CN101989962B - Channel estimation method and system of physical broadcasting channel (PBCH) - Google Patents

Abstract

The invention discloses a channel estimation method of a physical broadcasting channel, comprising the following steps that a terminal acquires a channel estimation value on a secondary synchronization channel (S-SCH); the terminal acquires the channel estimation value of the PBCH according to the channel estimation value on the secondary synchronization channel after receiving an orthogonal frequency division multiplexing (OFDM) symbol containing the PBCH. The invention also correspondingly discloses a channel estimation system of the PBCH, comprising an S-SCH estimation unit, an OFDM symbol receiving unit and a PBCH estimation unit. Due to the fact that the invention can be simultaneously suitable for LTE systems of FDD (Frequency Division Duplex) frame structures and TDD (Time Division Duplex) frame structures, the application range is wider; moreover, due to the fact that the foothold of the invention is simultaneously utilizing the gains of the two aspects of a reference signal and a synchronizing channel, the channel estimation accuracy can be improved.

Description

A kind of channel estimation methods of Physical Broadcast Channel and system

Technical field

The present invention relates to cellular mobile communication technology, relate in particular to channel estimation methods and the system of a kind of Physical Broadcast Channel (PBCH).

Background technology

In Long Term Evolution (LTE) system, require terminal can be correctly decoded broadcast channel (BCH) under low signal-to-noise ratio.Can't obtain correct system bandwidth value in Cell searching due to terminal, so this moment, channel estimator can only be operated in 1.08MHz bandwidth corresponding to PBCH that BCH shines upon, and under the 1.08MHz bandwidth, the reference signal that the LTE system provides for channel estimator (RS) number is considerably less, thereby the performance of channel estimating is sharply descended.

Publication number be the patent application of US2008/0019350A1 for the LTE system of FDD frame structure a kind of method of channel estimating of broadcast channel, the channel estimation value of primary synchronization channel (P-SCH) is adopted in auxiliary synchronization channel (S-SCH) and PBCH, this scheme has solved few, the traditional inaccurate problem of channel estimation methods of reference signal quantity to a certain extent, its advantage be directly perceived, complexity is low.Yet, also there are some shortcomings in the method, at first, this method is only applicable to the LTE system of FDD frame structure, in the LTE of tdd frame structure system, P-SCH occurs after PBCH, and S-SCH occurred before PBCH, thereby the scheme that the channel estimating that can't adopt this patent application to propose sequentially adopts is carried out channel estimating to PBCH, so, this scheme has limitation on range of application, and precision of channel estimation is lower.

Summary of the invention

In view of this, main purpose of the present invention is to provide a kind of channel estimation methods and system of Physical Broadcast Channel, can be applicable to simultaneously the LTE system of FDD frame structure and tdd frame structure, and range of application is wider, and precision of channel estimation is higher.

For achieving the above object, technical scheme of the present invention is achieved in that

A kind of channel estimation methods of Physical Broadcast Channel comprises:

Terminal is obtained the channel estimation value on auxiliary synchronization channel S-SCH;

Terminal according to the channel estimation value on the S-SCH that obtains, is obtained the channel estimation value of PBCH after receiving and containing the orthogonal frequency division multiplex OFDM symbol of Physical Broadcast Channel PBCH.

The channel estimation value that described terminal is obtained PBCH is:

Obtain the channel of PBCH and estimate evaluation;

The channel of PBCH is estimated evaluation carry out frequency domain filtering, obtain the channel estimation value of PBCH.

The channel of the described PBCH of obtaining is estimated evaluation:

The subcarrier of PBCH is not reference signal, and it is channel estimation value on the described S-SCH that obtains that the channel of determining corresponding PBCH is estimated evaluation;

The subcarrier of PBCH is reference signal, obtains the channel estimation value on described reference signal, and the channel of determining corresponding PBCH is estimated channel estimation value that evaluation is the reference signal obtained and the interpolate value of the channel estimation value on S-SCH.

Before the described channel estimation value that obtains on S-SCH, also comprise step: obtain the channel estimation value on primary synchronization channel P-SCH;

The channel of the described PBCH of obtaining is estimated evaluation:

The subcarrier of PBCH is not reference signal, and the channel of determining corresponding PBCH is estimated the interpolate value of the channel estimation value of channel estimation value that evaluation is the P-SCH that obtains and S-SCH;

The subcarrier of PBCH is reference signal, obtain the channel estimation value on described reference signal, and the channel of determining corresponding PBCH is estimated the interpolate value that evaluation is channel estimation value, the channel estimation value on P-SCH and the channel estimation value on S-SCH of the reference signal obtained.

Described frequency domain filtering is the frequency domain low-pass filtering.

A kind of channel estimation system of Physical Broadcast Channel comprises: S-SCH channel estimating unit, OFDM symbol receiving element and PBCH channel estimating unit, wherein,

Described S-SCH channel estimating unit is used for obtaining the channel estimation value on S-SCH;

Described OFDM symbol receiving element is used for receiving the OFDM symbol;

Described PBCH channel estimating unit is used for the OFDM symbol that contains PBCH that receives according to OFDM symbol receiving element, and the channel estimation value on the S-SCH that obtains of S-SCH channel estimating unit, obtains the channel estimation value of PBCH.

Described PBCH channel estimating unit specifically comprises: PBCH channel pre-estimation unit and frequency domain filtering unit, wherein,

Described PBCH channel pre-estimation unit is used for the OFDM symbol that contains PBCH that receives according to OFDM symbol receiving element, and the channel estimation value on the S-SCH that obtains of S-SCH channel estimating unit, obtains the channel of PBCH and estimates evaluation;

Described frequency domain filtering unit, the channel that is used for PBCH that PBCH channel pre-estimation unit is obtained is estimated evaluation and is carried out frequency domain filtering, to obtain the channel estimation value of PBCH.

This system also comprises the reference signal channel estimating unit, is used for obtaining the channel estimation value on reference signal;

Described PBCH channel pre-estimation unit, channel estimation value on the S-SCH that channel estimation value on the OFDM symbol that contains PBCH that also is used for receiving according to OFDM symbol receiving element, the reference signal that the reference signal channel estimating unit is obtained and S-SCH channel estimating unit are obtained, obtain the channel of PBCH and estimate evaluation, concrete, the subcarrier of PBCH is not reference signal, and it is channel estimation value on the described S-SCH that obtains that the channel of determining corresponding PBCH is estimated evaluation; The subcarrier of PBCH is reference signal, obtains the channel estimation value on described reference signal, and the channel of determining corresponding PBCH is estimated channel estimation value that evaluation is the reference signal obtained and the interpolate value of the channel estimation value on S-SCH.

This system also comprises the P-SCH channel estimating unit, is used for obtaining the channel estimation value on P-SCH;

Described PBCH channel pre-estimation unit, channel estimation value on the S-SCH that channel estimation value on the OFDM symbol that contains PBCH that also is used for receiving according to OFDM symbol receiving element, the P-SCH that the P-SCH channel estimating unit is obtained and S-SCH channel estimating unit are obtained, obtain the channel of PBCH and estimate evaluation, concrete, the subcarrier of PBCH is not reference signal, and the channel of determining corresponding PBCH is estimated the interpolate value of the channel estimation value of channel estimation value that evaluation is the P-SCH that obtains and S-SCH.

This system also comprises the reference signal channel estimating unit, is used for obtaining the channel estimation value on reference signal;

described PBCH channel pre-estimation unit, also be used for the OFDM symbol that contains PBCH according to the reception of OFDM symbol receiving element, channel estimation value on the reference signal that the reference signal channel estimating unit is obtained, channel estimation value on the P-SCH that the P-SCH channel estimating unit is obtained, and the channel estimation value on the S-SCH that obtains of S-SCH channel estimating unit, obtain the channel of PBCH and estimate evaluation, concrete, the subcarrier of PBCH is reference signal, the channel of determining corresponding PBCH is estimated the channel estimation value that evaluation is the reference signal obtained, channel estimation value on P-SCH and the interpolate value of the channel estimation value on S-SCH.

The channel estimation methods of Physical Broadcast Channel of the present invention and system utilize the reference signal in the subframe comprise PBCH and the channel estimation value of the synchronizing channel that is adjacent simultaneously, and the channel on the shared subcarrier of PBCH is estimated.Can be applicable to simultaneously the LTE system of FDD frame structure and tdd frame structure due to the present invention, so the scope of application is wider; And, due to foothold of the present invention for to utilize the gain of this two aspect of reference signal and synchronizing channel simultaneously, so can improve precision of channel estimation.

Description of drawings

Fig. 1 is the channel estimation methods schematic flow sheet of Physical Broadcast Channel of the present invention;

Fig. 2 is under the common CP pattern, LTE-TDD frame structure schematic diagram;

Fig. 3 is under the common CP pattern, LTE-FDD frame structure schematic diagram;

Fig. 4 is the channel estimation system structural representation of Physical Broadcast Channel of the present invention.

Embodiment

Basic thought of the present invention is: utilize simultaneously the reference signal in the subframe comprise PBCH and the channel estimation value of the synchronizing channel that is adjacent, the channel on the shared subcarrier of PBCH is estimated.

Be described in further detail below in conjunction with the enforcement of accompanying drawing to technical scheme.

Fig. 1 is the channel estimation methods schematic flow sheet of Physical Broadcast Channel of the present invention, and as shown in Figure 1, the channel estimation methods of Physical Broadcast Channel of the present invention generally comprises following steps:

Step 11: terminal is obtained the channel estimation value on P-SCH.

In Cell searching, the detection of P-SCH and demodulation are carried out at first, and after successful demodulation P-SCH, the P-SCH sequence that demodulation is obtained is as known array, ask channel estimation value H' on the corresponding subcarrier of P-SCH according to formula (1) at frequency domain _P-SCH:

$H_{P-\mathrm{SCH}}^{\′}\left(i\right)=R_{P-\mathrm{SCH}}\left(i\right)S_{P-\mathrm{SCH}}^H\left(i\right)---\left(1\right)$

Wherein, R _P-SCH(i) be the reception signal of i subcarrier on P-SCH, S _P-SCH(i) be the value of i subcarrier of the known signal after demodulation P-SCH.

Fig. 2 is under the common CP pattern, LTE-TDD frame structure schematic diagram, under the common CP pattern, a subframe comprises two time slots, each time slot comprises seven OFDM symbols, as shown in Figure 2, in the tdd frame structure, the position of P-SCH second subframe, be that on the 3rd OFDM (OFDM) symbol of subframe 1, distance P BCH channel is far away, so, in the situation that terminal mobility is higher, the channel relevancy of P-SCH and PBCH is lower, and the channel estimation value on P-SCH can be ignored the impact of the channel estimation value of PBCH, and namely this step can not carried out; And in the situation that terminal mobility is lower, P-SCH still can provide the correlation gain, channel estimation value on P-SCH be can not ignore the impact of the channel estimation value of PBCH, and the channel estimation value on P-SCH should be used for assisting the PBCH channel estimating, namely needs to carry out this step.

Fig. 3 is under the common CP pattern, LTE-FDD frame structure schematic diagram, under the common CP pattern, a subframe comprises two time slots, each time slot comprises seven OFDM symbols, as shown in Figure 3, in the FDD frame structure, P-SCH is in first subframe, is on the penultimate OFDM symbol of subframe 0, with the PBCH close together, so, regardless of terminal mobility, channel estimation value on P-SCH all be can not ignore the impact of the channel estimation value of PBCH, and the channel estimation value on P-SCH should be used for assisting the PBCH channel estimating, namely needs to carry out this step.

Step 12: terminal is obtained the channel estimation value on S-SCH.

Carry out detection and the demodulation of S-SCH, after the S-SCH demodulation was completed, the S-SCH sequence that demodulation is obtained was as known array, asked channel estimation value H' on the corresponding subcarrier of S-SCH at frequency domain _S-SCH, H' _S-SCHConcrete acquisition methods be prior art, do not describe in detail at this.

As shown in Figure 2, in the tdd frame structure, S-SCH is in first subframe, is on last OFDM symbol of subframe 0, and as shown in Figure 3, in the FDD frame structure, S-SCH is in first subframe, be on last OFDM symbol of first time slot of subframe 0.Although S-SCH residing position under above-mentioned two kinds of frame structures is different, which kind of frame structure no matter, the channel estimation value on S-SCH all be can not ignore the impact of the channel estimation value of PBCH, and namely S-SCH all should be used for auxiliary PBCH channel estimating.

Step 13: terminal is obtained the evaluation of estimating of PBCH according to the channel estimation value on P-SCH, the channel estimation value on S-SCH.

Here, after terminal received and contains the OFDM symbol of PBCH, by PBCH being made the time domain interpolation, the channel that obtains PBCH was estimated evaluation H' _PBCHConcrete:

In the situation of execution in step 11, to each subcarrier of PBCH, if this subcarrier is not reference signal, determine that the channel of this PBCH is estimated evaluation H' _PBCHChannel estimation value H' for P-SCH _P-SCHChannel estimation value H' with S-SCH _S-SCHInterpolate value, be λ ₁H' _P-SCH(i)+λ ₂H' _S-SCH(i), λ wherein ₁+ λ ₂=1; If this subcarrier is reference signal, obtain the channel estimation value H' on reference signal _RS, and the channel of definite this PBCH is estimated evaluation H' _PBCHChannel estimation value H' for reference signal _RS, the channel estimation value H' on P-SCH _P-SCHWith the channel estimation value H' on S-SCH _S-SCHInterpolate value, i.e. λ ₁H' _P-SCH(i)+λ ₂H' _S-SCH(i)+λ ₃H' _RS(i), λ wherein ₁+ λ ₂+ λ ₃=1.Here, the channel estimation value H' on reference signal _RSBe the correlation of the locational reception signal of reference signal and local sequence, concrete acquisition methods is prior art, does not describe in detail at this.

In the situation of execution in step 11, to each subcarrier of PBCH, if this subcarrier is not reference signal, do not determine that the channel of this PBCH is estimated evaluation H' _PBCHChannel estimation value H' for S-SCH _S-SCHIf this subcarrier is reference signal, obtain the channel estimation value H' on reference signal _RS, and the channel of definite this PBCH is estimated evaluation H' _PBCHChannel estimation value H' for reference signal _RSWith the channel estimation value H' on S-SCH _S-SCHInterpolate value, i.e. λ ₁H' _S-SCH(i)+λ ₂H' _RS(i), wherein, λ ₁+ λ ₂=1.

Especially, if λ ₁=λ ₂=λ ₃, interpolation is equivalent to and asks for average, specifically chooses the method for coefficient and can according to requirements determine.

Step 14: terminal is estimated evaluation to the channel of PBCH and is carried out frequency domain filtering, obtains the channel estimation value of PBCH.

Generally, the channel of the PBCH that obtains of interpolation is estimated evaluation H' _PBCHThe band noise at this moment, also needs the channel of PBCH that interpolation is obtained to estimate evaluation H' _PBCHMake the frequency domain low-pass filtering, namely adopt the outer noise of low pass filter filters out multipath, obtain the channel estimation value H of PBCH _PBCH

The transmission means that it is pointed out that Physical Broadcast Channel (PBCH) has three kinds, single-antenna transmission, double-antenna transmit diversity and four antenna transmit diversities.The channel estimating of P-SCH and S-SCH can only be assisted the channel estimating with the PBCH signal of its use same transmit antenna.Emulation shows, adopts the present invention, can obtain the gain of 1.5-2dB in the corresponding transmission channel decoding of the transmitting antenna of SCH.

Fig. 4 is the channel estimation system structural representation of Physical Broadcast Channel of the present invention, as shown in Figure 4, the channel estimation system of Physical Broadcast Channel of the present invention comprises: S-SCH channel estimating unit 41, OFDM symbol receiving element 42 and PBCH channel estimating unit 43, wherein

S-SCH channel estimating unit 41 is used for obtaining the channel estimation value on S-SCH;

OFDM symbol receiving element 42 is used for receiving the OFDM symbol;

PBCH channel estimating unit 43 is used for the OFDM symbol that contains PBCH that receives according to OFDM symbol receiving element 42, and the channel estimation value on the S-SCH that obtains of S-SCH channel estimating unit 41, obtains the channel estimation value of PBCH.

PBCH channel estimating unit 43 specifically comprises: PBCH channel pre-estimation unit 431 and frequency domain filtering unit 432, wherein,

PBCH channel pre-estimation unit 431 is used for the OFDM symbol that contains PBCH that receives according to OFDM symbol receiving element 42, and the channel estimation value on the S-SCH that obtains of S-SCH channel estimating unit 41, obtains the channel of PBCH and estimates evaluation;

Frequency domain filtering unit 432, the channel that is used for PBCH that PBCH channel pre-estimation unit 431 is obtained is estimated evaluation and is carried out frequency domain filtering, to obtain the channel estimation value of PBCH.

This system also comprises reference signal channel estimating unit 44, is used for obtaining the channel estimation value on reference signal;

PBCH channel pre-estimation unit 431, channel estimation value on the S-SCH that channel estimation value on the OFDM symbol that contains PBCH that also is used for receiving according to OFDM symbol receiving element 42, the reference signal that reference signal channel estimating unit 44 is obtained and S-SCH channel estimating unit 41 are obtained obtains the channel of PBCH and estimates evaluation.

This system also comprises P-SCH channel estimating unit 45, is used for obtaining the channel estimation value on P-SCH;

PBCH channel pre-estimation unit 431, channel estimation value on the S-SCH that channel estimation value on the OFDM symbol that contains PBCH that also is used for receiving according to OFDM symbol receiving element 42, the P-SCH that P-SCH channel estimating unit 45 is obtained and S-SCH channel estimating unit 41 are obtained obtains the channel of PBCH and estimates evaluation.

PBCH channel pre-estimation unit 431, channel estimation value on the S-SCH that channel estimation value on channel estimation value on the OFDM symbol that contains PBCH that also is used for receiving according to OFDM symbol receiving element 42, the reference signal that reference signal channel estimating unit 44 is obtained, the P-SCH that P-SCH channel estimating unit 45 is obtained and S-SCH channel estimating unit 41 are obtained obtains the channel of PBCH and estimates evaluation.

The above is only preferred embodiment of the present invention, is not for limiting protection scope of the present invention.

Claims (6)

1. the channel estimation methods of a Physical Broadcast Channel, is characterized in that, the method comprises:

Terminal is obtained the channel estimation value on auxiliary synchronization channel S-SCH;

Terminal according to the channel estimation value on the S-SCH that obtains, is obtained the channel estimation value of PBCH after receiving and containing the orthogonal frequency division multiplex OFDM symbol of Physical Broadcast Channel PBCH,

The channel estimation value that described terminal is obtained PBCH is:

Obtain the channel of PBCH and estimate evaluation;

The channel of PBCH is estimated evaluation carries out frequency domain filtering, obtain the channel estimation value of PBCH,

The channel of the described PBCH of obtaining is estimated evaluation:

The subcarrier of PBCH is not reference signal, and it is channel estimation value on the described S-SCH that obtains that the channel of determining corresponding PBCH is estimated evaluation;

The subcarrier of PBCH is reference signal, obtains the channel estimation value on described reference signal, and the channel of determining corresponding PBCH is estimated channel estimation value that evaluation is the reference signal obtained and the interpolate value of the channel estimation value on S-SCH.

2. channel estimation methods according to claim 1, is characterized in that, before the described channel estimation value that obtains on S-SCH, also comprises step: obtain the channel estimation value on primary synchronization channel P-SCH;

The channel of the described PBCH of obtaining is estimated evaluation:

The subcarrier of PBCH is not reference signal, and the channel of determining corresponding PBCH is estimated the interpolate value of the channel estimation value of channel estimation value that evaluation is the P-SCH that obtains and S-SCH;

The subcarrier of PBCH is reference signal, obtain the channel estimation value on described reference signal, and the channel of determining corresponding PBCH is estimated the interpolate value that evaluation is channel estimation value, the channel estimation value on P-SCH and the channel estimation value on S-SCH of the reference signal obtained.

3. channel estimation methods according to claim 1, is characterized in that, described frequency domain filtering is the frequency domain low-pass filtering.

4. the channel estimation system of a Physical Broadcast Channel, is characterized in that, this system comprises: S-SCH channel estimating unit, OFDM symbol receiving element and PBCH channel estimating unit, wherein,

Described S-SCH channel estimating unit is used for obtaining the channel estimation value on S-SCH;

Described OFDM symbol receiving element is used for receiving the OFDM symbol;

Described PBCH channel estimating unit is used for the OFDM symbol that contains PBCH that receives according to OFDM symbol receiving element, and the channel estimation value on the S-SCH that obtains of S-SCH channel estimating unit, obtains the channel estimation value of PBCH,

Described PBCH channel estimating unit specifically comprises: PBCH channel pre-estimation unit and frequency domain filtering unit, wherein,

Described PBCH channel pre-estimation unit is used for the OFDM symbol that contains PBCH that receives according to OFDM symbol receiving element, and the channel estimation value on the S-SCH that obtains of S-SCH channel estimating unit, obtains the channel of PBCH and estimates evaluation;

Described frequency domain filtering unit, the channel that is used for PBCH that PBCH channel pre-estimation unit is obtained is estimated evaluation and is carried out frequency domain filtering, obtaining the channel estimation value of PBCH,

This system also comprises the reference signal channel estimating unit, is used for obtaining the channel estimation value on reference signal;

Described PBCH channel pre-estimation unit, channel estimation value on the S-SCH that channel estimation value on the OFDM symbol that contains PBCH that also is used for receiving according to OFDM symbol receiving element, the reference signal that the reference signal channel estimating unit is obtained and S-SCH channel estimating unit are obtained, obtain the channel of PBCH and estimate evaluation, concrete, the subcarrier of PBCH is not reference signal, and it is channel estimation value on the described S-SCH that obtains that the channel of determining corresponding PBCH is estimated evaluation; The subcarrier of PBCH is reference signal, obtains the channel estimation value on described reference signal, and the channel of determining corresponding PBCH is estimated channel estimation value that evaluation is the reference signal obtained and the interpolate value of the channel estimation value on S-SCH.

5. channel estimation system according to claim 4, is characterized in that, this system also comprises the P-SCH channel estimating unit, is used for obtaining the channel estimation value on P-SCH;

Described PBCH channel pre-estimation unit, channel estimation value on the S-SCH that channel estimation value on the OFDM symbol that contains PBCH that also is used for receiving according to OFDM symbol receiving element, the P-SCH that the P-SCH channel estimating unit is obtained and S-SCH channel estimating unit are obtained, obtain the channel of PBCH and estimate evaluation, concrete, the subcarrier of PBCH is not reference signal, and the channel of determining corresponding PBCH is estimated the interpolate value of the channel estimation value of channel estimation value that evaluation is the P-SCH that obtains and S-SCH.

6. channel estimation system according to claim 5, is characterized in that, this system also comprises the reference signal channel estimating unit, is used for obtaining the channel estimation value on reference signal;

described PBCH channel pre-estimation unit, also be used for the OFDM symbol that contains PBCH according to the reception of OFDM symbol receiving element, channel estimation value on the reference signal that the reference signal channel estimating unit is obtained, channel estimation value on the P-SCH that the P-SCH channel estimating unit is obtained, and the channel estimation value on the S-SCH that obtains of S-SCH channel estimating unit, obtain the channel of PBCH and estimate evaluation, concrete, the subcarrier of PBCH is reference signal, the channel of determining corresponding PBCH is estimated the channel estimation value that evaluation is the reference signal obtained, channel estimation value on P-SCH and the interpolate value of the channel estimation value on S-SCH.

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