This Q&A is an ongoing list, where new questions and answers are constantly added.
Q1. What is mediumband?
Ans: Mediumband is a "class of channels" or "a set of constraints" defined in terms of delay spread and symbol period. It does not refer to any particular band of frequencies in the electromagnetic spectrum.
Q2. Do "mediumband" and "mid-band" refer to the same thing?
Ans: It is true that the words, mediumband and mid-band look and sound very similar. However, mid-band, which just refers to a band of frequencies in the electromagnetic (EM) spectrum roughly from 3.5GHz to 25GHz, conceptually has nothing to do with mediumband.
Q3. What is "delay spread" in the context of wireless communication?
Ans: When you transmit a signal from a wireless transmitter, what you receive at your receiver is not a clean signal, but is a mixture of multiple delayed and attenuated versions of the transmit signal. There replicas are known as multi-path components (MPCs). The delay spread is a measure that quantifies the time difference between the latest and earliest MPCs.
Q4. Why do multi-path components (MPCs) occur?
Ans: MPCs occur due to the scattering of the transmit signal from objects in the wireless propagation environment between the transmitter and the receiver. Typically, a wireless signal is a modulated electromagnetic wave. So, any object that scatters and reflects electromagnetic waves could give rise to MPCs.
Q5. What is "symbol period" in the context of wireless communication?
Ans: In digital wireless communication, not all parts of the transmit signal carry useful information, but only the signal points regularly separated in time. This time separation is the symbol period, and is one of the most important parameters in digital wireless communication systems.
Q6. What is mediumband wireless communication?
Ans: Any wireless communication system that satisfies the mediumband constraints (see Fig. 1) defined in terms of delay spread and symbol period is a mediumband wireless communication system.
Q7. What is deep fading?
Ans: The MPCs typically have random delays and attenuations. When they add at the receiver, the addition is often destructive resulting a net signal that is weak. A given wireless communication is said to be in deep fading if the MPCs add destructively giving rise to a weak signal. When a system is in deep fade, increasing the transmit power has little or no effect in increasing the strength of the receive signal.
Q8. What is "the effect of deep fading avoidance" in mediumband wireless communication?
Ans: The deep fading occurs when MPCs are allowed to add freely. When a wireless communication system operates in the mediumband, it subtly imposes restrictions on the addition of MPCs reducing the likelihood of highly destructive addition. It is this ability to reduce those highly destructive additions is known as the effect of deep fading avoidance. This deep fading avoidance is unique to mediumband wireless communication.