TWM446399U - Equalization maximum likelihood sequence receiving device - Google Patents

Description

Equalization maximum likelihood sequence receiving device

The present invention relates to a sequence receiving device, and more particularly to an equalized maximum likelihood sequence receiving device for a high density magnetic recording system.

At present, as the magnetic recording density in the magnetic system increases, nonlinear effects (transition shift and partial erasure) also appear, and this nonlinear effect limits the performance of the detector. Several models have been proposed before to describe the phenomenon of nonlinear distortion. Moreover, many studies have confirmed that the complexity of this model detector can become very high if the channel model is more complex.

In recent studies, the channel is usually first equalized to a shorter length of target response. Next, the stored data data is recovered by a maximum likelihood sequence detector, mainly a Viterbi decoder. This method is classified as a partial response maximum likelihood (PRML) sequence, by which an acceptable performance can be achieved in a reasonable implementation complexity. So a partial equalizer is designing a partial response maximum likelihood (PRML) detector, and the design of these equalizers will directly affect the performance of the corresponding Viterbi decoder.

However, the correlation coefficient of the decoder matched by the equalizer and the target response is usually a fixed value, that is, it may not be able to accurately decode the data data that is close to the original input signal, so the design is equalized. The maximum likelihood sequence receiving device is applied to a magnetic recording system, which has become an urgent problem in research and development.

In view of the above-mentioned problems of the prior art, the purpose of the present invention is to provide an equalization maximum likelihood sequence receiving apparatus to solve the problem that the correlation coefficient of the decoder matched by the equalizer and the target response is a fixed value. Accurately decode the data data that is closer to the original input signal.

According to the purpose of the present invention, an equalization maximum likelihood sequence receiving apparatus is proposed for a magnetic recording system, and the magnetic recording system outputs an input encoded signal. The equalization maximum likelihood sequence receiving apparatus comprises: a channel response unit, a part of the equalization unit, a target response unit, a processing unit and a decoding unit. The channel response unit receives a first combined signal of the input encoded signal outputted by the magnetic recording system and a nonlinear simplified parameter to generate a channel response output signal; the partial equalization unit can receive the channel response output signal and an external impurity The signal combines a second combined signal to generate an equalizer output value; the target response unit can receive the input encoded signal output by the magnetic recording system to generate a target response output value; the processing unit can output the target response output value The difference between the output value of the equalizer and the equalizer is squared to obtain a mean square error, and then the mean square error is taken as an expected value. The expected value can be a mean square error, and the mean square error can be minimized according to the orthogonal principle. Corresponding to at least a portion of the input encoded signal and the at least one target response unit coefficient; and the decoding unit may be configured with a matching target response unit coefficient, and the decoding unit may receive the equalizer output value and decode the equalizer output value into a Outputting a coded signal; wherein the equalized maximum likelihood sequence receiving device can reduce the output of the output Phase encoded signal one bit error rate for the signal input.

Preferably, the channel response output signal output by the channel response unit satisfies the following conditions.

Where y _m is the channel response output signal, r _m is the mth nonlinear simplification parameter, b _m is the mth input coding signal, and the channel response output signal can be the sample function h(kT) satisfying the period, k is the period The numbers L ₁ and L ₂ are one value selected from the h(kT) function.

Preferably, the equalizer output value output by the partial equalization unit satisfies the following conditions.

among them For the equalizer output value, y _m is the channel response output signal, n _m is the external noise, q is the partial equalization unit coefficient, and N ₁ and N ₂ are different positive integers.

Preferably, the target response output value output by the target response unit satisfies the following conditions.

Where d _m is the target response output value and b _m is the mth input coded signal, a transposed matrix having a vector of target response unit coefficients p, Is a vector with the mth input coded signal.

Preferably, the decoding unit may convert the equalizer output value according to the target response unit coefficient p and may output the output encoded signal by using a Viterbi decoding manner.

Preferably, the mean square error satisfies the following conditions.

Among them, E[*] is the action of taking the expected value, and the action of minimizing the mean square error according to the orthogonal principle.

Preferably, the external noise can be a white Gaussian noise.

Preferably, the channel response output signal is not affected by white Gaussian noise.

As described above, the equalized maximum likelihood sequence receiving apparatus of the present invention may have one or more of the following advantages:

The equalized maximum likelihood sequence receiving device can adjust the target response unit coefficient and the partial equalization unit coefficient by the input coded signal outputted by the magnetic recording system lock, thereby improving the correctness of the decoding of the equalized maximum likelihood sequence receiving device.

The embodiments of the equalized maximum likelihood sequence receiving apparatus according to the present invention will be described below with reference to the related drawings. For ease of understanding, the same elements in the following embodiments are denoted by the same reference numerals.

Please refer to FIG. 1 , which is a block diagram of an equalized maximum likelihood sequence receiving apparatus of the present invention. As shown, the equalized maximum likelihood sequence receiving device is used in the magnetic recording system 10, and the magnetic recording system 10 outputs the input encoded signal 20. The equalization maximum likelihood sequence receiving apparatus includes a channel response unit 11, a partial equalization unit 12, a target response unit 13, a processing unit 14, and a decoding unit 15. The channel response unit 11 can receive the first combined signal of the input encoded signal 20 outputted by the magnetic recording system 10 and the nonlinear simplified parameter 21 to generate a channel response output signal 22; the partial equalization unit 12 can receive the channel response output signal. 22 combining the second combined signal with the external noise 23 to generate an equalizer output value 24; the target response unit 13 can receive the input encoded signal 20 output by the magnetic recording system 10 to generate a target response output value 25; Unit 14 may square the difference between the target response output value 25 and the equalizer output value 24 to obtain a mean square error, and then take the mean square error to take the expected value, the expected value is the mean square error, and may be further according to the orthogonal principle. The mean square error is minimized to obtain at least a portion of the equalization unit coefficient 26 and the at least one target response unit coefficient 27 corresponding to the input encoded signal 10; and the decoding unit 15 may be provided with a matching target response unit coefficient 27, and the decoding unit 15 may The equalizer output value 24 is received and the equalizer output value 24 is decoded into an output encoded signal 28. The equalization maximum likelihood sequence receiving device reduces the bit error rate of the output encoded signal 28 output relative to the input encoded signal 20.

It should be noted that the nonlinear simplification parameter 21 satisfies the following conditions by the input coded signal 20 in combination with the nonlinear simplification parameter 21 and the channel response to generate the channel response output signal 22:

Wherein, _m m nonlinear non-linear simplification parameters 21, γ1 and γ2 are simplified parameters, and b _m is the mth input coding signal 20.

In addition, the channel response output signal 22 output by the channel response unit 11 satisfies the following conditions:

Where y _m is the channel response output signal 22, r _m is the mth nonlinear simplification parameter 21, b _m is the mth input coding signal 20, and the channel response output signal 22 is the sample function h(kT) satisfying the period, k For the number of cycles, L ₁ and L ₂ are values selected from the h(kT) function.

In addition, the equalizer output value 24 output by the partial equalization unit 12 satisfies the following conditions:

among them For the equalizer output value 24, y _m is the channel response output signal 22, n _m is the external noise 23, q is the partial equalization unit coefficient 26, and N ₁ and N ₂ are different positive integers.

Further, the target response output value 25 output by the target response unit 13 satisfies the following conditions:

Where d _m is the target response output value 25, and b _m is the mth input coded signal 20, a transpose matrix having a vector of target response unit coefficients p, Is the vector with the mth input encoded signal.

According to the above obtained d _m and The processing unit 14 may square the difference between the target response output value 25 and the equalizer output value 24 to obtain a mean square error, and then take the mean square error to obtain an expected value. The expected value is a mean square error, and the mean square error satisfies the following conditions:

Where E[*] is the action of taking the expected value, and the action of minimizing the mean square error according to the orthogonal principle, to obtain the partial equalization unit coefficient 26 and the target response unit coefficient 27, and corresponding coefficients are respectively corresponding to The partial equalization unit 12 and the target response unit 13 are matched, and the decoding unit 15 is matched to the target response unit coefficient p, and the equalizer output value 24 is converted by the Viterbi decoding method to output the decoded output encoded signal 28 .

It is worth noting that, according to different input coding signals 20, different partial equalization unit coefficients 26 and target response unit coefficients 27 will be obtained, that is, the maximum likelihood sequence receiving device of the present invention can be based on different inputs. The encoded signal 20 is adjusted to adjust the partial equalization unit coefficient 26 and the target response unit coefficient 27 such that the bit error rate of the output encoded signal 28 relative to the input encoded signal 20 is substantially reduced.

In addition, when the equalization unit 12 generates the equalizer output value 24 by using the second combined signal of the channel response output signal 22 and the external noise 23, the external noise 23 can be white Gaussian noise, but not For limitations. And the channel response output signal 22 is not affected by this white Gaussian noise.

Please refer to FIG. 2, which is a schematic diagram of a first embodiment of the equalized maximum likelihood sequence receiving apparatus of the present invention. As shown in the figure, in this embodiment, an EML-PR4 equalization channel module is used in conjunction with the equalized maximum likelihood sequence receiving apparatus of the present invention, and decoded by a decoding unit 15 having a corresponding matching target response unit coefficient 27. The decoding unit is an exemplary embodiment of the Viterbi decoder using the Viterbi decoding method. In this embodiment, the Viterbi decoder is used, but the limitation should not be used as a limitation. The scope of the patent application.

As shown in the figure, when the shortest path dynamic programming is performed, for example, when the m-1th input encoded signal b _m-1 of the current state is 2, the mth input encoded signal b _m can be 0 respectively. Or -2, so the next state can be 0 or -2, and the output coded signal corresponding to this module can be evaluated as 2 or 0 by y _m =b _m + b _m-1 .

Please refer to FIG. 3, which is a schematic diagram of a second embodiment of the equalized maximum likelihood sequence receiving apparatus of the present invention. As shown in the figure, in this embodiment, an EML-EPR4 equalization channel module is used in conjunction with the equalized maximum likelihood sequence receiving apparatus of the present invention, and decoded by a decoding unit 15 having a corresponding matching target response unit coefficient 27. The decoding unit is an exemplary embodiment of the Viterbi decoder using the Viterbi decoding method. In this embodiment, the Viterbi decoder is used, but the limitation should not be used as a limitation. The scope of the patent application.

As shown in the figure, when the shortest path dynamic programming is performed, the current state can be defined as [b _m-2 , b _m-1 ], which represents the mth input encoded signal, so the next state can be defined as [b _m-1 , b _m ]. For example, when the current state [b _m-2 , b _m-1 ] is [0, 2], and the mth input coded signal b _m is -2, the output coded signal corresponding to the module can be used y _m = p ₀ b _m +p ₁ b _m-1 + p ₂ b _m-2 =−2+2p ₁ , so the next state [b _m-1 , b _m ] can be decoded as [2, -2]; When the input coded signal b _m =0, the corresponding output coded signal of the next state can therefore be decoded as [2, 0]. It is worth noting that under this channel module, p ₀ =1, and the EML-EPR4 equalization channel module has seven states.

Please refer to FIG. 4, which is a data comparison diagram of an embodiment of the equalized maximum likelihood sequence receiving apparatus of the present invention. As shown in the figure, the vertical axis is the bit error rate and the horizontal axis is the signal-to-noise ratio. It can be clearly seen from the data in Fig. 4 that the same likelihood ratio is used in the case of the EML-PR4 or EML-EPR4 equalization channel module, using the equalized maximum likelihood sequence receiving device of the present creation. Within, corresponding to the traditional PR4 or EPR4 have a small bit error rate. Among them, the output coding signal of EML-EPR4 can achieve a 1.5 dB less signal-to-noise ratio than the traditional EPR4 at a bit error rate lower than 10 ^-4 . That is to say, the equalization sequence maximum likelihood sequence receiving apparatus using the present invention can eliminate the interference of external noise more than the conventional apparatus to achieve better output of the encoded signal.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of this creation shall be included in the scope of the appended patent application.

10‧‧‧Magnetic Recording System
11‧‧‧Channel response unit
12‧‧‧Partial equalization unit
13‧‧‧Target response unit
14‧‧‧Processing unit
15‧‧‧Decoding unit
20‧‧‧Input coded signal
21‧‧‧Nonlinear simplification parameters
22‧‧‧ channel response output signal
23‧‧‧External noise
24‧‧‧ Equalizer output value
25‧‧‧ Target response output value
26‧‧‧Partial equalization unit coefficients
27‧‧‧ Target response unit coefficients
28‧‧‧ Output coded signal

The first figure is a block diagram of the equalized maximum likelihood sequence receiving apparatus of the present creation.
Figure 2 is a schematic diagram of a first embodiment of an equalized maximum likelihood sequence receiving apparatus of the present invention.
Figure 3 is a schematic diagram of a second embodiment of the equalized maximum likelihood sequence receiving apparatus of the present invention.
Figure 4 is a data comparison diagram of an embodiment of the equalized maximum likelihood sequence receiving apparatus of the present creation.

10‧‧‧Magnetic Recording System

11‧‧‧Channel response unit

12‧‧‧Partial equalization unit

13‧‧‧Target response unit

14‧‧‧Processing unit

15‧‧‧Decoding unit

20‧‧‧Input coded signal

21‧‧‧Nonlinear simplification parameters

22‧‧‧ channel response output signal

23‧‧‧External noise

24‧‧‧ Equalizer output value

25‧‧‧ Target response output value

26‧‧‧Partial equalization unit coefficients

27‧‧‧ Target response unit coefficients

28‧‧‧ Output coded signal

Claims (8)

An equalization maximum likelihood sequence receiving apparatus is used for a magnetic recording system, wherein the magnetic recording system outputs an input encoded signal, wherein the equalized maximum likelihood sequence receiving apparatus comprises:
a channel response unit receives a first combined signal of the input encoded signal outputted by the magnetic recording system and a nonlinear simplified parameter to generate a channel response output signal;
a portion of the equalization unit receives a second combined signal of the channel response output signal and an external noise to generate an equalizer output value;
a target response unit receives the input encoded signal output by the magnetic recording system to generate a target response output value;
a processing unit is configured to square the difference between the target response output value and the output value of the equalizer to obtain a mean square error, and then take the mean square error to obtain an expected value, the expected value is a mean square error, and according to the positive The intersection principle minimizes the mean square error error to obtain at least a portion of the equalization unit coefficient and the at least one target response unit coefficient corresponding to the input encoded signal; and a decoding unit configured to match the target response unit coefficient, the decoding The unit receives the equalizer output value and decodes the equalizer output value into an output encoded signal;
The equalized maximum likelihood sequence receiving device reduces the bit error rate of the output encoded signal that is output relative to the input encoded signal. The equalization maximum likelihood sequence receiving apparatus according to claim 1, wherein the channel response output signal output by the channel response unit satisfies the following conditions:


Where y _m is the channel response output signal, r _m is the mth nonlinear simplified parameter, b _m is the mth input coding signal, and the channel response output signal is a sample function h(kT) satisfying the period k is the number of cycles, and L ₁ and L ₂ are values selected from one of the h(kT) functions. The equalization maximum likelihood sequence receiving device according to claim 1, wherein the equalizer output value of the partial equalization unit meets the following conditions:


among them Is the output value of the equalizer, y _m is the channel response output signal, n _m is the external noise, q is the partial equalization unit coefficient, N ₁ and N ₂ are different positive integers . The equalization maximum likelihood sequence receiving apparatus according to claim 1, wherein the target response output value output by the target response unit satisfies the following conditions:


Where d _m is the target response output value, and b _m is the mth input coding signal. Is a transposed matrix with a vector of target response unit coefficients p, Is a vector with the mth input coded signal. The equalization maximum likelihood sequence receiving apparatus according to claim 1, wherein the decoding unit converts the equalizer output value according to the target response unit coefficient p, and outputs the output value by using a Viterbi decoding method. The output encodes a signal. The equalization maximum likelihood sequence receiving apparatus according to claim 1, wherein the mean square error system satisfies the following conditions:


Among them, E[*] is the action of taking the expected value, and the action of minimizing the mean square error according to the orthogonal principle. The equalization maximum likelihood sequence receiving apparatus according to claim 1, wherein the external noise system is a white Gaussian noise. The equalization maximum likelihood sequence receiving apparatus according to claim 7, wherein the channel response output signal is not affected by the white Gaussian noise.