Tag Archives: 5G

Wireless Book

About this book

This textbook covers fundamental topics in Telecommunication including Channel Modeling, Modulation/Demodulation, Channel Coding/Decoding, Multicarrier, Capacity, Antenna Arrays, Diversity, and 4G/5G. It will also cover advanced topics such as High-Resolution Spectral Estimation, Reconfigurable Intelligent Surfaces, Index Modulation, Full-Duplex, and Millimeter Wave. This book will mainly target engineering students (both graduate and advanced undergraduate) who are new to the fields of Communication and Signal Processing and are struggling to understand the fundamental concepts. This book will help the students step by step by introducing the concepts first in their most basic form and then providing the code that the students can experiment with. It contains pedagogical elements such as chapter introductions, end-of-chapter questions and numerical problems, MATLAB/Octave/Python code, figures and tables, and a website (raymaps.com) for feedback and interaction. It will not only be helpful for undergraduate and graduate students but also for professional engineers and hobbyists.

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About the author

Yasir Ahmed has more than 20 years of experience in various organizations in Pakistan, Europe, and the USA in both Engineering and Management roles. He worked as a Research Assistant in the Mobile and Portable Radio Group (MPRG) of Virginia Tech under the supervision of Dr. Jeff Reed and was one of the first researchers to propose Space Time Block Codes (STBCs) for eight transmit antennas. The collaboration with MPRG has continued over the years and has resulted in 12 research publications and a book on Wireless Communications. Yasir worked as GM SEED at Ignite National Technology Fund, a company involved in supporting the innovation and entrepreneurship ecosystem in the country. He previously worked for Qualcomm USA, leading the physical layer performance and conformance testing of GSM/UMTS modems, and for COMSATS Islamabad as an Assistant Professor, teaching various subjects in the Telecom and Networks area. He was part of the Ignite team that evaluated multi-billion-rupee NIC and DigiSkills programs and has also helped fund a number of startups that have gone on to become successful commercial ventures.

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5G Data Rates and Shannon Capacity

Recently I came across a post from T-Mobile in which they claim to have achieved a download speed of 5.6 Gbps over a 100 MHz channel resulting in a Spectral Efficiency of more than 50 bps/Hz. This was achieved in an MU-MIMO configuration with eight connected devices having an aggregate of 16 parallel streams i.e. two parallel streams per device. The channel used for this experiment was the mid-band frequency of 2.5 GHz.

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5G Rollout in the USA: Long Way to Go

There is a 3 way race for 5G leadership in the US between T-Mobile(+Sprint), Verizon and AT&T. There are competing claims for the number of 5G subscribers, coverage area and download speeds. But let us look where the 5G industry stands today compared to the expectations a few years back. More than 80% of US population lives in urban areas which comprise of 2% of the total land area of about 10 million squared kilometers. That is 80% of the population lives in an area of about 200,000 squared kilometers.

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5G Millimeter Waves: Are They Really Harmful

There has been a continuous debate about harmful effects of Electromagnetic Radiations ever since they came into existence. Most of the research results suggest that there are no harmful effects, if the rules and regulations are followed. But there is a small body of research that suggests that there might be some harmful effects and more research needs to be carried out. This is particularly important now as 5G Wireless Technology is being rolled out around the world and it uses millimeter waves for which we have limited data. Also, 5G would be using much smaller cells meaning that base stations would be closer to human beings.

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Low Density Parity Check Codes

We have previously discussed Block Codes and Convolutional Codes and their coding and decoding techniques particularly syndrome-based decoding and Viterbi decoding. Now we discuss an advanced form of Block Codes known as Low Density Parity Check (LDPC) codes. These codes were first proposed by Robert Gallager in 1960 but they did not get immediate recognition as they were quite cumbersome to code and decode. But in 1995 the interest in these codes was revived, after discovery of Turbo Codes. Both these codes achieve the Shannon Limit and have been adopted in many wireless communication systems including 5G.

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Beyond Massive MIMO

Recently Björnson and Marzetta in their publication on Antenna Arrays [1] discussed five possible future research directions. In their opinion Massive MIMO is no longer a theoretical concept and it is already being adopted in the industry. It is not uncommon to find 64 element antenna arrays being deployed in wireless communication systems. So we now need to look beyond Massive MIMO or MaMIMO as it is popularly referred to. Here are three possible future research directions that we find most interesting.

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