In this paper we propose an optimal strategy to do rank adaptation, power control and user selection (pairing) for both Single-User (SU) & Multi-User (MU) MIMO in Massive MIMO (MM) systems. In this approach, we redefine the user selection and rank adaptation problem as a power control problem. We then use the Network Utility Maximization (NUM) framework to optimize the power vector. The benefit is that user selection and rank adaptation problems are typically centralized, combinatorial and thus NP hard, while power control problems are typically distributed and only linear in complexity. The Coordinated Massive MIMO with Power Control (CMM-PC) solution proposed in this paper only operates on a cell level, it extends naturally to a network level. As such, we currently do not require inter cell information exchange. Simulations show a continuously increasing performance gain as the number of antennas are increased over the range from 8 to 64.

Advanced radio channel modeling continues to be of great interest in order to facilitate innovation and pursue performance prediction of wireless networks; in particular, dual-polarized antenna systems for 4.5 and 5G require models that properly capture the complex phenomenon of depolarization. Accordingly, we present and validate a ray-based model for dual-polarized channel characterization. We present the model and describe the measurement campaign used to obtain field data for evaluation. We also compare our approach to the largely used WINNER-based stochastic model, and discuss the impact of antennas and diffuse scattering in the prediction of depolarization. The paper indicates that a 3D space-time deterministic propagation model must be used if a well correlated channel model, both in LoS and NLoS conditions, is required to assess a system performance.

This paper analyzes the average bit error probability (BEP) of the differential binary and quaternary phase-shift keying (DBPSK and DQPSK respectively) with multiple-input multiple-output (MIMO) systems employing postdetection equal gain combining (MIMO EGC) diversity reception over Rayleigh fading channels. Finite closed-form expressions for the average BEP of DBPSK and DQPSK are presented. Two approaches are introduced to analyze the error rate of DQPSK. The proposed structure for the differential phase-shift keying (DPSK) with MIMO EGC provides a reduced-complexity and low-cost receiver for MIMO systems compared to the coherent phase-shift keying system (PSK) with MIMO employing maximal ratio combining (MIMO MRC) diversity reception. Finally, a useful procedure for computing the associated Legendre functions of the second kind with half-odd-integer order and arbitrarily degree is presented.

This paper derives the average bit error probability (BEP) of differential quaternary phase shift keying (DQPSK) with postdetection equal gain combining (EGC) diversity reception over independent and arbitrarily correlated fading channels. First, using the associated Legendre functions, the average BEP of DQPSK is analyzed over independent Rayleigh, Nakagami-m, and Rician fading channels. Finite-series closed-form expressions for the average BEP of DQPSK over L-branch independent Rayleigh and Nakagami-m fading channels (for integer Lm) are presented. Besides, a finite-series closed-form expression is given for the average BEP of differential binary phase shift keying (DBPSK) with EGC over independent Rician fading channels. Second, an alternative approach is propounded to study the performance of DQPSK over arbitrarily correlated Nakagami-m and Rician fading channels. Relatively simple BEP expressions in terms of a finite sum of a finite-range integral are proposed. Moreover, the penalty in signal to noise ratio (SNR) due to arbitrarily correlated channel fading is also investigated. Finally, the accuracy of the results is verified by computer simulation.

This paper analyzes the average bit error prob- ability (BEP) of the differential binary and quaternary phase shift keying (DBPSK and DQPSK respectively) with multiple input/multiple output (MIMO) systems employing postdetection equal gain combining (EGC) diversity reception (MIMO EGC) over Rayleigh fading channels. Finite closed form expressions for the average BEP of DBPSK and DQPSK are presented. The average BEP of DQPSK is obtained using the associated Legendre functions. The proposed structure for the differential phase shift keying (DPSK) with MIMO EGC provides a reduced- complexity and low-cost receiver for MIMO systems compared to the coherent phase shift keying system (PSK) employing maximum ratio combining (MRC) diversity reception (MIMO MRC). Finally, a useful procedure for computing the associated Legendre functions of the second kind with half integer order and arbitrarily degree is presented.

This paper derives the average bit error probability (BEP) of the differential quaternary phase shift keying (DQPSK) with postdetection equal gain combining (EGC) diversity reception over arbitrarily correlated Nakagami-m and Rician fading channels. Our main contribution lies in presenting relatively simple BEP expressions, the error expressions are given in terms of a finite sum of a finite-range integral. The penalty in signal to noise ratio (SNR) due to arbitrarily correlated channel fading is investigated. It is observed that the performance degradation due to the correlation among the diversity branches in Rician fading channels is severer than that in Nakagami-m fading channels as a result of the presence of the specular component.

A method for computing the exact average symbol error probability (SEP) of the rectangular M-ary quadrature amplitude modulation (MQAM) with maximum ratio combining (MRC) diversity over L independent and equal-correlated Nakagami-m fading channels with arbitrary fading index m is presented. Two models of MQAM receivers are analyzed. Closed-form expressions are provided for the average SEP in terms of the Appell and Gauss hypergeometric functions. Simplified error expressions are proposed when the product Lm is either integer or half integer. The distinction between the performance of the two MQAM schemes is discussed. Finally, the penalty in signal to noise ratio (SNR) due to equal-correlated Nakagami-m channel fading is investigated