HS/MRC (hybrid selection/maximal ratio combining)

HS/MRC, which stands for hybrid selection/maximal ratio combining, is a technique used in wireless communication systems to increase the reliability of received signals in the presence of interference and noise. This technique combines the benefits of two different types of diversity: antenna diversity and space diversity.

Antenna diversity involves using multiple antennas at the receiver to receive the same signal from multiple paths, while space diversity involves using multiple antennas at the transmitter to send the same signal from multiple directions. HS/MRC combines these two techniques to improve signal quality and reduce the effects of interference and noise.

In HS/MRC, the received signal from each antenna is first preprocessed to remove any common noise or interference. The signals are then combined using a maximal ratio combining (MRC) algorithm, which weights each signal based on its signal-to-noise ratio (SNR) to maximize the overall signal quality.

The MRC algorithm calculates the weights for each antenna by taking the ratio of the signal power to the noise power for each antenna. The weights are then normalized so that they add up to one. The combined signal is then reconstructed by adding up the weighted signals from each antenna.

The hybrid selection part of HS/MRC involves selecting the best set of antennas to use for the MRC algorithm. This selection is based on the signal-to-interference-plus-noise ratio (SINR) for each antenna, which is a measure of how much the signal power exceeds the interference and noise power.

The hybrid selection process involves selecting a subset of antennas with the highest SINR values and using those antennas for the MRC algorithm. The selection is based on a threshold SINR value, which is chosen based on the tradeoff between diversity gain and complexity.

The benefits of HS/MRC are numerous. First, it provides both antenna and space diversity, which improves the reliability of the signal by reducing the effects of fading, interference, and noise. Second, it provides a higher diversity gain compared to using either antenna diversity or space diversity alone. Third, it is relatively easy to implement and does not require a significant increase in hardware complexity.

One of the key challenges in implementing HS/MRC is determining the optimal threshold SINR value for antenna selection. This value depends on various factors such as the number of antennas, the channel conditions, and the level of interference and noise. In addition, the selection process can be computationally intensive, particularly for systems with a large number of antennas.

Despite these challenges, HS/MRC has been successfully implemented in many wireless communication systems, including cellular networks, Wi-Fi, and satellite communication systems. It has been shown to significantly improve the reliability and quality of the received signal, particularly in environments with high levels of interference and noise.

In summary, HS/MRC is a powerful technique that combines antenna diversity and space diversity to improve the reliability and quality of wireless communication signals. By using a hybrid selection process to select the best set of antennas for the MRC algorithm, it provides a high diversity gain with relatively low hardware complexity. While there are challenges in determining the optimal threshold SINR value and implementing the selection process, HS/MRC has been widely adopted in many wireless communication systems and is a key technology for improving signal quality in challenging environments.