Essential Concepts of Multi–Antenna Signal Processing
ArrayComm has two decades of experience in delivering real world implementations of advanced MAS technology that translate to impactful spectrum efficiency gains. Here is a brief summary of the core MAS concepts.
All MAS architectures and processing approaches leverage some combination of the following four applications and benefits:
Spatial diversity takes advantage of inherent channel differences, where they exist, between antennas separated in space. Spatial diversity is only useful when not all of the channels are in deep fades at the same time, the likelihood of which is positively correlated to the amount of scattering in the environment.
Coherent (or combining) gain uses an understanding of the characteristics of the radio channel (channel state information) to weight the signals to or from multiple antennas to create maximum coherently-combined signal (or sensitivity) in the radio-space direction of interest. This additionally provides some amount of passive interference mitigation, as the more-focused energy distribution reduces inherent co-channel interference to some degree. Approaches tapping coherent gains are often referred to as “beamforming.”
Interference mitigation adds calculations to the coherent combining gain baseline in order to send or receive the absence of energy in the radio-space direction of co-channel interferers. This is often referred to as “nulling” or active interference cancelation.
Spatial multiplexing is an application of coherent processing to create two or more distinct spatial channels on the same time-frequency radio resource. The multiple spatial channels can be used to enhance the link reliability or data rate to/from a single client device (also called MIMO layers), or to establish simultaneous links to/from multiple client devices (also called spatial division multiple access, or SDMA). Both approaches improve spectrum reuse and enhance network capacity.
These benefits (illustrated below) are additive — ArrayComm has in some cases delivered all four in the same system.
All MAS solutions employ some combination of these basic forms of gains or benefits. These MAS concepts were at one time only found in textbooks or the very leading-edge proprietary wireless networks, many of which were supplied by ArrayComm. The emergence of virtually unlimited demand for wireless broadband capacity has promoted these spectral efficiency improvements into the mainstream of today’s 4G technology roadmaps. ArrayComm has a deep understanding of the scientific foundations of MAS. Just as important, we have practical experience implementing advanced MAS features on real-time platforms in commercial deployments. Please review our A-MAS for LTE and LTE-A product page for an overview of how we can partner with your development team to keep your products in the forefront of performance.