CN1719751A - Burst receiving automatic gain controlling method for time division duplex mobile communication system - Google Patents

Abstract

This invention is aimed to provide an automatic gain control (AGC) method and a device for UE in TD-SCDMA mobile communication system, which tests a time slot signal energy of the burst, when the energy is lower than a certain threshold, it is considered that no signal exists in said time slot, the AGC iterative process is stopped and a certain rule is applied to process it, which can keep the gain of AGC in a reasonable sphere and increase the successive rate of burst receiving when the UE carries out burst receiving. This invention also provides a method for regulating gains of burst receiving by the gain difference controlled by the DWPTS automatically to increase the accuracy of the AGC.

Description

Burst receives the method for automatic gain controlling in the time division duplex mobile communication system

Technical field

The present invention relates to a kind of wireless communication system of being applied to, be particularly related to a kind of TD SDMA (Time Division Synchronous Code-Division Multiple Access that is applied to, abbreviation TD-SCDMA) in the mobile communication system, the method and apparatus of automatic gain control (AGC) when subscriber terminal equipment happens suddenly reception.

Background technology

In mobile communication system,, must guarantee the precision of input signal for the reception that can obtain.But because receiving system is in the process that constantly moves, channel situation will constantly change, the influence that the signal amplitude of input A/D is declined changes more violent, therefore need before A/D, increase automatic gain control equipment, thereby the amplitude almost fixed of analog signal that guarantees to be input to A/D is near certain numerical value.

As shown in Figure 1, be the frame structure schematic diagram of TD-SCDMA system.This structure is according to low spreading rate time division duplex (LCR-TDD) pattern (1.28Mcps) among 3G collaborative project (3GPP) the standard TS 25.221 (Release 4), perhaps provides among China Wireless Telecommunication Standar (CWTS) the standard TSM 05.02 (Release 3).The spreading rate of TD-SCDMA system is 1.28Mcps, each radio frames (Radio Frame) 10 ₀, 10 ₁Length be 5ms, i.e. 6400 chips (for 3GPP LCR-TDD system, each radio frames length is 10ms, and the subframe (subframe) that can be divided into two length be 5ms, and wherein each subframe comprises 6400 chips).Wherein, the radio frames in each TD-SCDMA system (the perhaps subframe in the LCR system) 10 ₀, 10 ₁(TS0～TS6) 11 can be divided into 7 time slots again ₀-11 ₆, and two pilot time slots: descending pilot frequency time slot (DwPTS) 12 and uplink pilot time slot (UpPTS) 14, and protection interval (Guard) 13.Further, the TS0 time slot 11 ₀Be used to bearing system broadcast channel and other possible downlink traffic channel; And TS1～TS6 time slot 11 ₁-11 ₆Then be used to carry the uplink and downlink Traffic Channel.It is synchronous that uplink pilot time slot (UpPTS) 14 and descending pilot frequency time slot (DwPTS) time slot 12 are used to set up initial uplink and downlink respectively.TS0～TS6 time slot 11 ₀-11 ₆Length is 0.675ms or 864 chips, wherein comprises data segment DATA1 (17) and DATA2 (19) that two segment lengths are 352 chips, and a middle segment length is the training sequence of 144 chips---in lead sign indicating number (Midamble) sequence 18.The Midamble sequence is significant at TD-SCDMA, comprise cell ID, channel estimating and synchronously modules such as (comprising Frequency Synchronization) all to use it.The protection that DwPTS time slot 12 comprises 32 chips at interval 20 and one long be descending synchronous code (SYNC-DL) code word 15 of 64 chips, its effect is cell ID and sets up initial synchronisation; And the UpPTS time slot comprise one long be uplink synchronous code (SYNC-UL) code word 16 of 128 chips, subscriber terminal equipment utilizes it to carry out relevant up access procedure.

Because the system frame structure of TD-SCDMA is the time-division, therefore for each descending time slot, automatic gain control equipment (AGC) needs the current signal energy of statistics as the foundation to this time slot signal gain controlling of next subframe.In order to make the gain controlling of AGC more accurate, often adopt iterative algorithm that the gain of AGC is upgraded.Fig. 2 has provided AGC iteration structure commonly used at present, and as can be seen from the figure, the AGC yield value of controlling certain time slot reception of current subframe can be expressed from the next:

G(n)＝G(n-τ)+K×ε(n-τ)

In the formula, G (n) represents the AGC yield value of certain descending time slot of n frame, the AGC yield value of this descending time slot of G (n-τ) expression n-τ frame.Weighted factor when K represents iteration.ε (n-τ) represents the poor of n-τ certain descending time slot energy of frame and reference energy.

This iteration structure needs received signal to launch continuously, and AGC can reach desirable gain through convergence after a while like this.But in the system of TD-SCDMA, there is the channel of some bursty nature, such as FPACH, PICH, PCH and FACH or the like.The characteristics of these channels are that shared number of sub frames (sub-frame) is discontinuous, and the number of sub frames that may continue is very limited, and for example FPACH is each only uploads defeated a subframe.This specific character brings certain degree of difficulty for the control of AGC.Probably owing to AGC has little time to restrain the reception mission failure that causes system.Fig. 3 has provided the example that takes defeat owing to the improper Burst Channel that causes of AGC gain controlling.In this example, Burst Channel is mapped on the time slot 4 of N frame (TS4), and from the N-1 frame to the N+K-1 frame, all do not have signal on this time slot.If in the N+K-1 frame, adopt the AGC iterative algorithm of Fig. 2 that the yield value of TS4 is controlled at the N-1 frame, can cause yield value to increase gradually.The yield value that when the N+K frame carries out the Burst Channel Data Receiving, need adopt the N+K-1 frame to produce, and the yield value of this moment is quite big, adopts this yield value to receive and probably can cause bursty data to overflow, and makes to receive mission failure.Therefore when the AGC control of handling Burst Channel, must carry out particular processing, to prevent since improper the causing of control of AGC take defeat.

Summary of the invention

The invention provides a kind of auto gain control method and device of the TD-SCDMA of being used for mobile communication system, the assurance system still can obtain suitable yield value when carrying out the reception of Burst Channel.To prevent since improper the causing of control of AGC take defeat.

Scheme of the present invention is that to received signal energy (RSSI) is added up, when the energy of system's received signal is lower than certain thresholding, promptly think and do not comprise the signal that needs receive in this subframe, to cause the yield value of AGC to produce bigger error if carry out the AGC iteration this moment, will cause probably when receiving to take defeat next time with this gain controlling.In this case, the iterative process of AGC is stopped, and adopt specific criterion to handle, the assurance system can correctly receive.

The present invention adopts different schemes according to the different conditions that Burst Channel receives: the first adopts the AGC yield value of the AGC yield value of pilot signal as the reception of control Burst Channel at the situation that receives for the first time Burst Channel; Another kind is Burst Channel or the preceding Burst Channel that once takes defeat and need receive again that receives at periodicity, and the gain of Burst Channel place time slot adds the AGC gain that poor this Burst Channel of conduct control of the AGC gain of pilot channel when the AGC of current subframe pilot channel gains with last the reception receives in the time of can adopting last the reception.

The present invention mainly comprises following steps:

Step 1 is added up the energy (RSSI) of the received signal of current subframe Burst Channel place time slot; The computing formula of concrete TS#n signal energy is as follows:

$r\left(n\right)=\underset{l=0}{\overset{L-1}{\mathrm{\Σ}}}{\left\{I(n,l)\right\}}^2+\underset{l=0}{\overset{L-1}{\mathrm{\Σ}}}{\left\{Q(n,l)\right\}}^2$

In the formula, the signal energy that receives data I, Q two-way is added up, accumulation length L is the number of chips that this time slot comprised;

Step 2 compares received signal energy and certain predefined thresholding (RSSI_Target), when the received signal energy is higher than thresholding, jumps to step 4, otherwise jumps to step 3;

Determining of this thresholding can be reference data with the RSSI on the TS0 that comprises beacon channel (Beacon Channel), deducts the deviant of 3～6dB:

Thre＝r(0)-offset

In the formula, r (0) is the RSSI of TS0, and the offset value is about 3～6dB;

Step 3 according to the difference of the accepting state of Burst Channel, is carried out the renewal of AGC gain, and is jumped to step 5;

Step 4 according to the signal energy of current subframe, adopts iterative algorithm to upgrade the yield value of AGC;

Step 5, the AGC gain that produces according to step 3 or step 4 receives the Burst Channel data of next subframe.

Adopt method of the present invention, can occur under the situation of Burst Channel, guarantee that the yield value of AGC is in the comparison reasonable range, avoid owing to AGC has little time to restrain the reception mission failure that causes system.

Description of drawings

Fig. 1 is a TD-SCDMA system frame structure schematic diagram.

Fig. 2 is AGC iteration structure figure commonly used.

Fig. 3 is because the improper example that causes Burst Channel to take defeat of AGC gain controlling.

Fig. 4 is for after adopting the solution of the present invention, and Burst Channel is subjected to the example of appropriate AGC control.

Fig. 5 receives the state transition diagram that carries out automatic gain control for the present invention to Burst Channel.

Fig. 6 calculates the state transition diagram of AGC gain down for Burst Channel receives different conditions.

Embodiment

Below in conjunction with Fig. 4 a specific embodiment of the present invention is described, so that further understand of the present invention

Summary of the invention.

As shown in Figure 4: Burst Channel is mapped on the TS4 of N frame and N+K frame, and the signal energy (RSSI) on other frames TS4 is all less than RSSI_Target.When the N frame will receive Burst Channel for the first time, because the signal energy on the N-1 frame TS4 is less than threshold value (RSSI_Target), this moment was with the yield value LastGain of N-1 frame downlink pilot frequency channel _DwPtsAs the AGC yield value CurGain on the TS4 _TS4Burst Channel data to the N frame receive.Therefore signal energy on the N frame TS adopts iteration structure shown in Figure 2 to produce new AGC yield value LastGain greater than thresholding _TS4The signal energy of N+1 frame to the N+K-2 frame TS4 be all less than RSSI_Target, and next frame do not need to receive Burst Channel, therefore keeps the AGC yield value on the TS4 constant.At the N+K-1 frame, because next subframe need receive Burst Channel, downlink pilot frequency channel AGC yield value and current subframe (N+K-1 frame) downlink pilot frequency channel AGC yield value was poor when we at first calculated last Burst Channel reception (N-1 frame):

ΔGain＝CurGain _DwPts-LastGain _DwPts

AGC yield value when receiving with last Burst Channel then adds the AGC yield value that this difference receives as next subframe Burst Channel of control:

CurGain _TS4＝LastGain _TS4+ΔGain

By this new AGC gain calculating algorithm, the gain stabilization that can keep AGC in less than the subframe of thresholding in signal energy, avoid the mistuning of AGC yield value, can not cross yield value low but AGC and increase gradually, receive the Burst Channel data failure thereby cause because of signal energy.

Fig. 5 is that the present invention receives the state transition diagram that carries out automatic gain control to Burst Channel, and the present invention mainly comprises the steps:

Step 1 is added up the energy (RSSI) of the received signal of current subframe Burst Channel place time slot; The computing formula of concrete TS#n signal energy is as follows:

$r\left(n\right)=\underset{l=0}{\overset{L-1}{\mathrm{\Σ}}}{\left\{I(n,l)\right\}}^2+\underset{l=0}{\overset{L-1}{\mathrm{\Σ}}}{\left\{Q(n,l)\right\}}^2$

In the formula, the signal energy that receives data I, Q two-way is added up, accumulation length L is the number of chips that this time slot comprised;

Step 2 compares received signal energy and certain predefined thresholding (RSSI_Target), when the received signal energy is higher than thresholding, jumps to step 4, otherwise jumps to step 3;

Determining of this thresholding can be reference data with the RSSI on the TS0 that comprises beacon channel (Beacon Channel), deducts the deviant of 3～6dB:

Thre＝r(0)-offset

In the formula, r (0) is the RSSI of TS0, and the deviant value is about 3～6dB;

Step 3 according to the difference of the accepting state of Burst Channel, is carried out the renewal of AGC gain, and is jumped to step 5;

Step 4 according to the signal energy of current subframe, adopts iterative algorithm to upgrade the yield value of AGC;

Step 5, the AGC gain that produces according to step 3 or step 4 receives the Burst Channel data of next subframe.

Shown in figure six, described step 3 also comprises the steps:

Step 3.1 judges whether it is to carry out the reception of Burst Channel for the first time, if jump to step 3.2, otherwise jumps to step 3.3;

Step 3.2 adopts the AGC gain of this frame pilot channel to gain as the AGC that next subframe receives Burst Channel, jumps to step 3.4;

Step 3.3, the gain of Burst Channel place time slot adds the AGC gain that poor this Burst Channel of conduct control of the AGC gain of pilot channel when the AGC of current subframe pilot channel gains with last the reception receives when adopting last the reception;

Step 3.4, according to step 3.2 or step 3.3 produce the AGC gain receive the Burst Channel data of next subframe.

In the step 4, according to the signal energy of current subframe, generation is poor with reference energy, adopts iterative algorithm to upgrade the yield value of AGC then, and this iterative algorithm is characterized by with formula:

G(n)＝G(n-1)+K×ε(n-1)

In the formula, G (n) represents the AGC yield value of next subframe Burst Channel place time slot, the AGC yield value of current this descending time slot of subframe of G (n-1) expression.Weighted factor when K represents iteration.ε (n-1) represents the poor of this descending time slot energy of current subframe and reference energy.

Step 3.3 comprises following steps:

3.3.1 downlink pilot frequency channel AGC yield value and current subframe N+K-1 frame downlink pilot frequency channel AGC yield value is poor when calculating last Burst Channel and receiving the N-1 frame:

ΔGain＝CurGain _DwPts-LastGain _DwPts；

3.3.2 the AGC yield value when receiving with last Burst Channel adds the AGC yield value that this difference receives as next subframe Burst Channel of control:

CurGain _TS4＝LastGain _TS4+ΔGain。

Adopt method of the present invention, can occur under the situation of Burst Channel, guarantee that the yield value of AGC is in the comparison reasonable range, avoid owing to AGC has little time to restrain the reception mission failure that causes system.

Claims (5)

1. burst receives the method for automatic gain controlling in the time division duplex mobile communication system, and it comprises following steps:

Step 1 is added up the energy of the received signal of current subframe Burst Channel place time slot; The computing formula of concrete TS#n signal energy is as follows:

$r\left(n\right)=\underset{l=0}{\overset{L-1}{\mathrm{\Σ}}}{\left\{I(n,l)\right\}}^2+\underset{l=0}{\overset{L-1}{\mathrm{\Σ}}}{\left\{Q(n.l)\right\}}^2,$

In the formula, the signal energy that receives data I, Q two-way is added up, accumulation length L is the number of chips that this time slot comprised;

Step 2 compares received signal energy and certain predefined thresholding, when the received signal energy is higher than thresholding, jumps to step 4, otherwise jumps to step 3;

Step 3 according to the difference of the accepting state of Burst Channel, is carried out the renewal of AGC gain, and is jumped to step 5;

Step 4 according to the signal energy of current subframe, adopts iterative algorithm to upgrade the yield value of AGC;

Step 5, the AGC gain that produces according to step 3 or step 4 receives the Burst Channel data of next subframe.

2. burst receives the method for automatic gain controlling in the time division duplex mobile communication system as claimed in claim 1, it is characterized in that, in the step 2, determining of described predefined thresholding can be reference data with the RSSI on the TS0 that comprises beacon channel, deducts the deviant of 3～6dB:

Thre＝r(0)-offset

In the formula, r (0) is the signal energy of TS0, and deviant offset value is about 3～6dB.

3. burst receives the method for automatic gain controlling in the time division duplex mobile communication system as claimed in claim 1 or 2, it is characterized in that described step 3 also comprises the steps:

Step 3.1 judges whether it is to carry out the reception of Burst Channel for the first time, if jump to step 3.2, otherwise jumps to step 3.3;

Step 3.2 adopts the AGC gain of this frame pilot channel to gain as the AGC that next subframe receives Burst Channel, jumps to step 3.4;

Step 3.3, the gain of Burst Channel place time slot adds the AGC gain that poor this Burst Channel of conduct control of the AGC gain of pilot channel when the AGC of current subframe pilot channel gains with last the reception receives when adopting last the reception;

Step 3.4, according to step 3.2 or step 3.3 produce the AGC gain receive the Burst Channel data of next subframe.

4. burst receives the method for automatic gain controlling in the time division duplex mobile communication system as claimed in claim 3, it is characterized in that, in the step 4, according to the signal energy of current subframe, adopt iterative algorithm to upgrade the yield value of AGC, this iterative algorithm is characterized by with formula:

G(n)＝G(n-τ)+K×ε(n-τ)，

In the formula, G (n) represents the AGC yield value of next subframe Burst Channel place time slot, the AGC yield value of current this descending time slot of subframe of G (n-1) expression, the weighted factor when K represents iteration, ε (n-1) represents the poor of this descending time slot energy of current subframe and reference energy.

5. burst receives the method for automatic gain controlling in the time division duplex mobile communication system as claimed in claim 4, it is characterized in that step 3.3 comprises following steps:

3.3.1 downlink pilot frequency channel AGC yield value and current subframe N+K-1 frame downlink pilot frequency channel AGC yield value is poor when calculating last Burst Channel and receiving the N-1 frame:

ΔGain＝CurGain _DwPts-LastGain _DwPts；

3.3.2 the AGC yield value when receiving with last Burst Channel adds the AGC yield value that this difference receives as next subframe Burst Channel of control:

CurGain _TS4＝LastGain _TS4+ΔGain。

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