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1. Spectrum Sharing of the 12 GHz Band with Two-way Terrestrial 5G Mobile Services: Motivations, Challenges, and Research Road Map

   Zoheb Hassan, Erika Heeren-Moon (July 2023, IEEE communications magazine)

   Telecommunication industries and spectrum regulation authorities are increasingly interested in unlocking the 12 GHz band for two-way 5G terrestrial services. The 12 GHz band has a much larger bandwidth than the current sub-6 GHz band and better propagation characteristics than the millimeter wave (mmWave) band. Thus, the 12 GHz band offers great potential for improving the coverage and capacity of terrestrial 5G networks. However, interference issues between incumbent receivers and 5G radio links present a major challenge in the 12 GHz band. If one could exploit the dynamic contexts inherent to the 12 GHz band, one could reform spectrum sharing policy to create spectrum access opportunities for 5G mobile services. This article makes three contributions. First, it presents the characteristics and challenges of the 12 GHz band. Second, we explain the characteristics and requirements for spectrum sharing at a variety of levels to resolve those issues. Lastly, we present several research opportunities to enable harmonious coexistence of incumbent licensees and 5G networks within the 12 GHz band. 

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2. Terahertz Wireless Communications: Co-Sharing for Terrestrial and Satellite Systems Above 100 GHz

   Yunchou Xing, Theodore S. (October 2021, IEEE communications letters)

   Abstract—This letter demonstrates how spectrum up to 1 THz will support mobile communications beyond 5G in the coming decades. Results of rooftop surrogate satellite/tower base station measurements at 140 GHz show the natural isolation between terrestrial networks and surrogate satellite systems, as well as between terrestrial mobile users and co-channel fixed backhaul links. These first-of-their-kind measurements and accompanying analysis show that by keeping the energy radiated by terrestrial emitters on the horizon (e.g., elevation angles g.t. 15 deg), there will not likely be interference in the same or adjacent bands between passive satellite sensors and terrestrial terminals, or between mobile links and terrestrial backhaul links at frequencies above 100 GHz. Index Terms—Mmwave, terahertz, spectrum sharing and coexistence, satellite, OOBE, interference mitigation. 

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3. Programmable Millimeter-Wave MIMO Radios with Real-Time Baseband Processing

   Qi, Zhenzhou; Gao, Zhihui; Tung, Chung-Hsuan; Chen, Tingjun (October 2023, ACM MobiCom’23 Workshop on Wireless Network Testbeds, Experimental Evaluation & CHaracterization (WiNTECH’23))

   Baseband processing is one of the most time-consuming and computationally expensive tasks in radio access networks (RANs), which is typically realized in dedicated hardware. The concept of virtualizing the RAN functions by moving their computation to edge data centers can significantly reduce the deployment cost and enable more flexible use of the network resources. Recent studies have focused on software-based baseband processing for large-scale sub-6 GHz MIMO systems, while 5G also embraces the millimeter-wave (mmWave) frequency bands to achieve further improved data rates leveraging the widely available spectrum. Therefore, it is important to build a platform for the experimental investigation of software-based baseband processing for mmWave MIMO systems. In this paper, we implement programmable mmWave MIMO radios equipped with real-time baseband processing capability, leveraging the open-access PAWR COSMOS testbed. We first develop Agora-UHD, which enables UHD-based software-defined radios (SDRs) to interface with Agora, an open-source software realization of real-time massive MIMO baseband processing. Next, we integrate Agora-UHD with the USRP SDRs and IBM 28 GHz phased array antenna module (PAAM) subsystem boards deployed in the PAWR COSMOS testbed. We demonstrate a 2×2 28 GHz polarization MIMO link with a bandwidth of 122.88 MHz, and show that it can meet the real-time processing deadline of 0.375 ms (3 transmission time intervals for numerology 3 in 5G NR FR2) using only 8 CPU cores. The source code of Agora-UHD and its integration with the programmable 28 GHz radios in the COSMOS testbed with example tutorials are made publicly available. 

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4. Programmable and Open-Access Millimeter-Wave Radios in the PAWR COSMOS Testbed

   https://doi.org/10.1145/3477086.3480834  

   Chen, Tingjun; Maddala, Prasanthi; Skrimponis, Panagiotis; Kolodziejski, Jakub; Gu, Xiaoxiong; Paidimarri, Arun; Rangan, Sundeep; Zussman, Gil; Seskar, Ivan (October 2021, Proc. ACM MobiCom’21 Workshop on Wireless Network Testbeds, Experimental evaluation & CHaracterization (WiNTECH’21) (to appear))

   null (Ed.)

   While millimeter-wave (mmWave) wireless has recently gained tremendous attention with the transition to 5G, developing a broadly accessible experimental infrastructure will allow the research community to make significant progress in this area. Hence, in this paper, we present the design and implementation of various programmable and open-access 28/60 GHz software-defined radios (SDRs), deployed in the PAWR COSMOS advanced wireless testbed. These programmable mmWave radios are based on the IBM 28 GHz 64-element dual-polarized phased array antenna module (PAAM) subsystem board and the Sivers IMA 60 GHz WiGig transceiver. These front ends are integrated with USRP SDRs or Xilinx RF-SoC boards, which provide baseband signal processing capabilities. Moreover, we present measurements of the TX/RX beamforming performance and example experiments (e.g., real-time channel sounding and RFNoC-based 802.11ad preamble detection), using the mmWave radios. Finally, we discuss ongoing enhancement and development efforts focusing on these radios. 

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5. Programmable and Open-Access Millimeter-Wave Radios in the COSMOS Testbed: Design, Deployment, and Experimentation,”

   T. Chen, P. Maddala (October 2023, Computer networks communications)

   While millimeter-wave (mmWave) wireless has recently gained tremendous attention with the transition to 5G, developing a broadly accessible experimental infrastructure will allow the research community to make significant progress in this area. Hence, in this paper, we present the design and implementation of various programmable and open-access 28/60 GHz software-defined radios (SDRs), deployed in the PAWR COSMOS advanced wireless testbed. These programmable mmWave radios are based on the IBM 28 GHz 64-element dual-polarized phased array antenna module (PAAM) subsystem board and the Sivers IMA 60 GHz WiGig transceiver. These front ends are integrated with USRP SDRs or Xilinx RFSoC boards, which provide baseband signal processing capabilities. Moreover, we present measurements of the TX/RX beamforming performance and example experiments (e.g., real-time channel sounding and RFNoC-based 802.11ad preamble detection), using the mmWave radios. Finally, we discuss ongoing enhancement and development efforts focusing on these radios. 

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