# <center> **Daily Report 6** </center>
###### tags: `O-RAN` `IVC` `5G O-RAN` `ITB NTUST 5G course`
> Date: 26/07
## <center> **5G PHY** </center>

### **Important Aspects**
#### **1. 5G NR Physical Layer Design**
#### **2. OFDM System**
#### **3. Tutorial of OFDM System**

### **Summary**
5G PHY is differences from 4G (LTE). 5G has more use cases like eMBB, mMTC, URLLC. Latency less than < 1 ms. Band up to 60 GHz. Bandwith up to 100 MHz below 6 GHz / up to 400 MHz above 6 GHz. Variable Subcarrier spacing. Frequency allocation use of bandwith parts. Avoid always on signals, the only one is the SS block. The key technology components of the NR physical layer are: Waveform, Modulation, Multiantenna transmission (MIMO), Channel coding. 5G still use OFDM-based modulation as in LTE such as OFDMA, CP-OFDMA, SC-FDMA. NR supports QPSK, 16 QAM, 64 QAM and 256 QAM. 256QAM is used to support higher data rate transmission. π/2-BPSK to reduce peak-to-average power ratio & to enhanced power amplifier efficiency at lower data rates, which is important for mMTC services. Massive MIMO is base station with hundreds of antennas multiple users and low power antennas. The characteristics in MIMO are more antennas than number of users, multiplexing gain, small low power antennas, very directive signals. little interference leakage. Massive MIMO benefits are high spectral efficiency, array gain, high energy efficiency, high data rate, user tracking, low power consumption, less fading, low latency, more reliability. Massive MIMO challenge are: Pilot contamination, Channel Estimation, Precoding, User Scheduling, Hardware Impairments, Energy efficiency, Signal detection. Flexible channel coding scheme is one of the fundamental components of the NR access technology, to meet higher data rates and more diverse requirements of typical NR scenarios: eMBB, mMTC, and URLLC. Candidate schemes: CC, Turbo Coding, LDPC, Polar Coding. There are several types of modulation that can be done in the OFDM system: BPSK, QPSK, QAM-16, QAM-64. Fourier (IFFT / FFT) is the main part of OFDM system for multicarrier modulation-demodulation process, Convert data to time domain and vice versa, Transmitter -> IFFT & Receiver -> FFT, Fourier specifications: 256 parallel data. Cyclic Prefix is added to the symbol data with the aim of overcoming the effects of inter symbol interference, because of multipath fading. Cyclic Prefix insertion process is carried out by duplicating the back of the symbol to the front. OFDM transmission typically defined by IEEE 802.11a standard specification. In OFDM transmission, all the available subcarriers from the DFT is not used for data transmission. Typically, some subcarriers at the edge are left unused to ensure spectrum roll off.

### Comment
5G NR (new radio) is very important because it is a data transmission on 5G, it is applied to 5G networks. Massive MIMO is a new technological breakthrough that has many advantages, but still has its own challenges.

## <center> **Discussion with team** </center>
:::info
### 1. Research About Sub-topics
### 2. Discuss About Next Meeting
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