CN1794605A - Automatic gain control method of public channel - Google Patents

Abstract

This invention discloses a control method for automatic gain of public channels, when the SIR value at the public channel is greater or equals to a first threshold value, the RSSI value is computed and judged if it is greater or equals to a second threshold value, if so, said RSSI and a computed path loss value are used to compute the AGC gain value, if it is smaller than the second threshold value, then only the path loss value is used to compute the AGC gain value.

Description

Automatic gain control method of public channel

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 for automatic gain control (AGC) when subscriber terminal equipment carries out the common signal channel 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.

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.This iteration structure needs received signal to launch continuously, and AGC can reach desirable gain through convergence after a while like this.But the Common Control Channel in the TD-SCDMA system often has bursty nature 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.Have little time to restrain the receptivity of the system of influence probably owing to AGC.

Summary of the invention

In order to solve the above-mentioned problems in the prior art and defective, the invention provides a kind of automatic gain control method of public channel of the TD-SCDMA of being used for mobile communication system, so that system is carrying out can obtaining proper A GC yield value when common signal channel receives.

The objective of the invention is to be achieved through the following technical solutions:

A kind of automatic gain control method of public channel, it comprises the steps:

S1, judge this common signal channel sir value whether more than or equal to first threshold value, if, then carry out step S7, if not, then carry out step S2;

S2, calculating path loss value;

RSSI value on S3, the calculating common signal channel receiving slot;

S4, whether judge this RSSI value more than or equal to second threshold value, if, then carry out step S5, if not, then carry out step S6;

S5, utilize this RSSI value and this path loss values to calculate the AGC yield value that receive the common signal channel receiving slot next time;

S6, utilize this path loss values to receive the AGC yield value of common signal channel receiving slot next time;

S7, utilize the iterative algorithm of AGC to calculate, with result of calculation as the AGC yield value that receives next time on the common signal channel time slot.

Among the step S5, utilize following method to calculate the AGC yield value that receive the common signal channel receiving slot next time:

P _e＝RSSI+N _code(L _i-1-L _i+P _rscp)

Wherein, P _eBe the received power on the common signal channel receiving slot of estimating, L _iBe the path loss that current time calculates, L _I-1Path loss values when receiving the common signal channel time slot for the last time, P _RscpBe the code channel power on the last time reception common signal channel time slot, N _CodeBe the common signal channel code channel number.

Described P _RscpInitial value set by following method:

P _{rscp_init}＝P _{PCCPCH_RSCP}-Δ

P in the formula _{PCCPCH RSCP}Be the PCCPCH-RSCP value, Δ is the side-play amount of PCCPCH-RSCP value and common signal channel code channel power.

Among the step S6, utilize following method to calculate the AGC yield value that receive the common signal channel receiving slot next time:

P _e＝N _code(L _i-1-L _i+P _rscp)

Wherein, P _eBe the received power on the common signal channel receiving slot of estimating, L _iBe the path loss that current time calculates, L _I-1Path loss values when receiving the common signal channel time slot for the last time, P _RscpBe the code channel power on the last time reception common signal channel time slot, N _CodeBe the common signal channel code channel number.

Described second threshold value is set according to following method:

RSSI _T＝RSSI _TS0-ΔR _SSI

In the formula, RSSI _TPromptly be this second threshold value, RSSI _TS0Be the RSSI value on the current subframe time slot 0, Δ _RSSIIt is the side-play amount of RSSI value on time slot 0 and the common signal channel receiving slot.

Among the step S7, calculate earlier and receive common signal channel code channel performance number, utilize following method to obtain:

P _rscp＝P _{rscp_meas}

In the formula, P _{Rscp_meas}It is the measured value of common signal channel code channel power.

The initial value of this path loss values is set to a minus number.

Positive progressive effect of the present invention is: this method has reduced the probability that causes system's reception mission failure when adopting AGC iterative algorithm receiving common control channels owing to the deviation of AGC yield value largely, and the system that makes is carrying out can obtaining proper A GC yield value when common signal channel receives.

Description of drawings

Fig. 1 is the process schematic diagram of one embodiment of the invention.

Embodiment

Provide preferred embodiment of the present invention below in conjunction with accompanying drawing, to describe technical scheme of the present invention in detail.

As shown in Figure 1, a kind of automatic gain control method of public channel is at first judged the common signal channel (step 100) that will receive, and as PICH, whether PCH and FACH etc. are on time slot 0.Because there is signal to exist on the time slot 0 always, as broadcast BCH, so the gain of the AGC on the time slot 0 AGC yield value that can adopt the iterative algorithm of AGC to calculate, can finish.

If the common signal channel that receives then calculates the signal to noise ratio on this receptions common signal channel not on time slot 0, i.e. sir value (step 110), this sir value has reflected whether the corresponding code channel of common signal channel has the signal transmission on this time slot.

Whether we judge whether iterative algorithm result of calculation (step 120) with AGC more than or equal to a preset first threshold by sir value.

If the SIR that calculates, illustrates then that the corresponding code channel of common signal channel has signal to send on this receiving slot more than or equal to first threshold value, adopt the iterative algorithm result of calculation of AGC as the AGC yield value (step 140) that receives next time on the common signal channel time slot this moment.

Before the calculating, obtain and receive common signal channel code channel performance number (step 130), can utilize following method to obtain:

P _rscp＝P _{rscp_meas}

In the formula, P _{Rscp_meas}It is the measured value of common signal channel code channel power.

If the sir value that calculates is less than threshold value, think that then corresponding code channel does not send signal on the common signal channel receiving slot, then calculate path loss values (step 150) and the received signal strength indicator value on corresponding this time slot, i.e. the RSSI value (step 160) of this moment.

Judge that whether the RSSI value is more than or equal to second threshold value (step 170).

Send signal (step 180) if the RSSI value that calculates more than or equal to second threshold value, then illustrates to exist on other code channel on this receiving slot, the method for calculating the AGC gain that receives the common signal channel receiving slot next time this moment is:

P _e＝RSSI+N _code(L _i-1-L _i+P _rscp)

In the formula

P _eBe the received power on the common signal channel receiving slot of estimating;

L _iThe path loss that calculates for current time;

L _I-1Path loss when receiving the common signal channel time slot for the last time;

P _RscpBe the code channel power on the last time reception common signal channel time slot;

N _CodeBe the common signal channel code channel number;

About P _RscpSetting, its initial value P _{Rscp_init}Be set to the PCCPCH-RSCP value, promptly

P _{rscp_init}＝P _{PCCPCH_RSCP}-Δ

P in the formula _{PCCPCH_RSCP}Be PCCPCH-RSCP (Primary Common Control PhysicalChannel Received Signal Code Power, Primary Common Control Physical Channel receive channel sign indicating number power) value, Δ is the side-play amount of PCCPCH-RSCP value and common signal channel code channel power.

About path loss initial value L _InitSetting, with L _InitBe set to any one minus number, work as L _I-1＜0 o'clock, L _I-1=L _i

Do not send signal (step 190) if the RSSI value that calculates less than threshold value, is then thought on this receiving slot, the method for calculating the AGC gain that receives the common signal channel receiving slot next time this moment is:

P _e＝N _code(L _i-1-L _i+P _rscp)

About RSSI threshold value RSSI _TSetting:

RSSI _T＝RSSI _TS0-Δ _RSSI

In the formula

RSSI _{TS0 is}RSSI value on the current subframe time slot 0;

Δ _RSSIIt is the side-play amount of RSSI value on time slot 0 and the common signal channel receiving slot;

At last, upgrade receiving common signal channel code channel power storage value and path loss storing value, be used for calculating next time.

The method of above-mentioned calculating sir value, path loss values and RSSI value is a prior art.Described AGC iterative algorithm also is a prior art.

Claims (7)

1, a kind of automatic gain control method of public channel is characterized in that, this method comprises the steps:

S1, judge this common signal channel sir value whether more than or equal to first threshold value, if, then carry out step S7, if not, then carry out step S2;

S2, calculating path loss value;

RSSI value on S3, the calculating common signal channel receiving slot;

S4, whether judge this RSSI value more than or equal to second threshold value, if, then carry out step S5, if not, then carry out step S6;

S5, utilize this RSSI value and this path loss values to calculate the AGC yield value that receive the common signal channel receiving slot next time;

S6, utilize this path loss values to receive the AGC yield value of common signal channel receiving slot next time;

S7, utilize the iterative algorithm of AGC to calculate, with result of calculation as the AGC yield value that receives next time on the common signal channel time slot.

2, automatic gain control method of public channel according to claim 1 is characterized in that, among the step S5, utilizes following method to calculate the AGC yield value that receive the common signal channel receiving slot next time:

P _e＝RSSI+N _code(L _i-1-L _i+P _rscp)

Wherein, P _eBe the received power on the common signal channel receiving slot of estimating, L _iBe the path loss that current time calculates, L _I-1Path loss values when receiving the common signal channel time slot for the last time, P _RscpBe the code channel power on the last time reception common signal channel time slot, N _CodeBe the common signal channel code channel number.

3, automatic gain control method of public channel according to claim 2 is characterized in that, described P _RscpInitial value set by following method:

P _{rscp_init}＝P _{PCCPCH_RSCP}-Δ

P in the formula _{PCCPCH_RSCP}Be the PCCPCH-RSCP value, Δ is the side-play amount of PCCPCH-RSCP value and common signal channel code channel power.

4, automatic gain control method of public channel according to claim 3 is characterized in that, among the step S6, utilizes following method to calculate the AGC yield value that receive the common signal channel receiving slot next time:

P _e＝N _code(L _i-1-L _i+P _rscp)

Wherein, P _eBe the received power on the common signal channel receiving slot of estimating, L _iBe the path loss that current time calculates, L _I-1Path loss values when receiving the common signal channel time slot for the last time, P _RscpBe the code channel power on the last time reception common signal channel time slot, N _CodeBe the common signal channel code channel number.

5, automatic gain control method of public channel according to claim 4 is characterized in that, described second threshold value is set according to following method:

RSSI _T＝RSSI _TS0-Δ _RSSI

In the formula, RSSI _TPromptly be this second threshold value, RSSI _TS0Be the RSSI value on the current subframe time slot 0, Δ _RSSIIt is the side-play amount of RSSI value on time slot 0 and the common signal channel receiving slot.

6, automatic gain control method of public channel according to claim 5 is characterized in that, among the step S7, calculates earlier and receives common signal channel code channel performance number, utilizes following method to obtain:

P _rscp＝P _{rscp_meas}

In the formula, P _{Rscp_meas}It is the measured value of common signal channel code channel power.

7, automatic gain control method of public channel according to claim 6 is characterized in that, the initial value of this path loss values is set to a minus number.

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