Chapter 3
Cellular Connectivity
Cellular connectivity has revolutionized the way we communicate with each other. The latest generation of cellular connectivity, 5G New Radio (5G NR), is unifying the digital experience for billions of connected devices. It enables cellular connectivity that is much faster and has lower latency and higher reliability than the current 4G LTE systems. The scope of 5G will range from mobile broadband services to next-generation self-driven automobiles and connected IoT devices, as defined by three use cases for 5G NR:
- eMBB (enhanced mobile broadband)
- URLLC (ultra-reliable low-latency communications)
- mMTC (massive machine type communications)
5G requires substantially different architectures, radio access technology, and physical layer algorithms. Key among these new physical layer–enabling technologies are:
- Flexible and mixed numerology including increased subcarrier spacing leading to shorter slot durations for increased signal bandwidth and shorter latency
- The use of new channel coding algorithms such as LDPC for data and polar codes for control information
- Channel models for use at sub-7 GHz and mmWave frequencies
- Use of massive MIMO to achieve greater spectral efficiency
Several physical layer (PHY) challenges and use cases are associated with the design of 5G cellular connectivity systems.
Waveform Generation and Testing
Easy access to fully compliant waveforms is essential for using golden references for design verification. To verify that your system conforms to the standards, you need to generate off-the-shelf waveforms specified by 3GPP specifications, including New Radio test models (NR-TMs) or fixed-reference channels (FRCs). You may also need to generate fully customized uplink and downlink waveforms. After transmitting 5G signals over the air, you need to analyze waveforms and obtain quality metrics. You can easily and interactively generate and test waveforms using the 5G Waveform Generator app in 5G Toolbox™.
End-to-End Link-Level Simulation
System designers need to predict and customize the performance of 5G systems and ensure that their design meets standard specifications. They need to set up end-to-end simulations incorporating transmitters, channel models, RF impairments, and receivers and analyze performance metrics such as the throughput. Since 5G Toolbox provides open MATLAB source code for 5G link-level implementations, design space exploration for all these parameters is made easier and more flexible.
System-Level Simulation
Designers and operators of 5G systems need to optimize time-frequency resources shared among multiple users in a 5G NR network. They need to evaluate the network performance with different data traffic models, MAC scheduling strategies, and PHY algorithms. They also need to analyze the effect of intercell interference and measure overall throughput, scheduling fairness, spectrum efficiency, and other metrics.
Beam Management
5G NR systems can operate at millimeter wave frequencies (24.25 GHz to 52.6 GHz). At these frequencies, the transmitted signal undergoes high path loss and penetration loss. Beamforming is essential to improve the gain and to achieve better reception of the signals at higher frequencies. Beam management is a key procedure to establish and maintain an optimal beam pair (transmit beam and receive beam) for good connectivity. For example, the base station can transmit multiple channel state information reference signal (CSI-RS) resources in different directions in a scattering environment, then select the optimal transmit beam connecting the base station to a mobile unit based on reference signal received power (RSRP) measurements.
