functionalities of mobile phones, i.e., phone calls and SMSs, they are just minor features in the new mobile phones (or smartphones) that are getting substituted by apps running directly through the internet connection. In addition, the number of devices connected to the mobile network is increasing at huge rates, not only more people have access to smartphones now (some people even have more than one), but also new devices are getting connected to this network including tablets, TVs, cars, sensors... All these devices require high data rates to run their services smoothly, and with the current networks it's getting harder and harder to be able to serve those data rates. This is one of the main reasons for the development of 5G, the next generation of mobile communications that will come to solve the increasing need of high data rates as well as other issues related.

Many technologies are being considered to improve the data rates in 5G. Some include putting a lot of antennas in the base stations, putting a lot of base stations to serve smaller areas, or using new frequency bands that are highly unoccupied. In the current generation of mobile communications, i.e. 4G, one of the improvements with respect to the previous generation to get higher data rates was to put several antennas in the smartphones or, in general, any device that is to be connected to the mobile network. Thus, in 5G we expect to have smartphones with several antennas, probably even more than in 4G, so that we can still take benefit of them. However, the way the base stations will work in 5G is quite different to the way they used to do in 4G. This means that we will have to think again how can we take benefit from the use of different antennas in the 5G devices. In this thesis we will propose some methods to utilize the antennas in these devices in a 5G scenario and study what benefits can we get from them.

• author: Vidal Alegria, Juan
• supervisor: Fredrik Rusek
• organization: Department of Electrical and Information Technology
• course: EITM02 20182
• year: 2018
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: UE, beamforming, codebook, phased array, antennas, detection, estimation, angle of arrival, 5G.
• report number: LU/LTH-EIT 2018-678
• language: English
• id: 8964230
• date added to LUP: 2018-12-21 19:25:53
• date last changed: 2019-01-18 14:38:39