Multiple-Input Multiple-Output (MIMO) antennas are increasingly used within cellular systems. They provide flexible beamforming and spatial multiplexing improving coverage and capacity. One drawback with large array antennas is the challenge to provide wide beams utilizing the full power of the MIMO antenna grid. A promising solution is to use dual polarization beamforming. In this paper this technique is demonstrated with a Fifth Generation (5G) New Radio (NR) 8x4 MIMO radio. Dual polarized precoders are designed that utilize all 64 power amplifiers creating a wide sector beam. The coverage is measured on the NR Synchronization Signal Block (SSB) in a macro deployment proving range coverage in combination with a wide horizontal angle.

We propose an efficient method for designing broad beams with spatially flat array factor and efficient power utilization for cell-specific coverage in communication systems equipped with large antenna arrays. To ensure full power efficiency, the method is restricted to phase-only weight manipulations. Our framework is based on the discovered connection between dual-polarized beamforming and polyphase Golay sequences. Exploiting this connection, we propose several methods for array expansion from smaller to larger sizes, while preserving the radiation pattern. In addition, to fill the gaps in the feasible array sizes, we introduce the concept of$\epsilon $-complementarity that relaxes the requirement on zero side lobes of the sum aperiodic autocorrelation function of a sequence pair. Furthermore, we develop a modified Great Deluge algorithm (MGDA) that finds$\epsilon $-complementary pairs of arbitrary length, and hence enables broad beamforming for arbitrarily-sized uniform linear arrays. We also discuss the extension of this approach to two-dimensional uniform rectangular arrays. Our numerical results demonstrate the superiority of the proposed approach with respect to existing beam-broadening methods.

Next-generation wireless communication systems will rely on multiple-antenna deployments enabling the beamforming functionality. In contrast to data transmission that benefits from user-specific beamforming (i. e., focusing the radiation at a particular user terminal), broadcasting of control information over a public channel requires cell-specific beamforming (i.e., cell-wide coverage). This paper presents a simple beamforming technique for cell-specific signaling for a four-port linear antenna array, based on exploiting two orthogonal polarizations and a maximum-ratio combining receiver. For instance, it is shown that by carefully tuning the excitation weights it is possible to design radiation patterns with any half-power beamwidth in the range from that of a narrow DFT beam to that of a single antenna element, while preserving the constant-modulus property of the excitation weights, thereby assuring excellent power utilization. The paper, furthermore, shows a direct connection between the underlying beamforming technique and the well-known concept of Alamouti space-time coding.