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Beamforming with Joint Phase and Time Array: System Design, Prototyping and Performance

Jianhua Mo, Ahmad AlAmmouri, Shenggang Dong, Younghan Nam, Won-Suk Choi, Gary Xu, Jianzhong, Zhan

TL;DR

This work tackles mmWave system limitations by introducing the Joint Phase-Time Array (JPTA), which augments phase shifters with true-time-delay elements to create frequency-dependent beams from a single RF chain. By formulating Type-1 discrete-angle and Type-2 rainbow beam designs, the approach enables simultaneous multi-user beams across subcarriers and reduces hardware complexity relative to hybrid precoding. Prototyping at 28 GHz demonstrates four-user, frequency-dependent beamforming with acceptable EVM and beamwidth, while simulations show large throughput and coverage gains—up to 830% throughput improvement at cell edge and extended coverage from 410 m to 790 m for a 1 Mbps target. Overall, JPTA presents a cost-effective, scalable mmWave MIMO architecture with substantial system-level benefits for future 5G/6G networks.

Abstract

Joint phase-time arrays (JPTA) is a new mmWave radio frequency front-end architecture constructed with appending time-delay elements to phase shifters for analog beamforming. JPTA allows the mmWave base station (BS) to form multiple frequency-dependent beams with a single RF chain, exploiting the extra degrees of freedom the time-delay elements offer. Without requiring extra power-hungry RF chains, a BS with JPTA can schedule multiple users in different directions in a frequency-division multiplexing (FDM) manner. A BS with JPTA achieves various advantages over the traditional analog beamforming system. Simulation results show that JPTA can bring significant system-level benefits, e.g., extending uplink throughput coverage by 100%. To realize these system benefits of JPTA, high-resolution delay elements with a wide delay dynamic range are essential. With newly developed delay elements, we demonstrate that a single TRX RF chain can serve four users in four different directions in the mmWave band.

Beamforming with Joint Phase and Time Array: System Design, Prototyping and Performance

TL;DR

This work tackles mmWave system limitations by introducing the Joint Phase-Time Array (JPTA), which augments phase shifters with true-time-delay elements to create frequency-dependent beams from a single RF chain. By formulating Type-1 discrete-angle and Type-2 rainbow beam designs, the approach enables simultaneous multi-user beams across subcarriers and reduces hardware complexity relative to hybrid precoding. Prototyping at 28 GHz demonstrates four-user, frequency-dependent beamforming with acceptable EVM and beamwidth, while simulations show large throughput and coverage gains—up to 830% throughput improvement at cell edge and extended coverage from 410 m to 790 m for a 1 Mbps target. Overall, JPTA presents a cost-effective, scalable mmWave MIMO architecture with substantial system-level benefits for future 5G/6G networks.

Abstract

Joint phase-time arrays (JPTA) is a new mmWave radio frequency front-end architecture constructed with appending time-delay elements to phase shifters for analog beamforming. JPTA allows the mmWave base station (BS) to form multiple frequency-dependent beams with a single RF chain, exploiting the extra degrees of freedom the time-delay elements offer. Without requiring extra power-hungry RF chains, a BS with JPTA can schedule multiple users in different directions in a frequency-division multiplexing (FDM) manner. A BS with JPTA achieves various advantages over the traditional analog beamforming system. Simulation results show that JPTA can bring significant system-level benefits, e.g., extending uplink throughput coverage by 100%. To realize these system benefits of JPTA, high-resolution delay elements with a wide delay dynamic range are essential. With newly developed delay elements, we demonstrate that a single TRX RF chain can serve four users in four different directions in the mmWave band.

Paper Structure

This paper contains 12 sections, 5 equations, 9 figures, 1 table.

Table of Contents

  1. Introduction
  2. JPTA Beamforming
  3. JPTA Architecture
  4. JPTA Beam Generation
  5. Type-1 JPTA Beam
  6. Type-2 JPTA Beam
  7. Comparison with Hybrid Precoding
  8. Prototyping
  9. Simulation Results
  10. Simulation Setup
  11. Simulation Results and Discussion
  12. Conclusion

Figures (9)

  • Figure 1: The considered JPTA architecture, where each antenna element is connected through a delay unit and a PS.
  • Figure 2: A simple illustration of Type-1 and Type-2 JPTA Beams.
  • Figure 3: JPTA demonstration setup
  • Figure 4: JPTA off. BS serves 4 users sequentially. This figure shows when a beam steered to UE4.
  • Figure 5: JPTA on. Four UEs are supported simultaneously.
  • ...and 4 more figures