Adaptive frequency‐hopping schemes for CR‐based multi‐link satellite networks

Abstract

Summary In this paper, we study two dynamic frequency hopping (DFH)–based interference mitigation approaches for satellite communications. These techniques exploit the sensing capabilities of a cognitive radio to predict future interference on the upcoming frequency hops. We consider a topology where multiple low Earth orbit satellites transmit packets to a common geostationary equatorial orbit satellite. The FH sequence of each low Earth orbit–geostationary equatorial orbit link is adjusted according to the outcome of out‐of‐band proactive sensing scheme, performed by a cognitive radio module in the geostationary equatorial orbit satellite. On the basis of sensing results, new frequency assignments are made for the upcoming slots, taking into account the transmit powers, achievable rates, and overhead of modifying the FH sequences. In addition, we ensure that all satellite links are assigned channels such that their minimum signal‐to‐interference‐plus‐noise ratio requirements are met, if such an assignment is possible. We formulate two multi‐objective optimization problems: DFH‐Power and DFH‐Rate. Discrete‐time Markov chain analysis is used to predict future channel conditions, where the number of states are inferred using k‐means clustering, and the state transition probabilities are computed using maximum likelihood estimation. Finally, simulation results are presented to evaluate the effects of different system parameters on the performance of the proposed designs.

Parameter Estimation of Multi Frequency Hopping Signals Based on Space-Time-Frequency Distribution

“…We first review the definition and basic properties of the STFDs. STFDs based on Cohen's class of TFD were introduced in [17], and its applications to direction finding and blind source separation have been discussed in [25][26][27].…”

“…where p(z) is the 2(M − 1) quadratic polynomial, when its root and unit circle are mirrored, the phase of the K rootsẑ 1 ,ẑ 2 , • • • ,ẑ K with the maximum amplitude in the unit circle is given to estimate the direction of the wave,θ m can be expressed as Formula (27).…”

Ultrafast and Wideband Microwave Photonic Frequency-Hopping Systems: A Review

“…The technology was not taken seriously in electronic countermeasures worldwide until the 1980s. With the merit of frequency-hopping systems, such as mitigating the effects of inter-symbol interference and jamming, it significantly increases the communication capacity of emerging RF wireless systems-making it an essential tool to fulfil the high RF spectral resource demand in the commercial, defense, and civilian federal marketplaces [2][3][4]. Furthermore, the fast frequency-hopping capability greatly increases the security of wireless services-the lack of amplitude variations and fast-changing in carrier frequency makes it challenging for Eve to interpret the information.…”