CN1466298A - Self-adaptive power control method - Google Patents

Abstract

An adaptive power control method controlling orders according to an emitting power demodulated from receiving signals by the demodulated module in the receiver or controlling the order bit according to the emitting power generated from a compared result between internal ring power control signal-to-interference ratio measurement value and outside ring power control signal-to-interference target value to be sent to the emitting power module and power control step generating module (2) computing coherent coefficient A(m) of emitting power control order at the step length k(m) based on A(m)(3) inputting the said k(m) into the emitting power control module to adjust the emitting power automatically to emit the modulated signal via the emitter.

Description

A kind of method of adaptive power control

Technical field:

The present invention relates to the spread spectrum communication field, be meant a kind of method that is used for the adaptive power control of mobile communication system especially.

Background technology:

Power control is mobile communication system, especially requisite a kind of critical function in the cdma system.The inner loop power control module that it comprises, by the signal interference ratio (hereinafter to be referred as SIR) that measures received signal, the sir target value of setting according to certain QoS in controlling with exterior ring power then compares, when the measured SIR value is lower than the sir target value, produce the power control command of " rising ", when the measured SIR value is higher than the sir target value, produce the power control command of " decline ".Travelling carriage (in the uplink power control) or base station (in the downlink power control) can carry out the adjustment of transmitting power by emissive power control command (hereinafter to be referred as the TPC) bit that receives with certain step-length.The selection of general power control step-length is some values of fixing.When this step-length can change, the power control process just can be adjusted according to the dynamic change situation of mobile channel.In patent EP1102416, the inventor has proposed to carry out the scheme that the power control step-length is selected at travelling carriage, and the statistical property of the signal that this scheme receives according to travelling carriage obtains the fluctuating range and the fluctuation speed of received signal, selects the step-length of power control thus.When the fluctuating range of received signal and fluctuation speed were big, this showed that channel variation is very fast, so the power control step-length is got bigger value; Otherwise, when the fluctuating range of received signal and fluctuation speed hour, show that then this moment channel variation is slower, so the power control step-length is selected less value.Like this, by the power control step-length selector of travelling carriage self, can dynamically select the power control step-length, thereby improve the performance of uplink power control according to channel situation.

Yet, method in the above-mentioned patent is only applicable to the received signal of continuous time, and can't use in the system of discontinuity received signal, because for the signal of discontinuity, according to method in the above-mentioned patent and thought, be difficult to the information of extract effective fluctuating range or fluctuation speed.For example in 3-G (Generation Three mobile communication system) TD-SCDMA (time-division-S-CDMA, Time-Duplex Synchronous Code Division Multiple Access), just belong to this kind situation.In the TD-SCDMA system, each radio frames is divided into two subframes, and each subframe is made up of a plurality of time slots.The general one or more upstream or downstream time slots of each CU, different user is distinguished by different spreading codes in each time slot.Therefore, no matter be base station or travelling carriage, all can't receive continuous signal of time, and can only be the signal fragment of a time slot of a time slot, be interrupted in time.

On the other hand, the power control step-length in the above-mentioned patent is selected technology, also is not optimum.Inner-loop power control generally carries out based on sir measurement, and what really the power control performance is worked is SIR information or its derived information, rather than the statistical nature of simple received signal.

Summary of the invention:

The technical problem to be solved in the present invention, overcome above-mentioned the deficiencies in the prior art exactly, mobility communication system in particular for discontinuity provides a kind of method that can select the adaptive power of power control step-length to control according to channel circumstance adaptively, thereby improves the performance of power control under various channel circumstances.

Technical solution of the present invention is as follows:

A kind of adaptive power control method that is used for mobile communication system is carried out by modules such as receiver, the generation of power control step-length, transmitting power control, transmitters, it is characterized in that this method comprises the following steps:

1. according to the demodulation module in the receiver receiving signal demodulation from reception antenna is obtained restituted signal, obtain the emissive power control command bit after the demodulation simultaneously, or, be sent to transmit power control module and power control step-length generation module simultaneously according to the emissive power control command bit that the comparative result of inner-loop power control signal-to-interference ratio measurement value and external circule power control signal interference ratio desired value obtains;

2. in power control step-length generation module, calculate the relative coefficient A (m) of emissive power control command, select power control step-length K (m) according to this relative coefficient A (m);

3. this power control step-length K (m) is input to transmit power control module, this module is automatically adjusted transmitting power according to emissive power control command and power control step-length K (m), and modulation signal is gone out through the transmission antennas transmit of transmitter.

M interior relative coefficient A (m) of power control cycle of said emissive power control command calculated by following formula: $A\left(m\right)=1/N\underset{i=m}{\overset{m-N+1}{\mathrm{\Σ}}}\mathrm{TPC}\left(i\right)*\mathrm{TPC}(i-1)$

In the formula:

1. N, m are positive integer;

2. N is the associated window size, i.e. the power control periodicity;

3. the span of A (m) is-1＜A (m)＜1;

4. emissive power control command value (bit) in TPC (i)-i cycle.

The selected step of said power control step-length K (m) is as follows:

1. with A (m) and the parameter P that sets ₀, P ₁, P ₂P _s[1＜P ₀＜P ₁＜P ₂P _s＜1] compare,

2. as-1＜=A (m)＜P ₀Selected power control step-length K (m)=0dB

P ₀＜＝A(m)＜P ₁?????????K(m)＝I ₁dB

P ₁＜＝A(m)＜P ₂?????????K(m)＝I ₂dB

……????……???????????????????????????????……????……

P _s＝A(m)＜＝1???????????K(m)＝I _sdB

I wherein ₁＜I ₂＜I ₃＜...＜I _s

When S=1, the selected step of then said power control step-length Km is as follows:

1. with A (m) and the parameter P that sets ₀, P ₁[1＜P ₀＜P ₁＜1] compares;

2. as-1＜=A (m)＜p ₀Selected power control step-length K (m)=1dB

P ₀＜＝A(m)＜P ₁?????????K(m)＝2dB

P ₁＜＝A(m)＜+1??????????K(m)＝3dB

The variable step power control scheme that the present invention proposes has been utilized TPC order relevant information in time, and this relevant information has reflected situations such as the rate of fading of interior propagation channel, the degree of depth for the previous period, is the power control thinking of channel self-adapting therefore.Utilize TPC order, computing increases considerably less, realizes simply, but can make power control have adaptability to channel condition, more can improve the power control performance under various channel circumstances effectively.

Description of drawings:

Fig. 1 is the basic structure schematic diagram of adaptive power control method of the present invention in the inner inner-loop power control process of travelling carriage.

Embodiment:

Be example with 3G (Third Generation) Moblie standard TD-SCDMA system below, illustrate how the present invention implements.Therefore because power control step-length generation modular structure is very simple, can be placed on travelling carriage or the base station either party can.Below we are that example illustrates in travelling carriage inside with the generation module of power control step-length.

Fig. 1 is the basic structure schematic diagram of the present invention in the inner inner-loop power control process of travelling carriage.In travelling carriage inside, comprise modules such as receiver, the generation of power control step-length, transmitting power control, transmitter.

Demodulation module in the receiver carries out demodulation to the received signal of reception antenna, obtains restituted signal, and (value is-1 or 1 to obtain TPC Command field bit after the demodulation simultaneously.Here illustrate that if the TPC Command field bit is not-1 or 1, then the TPC Command field bit that rises is made as " 1 ", the TPC Command field bit of decline is made as " 1 ");

Demodulation TPC Command field bit is sent to transmit power control module and power control step-length generation module simultaneously, power control step-length generation module comprises calculates TPC coefficient correlation and power control step-length selection two parts, what export is power control step-length selection result, and this step-length result is sent to transmit power control module simultaneously.If power control step-length generation module is positioned at the base station, then this step-length information must be launched by down channel as signaling).A typical calculation method of TPC coefficient correlation is: the employed associated window size of at first determining to carry out related calculation, in for example desirable N=1000 the power control cycle, comprising N TPC order in the period in this cycle at nearest N * T (T is the power control cycle, is generally 5ms in the TD-SCDMA system), if it is TPC (i), TPC (i-1) ..., TPC (i-N+1), value { 1,1}, i are current power control cyclical indicator, and hypothesis TPC (m)=0 when m＜0.The coefficient correlation in then current power control cycle can obtain according to following formula: $A\left(m\right)=1/N\underset{i=m}{\overset{m-N+1}{\mathrm{\Σ}}}\mathrm{TPC}\left(i\right)*\mathrm{TPC}(i-1)......\left(1\right)$

Certainly, the concrete method of calculating coefficient correlation A, can not exclusively carry out according to (1) formula of describing in the present embodiment, for example can continue A (m) is carried out smothing filtering, or summation is averaged computing changes into and get weighted average, or utilize known TPC Command field bit to obtain this relative coefficient by other statistical means.

How to obtain the power control step-length according to coefficient correlation A (m) below, general TPC order relative coefficient is more little, selects more little power control step-length:

Table 1: step-length selection scheme embodiment

Coefficient correlation A (m)	??-1＜＝A＜p0	??p0＜＝A＜p1	??P1＜＝A＜＝1
				Step-length K (m)	??1dB	??2dB	??3dB

(p0＜p1 is two parameters in the interval of setting (1,1) for p0 and p1.

Work as p0=-0.2, during p1=0.2, table 1 becomes table 2.

Table 2: the power control step-length generates the p0=-0.2 that tables look-up, p1=0.2

Coefficient correlation A (m)	????-1＜＝A＜-0.2	????-0.2＜＝A＜0.2	???0.2＜＝A＜＝1
				Step-length K (m)	????1dB	????2dB	???3dB

The step-length selective value here is not limited to get as above three values, and such as can getting 4,5 etc., and concrete value also can be different, especially can get 0dB as step-length, and the meaning is this power control cycle not regulate transmitting power.It is very useful when this point is not carried out power control under some channel circumstance transmitting power is adjusted.In addition, it is worthy of note, during this coefficient correlation calculating and power control step-length are selected, parameter N and p0, p1 and optional step-length etc. all are unusual important parameters, therefore, except obtaining the optimal parameter by test, we do not get rid of and utilize additive method to carry out these Parameter Optimization.

Transmit power control module is according to the TPC that receives order, raises or reduces transmitting power according to the step-length of input, and according to this transmitting power modulation signal is gone out through transmission antennas transmit.Certainly, transmit power control module is to select fixing step-length, the variable step-length of still selecting the process step-length to select module to obtain, or even select not carry out the power adjustment, can freely set by system.

Claims (4)

1, a kind of adaptive power control method that is used for mobile communication system is carried out by modules such as receiver, the generation of power control step-length, transmitting power control, transmitters, it is characterized in that this method comprises the following steps:

1. according to the demodulation module in the receiver receiving signal demodulation from reception antenna is obtained restituted signal, obtain the emissive power control command bit after the demodulation simultaneously, or, be sent to transmit power control module and power control step-length generation module simultaneously according to the emissive power control command bit that the comparative result of inner-loop power control signal-to-interference ratio measurement value and external circule power control signal interference ratio desired value obtains;

2. in power control step-length generation module, calculate the relative coefficient A (m) of emissive power control command, select power control step-length K (m) according to this relative coefficient A (m);

3. this power control step-length K (m) is input to transmit power control module, this module is automatically adjusted transmitting power according to emissive power control command and power control step-length K (m), and modulation signal is gone out through the transmission antennas transmit of transmitter.

2, adaptive power control method according to claim 1 is characterized in that m interior relative coefficient A (m) of power control cycle of said emissive power control command calculated by following formula: $A\left(m\right)=1/N\underset{i=m}{\overset{m-N+1}{\mathrm{\Σ}}}\mathrm{TPC}\left(i\right)*\mathrm{TPC}(i-1)$

In the formula:

1. N, m are positive integer;

2. N is the associated window size, i.e. the power control periodicity;

3. the span of A (m) is-1＜A (m)＜1;

4. emissive power control command value (bit) in TPC (i)-i cycle.

3, adaptive power control method according to claim 2 is characterized in that the selected step of said power control step-length K (m) is as follows:

1. with A (m) and the parameter P that sets ₀, P ₁, P ₂P _s[1＜P ₀＜P ₁＜P ₂P _s＜1] compare,

2. as-1＜=A (m)＜P ₀Selected power control step-length K (m)=0dB

P ₀＜＝A(m)＜P ₁?????????K(m)＝I ₁dB

P ₁＜＝A(m)＜P ₂?????????K(m)＝I ₂dB

P _s＜＝A(m)＜＝1?????????K(m)＝I _sdB

I wherein ₁＜I ₂＜I ₃＜...＜I _s

4, adaptive power control method according to claim 3 is characterized in that the selected step of said power control step-length Km is as follows:

1. with A (m) and the parameter P that sets ₀, P ₁[1＜P ₀＜P ₁＜1] compares;

2. as-1＜=A (m)＜P ₀Selected power control step-length K (m)=1dB

P ₀＜＝A(m)＜P ₁?????????K(m)＝2dB

P ₁＜＝A(m)＜+1??????????K(m)＝3dB