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Time Division Duplex (TDD) Multi-User Multiple-Input, Multiple-Output (MU-MIMO) Mobile Ad-Hoc Network (MANET)

Abstract Details

2019, MS, University of Cincinnati, Engineering and Applied Science: Electrical Engineering.
Multiple antenna technologies are well proven to improve radio-frequency (RF) wireless communications. Many modern communication standards have adopted multiple antenna technologies to provide throughput and reliability gains. Multiple-input, multiple-output (MIMO) refers to using multiple transmit antennas and multiple receive antennas. MIMO is well studied in cellular networks involving base-stations and multiple subscribing users (hub and spoke topologies) and less studied in mobile ad-hoc networks (MANETs). MANETs are infrastructure-less networks where each network node is free to move independently of other nodes. Self-configuring and self-healing algorithms maintain link communications and provide routing capability across the network. In this work, multi-antenna technologies are investigated in order to enhance the throughput and resilience of terrestrial MANETs, such as those used by first responders, in military environments and rural settings. Multi-user (MU-) MIMO offers the potential of a significant leap towards increased data rates, improved spatial reuse, reduced mutual interference, extended reach, and low-probability interception/detection (LPI/LPD). The primary focus in MU-MIMO MANETs is maximizing network sum rates while appropriately handling the multi-user interference generated in mobile networks. Mobile nodes present a constantly changing channel environment which requires a resilient MU-MIMO algorithm to ensure maximized throughput. To provide support for terrestrial concept-of-operations (CONOPS), this work has focused on development of time-division duplex (TDD) MU-MIMO networks. TDD was chosen over frequency-division duplex (FDD) due to the anticipated disruptive, fast-changing channels of terrestrial and low-altitude networks of interest as well as to limit spectral usage. This work relies on using multiple-antenna radio nodes to enable simultaneous link communication between sets of transmitting and receiving nodes. The mutual interference generated at receiving nodes by such simultaneous transmissions presents a significant challenge in traditional radio systems. The traditional solution is to ensure communications via interference avoidance where orthogonal time and/or frequency are used to limit mutual interference at a node; however, such system designs do not utilize system resources to their fullest potential. The sum-rate gains of this work are obtained by operating each of the simultaneous links in a cooperative manner. The MIMO pre-coder formulation used in this work transmits signals in such a way that the total interference at receiving nodes occurs in a time, frequency and spatial domain which is distinct from that of the desired signal-of-interest’s (SOIs) time, frequency, and spatial domain, thereby providing separability of the SOI from the interference at the receiving node. This effort focuses on spatial orthogonality where time and frequency overlap. In addition to studying TDD MU-MIMO MANETs, this work develops a full system design and implements this design on a prototype software-defined radio (SDR). Performance results of simulations and a hardware implementation are provided.
Xuefu Zhou, Ph.D. (Committee Chair)
Rui Dai, Ph.D. (Committee Member)
Robert Hayes, PhD (Committee Member)
Badri Narayanan Vellambi Ravisankar (Committee Member)
89 p.

Recommended Citations

Citations

  • Peters, G. M. (2019). Time Division Duplex (TDD) Multi-User Multiple-Input, Multiple-Output (MU-MIMO) Mobile Ad-Hoc Network (MANET) [Master's thesis, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563525886227608

    APA Style (7th edition)

  • Peters, Gavin. Time Division Duplex (TDD) Multi-User Multiple-Input, Multiple-Output (MU-MIMO) Mobile Ad-Hoc Network (MANET). 2019. University of Cincinnati, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563525886227608.

    MLA Style (8th edition)

  • Peters, Gavin. "Time Division Duplex (TDD) Multi-User Multiple-Input, Multiple-Output (MU-MIMO) Mobile Ad-Hoc Network (MANET)." Master's thesis, University of Cincinnati, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1563525886227608

    Chicago Manual of Style (17th edition)