Research On The Effective Capacity In Massive MIMO Wireless Communication Systems

Because of the rapid development of the Internet, in the next generation wireless communication systems, the demand for wireless traffic is increasing rapidly and a majority of the traffic demands come out of various multimedia applications. To meet the vast demand for the traffic, the massive multiple-input multiple-output(MIMO) technique is recognized as a key enabler for the future 5G mobile communication systems due to its high spectral efficiency. Because of the limited space in BSs, if we have to deploy so many antennas in it, definitely the antennas have to be deployed very compact. So the mutual coupling effect among antennas on the system capacity will become so significant that we can't ignore it.This paper studies the effect of a rectangle array of antennas on the massive MIMO wireless communication systems. To evaluate the impact of the mutual coupling effect on massive multi-input-multi-output(MIMO) wireless communication systems with a rectangular antenna array, the receive diversity gain is defined and analyzed with different antenna spacings and antenna numbers in this paper. Furthermore, the uplink ergodic achievable rate as well as its upper bound considering mutual coupling have been derived and analyzed through simulation. Simulation results indicate that the mutual coupling has an obvious impact on the uplink ergodic achievable rate of massive MIMO wireless communication systems. Moreover, in the fixed size antenna array there exists a maximum for the uplink ergodic achievable rate when the antenna spacing is configured as 0.5 wavelength.As we all know, it's very expensive to deploy many RF chains in wireless communication systems, while in traditional massive MIMO wireless communication systems, each antenna corresponds to one RF chain, which results in lots of waste. To further save the cost of hardware, i.e., radio frequency(RF) chain circuits in massive MIMO wireless systems, an optimal equivalent pre-coding scheme is presented for 5G multimedia massive MIMO communication systems in which the mutual coupling effect is considered. And the expression of the effective capacity of the system as well as the expression of its upper-bound are derived with the equivalent pre-coding matrix and quality of service requirement. And this paper analyzes how the effective capacity changes with the parameters such as independent incident directions, antenna spacing of the rectangle antenna array and QoS statistical exponent. Furthermore, the upper bound of the effective capacity is derived for 5G multimedia massive MIMO communication systems. Based on the numerical simulation results, compared with the conventional zero-forcing precoding scheme, the optimal equivalent precoding scheme can improve the achievable rate of 5G multimedia massive MIMO communication systems.