Degrees of Freedom of the Field as the Upper Bound for the Number of MIMO Independent Channels

Wireless communication systems have rapidly evolved, becoming a driving force behind the global digital transformation. This has fostered connectivity and enabled the seamless exchange of information. Electromagnetic Information Theory (EMIT) represents a theoretical framework that explores the fundamental principles governing the transmission and reception of information through electromagnetic waves. Indeed, in wireless communication systems, the electromagnetic field acts as a medium for information transfer. EMIT has therefore emerged as a transformative paradigm, promising to redefine the landscape of next-generation wireless communication. At its core, the concept of Degrees of Freedom (DoF) of the electromagnetic field refers to the inherent capacity of the field to assume multiple independent configurations, allowing for the simultaneous transmission of diverse information streams. This capacity for simultaneous transmission is crucial in the context of next-generation wireless communication, where the demand for higher data rates, lower latency, and increased reliability is ever-growing. The DoF of the field can be harnessed to create multiple independent channels, each capable of carrying distinct information payloads. By understanding and manipulating these DoF, researchers and engineers can optimize the utilization of the electromagnetic spectrum, overcoming the limitations posed by traditional communication systems.