Approximate Calculation Method for Average Capacity of Atmospheric Light MIMO System Under the Influence of Combined Effect

Abstract

The invention discloses an approximate calculation method of atmospheric light MIMO system average capacity under combined effect influences. The method includes calculation of a light intensity attenuation coefficient matrix G, modeling of light MIMO system signal channels, calculation of average signal channel capacity, calculation of a light intensity attenuation coefficient accumulation sum and a probability density number thereof and approximate simplification of the average signal channel capacity. G is obtained through respectively carrying out left multiplication and right multiplication of an exponential correlation matrix at two ends of an independent signal channel light intensity attenuation coefficient matrix H. MPPM modulation is combined, and a Poisson photon counting modelis employed to establish a signal channel model of a light MIMO system at the same when signal channels are correlated under a combined effect; and the average signal channel capacity of the light MIMO system is derived on the basis thereof, and the light MIMO system average signal channel capacity originally needing calculation of MN times of integration is further approximated by a simplest expression, which only needs calculation of one time of integration, through simplifying the accumulation sum of light intensity attenuation coefficients.

Description

technical field [0001] The invention relates to the technical field of wireless optical communication, in particular to the calculation and approximation method of the average channel capacity of a wireless optical MIMO system under joint effect MPPM modulation. Background technique [0002] Wireless optical communication combines the advantages of optical fiber communication and wireless communication. It has the advantages of no frequency license, low cost, fast and convenient installation, and safe and confidential communication. It is considered to be an effective way to solve the "last mile" problem in global high-speed communication. However, when laser signals are transmitted in complex atmospheric channels, they will be affected by factors such as atmospheric attenuation and atmospheric turbulence. In addition, the platform of the fixed transceiver terminal equipment will produce aiming errors due to random jitter, which makes the received signal appear random. At t...

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Problems solved by technology

However, the above studies all assume that the signal sent by each transmitter and the signal received on the receiving aperture are uncorrelated, and the channel obeys the independent and identically distributed fading characteristic

[0005] However, Professor Phillips and others have pointed out through research that due to the influence of factors such as the antenna array spacing, transmission distance, and turbulence conditions at the transmitting and receiving ends, there is a certain correlation between the transmitted signals, which will seriously affect the capacity characteristics of the MIMO system. And this makes the assumption about channel independence too idealistic

In practical applications, the optical MIMO system will be affected by the joint effects of atmospheric attenuation, turbulence, aiming error and spatial correlation, and it is not comprehensive enough to only consider some of these factors

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