## 4 Comparison of Massive MIMO Structure with Two Element MIMO Structure  
We have identified a few advantages and disadvantages from our previously published results [9; 10; 35] and other published structures [36; 37; 38; 39]. The advantages of a 1 \(\times\) 2 MIMO (multiple-input single-output) structure versus a 2 \(\times\) 3 MIMO structure (or massive MIMO structure) in wireless communication systems can be summarized as follows:  
Advantages of 1 \(\times\) 2 MIMO:  
* Simplicity: A 1 \(\times\) 2 MIMO structure involves one transmit antenna and two receive antennas. It is a relatively simple configuration compared to higher-order MIMO structures, such as 2 \(\times\) 3, in terms of hardware complexity, implementation, and cost.
* Lower System Complexity: With fewer antennas involved, a 1 \(\times\) 2 MIMO system typically has lower system complexity in terms of signal processing, antenna design, and RF (radio frequency) front-end requirements. This can result in easier system design and reduced complexity in terms of implementation and deployment.
* Lower Power Consumption: Due to its lower system complexity, a 1 \(\times\) 2 MIMO structure may require less power consumption compared to higher-order MIMO configurations, which can be beneficial in scenarios where power efficiency is a concern, such as in battery-powered devices or energy-constrained environments. Advantages of 2 \(\times\) 3 MIMO:
* Higher Spatial Diversity: A 2 \(\times\) 3 MIMO structure provides higher spatial diversity compared to a 1 \(\times\) 2 MIMO structure. With two transmit antennas and three receive antennas, it can leverage multiple spatial paths for communication, leading to improved performance in terms of signal quality, reliability, and robustness against fading and interference.
* Increased Capacity: A 2 \(\times\) 3 MIMO system can potentially offer higher capacity compared to a 1 \(\times\) 2 MIMO system, as it can support the transmission of more data streams simultaneously. This can result in higher data rates and increased throughput, which can be advantageous in high-data-rate communication scenarios.
* Enhanced Performance: With more antennas involved, a 2 \(\times\) 3 MIMO system can offer improved performance in terms of link quality, coverage area, and interference mitigation.  
Figure 16: Calculated values of the CCL for antenna Design 5.  
tion. It can provide better signal strength, extended coverage, and increased resilience against channel impairments, leading to more reliable and robust communication.
* Flexibility in Spatial Multiplexing: A 2 \(\times\) 3 MIMO system can support higher-order spatial multiplexing, which refers to the simultaneous transmission of multiple data streams on the same frequency band. This allows for more flexibility in terms of data transmission and can enable higher capacity and improved spectral efficiency. We can identify from the key points above that the advantages of a 1 \(\times\) 2 MIMO versus a 2 \(\times\) 3 MIMO structure depend on the specific requirements of the communication system and the trade-offs between system complexity, performance, and capacity. While a 1 \(\times\) 2 MIMO structure offers simplicity and lower system complexity, a 2 \(\times\) 3 MIMO structure provides higher spatial diversity, increased capacity, and enhanced performance. The choice between the two would depend on the specific application, deployment scenario, and performance requirements of the wireless communication system.