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.
Continue reading 5G Rollout in the USA: Long Way to GoMy Top 12 Marconi Award Winners
While reading an article on social media I came to know that Siavash M. Alamouti has been awarded the Marconi Award for the year 2022. It came as no surprise as his work on MIMO technology has been ground breaking and has influenced the work of thousands of researchers. If there is a moot point it is that this award must have been given earlier. Just look up his 1998 paper on Google Scholar and you will find that the number of citations has reached a staggering figure of 18,756. On a personal front, I must admit that when I started my research on MIMO I was having difficulty grasping the concepts and it was Alamouti’s paper that set my direction of research.
Continue reading My Top 12 Marconi Award WinnersNear Field of an Antenna
The Electromagnetic Radiation from an antenna, particularly dipole antenna, has been studied in great detail. The mathematical framework proposed by Maxwell has stood the test of time and theoretical concepts have been verified through physical measurements. But the behavior of Electromagnetic (EM) waves close to the radiating antenna is not that well understood. This region that extends to about a wavelength from the antenna is called Near Field, as opposed to Far Field, which extends further out. The Near Field is further divided into Reactive Near Field and Radiative Near Field.
Continue reading Near Field of an Antenna5G 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.
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.
Continue reading Low Density Parity Check CodesConvolutional Codes and Viterbi Decoding
In the previous post we discussed block codes and their decoding mechanisms. It was observed that with syndrome-based decoding there is only a minimal advantage over the no coding case. With Maximal Likelihood (ML) decoding there is significant improvement in performance but computational complexity increases exponentially with length of the code and alphabet size. This is where convolutional codes come to the rescue.
Continue reading Convolutional Codes and Viterbi Decoding