Analog and RF building blocks in C-V2X radio communications

Vehicle-to-everything (V2X) communication is one step closer to the commercial realization after the arrival of 3GPP 5G Release 16 that enables cellular V2X (C-V2X) within the 5G New Radio (NR) framework. The new standards release also supports sidelinking, a direct device-to-device communication mode that bypasses cellular networks’ need and enhances semi-autonomous or autonomous driving.

The long-term evolution (LTE)-based C-V2X radio technology offers an alternative to more specialized direct short-range communication (DSRC) technology for V2X environments. However, C-V2X has lower latencies than DSRC, provides 20% to 30% more range, and performs much better in the presence of obstructions.

Like other wireless communication technologies, C-V2X technology comprises both analog and digital building blocks. This blog explains one of the most prominent analog and mixed-signal parts of the C-V2X design: C-V2X radio that involves a lot of high-frequency analog in the receiver chain.

Figure 1 The block diagram shows three types of radio architectures for a C-V2X sampling receiver. Source: IEEE

Figure 1 shows three types of radio architectures for sampling receivers: a) baseband sampling receiver, b) IF sampling receiver, c) RF sampling receiver. The RF analog-to-digital converters (ADCs) will determine what type of receiver the designer chooses—a, b, or c—depending on the input frequency.

Figure 2 The block diagram shows a direct-to-RF radio transmitter architecture. Source: Analog Devices Inc.

The radio transmit side has a digital-to-analog converter (DAC) and other associated RF components, as shown in Figure 2.

Now, take a look at Qualcomm’s development platform for C-V2X applications with many analog functions (Figure 3). Here, Qualcomm’s C-V2X chipset solution is compatible with 5G and advanced driver assistance system (ADAS) sensors. The 9150 chipset features a C-V2X direct communication mode, which ensures low latency in vehicles and roadside equipment for vehicle-to-infrastructure (V2I), vehicle-to-vehicle (V2V), and vehicle-to-pedestrian (V2P) communications with or without the involvement of a cellular network.

Figure 3 Qualcomm’s C-V2X development platform shows a plenty of analog content. Source: Qualcomm

More profound changes are looming on the C-V2X radio horizon with the entry of semi-autonomous and autonomous vehicles. For instance, the integration of latency-sensitive collision avoidance capabilities will be a challenge and an opportunity for the V2X communication designs.

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