Which technology affects the spectral efficiency in modern wireless communication services?

The choice of Multiple Input Multiple Output - Orthogonal Frequency-Division Multiplexing (MIMO-OFDM) is correct because this technology significantly enhances spectral efficiency in wireless communication. MIMO technology employs multiple antennas at both the transmitter and receiver to send and receive more than one data signal simultaneously over the same radio channel. This increases the capacity of a communication link without requiring additional bandwidth.

Additionally, OFDM is a digital modulation technique that divides the radio spectrum into multiple closely spaced sub-carriers, allowing for efficient data transmission. By combining MIMO and OFDM, the technology can exploit multipath propagation, leading to more robust and higher data rate communication in various environments, particularly in urban areas where signal reflections occur.

Spectral efficiency, which measures how well a limited frequency spectrum is utilized for data transmission, is greatly improved with MIMO-OFDM. This technology allows for greater amounts of data to be transmitted in the same bandwidth, addressing the increasing demand for high-speed wireless communication.

In contrast, the other options, such as SISO, DSSS, and FHSS, while useful in their own contexts, do not provide the same level of enhancement in spectral efficiency as MIMO-OFDM. SISO uses a single antenna, limiting