The shortage of bandwidth is a global problem from cellular service point of view. Many cellular service providers are switching from 4G to 5G in context with change of technology. A solution to the effective utilization of band, bandwidth and mapped technologies is the millimetre wave (mmWave) massive MIMO (multiple input multiple output).The world seen the transition of technology from 1G to 4G and very soon 5G also. The key factor of 5G technologies is based on mmWave band which has potential to increase user throughput, spectral efficiency, energy efficiency, handling traffic capacity, enhanced data rate, device to device (D2D) communication, low latency, cell coverage and, many more. The 5G system with use of mmWave will be a stepping stone in the change of technology and satisfaction of the user in terms of data rate will be at the peak. To sustain with this extensive global challenges, use of antenna array is essential at the base station and cell site which will make use of mmWave band for antenna array design and overcome the problems of small size, hardware constraints and path loss because of very small wavelength associated with it.
Index Terms: mmWave, massive MIMO, Antenna array, 5G, Base station, half power beamwidth
In today’s world, high date rate is prime requirement for any user and any application to be run on OS. The necessity of high-data-rate transmission is increased drastically because of large no. of users and services available in the market . Millimeter Waves (mmWave) are viewed as the key recurrence possibility for 5G, which can offer extremely high transmission data rate in cellular communication .
Massive MIMO also known as full dimension MIMO, very large MIMO or large scale antenna systems which clearly indicates that Base Station (BS) uses large no. of antennas. Compared to conventional MIMO, large no. of antennas are offered by massive MIMO which helps to focus on energy into smaller regions, low interference levels, user throughput and radiated energy efficiency. Also, massive MIMO provides extension in cell range or coverage more effectively for higher frequency bands in millimetre Waves (mmWave) as large number of operational antennas i.e. antenna array can be packed with a small footprint for high power directivity and helps in propagation for worse conditions of it .The amalgamation of 5G for mmWave spectrum at base station and mobile phone requires highly directional antenna with beamforming . Antenna arrays at the transmitter and receiver are capable of changing their radiation patterns over the time and frequency referred as spatial beamforming. Antenna arrays are able to do the spatial filtering also. It can be used to focus a signal at an arbitrary point in space which is a multipath propagation environment as shown in fig. 1 .
Now a day’s many mobile service providers making use of sub 3GHz spectrum but with the demand of service this is not able to fulfil the requirement of user and the solution to this problem comes out from a band of millimetre wave (mmWave) frequency. This band specifically ranges from 3GHz to 300 GHz as shown in fig. 2.
With this mmWave frequency, 57-64GHz band is found as oxygen absorption band and 164-200 GHz band as water vapour absorption band which is not suitable for propagation due to water vapour attenuation (mainly occurs at 180 GHz). In short, over the entire mmWave band 252 GHz spectrum is available for mobile broadband communication. [Red3], [Red4].