# On Deploying the Internet of Energy with 5G Open RAN Technology including Beamforming Mechanism
## 4 Implementation of Beamforming in Open RAN Networks
### Beamforming in Open RAN  
The Split 7-2x option introduces simplified communication interference within O-RAN units, especially in front-haul, where it supports all beamforming technologies (analogue, digital, or hybrid); analogue beamforming deployment modules and amplifies first the signal and then splits it among the antennas of the antenna array; digital beamforming deployment builds first the digital streams of each antenna of the array and then the signals are modulated and amplified and sent by the antennas; hybrid beamforming deployment is a combination of both with several digital streams that, after modulation and amplification, are sent to a number of antennas. Figure 2 describes the block diagram of the standard beamforming solution in O-RAN, which is hybrid beamforming in the general form. One of the challenges of Split Option 7-2x in the front-haul interface is the high bandwidth. We suggest using Category B to perform the precoding in O-RU and reduce the transported data from O-DU through the front-haul interface to overcome this challenge. This implementation will lead to inter-RU interferences in O-RU because each O-RU will determine beamforming matrices independently. Thus, it has been suggested to design the beamforming matrices in O-DU through the channel state information (CSI) and produce a precoding beam in O-RU. We propose using the zero-forcing (ZF) algorithm as a potentiality to reduce the interference in received signals while keeping the beamforming in one unit. Moreover, the cost of implantation and hardware complexity will be reduced [28; 29; 30]. O-RAN suggests the following beamforming methods to achieve acceptable performance in beamforming:  
* Beamforming indexing method (predefined-beam beamforming). O-DU in this method sends information about the beamforming type to the O-RU based on BeamID, which will carry by the C-pane, and the O-RU reserves this information in a table of beam  
Figure 2: O-RAN Hybrid beamforming block diagram. indexes. This table contains beam weights, frequency domain beam weights, time-domain beam weights, or hybrid beamforming; the BeamID is used as a pointer to a pre-defined beamforming weight vector. Hence, BeamID is only a weight vector value transferred between O-DU and O-RU to register which beam should be used. * Real-time weights method (weight-based dynamic beamforming). The O-DU in this method sends the beamforming weights generated in real-time to the O-RU to be allied with a specific user's data. A beam index can be assigned (and used in subsequent messages) if the beamforming weights are stable for a period of time. This method has two implementation cases: weight-based dynamic (which are digital and analogue beamforming) and weight-based dynamic (which is hybrid beamforming); in the first case, the beamforming weights can be updated in real-time with the BeamID value allied with the weights. For the second case, two sub-cases are held: (1) both the time-domain and frequency-domain weights may be updated in real-time, and (2) the time-domain beams are fixed while the frequency-domain weights may be updated in real-time. * Beam attributes method (attribute-based dynamic beamforming). The disadvantage of the Real-time weights method requires additional processing capability in the O-RU for modifying transmission to the beam weights provided by the O-DU. Therefore, an adjustment to the previous method has been introduced to obtain the beam attributes method. The adjustment is that the O-RU generated the beamforming weights using a set of beam attributes signalled by the O-DU and carried (to the O-RU) by the C-plane. These attributes are beamwidth (narrow, wide), azimuth and elevation, sidelobe destruction, and beam weights determined by RU. The consequence of this adjustment is that hybrid beamforming is not supported. Due to the weights generated by O-RU, it will be either frequency-domain or time-domain but not hybrid. * Channel information method (channel-information-based beamforming). This method is based on digital beamforming.