CN1688118A - Method for obtaining converting point position information by TDSCDMA repeater - Google Patents

Abstract

The invention relates to a method for obtaining the position information of a conversion point by a time division synchronous code division multiple access repeater station based on signal strength detection. The method includes the following steps: a. The repeater detects the intensity of the received downlink signal, and matches the detection result with the frame structure characteristics of TD-SCDMA, and obtains the position information of the first conversion point of the subframe; b. Verify the correctness of the position information of the first conversion point. If the position information of the first conversion point is correct, the repeater goes to step c, otherwise the repeater goes to step a; c. The repeater obtains the position information of the second conversion point by means of hypothesis verification. The invention has the characteristics of high reliability, simple and easy acquisition of position information of two switching points in the TD-SCDMA system.

Description

The Method of Obtaining the Position Information of Switching Point by Time Division Synchronous Code Division Multiple Access Repeater

Technical field

The invention relates to a method for a time-division synchronous code division multiple access TD-SCDMA repeater to obtain position information of a switching point.

Background technique

TD-SCDMA is one of the third-generation mobile communication air interface technical specifications officially released by the International Telecommunication Union ITU. Its key technologies include time-division duplex technology with adjustable uplink and downlink switching points, smart antenna technology, and joint detection technology. The advantages of TD-SCDMA are highlighted in the good balance between system anti-interference and system capacity, efficient support for mixed services, and the system itself has good sustainable development and technological evolution.

The multiple access scheme of TD-SCDMA belongs to DS-SCDMA, the chip rate is 1.28Mc/s, the spread spectrum bandwidth is about 1.6MHz, and it adopts the TDD working mode without matching frequency. Its downlink and uplink information are transmitted on different time slots of the same carrier frequency. The physical channel of TD-SCDMA adopts four-layer structure: system frame, wireless frame, subframe and time slot/code. Fig. 1 is the physical channel signal format of TD-SCDMA. Its frame structure divides the 10ms wireless frame into two 5ms subframes, and each subframe has 7 regular time slots and 3 special time slots. The three special time slots are downlink pilot time slot DwPTS, main guard time slot GP and uplink pilot time slot UpPTS. TS ₀ is always allocated to the downlink and TS ₁ is always allocated to the uplink in the 7 regular time slots. By flexibly configuring the number of uplink and downlink time slots, TD-SCDMA is suitable for uplink and downlink symmetric and asymmetric business modes. Uplink time slots and downlink time slots are separated by switching points. In the TD-SCDMA system, each 5ms subframe has two transition points: the first transition point is from the downlink to the uplink, and the position is GP between DwPTS and UpPTS; the second transition point It is from the uplink to the downlink, the position is between the last uplink time slot and the second downlink time slot in each subframe, and TS ₀ is the first downlink time slot. Wherein, the first conversion point is fixed with respect to the start time of each subframe; the second conversion point varies with the number of time slots allocated to uplink and downlink.

No matter what kind of wireless communication coverage area will produce weak signal areas and blind areas, and for some remote areas and blind areas with a small number of users, the cost of setting up base stations is too high, and the infrastructure is also relatively complicated. To provide a low-cost , The erection is simple, but it has the function of a small base station, and the economical and effective equipment---repeater is very necessary. Therefore, TD-SCDMA repeater plays an important role in TD-SCDMA network.

In the TD-SCDMA system, the uplink signal and the downlink signal are at the same frequency, and the uplink and downlink are distinguished by time division multiplexing. Therefore, the TD-SCDMA repeater needs to obtain the location information of two switching points to complete the uplink and downlink switching of radio frequency channels.

Existing methods for obtaining the position information of the first switching point include: a feature window search method and a downlink synchronization code correlation method. The basis of the feature window search method is: there is a guard interval of 48 chips before SYNC-DL, and a guard interval of 96 chips after SYNC-DL, and the power of the SYNC-DL signal is very large. Existing feature window search methods only search for SYNC-DL according to certain matching criteria. However, the existing feature window search method is prone to misjudgment due to interference from user terminals or adjacent base stations. The downlink synchronous code correlation method is not easily disturbed, but its technical complexity is high, and it is not easy for repeater manufacturers to realize it.

Someone proposed to realize the acquisition of the second switching point by broadcasting the position information of the second switching point in the broadcast channel of the TD-SCDMA system. This method has the following two problems: 1. Change the existing TD-SCDMA system protocol; 2. High technical complexity.

Contents of Invention

The object of the present invention is to overcome the defects or problems in the above-mentioned prior art, and provide a highly reliable and simple method for acquiring the position information of two switching points in the TD-SCDMA system.

The method comprises the steps of:

a. The repeater detects the intensity of the received downlink signal, matches the detection result with the frame structure characteristics of TD-SCDMA, and obtains the position information of the first conversion point of the subframe;

b. verify the correctness of the position information of the first conversion point, if the position information of the first conversion point is correct, the repeater goes to step c; otherwise, the repeater goes to step a;

c. The repeater acquires the position information of the second conversion point by means of hypothesis verification.

By analyzing the TD-SCDMA frame structure, it is found that it has obvious characteristics: TS ₀ and DwPTS are always assigned to the downlink, and the duration of DwPTS time slot transmission is different from other time slots. Therefore, matching the detected downlink received signal strength result with the TD-SCDMA frame structure feature can obtain the position information of the first transition point of the subframe.

In order to reduce the probability of false synchronization during the synchronous establishment process of the first transition point and improve the anti-interference ability after the synchronous establishment of the first transition point, the present invention adopts a synchronous protection algorithm. Synchronization protection algorithm is: the synchronization process is divided into two states - the capture state and the maintenance state; in the synchronization establishment process, only when the continuous multiple downlink received signal strength detection results match the TD-SCDMA frame structure characteristics, the direct playback The station changes from the capture state to the maintenance state; after the synchronization is established, the repeater changes from the maintenance state to the capture state only when the continuous downlink received signal strength detection results do not match the TD-SCDMA frame structure characteristics.

After the first conversion point of the subframe is established synchronously, the repeater adopts a hypothesis verification method to obtain the second conversion point. Suppose the verification method is as follows:

During the time slot TS _i , if the repeater first assumes that the time slot TS _i is an uplink time slot, the following operations and judgments are performed:

1. Turn on the uplink radio frequency link, close the downlink radio frequency link, and check the strength of the received uplink signal;

2. If it is detected that the received uplink signal strength is greater than the decision threshold, the time slot is considered to be an uplink time slot, and the time slot TS _i+1 to TS ₆ in this subframe and the time slot TS _i to TS in the next subframe will not be changed. Time slot TS ₆ assumes the state first, and ends the control and judgment of this time slot; otherwise, enter step 3;

3. Turn on the downlink radio frequency link, close the uplink radio frequency link, and check the strength of the received downlink signal;

4. If it is detected that the strength of the received downlink signal is greater than the decision threshold, the time slot is considered to be a downlink time slot, and time slot TS _i+1 to time slot TS ₆ in this subframe and time slot TS _i in the next subframe Slot TS ₆ is preferentially assumed to be a downlink time slot; otherwise, it cannot be determined whether the time slot is an uplink or downlink time slot, and the time slot TS _i+1 to TS ₆ in this subframe and the time slot TS _i in the next subframe will not be changed. To time slot TS ₆ priority assumes state.

During the time slot TS _i , if the repeater first assumes that the time slot TS _i is a downlink time slot, the following operations and judgments are performed:

I. Open the downlink radio frequency link, close the uplink radio frequency link, and check the strength of the received downlink signal;

II. If it is detected that the strength of the received downlink signal is greater than the decision threshold, then the time slot is considered to be a downlink time slot, and the priority assumption state of the time slot TS _i in the next subframe is not changed, and the control and judgment of the time slot are ended; otherwise, Go to step III;

III. Turn on the uplink radio frequency link, close the downlink radio frequency link, and perform strength detection on the received uplink signal;

IV. If it is detected that the received uplink signal strength is greater than the decision threshold, then it is considered that the time slot is an uplink time slot, and the time slot TS _i in the next subframe is preferentially assumed to be an uplink time slot; otherwise, it cannot be determined that the time slot is an uplink time slot. Whether the time slot is uplink or downlink, the priority assumption state of the time slot TS _i in the next subframe will not be changed.

Obtain the second conversion point of TD-SCDMA system through continuous hypothesis verification.

Description of drawings

Fig. 1 is the physical channel signal format of TD-SCDMA.

Figure 2 shows the time slot structure of DwPTS.

Figure 3 shows the time slot structure of the UpPTS.

Fig. 4 is a TD-SCDMA system conventional time slot burst structure.

Figure 5 is the output characteristic waveform of the downlink signal strength detector.

Fig. 6 is a flow chart of the present invention for the repeater to obtain the location information of the switching point.

Detailed ways

In order to make the solution of the present invention clearer, the present invention will be further described in detail below in conjunction with examples.

Fig. 1 is the physical channel signal format of TD-SCDMA. The physical channel of TD-SCDMA adopts a four-layer structure: system frame, radio frame, subframe and time slot/code. The frame structure divides a 10ms radio frame into two 5ms subframes, and each subframe has 7 conventional time slots. slot and 3 special time slots. The three special time slots are downlink pilot time slot DwPTS, main guard time slot GP and uplink pilot time slot UpPTS. TS ₀ is always allocated to the downlink and TS ₁ is always allocated to the uplink in the 7 regular time slots. By flexibly configuring the number of uplink and downlink time slots, TD-SCDMA is suitable for uplink and downlink symmetric and asymmetric business modes. Uplink time slots and downlink time slots are separated by switching points. In the TD-SCDMA system, each 5ms subframe has two transition points: the first transition point is from the downlink to the uplink, and the position is GP between DwPTS and UpPTS; the second transition point It is from the uplink to the downlink, the position is between the last uplink time slot and the second downlink time slot in each subframe, and TS ₀ is the first downlink time slot. Wherein, the first conversion point is fixed with respect to the start time of each subframe; the second conversion point varies with the number of time slots allocated to uplink and downlink.

Figure 2 is the time slot structure of DwPTS. DwPTS is designed for downlink pilot and synchronization, which consists of a 32-chip guard interval and a 64-chip downlink synchronization sequence SYNC-DL.

Fig. 3 is the time slot structure of UpPTS. UpPTS is designed for establishing uplink synchronization.

Figure 4 shows the TD-SCDMA system conventional time slot burst structure, which consists of two data blocks with a length of 352 chips, a midamble with a length of 144 chips and a guard interval with a length of 16 chips.

By analyzing the TD-SCDMA frame structure, it is found that there are obvious features: TS ₀ and DwPTS are always assigned to the downlink, and the duration of DwPTS time slot transmission is different from other time slots. When the downlink signal strength detector meets the following conditions: if the received signal strength is greater than the decision threshold, the detector outputs a high level, otherwise it outputs a low level, then the downlink signal strength detector will periodically output 5ms as shown in Figure 5 characteristic waveform. Therefore, the repeater can detect the strength of the received downlink signal and match the detection result with the frame structure characteristics of TD-SCDMA to obtain the first transition point of the subframe. In order to simplify the complexity of the repeater, in the actual feature matching process, the repeater can only match the output of the downlink signal strength detector with the 64-chip wide high pulse corresponding to the DwPTS.

The procedure for the TD-SCDMA repeater to obtain the position information of the switching point is as follows:

Step a The repeater detects the strength of the received downlink signal, and matches the detection result with the frame structure characteristics of TD-SCDMA. If the continuous multiple downlink received signal strength detection results match the TD-SCDMA frame structure characteristics, the repeater will enter the first conversion point synchronization maintenance state, and obtain the first conversion point position information, and then go to step b ; Otherwise, the repeater still performs the operation of step a.

Step b verifies the correctness of the first transformation point. If the position information of the first conversion point is correct, the repeater goes to step c; otherwise, the repeater goes to step a.

The correctness judgment method of the first conversion point is as follows:

If the repeater is in the synchronization maintenance state of the first conversion point, when the continuous multiple downlink received signal strength detection results do not match the TD-SCDMA frame structure characteristics, it is considered that the position information of the first conversion point is incorrect and goes to The first transition point is synchronously capturing state; otherwise, the position information of the first transition point is considered to be correct, and the first transition point is synchronously maintained in the maintaining state.

Step c Obtain the position information of the second conversion point by means of hypothesis verification.

Suppose the verification method is as follows:

During the time slot TS _i , if the repeater first assumes that the time slot TS _i is an uplink time slot, the following operations and judgments are performed:

1. Turn on the uplink radio frequency link, close the downlink radio frequency link, and check the strength of the received uplink signal;

2. If it is detected that the strength of the received uplink signal is greater than the decision threshold, the time slot is considered to be an uplink time slot, and the time slot TS _i+1 to TS ₆ in this subframe and the time slot TS _i to TS in the next subframe will not be changed. Time slot TS ₆ assumes the state first, and ends the control and judgment of this time slot; otherwise, enter step 3;

3. Turn on the downlink radio frequency link, close the uplink radio frequency link, and check the strength of the received downlink signal;

4. If it is detected that the strength of the received downlink signal is greater than the decision threshold, the time slot is considered to be a downlink time slot, and time slot TS _i+1 to time slot TS ₆ in this subframe and time slot TS _i in the next subframe Slot TS ₆ is preferentially assumed to be a downlink time slot; otherwise, it cannot be determined whether the time slot is an uplink or downlink time slot, and the time slot TS _i+1 to TS ₆ in this subframe and the time slot TS _i in the next subframe will not be changed. To time slot TS ₆ priority assumes state.

During the time slot TS _i , if the repeater first assumes that the time slot TS _i is a downlink time slot, the following operations and judgments are performed:

I. Open the downlink radio frequency link, close the uplink radio frequency link, and check the strength of the received downlink signal;

II. If it is detected that the strength of the received downlink signal is greater than the decision threshold, then the time slot is considered to be a downlink time slot, and the priority assumption state of the time slot TS _i in the next subframe is not changed, and the control and judgment of the time slot are ended; otherwise, Go to step III;

III. Turn on the uplink radio frequency link, close the downlink radio frequency link, and perform strength detection on the received uplink signal;

IV. If it is detected that the received uplink signal strength is greater than the decision threshold, then it is considered that the time slot is an uplink time slot, and the time slot TS _i in the next subframe is preferentially assumed to be an uplink time slot; otherwise, it cannot be determined that the time slot is an uplink time slot. Whether the time slot is uplink or downlink, the priority assumption state of the time slot TS _i in the next subframe will not be changed.

By continuously repeating step c, the repeater obtains the position information of the second conversion point of the TD-SCDMA system.

Claims (5)

1, a kind ofly obtains the method for two transfer points, it is characterized in that this method comprises the steps: based on repeater in the TDS-CDMA system of signal strength detection

Intensity detection is carried out to the downstream signal that receives in a, repeater, and the frame characteristics of testing result and TD SDMA TD-SCDMA is mated, and obtains first position of conversion point information of subframe;

B, verify the correctness of first position of conversion point information, if the positional information of first transfer point is correct, the repeater forwards step c to, otherwise the repeater forwards step a to;

C, repeater adopt the method for hypothesis verification to obtain second position of conversion point information.

2, method according to claim 1 is characterized in that: employing synchronous protection algorithm reduces first transfer point and sets up the false synchronous probability in the process synchronously and improve first transfer point foundation synchronously antijamming capability later on.

3, method according to claim 2 is characterized in that: the synchronous protection algorithm is: the process that first transfer point is synchronous is divided into two states---and catch attitude and keep attitude; Set up synchronously in the process at first transfer point, when having only continuous several times down receiving signal intensity detection result and TD SDMA TD-SCDMA frame characteristics coupling, the repeater just forwards to from synchronous seizure attitude and keeps attitude synchronously; After setting up synchronously, when having only continuous several times down receiving signal intensity detection result and TD-SCDMA frame characteristics not to match, the repeater just forwards synchronous seizure attitude to from keeping attitude synchronously.

4, method according to claim 1 is characterized in that: the repeater adopts the method for hypothesis verification to obtain second position of conversion point information.

5, method according to claim 4 is characterized in that: the method for hypothesis verification is as follows:

At time slot TS _iDuring this time, if time slot TS is preferentially supposed in the repeater _iBe ascending time slot, then carry out following operation and judgement:

(1) opens up radio frequency link, close the downlink radio frequency link, and the upward signal that receives is carried out intensity detection;

(2) if the uplink signal strength that detects reception greater than decision threshold, thinks that then this time slot is an ascending time slot, do not change book frame slot TS _I+1To time slot TS ₆And time slot TS in next subframe _iTo time slot TS ₆Preferential hypothesis state finishes the control and the judgement of this time slot; Otherwise, enter step 3;

(3) open the downlink radio frequency link, close up radio frequency link, and the downstream signal that receives is carried out intensity detection;

(4) if the downstream signal intensity that detects reception greater than decision threshold, thinks that then this time slot is a descending time slot, with book frame slot TS _I+1To time slot TS ₆And time slot TS in next subframe _iTo time slot TS ₆Preferentially be assumed to be descending time slot; Otherwise, can not determine that then this time slot is up or descending time slot, do not change book frame slot TS _I+1To time slot TS ₆And time slot TS in next subframe _iTo time slot TS ₆Preferential hypothesis state;

At time slot TS _iDuring this time, if time slot TS is preferentially supposed in the repeater _iBe descending time slot, then carry out following operation and judgement:

(I) open the downlink radio frequency link, close up radio frequency link, and the downstream signal that receives is carried out intensity detection;

(II) if the downstream signal intensity that detects reception greater than decision threshold, thinks that then this time slot is a descending time slot, do not change time slot TS in next subframe _iPreferential hypothesis state finishes the control and the judgement of this time slot; Otherwise, enter Step II I;

(III) open up radio frequency link, close the downlink radio frequency link, and the upward signal that receives is carried out intensity detection;

(IV) if the uplink signal strength that detects reception greater than decision threshold, thinks that then this time slot is an ascending time slot, with time slot TS in next subframe _iPreferentially be assumed to be ascending time slot; Otherwise, can not determine that then this time slot is up or descending time slot, do not change time slot TS in next subframe _iPreferential hypothesis state.

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