CN101582702A - 16QAM demodulating method and 16QAM demodulating device for HSDPA service - Google Patents

Abstract

The invention discloses a 16QAM demodulating method and a 16QAM demodulating device for HSDPA service. The demodulating method comprises the following steps: before soft demodulation is carried out on all complex symbols within a current time slot obtained from a combined detector, according to the number of activating code channels, generating multiplication factors so as to generate a multiplication table; accumulating absolute values of a real part and an imaginary part of all the complex symbols within the current time slot to obtain an accumulated summation; and according to the generated multiplication table, the obtained accumulated summation and the number of all of the complex symbols within the current time slot, obtaining an average signal amplitude estimation value. The demodulating device comprises a read address generating module, an average signal amplitude estimation value generating module and a soft demodulation module, wherein the average signal amplitude estimation value generating module multiplies and shifts the accumulated absolute values of the real part and the imaginary part of all the complex symbols and the generated multiplication table so as to obtain the average signal amplitude estimation value. The invention can guarantee the demodulating performance and can accurately and quickly obtain the average signal amplitude estimation value.

Description

A kind of 16QAM demodulation method and device that is used for the HSDPA business

Technical field

The present invention relates to wireless communication field, particularly a kind of 16QAM demodulation method and device that is applied to the HSDPA business of TD-SCDMA mobile communication system and WCDMA mobile communication system.

Background technology

HSDPA (High Speed Downlink Packet Access, the high speed downlink packet access) technology is TD-SCDMA (Time Division Synchronous Code Division Multiple Access, TD SDMA) mobile communication system and WCDMA (Wideband Code Division Multiple Access, Wideband Code Division Multiple Access (WCDMA)) one of main enhancement techniques of mobile communication system, in the HSDPA business, the adaptive modulation and coding specification requirement can be adopted QPSK (Quadrature Phase Shift Keying) and 16QAM (Quadrature Amplitude Modulation according to the different channels condition, 16 quadrature amplitude modulation) modulation system, compare with QPSK, have littler phase difference between the 16QAM constellation point.

From 16QAM standard planisphere, can see, the binary bits data flow is mapped as the 16QAM symbol, after combined detector receives the complex symbol of modulating through 16QAM, need carry out the 16QAM demodulation to it, the 16QAM demodulation method is divided into hard demodulation method and soft demodulating method usually in the prior art, described hard demodulation method is exactly that a complex symbol through the 16QAM modulation is obtained 4 binary bits data through demodulation, this process comprises the immediate symbol of received signal on search and the planisphere, and is mapped to 4 corresponding binary bits data according to planisphere.Described soft demodulating method is exactly that the complex symbol through the 16QAM modulation is being obtained one group of soft output through demodulation, this organizes soft output is not 4 binary bits, but one group of soft value, the approaching degree of reliability of corresponding symbol in this has organized soft value representation receiving symbol and the planisphere, the reliability that has also reflected each bit in this symbol, these bits have kept receiving symbol characteristic as much as possible.

The 16QAM soft demodulating method that adopts is diversified at present, usually adopt simple judgement demodulating algorithm to obtain the 16QAM demodulation value, when guaranteeing demodulation performance, this algorithm has the less advantage of amount of calculation, be illustrated in figure 1 as the standard constellation mapping graph of the soft demodulating algorithm of 16QAM institute foundation in the present HSDPA business, wherein table 1 is the mapping relations between data bit and the modulation symbol in the 16QAM standard constellation mapping graph.

Table 1:

Can know by Fig. 1 and above-mentioned table 1:

1) first bit b ₁=0 pairing constellation point is positioned at the right side of Y-axis, b ₁=1 pairing constellation point is positioned at the left side of Y-axis, with Y-axis as b ₁The judgement plane;

2) second bit b ₂=0 pairing constellation point is positioned at the upside of X-axis, b ₂=1 pairing constellation point is positioned at the downside of X-axis, with X-axis as b ₂The judgement plane;

3) the 3rd bit b ₃=0 pairing constellation point is positioned at $x=2/\sqrt{10}$ With $x=-2/\sqrt{10}$ Article two, the inboard of axis, b ₃=1 pairing constellation point is positioned at $x=2/\sqrt{10}$ With $x=-2/\sqrt{10}$ Article two, the outside of axis;

4) the 4th bit b ₄=0 pairing constellation point is positioned at $y=2/\sqrt{10}$ With $y=-2/\sqrt{10}$ Article two, the inboard of axis, b ₄=1 pairing constellation point is positioned at $y=2/\sqrt{10}$ With $y=-2/\sqrt{10}$ Article two, the outside of axis.

From foregoing description as can be seen, when carrying out simple decision algorithm, carrying out needing to determine earlier the line of demarcation that decision region is divided, i.e. average signal amplitude estimation value when decision region is divided into, for 16QAM standard planisphere, described average signal amplitude estimation value is $x=\±2/\sqrt{10}$ Or $y=\±2/\sqrt{10}$ Deng.But in the signals transmission of reality, there are various interference, in fixed point symbol data demodulating process, because the normalization operation that the complex symbol data of receiving terminal needed the multistep statistics to recover before demodulation, so produced the signal amplitude distortion, changed signal amplitude, thereby changed the 16QAM planisphere, the 16QAM planisphere of this moment is not the planisphere of standard, therefore, how to obtain average signal amplitude estimation value quickly and accurately and become the key that realizes the 16QAM soft demodulating method.

Summary of the invention

The 16QAM demodulation method and the device that the purpose of this invention is to provide a kind of HSDPA of being used for business use this invention can accurately obtain average signal amplitude estimation value, to realize the soft demodulation of 16QAM.

According to an aspect of the present invention, provide a kind of 16QAM demodulation method of HSDPA business, all complex symbols in the current time slots of obtaining from combined detector are carried out soft demodulation, obtain soft output, it is characterized in that, before complex symbol is carried out soft demodulation, also comprise following treatment step:

Step 11 according to the number of activated code channel, produces multiplier, generates multiplication table;

Step 12, the absolute value of all complex symbol real parts and imaginary part in the current time slots that adds up, obtain to add up and;

Step 13, adding up and obtain average signal amplitude estimation value according to the multiplication table of described generation, acquisition.

Connect above-mentioned scheme, in the described demodulation method, described step 13 specifically is achieved in that

With described acquisition add up and with described multiplication table in corresponding multiplier multiply each other obtain product after, be shifted, obtain described average signal amplitude estimation value.

Connect above-mentioned scheme, in the described demodulation method,

The number of the activated code channel in the described step 11 is determined according to the value of spreading factor;

The number of described activated code channel and multiplier are one to one.

Connect above-mentioned scheme, in the described demodulation method,

The soft output of described acquisition is 4 likelihood ratios on the soft bit, specifically:

L(m，4*n-3)＝real[R(m，n)]，

L(m，4*n-2)＝imag[R(m，n)]，

L(m，4*n-1)＝Mean_Amp-|real[R(m，n)]|，

L(m，4*n)＝Mean_Amp-|imag[R(m，n)]|

Wherein, (m n) is complex symbol to R, and m is the sequence number of activated code channel, n is the number of complex symbol in the activated code channel, and Mean_Amp is an average signal amplitude estimation value, real (), for getting the real part computing, imag () is for getting imaginary-part operation, || be the computing that takes absolute value.

According to a further aspect in the invention, provide a kind of 16QAM demodulating equipment of the HSDPA of being used for access service, comprise, read the address generation module, average signal amplitude estimation value generation module, soft demodulation module;

The described address generation module of reading, finish and read the address generation, obtain the complex symbol data of combined detector output and the complex symbol that obtains is sent into average signal amplitude estimation value generation module and soft demodulation module respectively according to the address of reading that produces, described average signal amplitude estimation value generation module, complex symbol according to input produces average signal amplitude estimation value, the average signal amplitude estimation value that obtains is sent into soft demodulation module, described soft demodulation module carries out demodulation to described complex symbol, obtains soft bit likelihood ratio.

Connect above-mentioned scheme, in the described demodulating equipment: described average signal amplitude estimation value generation module also comprises, mapping block, accumulator module and average generation module;

Thereby described mapping block is sent the multiplication table that obtains into the average generation module according to obtaining corresponding multiplier and generate multiplication table from reading in the current time slots that the address generation module obtains the number mapping of all complex symbols;

Described accumulator module is used to the add up real part of interior all complex symbols of current time slots and the absolute value of imaginary part, and the result who obtains that will add up then sends into the average generation module;

Described average generation module is used for the multiplication table that will obtain and adds up and multiply each other, be shifted, and the generation average signal amplitude estimation value is sent into described average signal amplitude estimation value described soft demodulation module then.

Adopt the present invention to obtain average signal amplitude estimation value accurately and rapidly, guarantee that simultaneously demodulation performance and realization are simple, can obviously improve the soft demodulation speed of 16QAM.

Description of drawings

Fig. 1 is the standard constellation mapping graph of the soft demodulating algorithm of 16QAM institute foundation among the HSDPA;

Fig. 2 is the handling process schematic diagram of the specific embodiment of demodulation method of the present invention;

Fig. 3 is the structured flowchart of the specific embodiment of demodulating equipment of the present invention;

Fig. 4 is the specific implementation structured flowchart of the average signal amplitude estimation value generation module among Fig. 3.

Embodiment

The present invention is described in detail below in conjunction with the drawings and specific embodiments.

As shown in Figure 2, the handling process of demodulation method of the present invention is as follows:

S201 according to the number of activated code channel, produces multiplier, generates multiplication table;

S202, the absolute value of all complex symbol real parts and imaginary part in the current time slots that adds up;

S203, according to the multiplication table of described generation, acquisition add up and and current time slots in all complex symbol numbers, obtain average signal amplitude estimation value;

S204 simply adjudicates demodulating algorithm according to the described average signal amplitude estimation value that obtains and handles, and obtains soft output.

If in time slot the complex symbol of combined detector output be R (m, n), when SF (Spreading Factor, spreading factor) value is 1 o'clock, the span of variable m and n is respectively: m=1, n=1 ..., 704; When the SF value was 16, the span of variable m and n was respectively: m=1 ..., K_Active, n=1 ..., 44.Wherein, m is the sequence number of activated code channel, and n is the number of complex symbol in the activated code channel, and K_Active is the number of activated code channel.

Work as SF=1, the computational methods of average signal amplitude estimation value Mean_Amp as shown in Equation (1):

$\mathrm{Mean}\_\mathrm{Amp}=\frac{1}{1408}\·\underset{m=1}{\overset{1}{\mathrm{\Σ}}}\underset{n=1}{\overset{704}{\mathrm{\Σ}}}\left\{\right|\mathrm{real}\left[R(m,n)\right]|+|\mathrm{imag}\left[R(m,n)\right]\left|\right\}---\left(1\right)$

In like manner, work as SF=16, the computational methods of average signal amplitude estimation value Mean_Amp as shown in Equation (2):

$\mathrm{Mean}\_\mathrm{Amp}=\frac{1}{K\_\mathrm{Active}\×88}\·\underset{m=1}{\overset{K\_\mathrm{Active}}{\mathrm{\Σ}}}\underset{n=1}{\overset{44}{\mathrm{\Σ}}}\left\{\right|\mathrm{real}\left[R(m,n)\right]|+|\mathrm{imag}\left[R(m,n)\right]\left|\right\}---\left(2\right)$

In above-mentioned two formula, real (), for getting the real part computing, imag () is for getting imaginary-part operation, || be the computing that takes absolute value.

When SF=1, by described formula (1), described average signal amplitude estimation value is to determine like this:

1) according to the number of activated code channel, obtains multiplier;

Described acquisition multiplier sees Table 2, and this table is a multiplication table used when asking average signal amplitude estimation value Mean_Amp:

Table 2:

2) the add up absolute value of all complex symbol real parts and imaginary part in the current time slots;

Get the real part of combined detector output complex symbol and the absolute value of imaginary part, totally 704 * 2=1408 data, each data are with [8,0, u] expression, and to the summation that adds up of above-mentioned 1408 data, acquisition adds up and uses [19,0, u] to represent.

3) according to the multiplication table of described generation, add up and, obtain average signal amplitude estimation value;

Described average signal amplitude estimation value equals described accumulation result [19,0, u] divided by 1408, specifically be achieved in that and add up real imaginary part absolute value with all complex symbols in the activated code channel element of the 2nd row multiplies each other in result [19,0, u] and the table 2 of summation, the result represents with [29,0, u]; Then The above results [29,0, u] is moved to right 20, get its least-significant byte again, can obtain average signal amplitude estimation value Mean_Amp.

When SF=16, by described formula (2), described average signal amplitude estimation value is to determine like this:

1) according to the number of activated code channel, obtains multiplier;

Described acquisition multiplier sees Table 3, and this table is a multiplication table used when asking average signal amplitude estimation value Mean_Amp:

Table 3:

2) the add up absolute value of all complex symbol real parts and imaginary part in the current time slots;

Get the real part of the complex symbol of exporting on all activated code channel in the combined detector and the absolute value of imaginary part, be total to K_Active * 44 * 2 data, each data is with [8,0, u] expression, to the summation that adds up of above-mentioned K_Active * 88 data, obtain to add up and use [19,0, u] expression, because 1≤K_Active≤16, so the number minimum value of cumulative data is 88, maximum is 16 * 88=1408.

3) according to the multiplication table of described generation, add up and, obtain average signal amplitude estimation value;

Described average signal amplitude estimation value equals described accumulation result [19,0, u] divided by K_Active * 88, specifically be achieved in that the add up result [19 of summation of real imaginary part absolute value with all complex symbols in the activated code channel, 0, u] with table 3 in the element of the 3rd row multiply each other, the result is with [29,0, u] expression; The above results is moved to right 20, get its least-significant byte again, can obtain average signal amplitude estimation value Mean_Amp.

In described S204, simply adjudicate demodulating algorithm according to the described average signal amplitude estimation value that obtains and handle, obtain soft output, can realize in the following way at simple judgement demodulating algorithm of the present invention:

When SF=1, this moment m=1, n=1 ..., 704

For n complex symbol of combined detector output, simply adjudicate 4 soft bit likelihood ratios exporting behind the demodulating algorithm through 16QAM and be followed successively by:

L(m，4*n-3)＝real[R(m，n)]，

L(m，4*n-2)＝imag[R(m，n)]，

L(m，4*n-1)＝Mean_Amp-|real[R(m，n)]|，

L(m，4*n)＝Mean_Amp-|imag[R(m，n)]|

When SF=16, this moment m=1 ..., K_Active, n=1 ..., 44

For n complex symbol on m the activated code channel of combined detector output, pass through the likelihood ratio that 16QAM simply adjudicates on 4 soft bits that demodulating algorithm exports and be followed successively by:

L(m，4*n-3)＝real[R(m，n)]，

L(m，4*n-2)＝imag[R(m，n)]，

L(m，4*n-1)＝Mean_Amp-|real[R(m，n)]|，

L(m，4*n)＝Mean_Amp-|imag[R(m，n)]|

Be the specific implementation structured flowchart of demodulating equipment of the present invention as shown in Figure 3, demodulating equipment as shown in the figure comprises, reads address generation module B01, average signal amplitude estimation value generation module B02, and soft demodulation module B03, and RAM memory B04.

The described address generation module B01 that reads, finish and read the address generation, generation is read the address to read the complex symbol data of combined detector output, then the complex symbol data that read are sent into average signal amplitude estimation value generation module B02 and soft demodulation module B03 respectively, described average signal amplitude estimation value generation module B02, complex symbol according to input produces average signal amplitude estimation value, the average signal amplitude estimation value that obtains is sent into soft demodulation module B03, described soft demodulation module B03 carries out demodulation to described complex symbol data, obtain soft bit likelihood ratio, and send into RAM memory B04 and store.

The specific implementation block diagram of average signal amplitude estimation value generation module as shown in Figure 4, described average signal amplitude estimation value generation module B02 comprises, mapping block A01, accumulator module A02 and average generation module A03, thereby described mapping block A01 generates multiplication table according to obtaining corresponding multiplier from the complex symbol number mapping of reading the current time slots that address generation module B01 obtains, the multiplication table that obtains is sent among the average generation module A03, described accumulator module A02 is used to the add up real part of interior all complex symbols of current time slots and the absolute value of imaginary part, the result who obtains that will add up then sends into average generation module A03, described average generation module A03, be used for the multiplication table that to obtain and add up and multiply each other, displacement, generate average signal amplitude estimation value, then described average signal amplitude estimation value is sent into soft demodulation module B03.

Certainly; the present invention also can have other various embodiments; under the situation that does not deviate from spirit of the present invention and essence thereof; those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection range of the appended claim of the present invention.

Claims (6)

1, a kind of 16QAM demodulation method of the HSDPA of being used for business comprises, all complex symbols in the current time slots of obtaining from combined detector are carried out soft demodulation, obtain soft output, it is characterized in that, before complex symbol is carried out soft demodulation, also comprise following treatment step:

Step 11 according to the number of activated code channel, produces multiplier, generates multiplication table;

Step 12, the absolute value of all complex symbol real parts and imaginary part in the current time slots that adds up, obtain to add up and;

Step 13, according to the multiplication table of described generation, acquisition add up and, obtain average signal amplitude estimation value.

2, demodulation method as claimed in claim 1 is characterized in that, described step 13 specifically is achieved in that

With described acquisition add up and with described multiplication table in corresponding multiplier multiply each other obtain product after, be shifted, obtain described average signal amplitude estimation value.

3, demodulation method as claimed in claim 1 is characterized in that,

The number of the activated code channel in the described step 11 is determined according to the value of spreading factor;

The number of described activated code channel and multiplier are one to one.

4, demodulation method as claimed in claim 1 or 2 is characterized in that, the soft output of described acquisition is 4 likelihood ratios on the bit, specifically:

L(m，4*n-3)＝real[R(m，n)]，

L(m，4*n-2)＝imag[R(m，n)]，

L(m，4*n-1)＝Mean_Amp-|real[R(m，n)]|，

L(m，4*n)＝Mean_Amp-|imag[R(m，n)]|

Wherein, (m n) is complex symbol to R, and m is the sequence number of activated code channel, n is the number of complex symbol in the activated code channel, and Mean_Amp is an average signal amplitude estimation value, real (), for getting the real part computing, imag () is for getting imaginary-part operation, || be the computing that takes absolute value.

5, a kind of 16QAM demodulating equipment that is used for the HSDPA business is characterized in that, comprises, reads the address generation module, average signal amplitude estimation value generation module, soft demodulation module;

The described address generation module of reading, finish and read the address generation, obtain the complex symbol data of combined detector output and the complex symbol that obtains is sent into average signal amplitude estimation value generation module and soft demodulation module respectively according to the address of reading that produces, described average signal amplitude estimation value generation module, complex symbol according to input produces average signal amplitude estimation value, the average signal amplitude estimation value that obtains is sent into soft demodulation module, described soft demodulation module carries out demodulation to described complex symbol, obtains soft bit likelihood ratio.

6, demodulating equipment as claimed in claim 5 is characterized in that:

Described average signal amplitude estimation value generation module also comprises, mapping block, accumulator module and average generation module;

Thereby described mapping block is sent the multiplication table that obtains into the average generation module according to obtaining corresponding multiplier and generate multiplication table from reading in the current time slots that the address generation module obtains the number mapping of all complex symbols;

Described accumulator module is used to the add up real part of interior all complex symbols of current time slots and the absolute value of imaginary part, and the result who obtains that will add up then sends into the average generation module;

Described average generation module is used for the multiplication table that will obtain and adds up and multiply each other, be shifted, and the generation average signal amplitude estimation value is sent into described average signal amplitude estimation value described soft demodulation module then.

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