Millimeter wave (mmWave) communication and massive multiple-input multiple-output (MIMO) are promising techniques to increase system capacity in 5G cellular networks. The prior frameworks for conventional cellular systems do not directly apply to analyze mmWave or massive MIMO networks, as (i) mmWave cellular networks differ in the different propagation conditions and hardware constraints; and (ii) with a order of magnitude more antennas than conventional multi-user MIMO systems, massive MIMO systems will be operated in time-division duplex (TDD) mode, which renders pilot contamination a primary limiting factor. In this dissertation, I develop stochastic geometry frameworks to analyze the system-level performance of mmWave, sub-6 GHz massive MIMO, and mmWave massive MIMO cellular networks. The proposed models capture the key features of each technique, and allow for tractable signal-to-interference-plus-noise ratio (SINR) and rate analyses. In the first contribution, I develop an mmWave cellular network model that incorporates the blockage effect and directional beamforming, and analyze the SINR and rate distributions as functions of the base station density, blockage parameters, and antenna geometry. The analytical results demonstrate that with a sufficiently dense base station deployment, mmWave cellular networks are capable to achieve comparable SINR coverage and much higher rates than conventional networks. In my second contribution, I analyze the uplink SINR and rate in sub-6 GHz massive MIMO networks with the incorporation of pilot contamination and fractional power control. Based on the analysis, I show scaling laws between the number of antennas and scheduled users per cell that maintain the uplink signal-to-interference ratio (SIR) distributions are different for maximum ratio combining (MRC) and zero-forcing (ZF) receivers. In my third contribution, I extend the sub-6 GHz massive MIMO model to mmWave frequencies, by incorporating key mmWave features. I leverage the proposed model to investigate the asymptotic SINR performance, when the number of antennas goes to infinity. Numerical results show that mmWave massive MIMO outperforms its sub-6 GHz counterpart in cell throughput with a dense base station deployment, while the reverse can be true with a low base station density.

Massive MIMO is a technology of using many antennas to control the beamforming and enable spatial multiplexing.

mmWave is a frequency range, often referring to 28 GHz or higher. Massive MIMO can be used in any frequency range. The technology is more mature in sub-6 GHz spectrum than in mmWave.

The early 5G deployments are mainly using ~3.5 GHz spectrum, but mmWave will also be utilized since it gives access to more bandwidth.

I am strongly agree with both of them (Mr Emil and Mr Abbas khan).Thanks Mr Abbas for your explaination based on the technical ground.

Agree Emil Björnson .

Massive MIMO systems is a large-scale antenna technology used to realize high beamforming array gain. Moreover, it is well known that wireless signals at millimeter-wave (mmWave) frequencies (30-300 GHz) experiences orders-of-magnitude more pathloss than the microwave signals (sub-6 GHz), which limits their range.

Hence, to overcome path loss at mmWave frequencies, mmWave communication systems must therefore, combine with massive MIMO (i.e., mmWave massive MIMO) systems, made possible by the decrease in wavelength, to combat pathloss with beamforming gain to extend the transmission range. That is, the combination of mmWave and massive MIMO has the potential to dramatically improve wireless access range and throughput performance. Such systems benefit from large available signal bandwidths and small antenna form factor.

The following publication gives more details:

1) https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9050553

2) https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=9153564

The following publications highlight the differences between conventional/sub-6 GHz/microwave massive MIMO and mmWave massive MIMO from different perspectives: propagation, use cases, etc.

1) "Massive MIMO in Sub-6 GHz and mmWave: Physical, Practical, and Use-Case Differences," Article Massive MIMO in Sub-6 GHz and mmWave: Physical, Practical, a...

2) "Millimeter-Wave Massive MIMO Communication for Future Wireless Systems: A Survey," Article Millimeter-Wave Massive MIMO Communication for Future Wirele...

3) "Massive MIMO 5G Cellular Networks: mm-wave vs. μ-wave Frequencies" Article Massive MIMO 5G Cellular Networks: mm-wave vs. \mu-wave Frequencies

5G will deliver more data to more devices with lower latency and higher consistency than previous-generation technologies. A large number of subscribers are anticipated to adopt the 5G network. To accommodate these users, there is a need for a larger bandwidth. Limited bandwidth is available in the mobile frequency spectrum (i.e., below mmWave band); hence, the mmWave band has been explored for a larger bandwidth. mmWave technology offers several advantages, such as high-speed data transfer (large bandwidth), high resolution, low interference (systems with high immunity to cramming), small form factor (small component sizes, such as smaller antenna dimensions), increased security, and cost-effectiveness; all these features make mmWave technology ideal for 5G network.  For 5G, antennas are most likely to operate 24, 26, 28, 37, and 39 GHz as at high frequencies, the wavelengths are very short, allowing many antenna elements to be placed in a compact, highly directive aperture.

According to Sachin Garg, Associate Vice President, Semiconductor and Electronics at MarketsandMarkets, “mmWave is likely to play a key role to support the burgeoning mobile data traffic growth. High data transfer rate offered by this spectrum, the growing involvement of various telecom service providers, and favorable federal mandates are driving the market growth for this frequency band.”

Massive MIMO: Antenna system with large number of antenna elements (>100) designed at any frequency less than mmWave band.

mmWave massive MIMO: Massive MIMO with antenna elements designed at mmWave frequency band (30GHz - 300GHz).

Massive MIMO systems render high beamforming gain to achieve higher spectral efficiency. In mmWave band, due to the reduced wavelength, large number of antennas can be packed with the small physical size, hence mmWave systems inherently use massive MIMO antennas, in other words called mmWave massive MIMO.

One difference from a *practical* aspect: with massive MIMO at mmWave, you can create many more antenna elements per unit area than what you could do with massive MIMO at say sub-6 GHz. This translates into larger array sizes at mmWave given the same antenna form factor. This applies to the base station antennas and the UE antennas alike.

Faris B. Mismar

MIMO is an antenna technology for wireless communications in which multiple antennas are used at both the source (transmitter) and the destination (receiver). Hence, the MIMO system is just sufficient to be used for the sub-6 GHz band.

However, since mmWave signals experience an orders-of magnitude increase in free-space pathloss, large arrays (i.e., massive MIMO) can provide the beamforming gain needed to overcome pathloss and establish links with a reasonable signal-to-noise ratio (SNR). Hence, mmWave uses massive MIMO combine with mmWave technology to overcome pathloss, which establishes link with a reasonable SNR.

To achieve massive MIMO, proper resource allocation is needed. Among the available resources, transmit power beamforming are the most important degrees of freedom to control the spectral efficiency and energy efficiency. Due to the use of massive MIMO technology and low-end hardware at the base station, new aspects of power allocation and beamforming compared to current systems (i.e., MIMO) arises. For example, in the MIMO system, digital processing, however, requires dedicated baseband and RF hardware for each antenna element. In massive MIMO from a *PRACTICAL* viewpoint, the high cost and power consumption of mixed-signal hardware preclude such a transceiver architecture at present and forces massive MIMO systems to rely heavily on analog or RF processing in the form of hybrid precoding.

Wireless data rates will continue to grow beyond the capacity of current wireless communication systems. To meet the increasing demand, one can

1) deploy smaller cells (e.g., femtocells and picocells) to reuse the spectrum as much as possible,

2) improve the spectral efficiency with advanced technologies [e.g., massive multiple-input, multiple-output (MIMO) and cognitive radio], or

3) utilize new frequency spectra

so both mm-waves and massive MIMO are the option we can increase wireless data rates.

Massive MIMO is just a technique whereas mmwave is the frequency range from 30-300 GHz.

I see how these two concepts are confusing.

Massive MIMO as was mentioned by the other answers is a technique that uses many antennas in the tx and rx sides of the communications to boost the data rate, control transmission direction (i.e. beamforming), and achieve spatial multiplexing. The term massive refers to tens or hundreds of antennas in both sides which is something hard to build with the small frequencies (traditional sub-6GHz bands) but is much easier to build for larger frequencies in the mmWave bands (theoritically 30-300 GHz but practically includes even 24, 26, and 28GHz bands) because these high frequencies have small wavelengths (in the millimeter scale) and that is why they are called mmWave frequencies. This enables putting the massive (huge number) MIMO antenna systems in small form factor sectors and the highest we have today is 64X64 MIMO.

I hope this answer your question

Regards

Dear Reshma Immaculate ,

I will not repeat the answer of my colleagues.

The main difference between the two MIMO systems stems from the much smaller wavelength of the mm-wave compared to the that of the microwaves up to 6GHz.

Accordingly the same number of antennas will occupy much less space. Therefore one can even increase the number of antennas and achieve more beam focusing. Or more spatial multiplexing.

Best wishes

The millimeter wave ranges from 30 GHz to 300 GHz, so for this frequency range where the wavelength goes from 10mm to 1mm.