Adaptive modulation method based on average BER constraint in distributed antenna system

Abstract

The invention discloses an adaptive modulation method based on average BER (Bit Error Rate) constraint in a wireless distributed multi-antenna system, and provides an optimization design scheme of an optimal adaptive switching threshold. Generally, an AM (Amplitude Modulation) scheme based on instant BER constraint can allow an average BER of the system to meet a service quality requirement, and can strictly control the average BER to be much less than a target BER, but the strict constraint results in failed adaptive optimization of the switching threshold according to a channel condition, thereby resulting in loss of SE (Spectrum Efficiency). In order to avoid the loss of the SE caused by the strict constraint, an adaptive threshold optimization scheme combining a KKT (Karush-Kuhn-Tucker) condition and a Newton method is provided by maximizing the SE of the system and designing the adaptive modulation method based on the average BER constraint under the target BER constraint condition. A Matlab simulation platform indicates that the provided AM method and the adaptive switching threshold can ensure that the SE of the system can be improved greatly under the condition that the average BER of the system meets a requirement of the target BER.

Description

technical field [0001] The invention belongs to the field of wireless communication, and relates to the design of an adaptive modulation scheme for wireless communication, and more specifically relates to an adaptive modulation switching threshold optimization algorithm in a distributed antenna system and a corresponding discrete rate adaptive modulation scheme design. Background technique [0002] With the rapid rise of mobile internet and computer communications, data services represented by broadband multimedia services have gradually become core services; such fast-growing data services require high-speed data access, which makes wireless spectrum resources increasingly tight. Therefore, research institutions at home and abroad are Continuously seek transmission technologies with higher spectral efficiency to alleviate limited spectrum resources. Future wireless communication technology needs to support high-quality and high-speed data transmission. In recent years, with...

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Problems solved by technology

In addition, for space-time coding, the members of the research group use the Lagrange method to maximize the ASE to obtain the optimal adaptive threshold value. When solving the nonlinear equation system, they use a simplified Newton iterative method to solve it, although it can avoid The original literature solves the threshold value through a large number of numerical searches, but its iterative Jacobi matrix is ​​only related to the initial value, and does not replace it in real time according to the iterative intermediate value, which eventually leads to a set of suboptimal solutions for the obtained threshold value

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