CN100372258C - Determination method of reference power in downlink power balance technology under soft handover - Google Patents

Abstract

The present invention discloses a method for determining downlink reference power under soft handoff condition, which comprises the following steps: the first step, a radio network controller RNC obtains transmitting code power and a measurement parameter used for reflecting the size of relative path loss from a plurality of nodes B participating in the soft handoff of user equipment UE; the second step, the RNC utilizes an obtained result to determine the downlink reference power P<ref><i> allocated to the UE by the i node B under the condition that the current total received power of the UE remains unchanged. The present invention also discloses a corresponding device for determining the downlink reference power under the soft handoff condition.

Description

Determination method of reference power in downlink power balance technology under soft handover

technical field

The present invention relates to a code division multiple access (CDMA) communication system, in particular, the present invention relates to a method and a system for determining reference power in downlink power balance technology in the case of soft handover in the code division multiple access system.

Background technique

In a CDMA communication system, the capacity and coverage performance of the system depend to a large extent on the interference received by users. Among them, power control technology, as an effective means to reduce inter-channel interference, has become a key technology of CDMA communication system. In an actual CDMA system, closed-loop power control is the main power control means, and it typically consists of two loops, an inner loop and an outer loop.

Fig. 1 shows a schematic diagram of downlink inner loop power control in the prior art. The receiving end of the inner loop power control obtains the estimated value of the signal-to-interference ratio (SIR) by measuring the received signal, and compares the estimated value with the SIR target value obtained through the outer loop power control to generate the power of the transmit power of the transmitting end. Control command, and transmit this command to the sending end through the reverse channel, and the sending end increases or decreases the current transmission power according to a certain adjustment step according to this command. Therefore, the inner loop power control is a feedback power control technology. The outer-loop power control is responsible for generating the required target SIR for the inner-loop power control. It adjusts the SIR target value to track changes in the wireless channel environment, thereby maintaining the system-agreed quality of service (QoS) when the service is established.

Inner loop power control can be applied to both uplink and downlink. Hereinafter, taking the Wideband Code Division Multiple Access (WCDMA) system of the Third Generation Partnership Project (3GPP) as an example, the inner loop power control process of the downlink will be described.

In the WCDMA system, downlink closed-loop power control is mainly applied to the downlink dedicated physical channel (DPCH). There is a Transmit Power Control (TPC) field in the uplink Dedicated Physical Control Channel (DPCCH), which is used to transmit the power control command generated by the mobile station (ie, user equipment UE) to the downlink DPCH channel transmitted by the base station (ie, Node B). If the Node B is required to increase the downlink transmission power, TPC=1, and if the Node B is required to decrease the downlink transmission power, then TPC=0.

In a specific implementation, the execution of the downlink inner loop power control command is usually completed by the Node B. According to the 3GPP protocol TS25.214, first, the Node B receives the uplink DPCCH channel from the UE and estimates the TPC command. Then, update the current transmit power P(k-1) according to the following formula:

P(k)＝P(k-1)+P _TPC (k)+P _bal (k) (1)

In the formula, each parameter is expressed in decibels (dB), P _TPC (k) is the inner loop power adjustment generated according to the TPC command, if _ΔTPC is the adjustment step size of the inner loop power control, then when there is no power increase limit , P _TPC (k) is calculated according to the following formula:

P _bal (k) in formula (1) is the correction amount to prevent downlink power drift in the case of soft handover. In order to clarify the reason for the correction amount, the macro-diversity technology in the soft handover in the CDMA system and the downlink power drift problem in the case of soft handover are explained below.

An important technical feature unique to the CDMA system is to support soft handover, that is, when the mobile station starts to establish a new wireless link with a target node B during the handover process, it does not immediately interrupt the wireless link with the original node B, that is, A mobile station can maintain communication with two or more Node Bs at the same time. Fig. 2 shows a schematic diagram of soft handover in a WCDMA system, wherein Node B is controlled by a Radio Network Controller (RNC), and UE communicates with two Node Bs simultaneously. Here, for ease of illustration, only two node Bs are drawn, but there may be more node Bs in practice.

The reception of uplink and downlink signals in soft handover can utilize the unique macro-diversity technology of soft handover, and the resulting soft handover gain can improve the performance of CDMA network coverage and capacity. As shown in FIG. 2 , in the downlink direction, the UE can perform maximum ratio combining on the downlink signals from different Node Bs. In the uplink direction, each Node B separately processes the same uplink signal received from the UE, and the data frames after channel decoding are finally sent to the RNC for further combining, and the RNC usually adopts a selective combining method.

Although uplink data frames can be combined in macro-diversity in the RNC, each Node B separately detects the TPC field of the uplink DPCCH and applies it to its own inner loop power control unit, and cannot be combined by the RNC. Otherwise, the inner-loop power control will have a large delay, and the control rate and tracking performance of the inner-loop power control will be greatly reduced. Therefore, the reception of the downlink power control command does not have the soft handoff gain produced by macro diversity. In this way, although there is only one downlink power control command generated by the UE, the signals carrying the uplink DPCCH channel of the command to different base stations have gone through different paths and have different SIRs, and because there is no soft handover gain available, the power Control bit TPC is not as reliable as data bits. Therefore, certain errors may occur in decoding the downlink power control command by each Node B, and the errors occur in different situations. A possible situation is: one base station reduces the transmit power for a certain UE, while another base station increases the transmit power for the UE. That is to say, during the soft handover process, downlink power drift occurs in downlink due to wrong decoding of downlink power control commands by different base stations.

Since the downlink power drift greatly degrades the performance of downlink soft handover, it is unacceptable. In order to compensate for the impact of power drift, the usual practice is to add a power balance adjustment loop to the inner loop power control. This method is also used in WCDMA. The correction value P _bal (k) in formula (1) is positive is introduced based on this technology. In the 3GPP standard TS25.433 and the document TSGR1-01-0197, the conditions that P _bal (k) should meet are given:

$\underset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; bal</span>}}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; r</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; init</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

The summation on the left side of equation (3) represents the total power balance adjustment in an adjustment period, Pre _ref is the downlink reference power, P _init is the initial value of the downlink power at the beginning of the adjustment period, and r is between 0 Convergence factor between 1 and 1, used to control the proportion of the total power adjustment in each adjustment period. The parameter adjustment period, Pre _ref and r in equation (3) are transmitted to Node B by RNC through the signaling path NBAP (Node B Application Part) between RNC and Node B. Wherein, the adjustment period and r are generally relatively fixed parameters taken according to actual experience, and _Pref is calculated by the RNC according to the dedicated measurement results of Node B. The dedicated measurements of the Node B related to _Pref calculation mainly include SIR and transmit code power. Regarding the dedicated measurements of the Node B, please refer to 3GPP's TS25.433, TS25.215, and TS25.133 protocols.

Patent application WO02/25836 "Downlink Power Control in Cellular Telecommunications Network" provides a method where Node B uses the parameters provided by RNC to determine the correction value P _bal ( k) method. Meanwhile, the patent application WO01/71941 "Determination of Reference Power Level in Diversity Handover Base Station" provides a calculation method of the downlink reference power _Pref . Among them, the calculation method of the downlink reference power P _ref proposed by the patent application WO01/71941 is mainly to take the downlink reference power as the average of the average transmission code power sum of each base station, or the dominant base station (with the largest uplink The average transmitted code power of the base station receiving the signal SIR).

Using the aforementioned downlink reference power calculation method has the following problem: the result of the downlink power balance adjustment loop is that the average value of the downlink power of each base station tends to the downlink reference power, thereby changing the distribution ratio of the current base station transmit power. In this way, even if the total transmission power of each base station through the inner loop power control has met the receiving SIR requirement of the mobile station before the power balance adjustment, since the calculation of the downlink reference power in the prior art does not take into account the downlink transmission power of each base station to the mobile station The path loss is different from this factor, therefore, the total transmit power after adjustment will be difficult to meet the receive SIR requirement of the mobile station. That is to say, unreasonable downlink reference power will cause the power balance adjustment loop to have a bad influence on the inner loop power control, thereby reducing the tracking performance of the downlink inner loop power control.

On the other hand, the patent application WO01/47145 and the patent US6104933 etc. relate to the allocation method of downlink transmission power in the case of soft handover. They all proposed that in the case of soft handover, the optimal allocation scheme of the downlink transmission power of each base station should be inversely proportional to the downlink path loss, that is, under the condition of ensuring the same reception rate of the mobile station, the downlink path loss is relatively small. A large base station should allocate less power, while a base station with a smaller downlink path loss should allocate more power. In this way, the total downlink transmission power can be minimized, thereby reducing interference to other channels, which is beneficial to increasing channel capacity.

With reference to the above-mentioned downlink transmission power optimization allocation scheme, it can be seen that the prior art does not consider the optimized downlink reference power allocation in determining the downlink reference power. The same downlink reference power is used, and the result is that each base station tends to This is also disadvantageous than transmitting the same power.

Contents of the invention

In order to overcome the above problems, the present invention proposes an effective method for determining reference power in the downlink power balance technology in the case of soft handover.

The method for determining the downlink reference power in the case of soft handover provided by the present invention includes: a first step, wherein the radio network controller RNC obtains the transmit code power from multiple Node Bs participating in soft handover of a user equipment UE and obtains the power for reflecting relative path loss measurement parameters; and a second step, wherein the RNC uses the obtained results to determine the downlink reference power P allocated by the i-th Node B to the UE under the condition that the current total received power of the UE remains unchanged _ref ⁱ .

The method of the present invention considers the current total receiving power value of the UE to be handed over, and determines the downlink reference power under the premise of keeping the value unchanged, so the inner loop power control balance of the UE itself will not be affected.

According to a preferred manner of the present invention, considering the optimized downlink reference power allocation scheme, the downlink reference power _Pre ⁱ allocated to the UE by the i-th Node B is determined by the following formula:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; TX</span>}}}{\underset{\mathrm{<span\; class="notranslate">\; J</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}$

Wherein, m represents the number of Node Bs participating in the soft handover, and L _j represents the average downlink loss from the jth node to the UE. A parameter α _i (representing the downlink power ratio of the i-th Node B allocated by the RNC to the first Node B) is introduced here, so that each Node B can allocate downlink reference power in different proportions. When the value of α _i for all Node Bs participating in the soft handover is 1, the traditional equal power allocation method is still adopted. If α _i is made to have different values for different Node Bs, an optimized downlink reference power allocation scheme can be realized through α _i .

According to yet another preferred manner of the present invention, the downlink reference power _Pref ⁱ allocated by the i-th node to the UE is determined by the following formula:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; SIR</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; TX</span>}}}{\underset{\mathrm{<span\; class="notranslate">\; J</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; SIR</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}$

Wherein SIR _j represents the SIR of any node B. Here, the measured value SIR _j of the Node B is preferably used to replace the measured value L _j of the UE. The reason is that the measurement report of the Node B does not occupy radio channel resources compared with the measurement report of the UE, and avoids the communication between the UE and the Node B. The more difficult problem is that the measured values are consistent in time.

The present invention also provides a device for determining the downlink reference power in the case of soft handover, including: obtaining means, a first step for obtaining transmit code power from multiple Node Bs participating in soft handover of a user equipment UE, and obtaining A measurement parameter used to reflect the size of the relative path loss; and a determining device, configured to determine the downlink allocated to the UE by the i-th Node B under the condition that the current total received power of the UE remains unchanged according to the result obtained by the obtaining device Reference power _Pref ⁱ .

Description of drawings

The above and other advantages of the present invention will become more apparent by describing preferred embodiments of the present invention in detail below with reference to the accompanying drawings. In the attached picture:

FIG. 1 is a schematic diagram of downlink inner loop power control in the prior art;

FIG. 2 is a schematic diagram of a soft handover process;

Figure 3 is a block diagram of the method according to the invention;

Figure 4 is a block diagram of a system according to the present invention;

FIG. 5 is a detailed representation of the method shown in FIG. 3 .

Detailed ways

Figure 3 is a block diagram of a method according to the invention. As mentioned above, the downlink reference power _Pref is determined by the RNC according to the dedicated measurement results of the Node B. In step 302, the RNC may request each Node B participating in the soft handover to report its own transmit code power. At the same time, the RNC can control the Node B to perform predetermined smoothing and filtering processing before the measurement report, and can also perform further averaging and other processing on the measurement report results in the RNC, and the power value thus obtained can be used as the current downlink transmission code of the Node B Estimated value of power.

In addition, the RNC also needs to obtain measurement parameters that reflect the relative size of the downlink path loss. Those skilled in the art should understand that these measurement parameters can be of various types and can be obtained in various ways, for example, they can be obtained by direct measurement, or they can be obtained by converting other values. The measurement parameters may include (but not limited to) the received signal code power RSCP _{CPICH,i of the common pilot channel CPICH} measured by the UE, the downlink path loss measured by the UE, or the received signal SIR measured by each of the Node Bs.

Next, in step 304, the RNC determines the downlink reference power allocated by each Node B under the condition that the current total received power of the UE remains unchanged, so as to obtain the power balance adjustment amount subsequently.

Figure 4 details a block diagram of an apparatus according to the invention. The RNC includes an obtaining means for obtaining the transmitted code power reported by each Node B and the aforementioned measurement parameters reflecting the relative size of the downlink path loss, and also includes a determining means for maintaining the current total receiving power of the UE The downlink reference power allocated to the UE by each Node B is determined under the same condition, so as to be used in a subsequent power balance adjustment loop. It should be understood that the connections shown in FIG. 4 only represent logical connections.

In the following, the principle of the method according to the present invention will be explained in detail.

First of all, for the convenience of analysis, all the following power-related parameters are expressed linearly. However, those skilled in the art should understand that the present invention is not limited to linear representation, and the present invention is also applicable in the case of using other representations such as logarithmic representation.

If there are m Node Bs connected to the UE in soft handover, and the estimated value of the current downlink transmit code power of each Node B can be expressed as P _i ^TX , the average downlink path loss from each Node B to the UE is L _i , then the total power P _total ^RX currently received by the UE is:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}^{\mathrm{<span\; class="notranslate">\; RX</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; TX</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

As mentioned above, the result of the downlink power balance adjustment loop is to make the average value of the downlink power of each Node B tend to the downlink reference power. Therefore, when the downlink power balance adjustment loop converges, the downlink power of each Node B , that is, the downlink reference transmit power _Pref ⁱ of each Node B set by the RNC should satisfy the following equation:

$\left\{\begin{array}{c}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}^{\mathrm{<span\; class="notranslate">\; j</span>}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; TX</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; total</span>}}^{\mathrm{<span\; class="notranslate">\; RX</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; )</span>\\ \frac{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}^{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 2,3</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span><span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; )</span>\end{array}\right.$

It can be seen that Equation (5a) indicates that after the downlink power balance adjustment, the total power received by the UE should remain unchanged, so that the downlink power balance adjustment loop does not affect the inner loop power control. In formula (5b), α _i is the downlink reference power ratio of the i-th Node B allocated by the RNC to a first Node B downlink reference power. It should be noted that the first Node B may be determined as any Node B participating in the soft handover process. Note that there is no restriction on the allocation method of downlink power in soft handover. The downlink reference transmit power of each Node B can be obtained from the above formula:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; TX</span>}}}{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 6</span>}<span\; class="notranslate">\; )</span>$

If referring to the downlink transmission power scheme of each node B in the case of soft handover proposed by the patent application WO01/47145 and the patent US6104933, it is desirable:

${\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 7</span>}<span\; class="notranslate">\; )</span>$

At this time, the downlink reference transmit power of each Node B is:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; TX</span>}}}{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 8</span>}<span\; class="notranslate">\; )</span>$

According to the usual equal power allocation, that is, α _i = 1, i = 1, 2, ... m, then the downlink reference transmit power of each Node B is:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; TX</span>}}}{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 9</span>}<span\; class="notranslate">\; )</span>$

Here, the downlink average path loss L _i from the i-th Node B to the UE is unknown, and can usually be obtained through the following two methods. One way is to calculate by:

${\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; RSCP</span>}}_{\mathrm{<span\; class="notranslate">\; CPICH</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}}{{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; CPICH</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; i</span>}}^{\mathrm{<span\; class="notranslate">\; TX</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 10</span>}<span\; class="notranslate">\; )</span>$

In the formula, P _CPICH,i ^TX is the downlink transmission power of the common pilot channel CPICH of each Node B, and RSCP _CPICH,i is the corresponding CPICH received signal code power measured by the UE. The calculation of this formula can be completed by the UE, at this time, the UE obtains the known _{PCPICH, i} ^TX from the cell broadcast; it can also be calculated by the RNC, at this time, the UE directly reports the measured value of the RSCP _{CPICH, i} , and the _{PCPICH, i} ^TX is a known quantity of RNC.

On the other hand, in the uplink direction, different Node Bs respectively receive the same uplink signal from the UE. Therefore, the ratio of the uplink average path loss is the ratio of the uplink received code power of each Node B. Although the uplink received code power is not a Node B measurement value specified in the standard, if the difference in the uplink interference of each Node B is ignored, the ratio of the uplink average path loss can be approximated by the ratio of the uplink received signal SIR. At the same time, in the frequency division duplex WCDMA system, the average path losses of the uplink and downlink wireless links are approximately equal because the carrier frequency is relatively close and they have experienced the same spatial propagation path. Therefore, the downlink average path loss ratio can be expressed as:

$\frac{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; \&ap;</span>\frac{{\mathrm{<span\; class="notranslate">\; SIR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}}{{\mathrm{<span\; class="notranslate">\; SIR</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 11</span>}<span\; class="notranslate">\; )</span>$

Using this result, the downlink reference transmit power for each Node B shown in equation (6) is:

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; SIR</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; TX</span>}}}{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; SIR</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 12</span>}<span\; class="notranslate">\; )</span>$

It is better to use the measured value SIR of Node B here than to use the measured value RSCP _CPICH,i of UE, because the measurement report of Node B does not occupy unlimited channel resources compared with the measurement report of UE, and avoids the It is a more difficult problem to be consistent in time.

Similarly, if referring to the downlink transmission power schemes of each Node B in the case of soft handover proposed in patent application WO01/47145 and patent US6104933, the downlink reference transmission power of each Node B shown in equation (8) can be calculated by the following formula :

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; SIR</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; SIR</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; TX</span>}}}{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; SIR</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 13</span>}<span\; class="notranslate">\; )</span>$

According to the usual power allocation, the downlink reference transmit power of each Node B shown in equation (9):

${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; SIR</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; TX</span>}}}{\underset{\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; SIR</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 14</span>}<span\; class="notranslate">\; )</span>$

FIG. 5 describes in detail the determination method of the reference power in the downlink power balance technology in the case of soft handover proposed by the present invention. As shown in the figure, when the UE is in the soft handover state, in step 502, the RNC obtains the parameters required for determining the downlink reference power of each Node B. According to one embodiment, the RNC can use NBAP dedicated measurement signaling to order each Node B participating in the soft handover of the UE to measure and report the received signal SIR and transmitted code power. Alternatively, the RNC may only obtain the transmit code power from each Node B, and at the same time obtain the CPICH received signal code power RSCP _CPICH,i , or the downlink path loss from the UE.

In step 504, the RNC decides whether to adopt the traditional equal power allocation scheme or the optimized power allocation scheme. If the decision in step 504 is "Yes", the process enters into step 506, and the downlink reference power of each Node B is determined according to the aforementioned formula (9) or (14). If the decision in step 504 is "No", the process goes to step 508 to determine the downlink reference power of each Node B according to the aforementioned formula (8) or (13).

Then, in step 510, the RNC sends each parameter of the downlink power balance adjustment loop including the downlink reference power of each Node B to each participating node B through the downlink power control command of NBAP. For the Node Bs in the soft handover of the UE, each Node B performs downlink power control according to the adopted downlink power balance adjustment loop algorithm according to the formula (1).

The preferred embodiment of the present invention has been described above with reference to the WCDMA system, but those skilled in the art should understand that the method for determining the reference power in the downlink power balance technology under the soft handover situation proposed by the present invention can also be applied to other application downlinks. In the CDMA mobile communication system with closed-loop power control, these systems include but are not limited to IS-95 system, WCDMA system, CDMA2000 system, and TD-SCDMA system.

The preferred embodiments given in the above detailed description are only for the purpose of illustration, and should not be construed as any limitation to the present invention. The present invention can be implemented in the form of software, hardware or a combination of both. Those skilled in the art can obtain any variations and improvements related to the present invention according to the above description, but these variations and improvements are all included in the scope and spirit of the present invention defined in the appended claims.

Claims (22)

1. A method for determining downlink reference power in a soft handover situation, comprising: A first step, wherein the radio network controller RNC obtains the transmit code power from multiple Node Bs participating in soft handover of a user equipment UE and obtains measurement parameters for reflecting the relative size of the path loss; and In the second step, the RNC uses the result obtained in the first step to determine the downlink reference power _Pref ⁱ allocated by the i-th Node B to the UE under the condition that the current total received power of the UE remains unchanged. 2. The method according to claim 1, wherein the measurement parameters used to reflect the relative size of the path loss include at least one of the following: the received signal code power RSCP _CPICH of the common pilot channel CPICH measured by the UE _{, i} , the downlink loss measured by the UE and the received signal SIR measured by each Node B. 3. The method according to claim 1 or 2, characterized in that: the second step comprises determining the downlink reference power P _ref ⁱ allocated to the UE by the i-th Node B according to the following formula: ${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; TX</span>}}}{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; ,</span>$ Wherein m represents the number of Node Bs participating in soft handover, and α _i represents the downlink power ratio of the i (i=1, 2, ..., m) Node Bs distributed by the RNC relative to the downlink power of the first Node B, L _j represents the average downlink loss from any Node B participating in the soft handover to the UE, P _j ^TX represents the estimated value of the current downlink transmit code power of any node participating in the soft handover, and the first Node B may Any one of a plurality of Node Bs set to participate in the soft handover. 4. The method according to claim 1 or 2, characterized in that: the second step comprises determining the downlink reference power P _ref ⁱ allocated to the UE by the i-th Node B according to the following formula: ${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; SIR</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; TX</span>}}}{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; SIR</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}$ Wherein m represents the number of Node Bs participating in soft handover, and α _i represents the downlink power ratio of the i (i=1, 2, ..., m) Node Bs distributed by the RNC relative to the downlink power of the first Node B, SIR _j represents the received signal SIR of any Node B participating in the soft handover, P _j ^TX represents the estimated value of the current downlink transmission code power of any node participating in the soft handover, and wherein the first Node B can be set to participate in Any one of the plurality of Node Bs for the soft handover. 5. The method according to claim 3, characterized in that: the downlink average loss _L of the i-th Node B to the UE is determined by the RNC according to the following formula: $L_i=\frac{{\mathrm{RSCP}}_{\mathrm{CPICH},i}}{P_{\mathrm{CPICH},i}^{\mathrm{TX}}},$ Wherein P _CPICH,i ^TX represents the downlink transmission power of the common pilot channel CPICH of each Node B known by the RNC, wherein RSCP _CPICH,i is the received signal code power of the common pilot channel CPICH measured by the UE. 6. The method according to claim 3, characterized in that: the downlink average loss _L of the i-th Node B to the UE is determined by the UE according to the following formula: $L_i=\frac{{\mathrm{RSCP}}_{\mathrm{CPICH},i}}{P_{\mathrm{CPICH},i}^{\mathrm{TX}}},$ Where P _CPICH,i ^TX is obtained by the UE through cell broadcast, where RSCP _CPICH,i is the received signal code power of the common pilot channel CPICH measured by the UE. 7. The method according to claim 3, characterized in that: the downlink average loss _L of the i-th Node B to the UE is determined by the RNC according to the following formula: $\frac{L_i}{L_1}\&ap;\frac{{\mathrm{SIR}}_i}{{\mathrm{SIR}}_1},$ SIR _i represents the received signal SIR of the i-th Node B. 8. The method according to claim 3, characterized in that: α _i =1, i=1, 2, . . . , m. 9. The method according to claim 3, characterized in that: α _i is determined according to the following formula: ${\mathrm{\&alpha;}}_i=\frac{L_i}{L_1},$ i=2, 3, . . . , m, α ₁ =1. 10. The method according to claim 4, characterized in that: α _i =1, i=1, 2, . . . , m. 11. The method according to claim 4, characterized in that: α _i is determined according to the following formula: ${\mathrm{\&alpha;}}_i=\frac{L_i}{L_1},$ i=2, 3, . . . , m, α ₁ =1. 12. An apparatus for determining downlink reference power in a soft handover situation, comprising: The obtaining means is used for obtaining the first step of transmitting code power from multiple Node Bs participating in soft handover of a user equipment UE and obtaining a measurement parameter for reflecting the relative size of path loss; and The determining means is configured to determine the downlink reference power _Pref i allocated to the UE by the i-th Node ^B under the condition that the current total received power of the UE remains unchanged according to the result obtained by the acquiring means. 13. The device according to claim 12, wherein the measurement parameters used to reflect the relative size of the path loss include at least one of the following: the received signal code power RSCP _CPICH of the common pilot channel CPICH measured by the UE _{, i} , the downlink loss measured by the UE and the received signal SIR measured by each Node B. 14. The device according to claim 12 or 13, wherein the determining means determines the downlink reference power _Pref ⁱ allocated to the UE by the i-th Node B according to the following formula: ${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&CenterDot;</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; TX</span>}}}{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; L</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}<span\; class="notranslate">\; ,</span>$ Wherein m represents the number of Node Bs participating in soft handover, and α _i represents the downlink power ratio of the i (i=1, 2, ..., m) Node Bs distributed by the RNC relative to the downlink power of the first Node B, L _j represents the average downlink loss from any Node B participating in the soft handover to the UE, P _j ^TX represents the estimated value of the current downlink transmit code power of any node participating in the soft handover, and the first Node B may Any one of a plurality of Node Bs set to participate in the soft handover. 15. The device according to claim 12 or 13, wherein the determining means determines the downlink reference power _Pref ⁱ allocated to the UE by the i-th Node B according to the following formula: ${\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; ref</span>}}^{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; SIR</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}^{\mathrm{<span\; class="notranslate">\; TX</span>}}}{\underset{\mathrm{<span\; class="notranslate">\; j</span>}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{\overset{\mathrm{<span\; class="notranslate">\; m</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}}{\mathrm{<span\; class="notranslate">\; SIR</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; j</span>}}}$ Wherein m represents the number of Node Bs participating in soft handover, and α _i represents the downlink power ratio of the i (i=1, 2, ..., m) Node Bs distributed by the RNC relative to the downlink power of the first Node B, SIR _j represents the received signal SIR of any Node B participating in the soft handover, P _j ^TX represents the estimated value of the current downlink transmission code power of any node participating in the soft handover, and wherein the first Node B can be set to participate in Any one of the plurality of Node Bs for the soft handover. 16. The device according to claim 14, characterized in that: the downlink average loss _L of the i-th Node B to the UE is determined by the RNC according to the following formula: $L_i=\frac{{\mathrm{RSCP}}_{\mathrm{CPICH},i}}{P_{\mathrm{CPICH},i}^{\mathrm{TX}}},$ Wherein P _CPICH,i ^TX represents the downlink transmission power of the common pilot channel CPICH of each Node B known by the RNC, wherein RSCP _CPICH,i is the received signal code power of the common pilot channel CPICH measured by the UE. 17. The method according to claim 14, characterized in that: the downlink average loss L _i from the ith Node B to the UE is determined by the UE according to the following formula: $L_i=\frac{{\mathrm{RSCP}}_{\mathrm{CPICH},i}}{P_{\mathrm{CPICH},i}^{\mathrm{TX}}},$ Where P _CPICH,i ^TX is obtained by the UE through cell broadcast, where RSCP _CPICH,i is the received signal code power of the common pilot channel CPICH measured by the UE. 18. The device according to claim 14, characterized in that: the downlink average loss _L of the i-th Node B to the UE is determined by the RNC according to the following formula: $\frac{L_i}{L_1}\&ap;\frac{{\mathrm{SIR}}_i}{{\mathrm{SIR}}_1},$ SIR _i represents the received signal SIR of the i-th Node B. 19. The device according to claim 14, characterized in that: α _i =1, i=1, 2, . . . , m. 20. The device according to claim 14, characterized in that: α _i is determined according to the following formula: ${\mathrm{\&alpha;}}_i=\frac{L_i}{L_1},$ i=2, 3, . . . , m, α ₁ =1. 21. The device according to claim 15, characterized in that: α _i =1, i=1, 2, . . . , m. 22. The device according to claim 15, characterized in that: _αi is determined according to the following formula: ${\mathrm{\&alpha;}}_i=\frac{L_i}{L_1},$ i=2, 3, . . . , m, α ₁ =1.

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