Hybrid Beamforming: Advantages and Disadvantages

This page covers the advantages and disadvantages of Hybrid Beamforming, along with its basic principles. It outlines the benefits and drawbacks associated with Hybrid Beamforming.

Introduction to Beamforming

The primary goal of beamforming is to enhance coverage by utilizing amplitude and phase variations through an antenna array. There are three main types of beamforming architectures:

• Analog beamforming
• Digital beamforming
• Hybrid beamforming

What is Hybrid Beamforming?

Hybrid beamforming combines both analog and digital beamforming techniques. In this approach, precoding is applied in both the analog and digital domains, meaning it employs precoding/beamforming at both RF and baseband levels.

Partially Connected Hybrid Beamforming

Figure 1 depicts a partially connected Hybrid Beamforming setup. This architecture uses a separate antenna array (referred to as a “sub-array”) for the RF beamformer of each individual AFE/RF chain. Due to its architecture, this type is also known as sub-array hybrid beamforming.

Fully Connected Hybrid Beamforming

Figure 2 illustrates a fully connected Hybrid Beamforming setup. In this architecture, the RF beamformer of each AFE/RF chain uses all the antennas. RF signals from different AFE/RF chains are combined before transmission through the antenna. This process is applied to each antenna in the system. Due to its architecture, this type is also known as full-array hybrid beamforming.

Both all-silicon and column-fed architectures can utilize hybrid beamforming.

Advantages of Hybrid Beamforming

Here are the benefits of Hybrid Beamforming:

• Suitable for mmWave Frequencies: It can be effectively used at millimeter-wave frequencies.
• Digital Flexibility: It provides the digital flexibility to dynamically form many beams and nulls without hardware changes.
• Reduced RF Chains: It doesn’t require a full RF chain per element; only a full RF chain per sub-array is needed.
• Extreme Flexibility: It offers extreme flexibility in terms of the number of beams and nulls.
• High Beam Count: It can provide a high number of beams.
• Dynamic Beam Adjustment: The number of beams can be changed dynamically without altering the hardware.
• Hardware Fit: Hardware can fit within the lattice at high frequencies (all-silicon array only).
• Simplified Signal Routing: It does not involve complex signal routing.
• No LO Distribution: There are no Local Oscillators (LOs) to distribute within the array.

Disadvantages of Hybrid Beamforming

Here are the drawbacks of Hybrid Beamforming:

• Sub-Array Gain Limitation: Each beam only benefits from the gain of its respective sub-array.
• Analog Beamforming Complexity: It shares the complexity associated with analog beamforming.
• High Power Consumption: It also exhibits high power consumption, similar to analog beamforming.