Further results on the performance improvement in mixed RF‐FSO systems using hybrid DF/AF (HDAF) relaying

Abstract

This paper presents the performance of a dual‐hop mixed radio frequency (RF)‐free space optical (FSO) system employing a hybrid‐decode/amplify‐and‐forward (HDAF) relaying protocol. The RF link forms the first hop and the FSO link is the second hop for the proposed system model. The assumption of the absence of the direct FSO and RF link between the source transmitter and the destination receiver ends is made for the analysis. The RF link is affected by short‐term multipath fading and long‐term shadowing phenomena and is characterized by the generalized‐K fading distribution, whereas the FSO link is modeled by the gamma‐gamma fading, representing moderate to strong turbulence scenarios. We assume pointing error‐induced misalignment fading to be significantly present over the FSO link. We analyze the outage probability for the system employing amplify‐and‐forward, decode‐and‐forward, and HDAF relaying protocols and show the benefits of using HDAF relaying in mixed RF‐FSO systems. The optimum relay position that results in the best outage performance is investigated. Furthermore, the bit error rate performance for a q‐ary phase shift keying (q‐PSK) modulated signal and the channel capacity for the proposed system employing HDAF relaying protocol are also evaluated. The expressions in closed form for the outage probability, bit error rate, and channel capacity are derived. The asymptotic outage and error performance at high signal‐to‐noise ratio is also evaluated. Furthermore, the performance of the system is demonstrated by numerical plots.

On the unified error performance of PSK modulation schemes over mm‐wave wireless channels affected by carrier phase synchronization errors

“…However, the usefulness of this model at 60 GHz and above is not available in the literature. In addition, various relaying protocols to transmit signals over long distances and hilly regions are employed in the systems such as amplify‐and‐forward (AF), decode‐and‐forward (DF), and more complex hybrid‐DF/AF (HDAF) and project‐and‐forward (PF) relaying protocols 20,27‐34 . Furthermore, the noisy reference loss is a convenient performance measure to quantify the degradation in system performance caused by phase errors 6,14 .…”

A Secure Hybrid Satellite-Terrestrial Communication Network With AF/DF and Relay Selection

“…Acting as a relay in the system, the satellite always works in two relay protocols, including amplified-and-forward (AF) and decoding-and-forward (DF). These two kinds of relay protocols have different characters and are often integrated by a selection scheme in relaying communication networks [21], [22]. An adaptive AF and DF selection scheme for two-way relay networks was proposed with an optimal switching scheme that allowed the relay switching between full-duplex and half-duplex modes to improve the outage performance [21].…”

“…An adaptive AF and DF selection scheme for two-way relay networks was proposed with an optimal switching scheme that allowed the relay switching between full-duplex and half-duplex modes to improve the outage performance [21]. The hybrid-decode/amplify-and-forward (HDAF) relay protocol was employed to a mixed radio frequency-free space optical system to enhance the average symbol error rate performance and the channel capacity [22]. The performance of an opportunistic DFâĂ"AF selection scheme for cognitive relay networks was also analysed and compared with the traditional DF and direct transmission (DT) schemes [23].…”

Performance Analysis and Power Optimization for Spectrum-Sharing Mixed RF/FSO Relay Networks With Energy Harvesting

“…To reduce the transmission overhead, the HRN is assumed to have no prior knowledge of the user's stored energy status. This proposed system model can be found in many practical applications such as increasing network density for real-time events, establishing of temporary wireless sensor networks, metropolitan area network extension, wireless body area networks, and connecting several smaller cells to the core network in 5G system [29]- [31]. Closed-form expressions for the system outage probability, average bit error rate (BER), and ergodic capacity are derived.…”