Beyond Massive MIMO
Massive MIMO is no longer a theoretical concept and it is already being adopted in the industry. So we now need to look beyond Massive MIMO or MaMIMO as it is popularly referred to.
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GSM, WCDMA, LTE, 5G.
Massive MIMO is no longer a theoretical concept and it is already being adopted in the industry. So we now need to look beyond Massive MIMO or MaMIMO as it is popularly referred to.
Read more60GHz Millimeter Wave Band is a band spread between 57GHz and 64GHz. This unlicensed band was first released in the US in 2001 but with limited allowance for transmit power (EIRP of 40dBm). Later on, in 2013, this limit was increased (EIRP of 82dBm) to allow for greater transmit power and larger range.
Read moreWe calculate the degradation in Bit Error Rate (BER) performance due to antenna correlation at the Mobile Station and the Base Station. Exponential Correlation Model is used in the simulation.
Read moreThe mmWave Channel It is well known that wireless signals at millimeter wave frequencies (mmWave) suffer from high path loss, which limits their range. In particular there are higher diffraction and penetration losses which makes reflected and scattered signals to be all the more important. Typical penetration losses for building materials vary from a few dBs to more than 40 dBs [1]. There is also absorption by the atmosphere which increases with frequency. But there are also some favorable bands where atmospheric losses are low (<1dB/km).
Read moreDiscussion of Multicarrier Beamforming particularly in the context of Massive MIMO and Millimeterwave
Read moreBackground Just like different frequency bands and time slots can be used to multiplex users, spatial domain can also be exploited to achieve the same result. It is well known that if there are 4 transmit antennas and 4 receive antennas then four simultaneous data streams can be transmitted over the air. This can be scaled up to 8 x 8 or in the extreme case to 128 x 128. When the number of transmit or receive antennas is greater than 100 we typically call it a Massive MIMO scenario and we need specialized signal processing techniques to handle this […]
Read moreIn the previous two posts we discussed the fundamentals of array processing particularly the concept of beamforming (please check out array processing Part-1 and Part-2). Now we build upon these concepts to introduce some linear estimation techniques that are used in array processing. These are particularly suited to a situation where multiple users are spatially distributed in a cell and they need to be separated based upon their angles of arrival. But first let us introduce the linear model; I am sure you have seen this before. x=Hs+w Here, s is the vector of symbols transmitted by M users, H […]
Read moreIn the previous post we had discussed the fundamentals of a Uniform Linear Array (ULA). We had seen that as the number of array elements increases the Gain or Directivity of the array increases. We also discussed the Half Power Beam Width (HPBW) that can be approximated as 0.89×2/N radians. This is quite an accurate estimate provided that the number of array elements ‘N’ is sufficiently large. But the max Gain is always in a direction perpendicular to the array. What if we want the array to have a high Gain in another direction such as 45 degrees. How can […]
Read moreOpen Signal is a mobile application that collects the data about your wireless network (2G/3G/4G) and generates coverage maps and host of other reports. The data is collected in the background while the user is busy in his daily routines. But data can also be collected on the request of the user. This is much better than drive testing since the data is collected in real life scenarios and on thousands of different devices that are in use. The app works while the user is indoor or outdoor, at rest or in motion, on land or on water, at sea […]
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