Cognitive MIMO-RF/FSO Cooperative Relay Communication With Mobile Nodes and Imperfect Channel State Information

Abstract

This work analyzes the performance of an underlay cognitive radio based decode-and-forward mixed multipleinput multiple-output (MIMO) radio frequency/free space optical (RF/FSO) cooperative relay system with multiple mobile secondary and primary user nodes. The effect of imperfect channel state information (CSI) arising due to channel estimation error is also considered at the secondary user transmitters (SU-TXs) and relay on the power control and symbol detection processes respectively. A unique aspect of this work is that both fixed and proportional interference power constraints are employed to limit the interference at the primary user receivers (PU-RXs). Analytical results are derived to characterize the exact and asymptotic outage and bit error probabilities of the above system under practical conditions of node mobility and imperfect CSI, together with impairments of the optical channel, such as path loss, atmospheric turbulence, and pointing errors, for orthogonal space-time block coded transmission between each SU-TX and relay. Finally, simulation results are presented to yield various interesting insights into the system performance such as the benefits of a midamble versus preamble for channel estimation.

On Secure Mixed RF-FSO Systems With TAS and Imperfect CSI

“…For example, the common performance of mixed multiple-input single-output (MISO) RF-FSO systems was investigated in [6]. Varshney et al analyzed cognitive multiple-input-multiple-output (MIMO) RF-FSO systems with perfect and imperfect channel state information (CSI) in [7], [8], and [9], respectively. Moreover, the performance of mixed RF-FSO systems with opportunistic scheduling scheme was investigated in [10].…”

Pairwise Error Probability Analysis of Dual Hop Relaying Network over Time Selective Nakagami-m Fading Channel with Imperfect CSI and Node Mobility

“…This work considers mobile nodes, because of this, fading channel links between destination, relay and source nodes become time-selective in nature and can be modeled using AR1 process. Further, it has been considered that the fading is approximately constant over the time interval of a single MIMO STBC code-word while varying in a time-selective manner from one MIMO STBC code-word to another MIMO STBC code-word [14], [16]. The variation of the SD, SR and RD channel matrix within a block is modeled as [17], [21] [21].…”

“…This work considers that the receiving node is employed by the low complexity maximal ratio combiner (MRC) receiver [9], [12] but due to time-selective nature of the fading channel links it is tough to obtain the knowledge of instantaneous CSI corresponding to the transmission of MIMO STBC code-word. Hence, in this paper, like the works [16]- [17], imperfect CSI is considered at the relay and destination nodes. The estimated channel matrices for RD, SR and SD links can be modeled as [16]…”

“…Hence, in this paper, like the works [16]- [17], imperfect CSI is considered at the relay and destination nodes. The estimated channel matrices for RD, SR and SD links can be modeled as [16]…”

“…To deal with the joint impact of imperfect channel estimation and smart attack, a Nash equilibrium (NE) based algorithm is proposed to suppress the smart attack from the UAV. In the work [16], the authors considered DF based mixed MIMO radio frequency/free space optics (RF/FSO) relaying network for underlay cognitive radio conditions. Consequently, a PEP performance analysis is demonstrated, and CF expressions are derived for the per-frame average OP, considering both orthogonal-STBC transmission and transmit antenna selection (TAS) at the secondary user (SU).…”