Array gain

In MIMO communication systems, array gain means a power gain of transmitted signals that is achieved by using multiple-antennas at transmitter and/or receiver, with respect to single-input single-output case. It can be simply called power gain. In a broadside array, the array gain is almost exactly proportional to the length of the array. This is the case provided that the elements of the antenna are not spaced to a point at which large radiation side lobes form in other directions and that the array length exceeds one or two wavelengths. The power gain of a broadside array is nearly independent of the number of broadside elements as long as both of these conditions are met. In MIMO communication systems, array gain means a power gain of transmitted signals that is achieved by using multiple-antennas at transmitter and/or receiver, with respect to single-input single-output case. It can be simply called power gain. In a broadside array, the array gain is almost exactly proportional to the length of the array. This is the case provided that the elements of the antenna are not spaced to a point at which large radiation side lobes form in other directions and that the array length exceeds one or two wavelengths. The power gain of a broadside array is nearly independent of the number of broadside elements as long as both of these conditions are met. The two main types of array gain when combining signals are average power of combined signals relative to the individual average power and the diversity gain related to the probability level of outage. The diversity gain is dependent on spatial correlation coefficients between antenna signals.