Article

Performance analysis of MIMO free-space optical systems in gamma-gamma fading.

Dept. of Electr. & Comput. Eng., Univ. of British Columbia, Vancouver, BC, Canada
IEEE Transactions on Communications (Impact Factor: 1.98). 11/2009; 57:3415-3424. DOI: 10.1109/TCOMM.2009.11.080168
Source: DBLP

ABSTRACT Atmospheric turbulence induced fading is one of the main impairments affecting free-space optics (FSO) communications. In recent years, Gamma-Gamma fading has become the dominant fading model for FSO links because of its excellent agreement with measurement data for a wide range of turbulence conditions. However, in contrast to RF communications, the analysis techniques for FSO are not well developed and prior work has mostly resorted to simulations and numerical integration for performance evaluation in Gamma-Gamma fading. In this paper, we express the pairwise error probabilities of single-input single-output (SISO) and multiple-input multiple-output (MIMO) FSO systems with intensity modulation and direct detection (IM/DD) as generalized infinite power series with respect to the signal-to-noise ratio. For numerical evaluation these power series are truncated to a finite number of terms and an upper bound for the associated approximation error is provided. The resulting finite power series enables fast and accurate numerical evaluation of the bit error rate of IM/DD FSO with on-off keying and pulse position modulation in SISO and MIMO Gamma-Gamma fading channels. Furthermore, we extend the well-known RF concepts of diversity and combining gain to FSO and Gamma-Gamma fading. In particular, we provide simple closed-form expressions for the diversity gain and the combining gain of MIMO FSO with repetition coding across lasers at the transmitter and equal gain combining or maximal ratio combining at the receiver.

0 Bookmarks
 · 
113 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The impact of relay placement on diversity order in adaptive selective decode-and-forward (DF) cooperative strategies is here investigated in the context of free-space optical (FSO) communications over atmospheric turbulence channels with pointing errors when line of sight is available. The irradiance of the transmitted optical beam here considered is susceptible to moderate-to-strong turbulence conditions, following a gamma-gamma (GG) distribution together with a misalignment fading model where the effect of beam width, detector size and jitter variance is considered. Novel closed-form approximate bit error-rate (BER) expressions are obtained for a cooperative FSO communication setup with N relays, assuming that these relays are located in an area similar to an annulus around source or destination node. An analytical expression is here found that determines the best selection criterion based on the knowledge of the channel state information (CSI) of source-relay or relay-destination links in order to significantly increase the diversity order corresponding to the cooperative strategy under study. It is concluded that the highest diversity order is achieved when the relation βSRmin > βSD + βRminD is satisfied, wherein βSRmin, βRminD and βSD are parameters corresponding to the atmospheric turbulence conditions of source-relay and relay-destination link with the greatest scintillation index, and source-destination link, respectively.
    Opt. Express. 02/2015; 23(3):2600-2617.
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, we analyze the performance of the cooperative optical wireless communication (OWC) systems under the effect of atmospheric turbulence. We consider a dual-hop OWC system having a relay-assisted link between source and destination using a decode and forward (DF) relaying protocol. The atmospheric turbulence channels are modeled by independent but not necessarily identically distributed (i.n.i.d) gamma-gamma fading statistics. The exact closed form expressions of outage probability and average bit-error rate (BER) are derived using the power series representations of the modified bessel function of second kind and illustrated through numerical plots.
    2014 International Conference on Signal Processing and Integrated Networks (SPIN); 02/2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A major performance degrading factor in free space optical communication (FSO) systems is atmospheric turbulence. Spatial diversity techniques provide a promising approach to mitigate turbulence-induced fading. In this paper, we study the error rate performance of FSO links with spatial diversity over atmospheric turbulence channels described by the Double Generalized Gamma distribution which is a new generic statistical model covering all turbulence conditions. We assume intensity modulation/direct detection with on-off keying and present the BER performance of single-input multiple-output (SIMO), multiple-input single-output (MISO) and multiple-input multiple-output (MIMO) FSO systems over this new channel model.
    02/2015;

Preview

Download
4 Downloads
Available from