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RF System Design for Radar and Wireless Communications

RF system design in radar and wireless communications involves the integration of various RF components, such as antennas, filters, amplifiers, modulators, and demodulators. Your RF system design must consider the tradeoffs in these components to mitigate noise and intermodulation distortion effects. This topic discusses RF system design considerations and provides cross-product workflows for radar, long-term evolution (LTE), and wireless local area network (WLAN) applications.

Design Considerations

Radar

Radar applications require RF transmitters and RF receivers. RF transmitters primarily consist of an amplifier and a filter. Since the filter is a linear device and the amplifier is a nonlinear device, you can split the RF transmitter into two subsystems. This separation allows the use of different simulation frequency sets in each subsystem and permits a tradeoff between faster simulation speed and the loss of inter-stage loading effects available in a cascaded chain.

For RF receiver design you can use the direct conversion structure with LNA and matching networks. The low noise amplifier (LNA) can be described in a touchstone file and the local oscillator must include a phase noise model. As with RF transmitters, you can split RF receivers into linear and nonlinear subsystems. The linear subsystem can contain matching networks, the LNA, and the filter, while the nonlinear subsystem can contain the Mixer block and final stage amplifiers.

LTE

LTE applications require characterizing the impact of LTE interference in the RF reception of a new radio (NR) waveform. To characterize the impact of LTE interferences, you can use RF Blockset™ to design an RF receiver and downconvert baseband LTE and NR waveforms. Using downconverted waveforms, you can calculate the error vector magnitude (EVM), adjacent channel leakage ratio (ACLR), occupied bandwidth, channel power, and complementary cumulative distributive functions (CCDF) with LTE Toolbox™ and 5G Toolbox™. You can use the rfsystem object as a device under test (DUT) to implement a measurement testbench for your RF receiver for LTE reception.

WLAN

WLAN applications require characterizing the impact of RF impairments, such as in-phase and quadrature (IQ) imbalance, phase noise, and power amplifier (PA) nonlinearities in the transmission of an 802.11ax waveform. To characterize the impact of RF impairments on an 802.11ax network, you can use WLAN Toolbox™ to generate and oversample a baseband 802.11ax waveform. This waveform can be imported as an RF signal into the RF transmitter block to upconvert. Using this upconverted waveform, you can calculate the spectral mask, occupied bandwidth, channel power, CCDF, and peak-to-average power ratio (PAPR).

Design Workflows

You can design RF systems for radar and wireless communications using these cross-product workflows:

  • Radar System Modeling — This workflow shows how to set up a radar system simulation consisting of a transmitter, a channel with a target, and a receiver. RF Blockset is used for modeling the RF transmitter and receiver sections.

  • Modeling RF Front End in Radar System Simulation (Phased Array System Toolbox) — This workflow shows how to incorporate RF front-end behavior into an existing radar system design. In a radar system, the RF front end often plays an important role in defining the system performance. For example, since the RF front end is the first section in the receiver chain, the design of its low noise amplifier is critical to achieving the desired SNR.

  • Modeling and Testing an NR RF Receiver with LTE Interference (5G Toolbox) — This workflow shows how to characterize the impact of RF impairments in the RF reception of an NR waveform coexisting with LTE interference. The baseband waveforms are generated using 5G Toolbox and LTE Toolbox, and the RF receiver is modeled using RF Blockset.

  • Modeling and Testing an 802.11ax RF Transmitter (WLAN Toolbox) — This workflow shows how to characterize the impact of RF impairments in an 802.11ax transmitter. The example generates a baseband IEEE® 802.11ax™ waveform by using WLAN Toolbox and models the RF transmitter by using RF Blockset.

  • RF Receiver Modeling for LTE Reception — This workflow shows how to model and test an LTE RF receiver using LTE Toolbox and RF Blockset.

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