WO2012100709A1

WO2012100709A1 - Frequency offset processing method and device for multimode terminal

Info

Publication number: WO2012100709A1
Application number: PCT/CN2012/070564
Authority: WO
Inventors: 刘俊英; 黄珍
Original assignee: 意法•爱立信半导体（北京）有限公司
Priority date: 2011-01-26
Filing date: 2012-01-19
Publication date: 2012-08-02
Also published as: CN102098250A

Abstract

Provided in the present invention are a frequency offset processing method and device for a multimode terminal. A reference clock is generated by the multimode terminal via a digitally compensated crystal oscillator (DCXO), and supported at least is communication with a first communication network and a TD-SCDMA network. The method comprises: establishing the multimode terminal in the first communication network, detecting a need to execute a TD-SCDMA service; the multimode terminal reading the broadcast information of a cell in the TD-SCDMA network, performing a frequency offset estimation by using P-CCPCH data at time slot 0, acquiring a frequency offset estimate value; and the multimode terminal performing a frequency offset compensation for the P-CCPCH data on the basis of the frequency offset estimate value. In the present invention, different service performances of the TD-SCDMA system are ensured when the multimode terminal is established in a disparate system.

Description

Frequency offset processing method and device for multimode terminal

The invention belongs to the field of mobile communications, and particularly relates to a digital compensation crystal oscillator

(DCXO) method and apparatus for frequency offset processing of multimode terminals. Background technique

At present, in the terminal's clock interface circuit, a transceiver including a voltage controlled crystal oscillator (VCXO) or an all-digital controlled crystal oscillator is commonly used. The VCXO itself has a temperature compensation circuit that can automatically compensate for frequency offset due to temperature changes. .

Due to the lower cost and smaller size of digitally compensated crystal oscillators (DCXOs), DCXOs are being used in terminals to generate system reference clocks. However, DCXO itself does not have the function of automatically adjusting the frequency according to temperature changes. Therefore, when performing different services, the terminal should consider the frequency offset caused by temperature changes.

In particular, for multimode terminals, when the multimode terminal resides in a different system (a system different from TD-SCDMA), when TD-SCDMA service is required, if the frequency offset is not compensated and/or adjusted in time, It affects various service performances of the TD-SCDMA system, and the prior art does not provide a solution for how to perform frequency offset processing for such a situation. Summary of the invention

The technical problem to be solved by the present invention is to provide a frequency offset processing method and apparatus for a multimode terminal to ensure various service performances of the TD-SCDMA system when the multimode terminal resides in a different system.

In order to solve the above technical problem, the present invention provides the following technical solutions:

A frequency offset processing method for a multimode terminal, wherein the multimode terminal generates a reference clock through a digitally compensated crystal oscillator DCXO, and supports communication with at least a first communication network and a TD-SCDMA network, the method comprising:

The multimode terminal resides in the first communication network, and detects that the multimode terminal in the TD-SCDMA industry needs to read the broadcast information of the cell in the TD-SCDMA network, and uses the time slot 0. The P-CCPCH data is subjected to frequency offset estimation to obtain a frequency offset estimation value;

The multimode terminal performs frequency offset compensation on the P-CCPCH data according to the frequency offset estimation value. The frequency offset processing method described above, further comprising: the multimode terminal adjusting the radio frequency according to the frequency offset estimation value.

The frequency offset processing method, wherein the step of adjusting the radio frequency by the multimode terminal according to the frequency offset estimation value specifically includes:

Each time a frequency offset estimate is obtained, the frequency offset estimate is stored;

When the stored number of frequency offset estimation values reaches a predetermined threshold, the stored frequency offset estimation values are averaged to obtain an average value of the frequency offset estimates;

The RF frequency is adjusted based on the average of the frequency offset estimates.

The frequency offset processing method described above, wherein the detecting that the TD-SCDMA service needs to be performed includes:

It is detected that all available TD-SCDMA-based PLMNs need to be searched;

It is detected that the broadcast information of the cell in the TD-SCDMA network needs to be read;

A cell that needs to be reselected or switched to the TD-SCDMA network is detected.

A frequency offset processing device for a multimode terminal, wherein the multimode terminal passes a digitally compensated crystal oscillator

The DCXO generates a reference clock and supports communication with at least the first communication network and the TD-SCDMA network, the apparatus comprising:

a detecting module, configured to reside in the first communication network, and detect that the need is performed

TD-SCDMA service;

a frequency offset estimation module, configured to read broadcast information of a cell in a TD-SCDMA network, and perform frequency offset estimation by using P-CCPCH data of time slot 0 to obtain a frequency offset estimation value;

And a frequency offset compensation module, configured to perform frequency offset compensation on the P-CCPCH data according to the frequency offset estimation value.

The frequency offset processing device further includes: a frequency offset adjustment module, configured to adjust the radio frequency according to the frequency offset estimation value.

The frequency offset processing device described above, wherein the frequency offset adjustment module is further used for:

When the stored number of frequency offset estimates reaches a predetermined threshold, the stored frequency offset estimates are performed. Average processing, obtaining the average value of the frequency offset estimation;

The above-mentioned frequency offset processing device, wherein the detecting that the TD-SCDMA service needs to be performed includes:

It is detected that all available TD-SCDMA-based PLMNs need to be searched;

Compared with the prior art, the beneficial effects of the present invention are:

In the above technical solution of the present invention, when the multimode terminal resides in the first communication network, if it is detected that the TD-SCDMA service needs to be performed, the broadcast information of the cell in the TD-SCDMA network is read, and the time slot 0 is used. The P-CCPCH data is subjected to frequency offset estimation, and then the P-CCPCH data is frequency offset compensated according to the frequency offset estimation result, thereby ensuring various kinds of TD-SCDMA systems when the multimode terminal resides in the different system. Business performance. DRAWINGS

1 is a flowchart of a frequency offset processing method of a multimode terminal according to an embodiment of the present invention;

2 is a schematic diagram of a subframe structure of a TD-SCDMA system;

3 is a structural diagram of a frequency offset processing apparatus of a multimode terminal according to an embodiment of the present invention. detailed description

The present invention will be described in detail below with reference to the drawings and specific embodiments.

1 is a flowchart of a frequency offset processing method of a multimode terminal according to an embodiment of the present invention. The multimode terminal generates a reference clock through a DCXO, and at least supports communication with the first communication network and the TD-SCDMA network. Referring to FIG. 1, the frequency offset processing method includes the following steps:

Step 101: The multimode terminal resides in a first communication network, and detects that a TD-SCDMA service needs to be performed;

Wherein, the detecting that the TD-SCDMA service needs to be performed includes:

It is detected that all available TD-SCDMA-based PLMNs need to be searched; It is detected that the broadcast information of the cell in the TD-SCDMA network needs to be read;

Step 102: The multimode terminal reads broadcast information of a cell in a TD-SCDMA network, and performs frequency offset estimation by using P-CCPCH data of time slot 0 to obtain a frequency offset estimation value.

Step 103: The multimode terminal performs frequency offset compensation on the P-CCPCH data according to the frequency offset estimation value.

Preferably, the multimode terminal further adjusts the radio frequency according to the frequency offset estimation value, and specifically includes:

An application example of the above-described frequency offset processing method is given below.

Assuming that the multimode terminal is a GSM/TD-SCDMA dual mode terminal, the multimode terminal adopts a DCXO transceiver, and resides in a GSM system, and when TD-SCDMA service is required, according to different TD-SCDMA services, The workflow of the implementation method is as follows:

(1) When the multimode terminal resides in the GSM system and needs to search all available PLMNs (Public Land Mobile Communication Network) of TD-SCDMA, the multimode terminal first detects the available downlink downlink codes according to the received data (SY). C-DL) a Midamble (training sequence) code corresponding to the data; after detecting the TD-SCDMA cell, reading the broadcast information corresponding to the cell, and calculating a frequency offset on the broadcast channel (BCH) of the cell; Finally, frequency offset compensation and frequency offset adjustment are performed according to the calculated frequency offset.

How to detect SYNC-DL code and Midamble code is a basic and well-known algorithm of TD-SCDMA system, and will not be described here. When reading the cell broadcast information, the frequency offset estimation is performed by using the main common control physical channel (P-CCPCH) data of slot 0 (TS0). Since the P-CCPCH always adopts QPSK modulation, the frequency offset estimation based on QPSK modulation is in the industry. It is a well-known algorithm. Here is a common algorithm as an example:

According to the slot structure of the TD-SCDMA system subframe (refer to FIG. 2), it is assumed that the symbol of the P-CCPCH located in front of the Midamble code after demodulation is ^;), which is located behind the Midamble code. The symbol of P-CCPCH is ^(), and the hard decisions obtained based on the demodulation symbols are 4W and (z), respectively. The process of estimating the frequency offset using the P-CCPCH data of TS0 is as follows:

First, ^ (/) = r, (/) * conj (d _x (/)) , Y{i) = r ₂ {i) *conj(d ₂ {i)^ , where, conj (Ώ, 表示求Conjugate operation

Then, multiply the conjugate of the Midamble before and after the symbol: ς. = |^() * , j = \, 2 is the code track number, and N is the number of symbols before or after the Midamble;

Since the P-CCPCH is mapped to two physical code channels, the conjugate multiplication results of the two code channels are accumulated: = ς+ ;

Finally, the frequency offset value is: /. _Ei = argp] / (2r7; (N2 + 144)), where argp] is the phase of the complex number, ρ is the spreading factor, τ; is the chip rate.

After obtaining the frequency offset value, the dual-mode terminal can compensate the currently demodulated symbol by using the estimated frequency offset value, and there are various compensation methods, one of which is as an example:

The compensation value of the mth data before the Midamble code is f = ^foffset *({N -m)xQ + 72);

The compensation value of the first data after the Midamble code is /, =- + 72); then the compensated data is: r' ( ) = r( )* , · is an imaginary unit.

After performing frequency offset compensation, the multimode terminal can perform operations such as decoding using the compensated data. Each time a frequency offset estimate is obtained, the dual mode terminal stores the frequency offset estimate. When accumulating to M frequency offset values, the physical layer will average the M (M can be adjusted according to the specific implementation, and its value range is preferably [1, 12]), and the average value is reported. For the upper level, the upper layer uses the average to adjust the frequency of the radio frequency.

(2) The multimode terminal resides in the GSM system. When the TD-SCDMA broadcast information needs to be read, the frequency offset value is first calculated on the broadcast channel, and then the frequency offset compensation and the frequency offset adjustment are performed according to the calculated frequency offset.

The difference between service (2) and service (1) is that service (1) does not know the available TD-SCDMA cell information, and needs to perform full-band search, while service (2) already knows TD-SCDMA cell information, and does not need to To perform a full-band search, only the broadcast channel of the cell needs to be read. In addition, the frequency offset estimation method, the frequency offset compensation, and the frequency offset adjustment strategy used in the service (2) are the same as the above service (1), and will not be described here. (3) The multimode terminal resides in the GSM system. When reselection or handover to the TD-SCDMA cell, the available SYNC-DL code and the corresponding Midamble code are first detected; then the broadcast information corresponding to the cell is read. And calculating a frequency offset on the broadcast channel of the cell; finally performing frequency offset compensation and frequency offset adjustment according to the calculated frequency offset.

The frequency offset estimation method, frequency offset compensation and frequency offset adjustment strategy used in the service (3) are the same as the above service (1), and will not be described here.

Corresponding to the frequency offset processing method described above, an embodiment of the present invention further provides a frequency offset processing apparatus. 3 is a structural diagram of a frequency offset processing apparatus of a multimode terminal according to an embodiment of the present invention. The multimode terminal generates a reference clock through a DCXO, and at least supports communication with the first communication network and the TD-SCDMA network. Referring to FIG. 3, the frequency offset processing apparatus includes:

The detecting module 10 is configured to reside in the first communications network, and detect that the TD-SCDMA service needs to be performed;

The frequency offset estimation module 20 is configured to read broadcast information of a cell in the TD-SCDMA network, perform frequency offset estimation by using P-CCPCH data of time slot 0, and obtain a frequency offset estimation value;

The frequency offset compensation module 30 is configured to perform frequency offset compensation on the P-CCPCH data according to the frequency offset estimation value.

Preferably, the frequency offset processing device further includes a frequency offset adjustment module (not shown), configured to adjust the radio frequency according to the frequency offset estimation value, specifically:

It is detected that all available TD-SCDMA-based PLMNs need to be searched;

In the above technical solution of the embodiment of the present invention, when the multimode terminal resides in the first communication network, if it is detected that the TD-SCDMA service needs to be performed, the broadcast information of the cell in the TD-SCDMA network is read, and the time slot is used. The P-CCPCH data of 0 is subjected to frequency offset estimation, and then, based on the frequency offset estimation knot The frequency offset compensation is performed on the P-CCPCH data, and thus, various service performances of the TD-SCDMA system when the multimode terminal resides in the different system can be guaranteed.

It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to be limiting, and those skilled in the art should understand that the technical solutions of the present invention may be modified or equivalently substituted without departing from the technical solutions of the present invention. The spirit of the scope should be covered by the scope of the claims of the present invention.

Claims

Claim

A frequency offset processing method for a multimode terminal, wherein the multimode terminal generates a reference clock through a digitally compensated crystal oscillator DCXO, and at least supports communication with the first communication network and the TD-SCDMA network, and is characterized in that :

The multimode terminal resides in the first communication network, and detects that the multimode terminal in the TD-SCDMA industry needs to read the broadcast information of the cell in the TD-SCDMA network, and uses the P-CCPCH data of the slot 0 to perform the frequency. Partial estimation, obtaining a frequency offset estimate;

The multimode terminal performs frequency offset compensation on the P-CCPCH data according to the frequency offset estimation value.

2. The frequency offset processing method according to claim 1, further comprising:

The multimode terminal adjusts the radio frequency according to the frequency offset estimation value.

The frequency offset processing method according to claim 2, wherein the step of adjusting the radio frequency by the multimode terminal according to the frequency offset estimation value specifically includes:

4. The frequency offset processing method according to claim 1, wherein the detecting that the TD-SCDMA service needs to be performed comprises:

It is detected that all available TD-SCDMA-based PLMNs need to be searched;

A frequency offset processing apparatus for a multimode terminal, wherein the multimode terminal generates a reference clock through a digitally compensated crystal oscillator DCXO, and at least supports communication with the first communication network and the TD-SCDMA network, and is characterized in that :

a detecting module, configured to reside in the first communications network, and detect that a TD-SCDMA service needs to be performed;

a frequency offset estimation module, configured to read broadcast information of a cell in a TD-SCDMA network, when utilized The P-CCPCH data of slot 0 is subjected to frequency offset estimation to obtain a frequency offset estimation value;

The frequency offset processing device according to claim 1, further comprising: a frequency offset adjustment module, configured to adjust the radio frequency according to the frequency offset estimation value.

7. The frequency offset processing apparatus according to claim 6, wherein the frequency offset adjustment module is further configured to:

8. The frequency offset processing apparatus according to claim 5, wherein the detecting that the TD-SCDMA service needs to be performed comprises:

It is detected that all available TD-SCDMA-based PLMNs need to be searched;