Adaptive modulation transmission method under high speed mobile environment

Abstract

The embodiment of the invention provides an adaptive modulation transmission method under the high speed mobile environment. The method comprises the steps that a mobile communication system establishes a fast time varying channel model in discrete time so as to obtain the average signal-to-noise ratio, and the average signal-to-noise ratio is transmitted to a transmitter through a feedback link;the transmitter establishes an optimization equation enabling the system average frequency spectrum efficiency to be maximum and meet the constraint according to the change of the average signal-to-noise ratio, the optimization equation is solved to obtain the optimal signal-to-noise ratio threshold value, the signal-to-noise ratio attenuation area subintervals are divided based on the threshold value and the corresponding adaptive power allocation scheme of the subintervals is determined; and the transmitter selects the optimal modulation transmission strategy according to the subintervals and adjusts the transmitting power according to the corresponding power allocation scheme of the subintervals to transmit the next data frame. The system frequency spectrum efficiency can be improved, and the system is ensured to achieve the optimal average throughput so that the problem of significant reduction of adaptive modulation code transmission performance under the condition that the transmitter cannot acquire the accurate channel information can be solved.

Description

technical field [0001] The invention relates to the technical field of wireless communication, in particular to an adaptive modulation transmission method in a high-speed mobile environment. Background technique [0002] Adaptive modulation and coding technology is an effective means to improve the spectrum efficiency of communication systems, which can effectively improve the impact of wireless channel fading on the throughput of mobile communication systems. Adaptive modulation and coding technology requires that the wireless transmitter can obtain accurate CSI (channel state information, channel state information), so that the transmitter can reasonably adjust transmission parameters such as transmission power and modulation mode according to CSI to maximize the average throughput. Purpose. [0003] An adaptive modulation transmission method in a high-speed mobile environment in the prior art: the transmitter selects the most suitable downlink modulation and coding metho...

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Problems solved by technology

[0004] The disadvantage of the above-mentioned adaptive modulation transmission method in a high-speed mobile environment is: when the wireless transmitter is in a high-speed mobile state (such as a high-speed railway mobile communication system), it is difficult for the transmitter to obtain accurate CSI

The reason comes from two aspects: first, the receiver is affected by factors such as channel estimation error, quantization error, and feedback error, and it is difficult to perform accurate channel estimation; second, the time-varying characteristics of high-speed mobile channels are more obvious, and the receiver will estimate the channel The feedback delay of information feedback to the transmitter will cause the CSI information to expire, and the inability to obtain accurate CSI will cause the transmitter to be unable to select appropriate parameters such as transmission power and modulation mode, so the spectral efficiency and effective throughput of the mobile communication system will be significantly affected. Impact

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