MEASURED GIGANTIC MU MIMO OFDM UP LINK

Abstract

Wireless communication systems are utilized everywhere in this digital era. Wi-fi, Mobile Communication Systems, Microwave Communication, Broadcast Radio are examples of wireless communication systems where “Multiple users (MU)-multiple inputs and multiple outputs (MIMO)” is implemented in these systems. Orthogonal frequency division multiplexing (OFDM) enhances the performance of the wireless systems by providing wide bandwidth which allows them to pass multiple signals at different frequencies. Mu-MIMO OFDM wireless systems provide significant power, cost savings and Significantly reduces the raw analog-to-digital converter (ADC) data that needs to be sent from the spatially separated antenna array to the baseband processing unit. . In this project we   look in to uplink performance of a measured gigantic MU-MIMO system that deploys orthogonal frequency-division multiplexing (OFDM) for wideband communication. Our results demonstrate the performance of the MU-MIMO systems in terms of the ratio between measured bits and signal to noise ratio(SNR) for different numbers of bits and multiple antenna.

Code Description & Execution

Algorithm Description

overview of MU - MIMO - OFDM uplink system The above figure describe model structure of MU-MIMO (Multiple user- multiple input and multiple output) system. We assume a coded MU-MIMO uplink system that employs spatial multiplexing. It consists of U independent single-antenna users 6 communicating with a BS with B ≥ U receive antennas. Consider a frame-based OFDM transmission, where each OFDM symbol consists of frequencies. We continue to assume that communication  takes place in two phases

• Training phase U consists of OFDM symbol

Followed by

• D data transmission phase consisting of OFDM symbol

Terminal user side: During the training phase, Data and pilot tones contain QPSK training symbols. Known to NB Guard tones remain unused in the meantime during the data transmission phase, each user encrypts his information Bits using Forward Error Correction (FEC) channel codes and Map encoded bits to constellation symbols. For data transmitted over data-carrying tones or Pilot tones include his BPSK symbols. In a real system, Used for residual phase noise or frequency compensation deviated Receiving side (Base station): Each of the B antennas BS produces a noisy mixture of time domain users. data. In particular, un quantize. The time-domain receive vector at antenna b after the distance from circular prefix. Received vector in each time domain Antenna B is quantized to and it is then forwarded to the channel estimation/data acquisition unit. During the training phase, the channel estimation unit is estimate for all OFDM tones. During the data transmission phase, the data acquisition unit Generate LLR values ​​for each encoded bit for each user Fundamentals of channel estimation and quantized reception vector. The resulting (approximate) soft information is used Perform decoding on a user basis.

Code Description

Allpath.m: Allpath.m file add required files (inputs, outputs and mains file )  to the path Err_plot.m: To plot the all outputs at different number of bits and multiple antenna, which is located in the results folder in the given zip file Note:

1. To known the more details about the codes and functions in the file open the files in matlab and read the tags (%) in the code for better understanding
2. Matlab file or codes are saved in .m  and .mat format

(Don’t worry if you don’t know the basics of the MATLAB Click here  to watch our video about MATLAB software basics) (Click here  to download the zip file of the project)

Steps to Execute the Code

1. Download the zip file of this project and unzip it.
2. Open matlab and click on the ‘browse for folder’ icon as shown  below

3. A pop up window appears from which we can select the folder.

3. Run “allpath.m”file to add required functions, inputs and outputs
4.  Go to plots folder in the given file you will find “err_plot.m” file, run the file you will get the required output.

5. Click on Editor (present at top), Run the No_plate-regonization.m by clicking on Run button , code will be executed and output will be displayed.

Result

Issues Faced

1. “Not enough input arguments” error occurs when you run the function files, which are not main codes these functions are utilized in main code.
2. The formulas and algorithm are implemented in the function, to understand formulas implemented read the tags in the function files.

Reference:

1. https://ieeexplore.ieee.org/document/7458830
2. https://www.researchgate.net/publication/282310851_Quantized_Massive_MU-MIMO-OFDM_Uplink
3.  https://www.arxiv-vanity.com/papers/1509.07928/