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A 4-channel code-multiplexed digital receiver is presented for multiple-input-multiple-output (MIMO) applications targeting 5G millimeter-wave (mm-Wave) communications. The receiver employs a code-multiplexing (CM) topology where multiple channels are encoded with unique orthogonal Walsh Hadamard codes and multiplexed into a single-channel for digitization. This approach overcomes the bottleneck of hardware complexity, cost, and power consumption in traditional multiplexing topologies by employing a single wideband analog-to-digital converter (ADC) to serve several channels. The article presents an end-to-end testbed to demonstrate the effectiveness of the proposed Code-Multiplexed Digital Receiver (CMDR) that consists of l ) ultrawideband (UWB) tightly-coupled dipole array (TCDA), 2) a custom-designed encoder circuit board (ECB), and 3) a Radio-Frequency System-on-Chip (RFSoC) field programmable gate array (FPGA) for encoding and decoding. The code sequences were generated at a maximum clock frequency of 400 MHz. Extensive experimental measurements were performed and test results were validated using performance metrics such as normalized mean square error (NMSE) and adjacent channel interference (ACI). Test results showed ACI of >20 dB, NMSE = -24.592 dB and little or no degradation in signal-to-noise ratio (SNR). To the best of our knowledge, this is the highest clock frequency and ACI value for hardware validation of channel multiplexing scheme reported in the literature.
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This content will become publicly available on March 19, 2026
Channel Decoding from Multiple Looks Under Receiver Impairments
Receiver impairments play a significant role in determining system performance, particularly in adversarial environments subject to intentional jamming that seek to impair operation by collapsing the dynamic range of the receiver. Clock jitter is one of the key impairments that limits analog-to-digital (A/D) converters, and it causes significant challenges for channel decoding as it distorts the received signal’s timing, making compensation difficult. Motivated by this challenge, we consider performance and design for the two-look channel, which utilizes two receivers with independent clock jitter. Using a statistical characterization of the jitter, we derive the degree to which mutual information is increased in the two-look scenario versus the case when a single receiver is employed. This analysis motivates the consideration of optimal decoder design, but this is complicated by the nonlinear timing jitter model. Hence, we turn to a machine learning (ML)-based decoding framework. Numerical results demonstrate the improvement in mutual information from having two looks, and simulation results demonstrate the improved channel decoding performance.
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- Award ID(s):
- 2029323
- PAR ID:
- 10653634
- Publisher / Repository:
- IEEE
- Date Published:
- Page Range / eLocation ID:
- 1 to 6
- Format(s):
- Medium: X
- Location:
- Baltimore, MD, USA
- Sponsoring Org:
- National Science Foundation
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