Method and device for improving ACLR index

Abstract

The invention provides a method for improving an ACLR index, comprising the following steps: presetting a primary phase of a digital intermediate-frequency oscillator (NCO) in a digital frequency conversion chip; and synchronizing the NCO of each carrier wave digital frequency conversion channel again to form same phase. The invention also provides a device for improving an ACLR index. By adopting the method and the device, the invention eliminates the carrier wave error brought by aliquant control words of the NCO, solves the problem that the peak-to-average power ratio of baseband data fluctuates in each subframe, thereby further achieving the aim of improving the ACLR index; in addition, the invention can sufficiently exert the performance of a digital intermediate-frequency chip so that the digital interpolating times are not limited.

Description

technical field [0001] The invention relates to the technical field of mobile communication, in particular to a method and a device for improving multi-carrier ACLR indicators in a TD-SCDMA system. Background technique [0002] In the existing TD-SCDMA (Time Division Synchronous CDMA, Time Division-Synchronous Code Division Multiple Access) system, ACLR (Adjacent Channel Leakage Ratio, adjacent channel leakage power ratio) is an important indicator in the radio frequency indicators of the base station. The indicator indicates the ratio of the transmit power of the working signal channel to the radiated power of the adjacent channel; among them, the most critical factor affecting ACLR is the linearity of the power amplifier and the peak-to-average ratio of the data, that is, increasing the rated power of the power amplifier and reducing the baseband The peak-to-average ratio of the data can improve the ACLR index. [0003] Among them, reducing the peak-to-average ratio of ba...

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Problems solved by technology

[0008] Among them, when the digital interpolation multiple (integer) cannot be divisible by the required NCO frequency, the NCO frequency control word is not an integer, and needs to be rounded, and the part that is not divisible will be discarded; and the carrier step defined according to the standard is 200Hz, so the required NCO frequency is an integer multiple of 200Hz. This frequency is controlled by the frequency control word. When the frequency control word is rounded, a very small frequency error will be generated, causing the corresponding carrier wave to not be divisible by 200Hz. In this way It will lead to using a time period of 5ms (that is, the observation frequency is 200Hz) to observe the carrier signal. The initial phase of the carrier signal observed every 5ms is different. The initial phase of the carrier signal of 5ms is the same; therefore, when the initial phase of the NCO of multiple carriers in each subframe in continuous multi-subframe data is not divisible, the peak-to-average ratio of the data after multi-carrier synthesis in each subframe will be different. Different, it is equivalent to NCO adding a rotation phase to each carrier signal, that is, changing the rotation phase of the carrier or user, which deteriorates the algorithm performance and then deteriorates the peak-to-average ratio of baseband data, thus deteriorating the ACLR index

[0009] In view of this, the existing method to solve this problem is to ensure that the digital interpolation multiple is the Nth power of 2, so that the frequency error of the NCO can be eliminated; however, at present, within the clock range allowed by the chip, the higher the digital interpolation speed, the better. However, when the solution ensures that the digital interpolation multiple is the Nth power of 2, it cannot guarantee that the digital interpolation multiple is large enough, so it cannot effectively utilize the performance of the digital intermediate frequency chip.

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