Abstract
In this paper we evaluate the feasibility of short range outdoor mm-wave MIMO links in the 70 GHz portion of the E-band (71–76 GHz). We use phased arrays in order to strongly reduce the impact of the multipath components, thus making the channel mainly line-of-sight (LOS). We design the array using a simple patch as a single element and simulate the performances for a 200 m link and a MIMO system with equal element spacing at the transmitter and the receiver. Each node of the MIMO system consists of a uniform rectangular array (URA) where the single element is a patch antenna, in order to achieve higher gains and narrow beams. Such configuration is much more compact compared to the antennas currently employed for the same bandwidth. We optimize the interelement distances at the transmitter and the receiver and evaluate the capacity achievable with different array sizes. The results show that, for the proposed link budget, capacity up to 29 bit/s/Hz is achievable at a range of 200 m, with practical dimensions. We also show that the beamforming capabilities make the design much more flexible than the single reflector antenna systems. In the last part of the paper, we verify that our antenna can also operate in rainy conditions and longer ranges.
Highlights
Research on mm-wave communications has been significantly increased during the last years
We show the possibility of using patch antenna arrays for short range outdoor MIMO links, which provide gain comparable to the commonly used parabolic reflectors, guaranteeing enough received power
Equation (1) shows that a MIMO system can be viewed as consisting of U parallel single-input-single-output (SISO) channels, where each channel has gain λi and an average signal-tonoise ratio (SNR) downscaled with the number of transmitters
Summary
Research on mm-wave communications has been significantly increased during the last years. Different LOS MIMO systems have been proposed and tested indoor [6] and outdoor [7, 8] Another unique characteristic of mmwave band communications is that highly directional beams can be obtained using relatively small antennas. We show the possibility of using patch antenna arrays for short range outdoor MIMO links, which provide gain comparable to the commonly used parabolic reflectors, guaranteeing enough received power. The beamforming capabilities of each URA could provide more flexible links, because each array could focus the beam towards receivers placed in different locations, avoiding the time consuming and costly positioning of very narrow beam antennas [12] Such a system could be used for communications in enterprises, for disaster recovery or fast deployed fiber replacement.
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