CN112702292B

CN112702292B - Baseband code element mapping method based on lookup table

Info

Publication number: CN112702292B
Application number: CN202011474112.2A
Authority: CN
Inventors: 李增红; 薛晓男; 台鑫; 马立坤
Original assignee: CLP Kesiyi Technology Co Ltd
Current assignee: CLP Kesiyi Technology Co Ltd
Priority date: 2020-12-15
Filing date: 2020-12-15
Publication date: 2022-12-09
Anticipated expiration: 2040-12-15
Also published as: CN112702292A

Abstract

The invention discloses a baseband code element mapping method based on a lookup table, which comprises the following steps: step 1: receiving a modulation format command sent by a user and calculating mapping data under the modulation format; and 2, step: converting the 01 sequence data into IQ mapping data through a RAM lookup table; and 3, step 3: the conversion of the 01 digital sequence baseband signal is realized by means of a lookup table. The invention realizes code element mapping by combining the lookup table and the processor, and has two advantages: one is that the circuit is relatively simple. And mapping of multiple modulation modes can be realized through a simple RAM lookup table. When the modulation mode is changed, corresponding modulation can be realized only by the content of the new RAM lookup table. And secondly, the upgrading is convenient, because the modulation mode is determined by the content of the RAM table, when a new modulation mode exists, only the content of the RAM needs to be changed.

Description

Baseband code element mapping method based on lookup table

Technical Field

The invention relates to the field of digital communication, in particular to a baseband code element mapping method based on a lookup table.

Background

With the development of communication technology, the modulation mode of a communication system is also changed from traditional analog modulation to vector modulation with better performance, and the modulation mode is changed from simple analog modulation such as AM, FM, PM and the like to more complex digital modulation such as ASK, FSK, MSK, PSK, QAM and the like. When implementing the digital modulation, firstly, the 01 data sequence transmitted by the user needs to be converted into a baseband signal, and then the baseband signal is sent to a rear-end modulator for modulation, so as to control the amplitude, frequency or phase of a carrier wave to implement information transmission. And the process of converting the 01 data sequence into a baseband signal is called symbol mapping.

Symbol mapping is a method of converting the digital signal of 01 into a baseband signal according to different modulation schemes. Vector modulation has been widely used in modern communication systems due to its superior modulation performance, superior bandwidth utilization, excellent security, and simple signal digital processing. A common symbol mapping method is to use a dedicated hardware circuit to implement the conversion of 01 data sequence to baseband analog signal. For example, for FSK modulation, FSK modulation is achieved by controlling a high-speed switch to switch an oscillator. For QPSK modulation, analog modulation is achieved by a simple analog comparator.

Existing symbol mapping techniques implement the mapping of 01 digital sequences to analog signals based on dedicated hardware circuitry. This approach has two disadvantages: 1) The hardware circuit is complex and the universality can not be realized. Because each modulation corresponds to a hardware circuit, if there are many modulation types, the hardware circuit is very complex. The hardware-based mapping is therefore only suitable for the specific modulation format. It has no universality. 2) The modulation mode is relatively troublesome to upgrade. Because the hardware circuit is adopted to realize the code element mapping, the modulation mode is very fixed. If a new modulation scheme needs to be added, the hardware circuit needs to be changed. With the development of the technology, various modulation modes are emerging continuously, and in order to aim at a new modulation mode, a hardware circuit needs to be changed continuously.

Accordingly, the prior art is deficient and needs improvement.

Disclosure of Invention

The invention provides a baseband code element mapping method based on a lookup table, aiming at solving the problems of complex circuit, poor universality, difficult upgrading of modulation mode and the like of the original code element mapping hardware, comprising the following steps:

step 1: receiving a modulation format command sent by a user and calculating mapping data under the modulation format; the method specifically comprises the following steps: receiving a modulation type input by a user, and then calculating the bit B x C of code element mapping data corresponding to modulation according to the modulation type, wherein B is the bit width corresponding to the modulation type, and C is the bit width of IQ data;

and 2, step: writing the mapping data into a RAM lookup table through a bus, using a 01 sequence sent by a user as an address of the RAM lookup table after serial-parallel conversion, and converting the 01 sequence data into IQ mapping data through the RAM lookup table;

and 3, step 3: converting the serial 01 data sequence into parallel B bit data, and reading data in a lookup table by taking the B bit data as the address of the lookup table; the C bit data output by the lookup table is divided into IQ two-way data, wherein the high C/2 bit is used as Q-way data, and the low C/2 bit is used as Q-way data and then processed.

In the above, C in step 1 is the bit width of the IQ data, and is determined by the implementation precision.

In the above, C in step 1 is a bit width of the IQ data, where C =32 bits, I data is 16 bits, and Q data is 16 bits.

In the above, after the step 3, the method further includes: when the modulation type set by the user is changed, corresponding code element mapping data is recalculated and written into the mapping table.

The invention realizes the code element mapping by combining a lookup table and a processor. The main advantages are two: one is that the circuit is relatively simple. And mapping of multiple modulation modes can be realized through a simple RAM lookup table. When the modulation mode is changed, corresponding modulation can be realized only by the content of the new RAM lookup table. And secondly, the upgrading is convenient, because the modulation mode is determined by the content of the RAM table, when a new modulation mode exists, only the content of the RAM needs to be changed.

Drawings

FIG. 1 is a flow chart of the present invention.

Fig. 2 is a schematic block diagram of the present invention.

Detailed Description

In order to facilitate an understanding of the invention, the invention is described in more detail below with reference to the accompanying drawings and specific examples. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

An embodiment of the present invention provides a baseband symbol mapping method based on a lookup table, where a flowchart is shown in fig. 1, and a schematic implementation block diagram is shown in fig. 2, specifically:

step 1: receiving a modulation format command sent by a user and calculating mapping data under the modulation format; the method specifically comprises the following steps: receiving a modulation type input by a user, and then calculating the bit B x C of code element mapping data corresponding to modulation according to the modulation type, wherein B is the bit width corresponding to the modulation type, and C is the bit width of IQ data; c is the bit width of IQ data and is determined by the implementation precision; c is the bit width of IQ data, where C =32 bits, I data is 16 bits, Q data is 16 bits;

step 2: writing the mapping data into a RAM lookup table through a bus, using a 01 sequence sent by a user as an address of the RAM lookup table after serial-parallel conversion, and converting 01 sequence data into IQ mapping data through the RAM lookup table;

and step 3: converting a serial 01 data sequence into parallel B bit data, and reading data in a lookup table by taking the B bit data as an address of the lookup table; dividing the C bit data output by the lookup table into IQ two paths of data, wherein the high C/2 bit is used as Q path data, and the low C/2 bit is used as Q path data and then processed; when the modulation type set by the user is changed, corresponding code element mapping data is recalculated and written into the mapping table.

On the basis of the above content, the invention also provides a baseband code element mapping device based on the lookup table, which realizes the conversion of the 01 digital sequence baseband signal in the manner of the lookup table. The CPU in the device comprises a general processor, a singlechip, a DSP or FPGA and other units with digital signal processing capability. The lookup table includes a general storage device, including a commonly used RAM, a memory bank, a FLASH, and other component units having a storage function.

The above features are combined with each other to form various embodiments not listed above, and all of them are regarded as the scope of the present invention described in the specification; also, modifications and variations may be suggested to those skilled in the art in light of the above teachings, and it is intended to cover all such modifications and variations as fall within the true spirit and scope of the invention as defined by the appended claims.

Claims

1. A method for baseband symbol mapping based on a look-up table, comprising the steps of:

step 1: receiving a modulation format command sent by a user and calculating mapping data under the modulation format; the method specifically comprises the following steps: receiving a modulation type input by a user, and then calculating code element mapping data B x C bit corresponding to modulation according to the modulation type, wherein B is a bit width corresponding to the modulation type, and C is a bit width of IQ data;

and 3, step 3: converting a serial 01 data sequence into parallel B bit data, and reading data in a lookup table by taking the B bit data as an address of the lookup table; c bit data output by the lookup table is divided into IQ two-path data, wherein high C/2 bit is used as Q-path data, and low C/2 bit is used as Q-path data and then processed;

c in the step 1 is the bit width of IQ data and is determined by the implementation precision; c in the step 1 is a bit width of IQ data, wherein C =32 bits, I data is 16 bits, and Q data is 16 bits; the step 3 is followed by: when the modulation type set by the user is changed, the corresponding code element mapping data is recalculated and written into the mapping table.