# Study of 5G-NR-MIMO Links in the Presence of an Interferer
## 1 Introduction  
The road map to advanced technologies such as Long Term Evolution (LTE) release 8-14 [1] and The 5 th Generation New Radio (5G-NR) technology [2] have led to significant breakthroughs. Many studies and researchers have created a scientific basis for engineering challenges and physical problems, such as peak spectral efficiency, fast fading channel response, and destructive effects in a multi-path channel [3, 4, 5, 6]. Dealing with fading and selective effects, a delay spread, high Doppler effects, fluctuation channels characterized in the time and frequency domains, and random scatters near the User Equipment (UE) or the small-cell are not trivial issues [4, 5]. In addition, the demands in the real world of next-generation mobile technology for high mobility, low latency, spectrum efficiency, peak data rates, and ultra multi-user experience, with emphasis on multiple users and sharing radio access, are increasing and have expanded the research field. There are a number of threshold conditions that must be met in order to operate multi-user access techniques such as Orthogonal Multiple Access (OMA)/Non-OMA (NOMA) techniques [7, 8, 9], or Multi-User (MU)- Multiple Input, Multiple Output (MIMO) [10, 11, 12]. The first condition is the ability to decoding a specific stream transmission, from spatial-multiplexing streams, under a random Signal Interference Noise Ratio (SINR) with random interference signals. The second condition is to combines unlicensed and licensed technology. The meaning of this combination is to manage a significant number of the wireless device under specific macro cell, without sharing any Physical Upload Shared Channel (PUSCH), Without sharing a common scheduler, and also without any Demodulation Reference-Signals (DM-RS), which help to run algorithms for estimating and offsetting interfering, likeMinimum Mean Square Error-Interference Rejection Combining (MMSE-IRC) [13; 14; 15]. For example, the use License Assisted Access (LAA) protocol [16; 17], or Device-To-Device (DTD) technique [18], to get a significant channel capacity, in an environment with multi-interferences. Complicated subjects, such as radio management and fairness access, which require peak data in real-time applications, and also emerging applications such as inter-vehicle communication [19], increase these engineering challenges. Previous works such as [20; 21; 22] have expanded this research area. These situations occur, especially in bands below 6 GHz, because spatial selectivity capacity requires instant time or frequency selectivity. The potential risk of exposure of essential international infrastructure in the private market or the military sector to a jammer attack or a multi-interference environment is troublesome. On the one hand, there is massive investment in information security networks and core layers against cyber attacks. On the other hand, with some simple jammer devices, it is possible to cut off radio links between Internet of Things (IoT) devices inside medical refrigerators in hospitals or to disrupt the communication of GPS location systems [23]. They can also jam vehicle-to-vehicle communication between autonomous cars [24] and other critical systems. Military systems are also vulnerable to many jammer techniques, and the cumulative damage can be devastating. In practice, we must develop and utilize two critical and advanced techniques when designing modern communication systems. First, an MIMO array or a massive MIMO technique is needed [25; 26]. Second, smart control systems under Channel State Information (CSI) are known to the receiver and transmitter at the same time, streamed through the remote control channel, or the Physical Upload Control Channel (PUCCH). This capability will allow us to configure a system with flexible immunity, which includes a trade-off between handling the jammer and handling the strong interference signals in a multi-interference environment, and in parallel to create a large number of receive paths that are orthogonal to each other.