Design and Analysis of FD MIMO Cellular Systems in Coexistence With MIMO Radar

Abstract

Spectrum sharing and full duplexing are two promising technologies for alleviating the severe spectrum crunch that has threatened to blight the progress of future wireless communication systems. In this paper, we consider a two tier coexistence framework involving a collocated multiple-inputmultiple-output (MIMO) radar system (RS) and a full-duplex MIMO cellular system (CS). Considering imperfect channel state information and hardware impairments at the CS, we focus on a spectrum sharing environment to improve the quality of service (QoS) for cellular users by designing i) precoders at CS via the minimization of sum mean-squared-errors, subject to the constraints of transmit powers of the CS and probability of detection (PoD) of the RS, and ii) precoders at the RS to mitigate the interference from RS towards CS. While the monotonically increasing relationship between PoD and its noncentrality parameter is exploited to resolve the PoD in terms of interference threshold towards the RS, a generalized likelihood ratio test for target detection is used to derive detector statistics of the precoded radar waveforms. Numerical results demonstrate the feasibility of the proposed spectrum sharing algorithms, albeit with certain tradeoffs in RS transmit power, PoD and QoS of cellular users.

In-Band Full-Duplex Dynamic Spectrum Sharing in Beyond 5G Networks

“…More recently, another important development towards DSS has risen: the co-existence of commercial cellular providers and federal incumbents (e.g., military radars), commonly referred to as communication-radar (ComRad) coexistence [4], [7]. Two approaches, in particular, have received significant attention: licensed shared Access (LSA) and spectrum access system (SAS) in the CBRS band of 3.55-3.7 GHz, also known as LTE band 48.…”

“…The limitations imposed on current DSS approaches have resulted in a significant technology revolution through the advent of IBFD DSS networks, where secondary (PAL/GAA) users can benefit from: i) simultaneous sensing and transmission (SST) and ii) simultaneous transmission and reception (STR) [4]. By utilizing proper SI mitigation technique at the IBFD spectrum sharing node, both sensing efficiencies, as well as secondary throughput can be maximized.…”

“…While the MIMO radar, located in the ocean at a distance = 400m from the coast is the IU, the operators/ users in the MBN located in the coastal region can be considered as the PAL/ GAA. A MIMO radar [4], [8] is considered because it achieves higher degrees of freedom than traditional phased-array radars. This is due to its enlarged virtual array aperture owing to its orthogonal waveforms.…”

“…The dualfunctional ComRad system (DFCR) presents key advantages in that a dual-functional design can drastically cut the hardware complexity, cost, and volume of a wide range of electronic equipment used for both communications and radar applications. Also, the joint radar and communication signaling can be designed to improve the real-time performance for both applications [4]. While appealing as a theoretic concept, this still faces a number of critical challenges: (i) the fundamental limits of DFCR operation are widely unknown and necessitate a new theoretical framework that jointly addresses both systems.…”

“…The incumbent users (IUs) operating in this band include federal users (military radars) and fixed satellite service earth stations who are protected from interference caused by PAL and GAA users through strict predefined guidelines. This forces the CBRS mobile broadband network (MBN) to either transmit in radar's white spaces or completely avoid any transmission inside predefined exclusive zones introduced by the National Telecommunications and Information Administration (NTIA) [4]. However, it is worth noting that a significant part of the US population resides in the exclusion zones, leading to very limited free spectrum opportunities being available for cellular operators utilizing the shared CBRS band in conjunction with incumbents.…”