CN1592172A - Forward power controlling method for CDMA clustered communication system - Google Patents

Abstract

This invention discloses a forward power control method in a CDMA cluster communication system including: determining the basic emit power of the base station, after setting up a forward shared channel at the cluster terminal, the current cluster set forward shared channel emit power value is regulated on the basis of ensuring the correct receiving by all clusters in the current cluster set form the basic emit power; which solves the problem of forward power control with one forward shared channel facing to multiple cluster terminals when increasing cluster functions in the CDMA system.

Description

Method for forward power control in code division multiple access trunking communication system

technical field

The invention relates to trunking communication technology, in particular to a method for forward power control of a code division multiple access trunking communication system.

Background technique

The Code Division Multiple Access (CDMA) standard belongs to one of the 3G system standard systems. It has been commercialized in many countries and provides voice and high-speed packet data services for terminals. The number of terminals that a single base station can support is limited by conditions such as code resources and power. .

The CDMA trunking communication system is a communication system that upgrades the existing CDMA network to realize dedicated dispatching services. On the one hand, it can enable multiple trunking terminals to share wireless resources and improve the capacity of the wireless cellular system. On the other hand, the trunking system can provide The cluster function can meet the special requirements of some special terminals. All the terminals of the CDMA trunking communication system share all the available channels of the system, that is, any terminal in the system wants to talk to another terminal in the system, as long as there is an idle channel, it can use the idle channel under the control of the central console. channel to communicate.

In the CDMA system, the forward traffic channel and the reverse traffic channel of the terminal are established in pairs, and each activated terminal corresponds to a forward traffic channel and a reverse traffic channel, and the base station performs power Control without interfering with each other. The forward power control process is that each terminal sends forward power control information to the base station through the reverse traffic channel, and the base station uses the forward power control information sent by the reverse traffic channel to The transmit power to the traffic channel is adjusted.

In the CDMA trunking communication system, since multiple trunking terminals share a forward shared channel (in order to distinguish it from the forward traffic channel in CDMA, a forward traffic channel shared by multiple trunking terminals is called a forward shared channel), The base station cannot perform power control on the respective forward traffic channels of each cluster terminal. Therefore, the forward power control method in the CDMA system cannot be directly applied in the CDMA cluster system. Moreover, since the CDMA system is a self-interference system, affected by network planning and other factors, the forward power resources of the base station subsystem are limited. If the forward power value that can be received correctly is transmitted, the forward power of the system will soon be saturated, seriously affecting the capacity of the cluster terminal, and also having a certain impact on the normal terminal use in the current CDMA system.

Contents of the invention

The purpose of the present invention is to provide a method for forward power control of a code division multiple access trunking communication system, to perform forward power control when a forward shared channel corresponds to multiple terminals when adding a trunking function in a CDMA system .

A method for forward power control of a code division multiple access trunked communication system, the method comprising:

Determine the basic transmission power of the base station. After the trunking terminal establishes the forward shared channel, starting from the basic transmission power, adjust the forward shared channel transmission of the current trunking group according to the condition that all trunking terminals in the current trunking group are correctly received. power value.

The adjustment of the transmit power value of the forward shared channel includes that each cluster terminal in the cluster group monitors the power control information from its forward shared channel at the same time, and judges whether the transmit power value of the current forward shared channel meets the requirements, if not If it is satisfied, the forward power adjustment application is reported through the reverse channel, and the base station judges the worst terminal according to the parameters in the forward power adjustment application, determines the current forward shared channel power value adjustment step size, and adjusts the current forward shared channel. power value, otherwise, reduce the transmit power value of the current forward shared channel by one step.

The adjusting the transmission power value of the forward shared channel may also include that each cluster terminal in the cluster group sends the current forward power control information to the base station, and at regular time intervals, the base station transmits the current forward power control information according to the current forward power control information Judging whether any cluster terminal expects to increase the transmit power value of the forward shared channel, if so, increase the transmit power value of the forward shared channel, otherwise decrease the transmit power value of the forward shared channel.

The present invention solves the situation that the cluster terminal shares the forward service channel, not only enables the cluster terminal at the edge of the network to correctly receive the content of the forward shared channel, but also under the condition that the terminal with the worst receiving condition correctly receives the content, through basic The transmission power begins to reduce the transmission power value of the forward shared channel, which reduces the consumption of forward power resources of the base station and improves the system capacity. Therefore, in the case of a large number of cluster groups, the situation of wasting forward power resources of the base station is very serious, and the bottleneck problem that restricts the base station from supporting the maximum number of cluster groups is solved.

Description of drawings

FIG. 1 is a schematic diagram of realizing forward power control of a cluster terminal in the present invention.

FIG. 2 is a schematic diagram of all cluster terminals in the current cluster group reporting a forward power adjustment application.

Fig. 3 is a schematic diagram of changes in the signal coverage area of the base station when the transmit power value of the forward shared channel is directly reduced without reporting the forward power adjustment application.

FIG. 4 shows the situation when the trunking terminal moves in overlapping coverage areas of two base stations.

Detailed ways

Since the forward power control method in the CDMA system is adjusted separately for each terminal in the system, and does not affect each other, while in the CDMA cluster system, the cluster terminals share the forward traffic channel, and it is impossible to control each cluster terminal separately. Forward power control adjustment, so the forward power control method in the CDMA system cannot be directly applied in the CDMA trunking system.

Due to the different distribution models of trunking terminals and ordinary terminals, in many cases, the trunking terminals are not uniformly distributed in the entire network. If the current trunking terminals are relatively close to the base station and the channel conditions are relatively good, through forward power control, it can greatly The transmission power of the forward shared channel is greatly reduced to save forward power resources, thereby improving the forward capacity of the system. Therefore, in order to meet the requirement that all cluster terminals in the current cluster group can correctly receive the information of the forward shared channel, its forward power control may be adjusted according to the condition of the cluster terminal in the current cluster group with the worst condition.

Example 1

Referring to FIG. 1 , FIG. 1 is a schematic diagram of realizing forward power control of a trunking terminal according to the present invention. The specific process is as follows:

Step 101, determine the basic transmit power of the base station. When the forward shared channel of the current trunking group is just established, because the network side does not know the distribution of the current trunking terminals in the area served by the local trunking group, the current trunking group All cluster terminals in the cluster can receive the information of the forward shared channel to determine the basic transmit power. Generally, the basic transmit power can be determined according to the value of the cell radius covered by the base station transmit power during network design.

Step 102, after the establishment of the forward shared channel, all cluster terminals of the current cluster group simultaneously monitor the information of the forward shared channel from the current cluster group, and judge the frame error rate (FER) from the forward shared channel of the current cluster group ) is greater than a specified value, so as to know whether the current transmit power value of the forward shared channel can ensure that the trunking terminal can receive correctly, if yes, perform step 103, otherwise, perform step 104.

The specified value above can be stipulated by the agreement, for example, the target frame error rate FER of the CDMA forward traffic channel = 1%, and can also be set according to the different priorities of the trunking terminals or other reasons.

Whether knowing the transmission power value of the current forward shared channel can ensure that the cluster terminal can receive it correctly can also be judged according to other parameters, for example, according to whether the forward frame cyclic redundancy check (CRC) is correct, or whether the forward frame It is judged whether the frame is a good frame or whether the signal-to-noise ratio (Eb/Nt) calculated from the frame error rate meets the target signal-to-noise ratio set by the trunking terminal.

Step 103, the trunking terminal reports a forward power adjustment application. Specifically: the cluster terminal transmits the user identification, current FER, received signal sensitivity (RSSI), the ratio of the actual chip energy of the received signal to the power density (Ec/Io) and the target Ec/Io value of the cluster terminal through the reverse channel Send to the base station, the base station counts all the parameters reported by the cluster terminal within a certain period of time, and after a certain algorithm, makes a comprehensive comparison of multiple cluster terminals, and judges that the cluster terminal with the worst reception condition is the worst in the satisfaction condition On the premise of the forward shared channel power requirement of the trunking terminal, the forward power control adjustment step size is determined. The step size is calculated from the forward power control parameters of the shared channel provided by the worst cluster terminal.

The reverse channel here can be a reverse fundamental channel (R-FCH), a reverse dedicated control channel (R-DCCH), a reverse common control channel (R-CCCH), or a reverse access channel (R-CCCH). -ACH) or Reverse Enhanced Access Channel (R-EACH). The trunking terminal that reports the forward power adjustment application may be all the trunking terminals in the current trunking group, as shown in FIG. 2 ; it may also be the trunking terminal that needs to adjust the forward power.

The cluster terminal with the worst reception condition can be determined as follows: first, the base station calculates the difference between the terminal target Ec/Io carried in the reported forward power adjustment application and the actual Ec/Io, and then selects the difference between all reported cluster terminals. The cluster terminal with the largest travel value is treated as the worst cluster terminal.

Some of the parameters carried in the forward power adjustment request can be added or deleted according to the actual needs of the system.

Step 104 , adjust the power of the forward shared channel according to a certain time interval, and reduce the transmit power value of the forward shared channel by one step every time starting from the basic transmit power just established at the beginning. Here, the step size of each reduction can be dynamically determined according to the current network situation, the priority of the cluster group, and the number and density of the cluster terminals in the cluster group.

As shown in Figure 3, assuming that the coverage radius of the base station is R1, when the cluster group is first established, the base station system does not know the distribution of cluster terminals in the cell, so the initial coverage of the basic transmission power is R1, for a period of time If there is no cluster terminal in the cell to initiate a forward power adjustment application, the base station controls the transmit power value of the forward shared channel to decrease by one step, which corresponds to the reduction of the coverage radius of the forward power shown in Figure 3 and becomes R2. If no cluster terminal initiates a forward power adjustment application after a period of time, the base station controls the transmit power value of the forward shared channel to decrease by one step on the basis of the current transmit power, corresponding to the forward power shown in Figure 3. Decrease the radius a little more to become R3, and so on.

For a cluster terminal on the edge of handover, the base station needs to judge whether to ignore the forward power adjustment application reported by the current cluster terminal, that is, the base station needs to judge whether the cluster terminal has left the handover area of the cell, and whether the cluster terminal needs to be transferred from the cell. Terminal delete. Referring to FIG. 4, FIG. 4 shows overlapping coverage areas of two base stations. The specific method is as follows:

The cluster terminal moves in the overlapping area of base station 1 and base station 2. When the cluster terminal is at point A, the cluster terminal accepts the service of base station 1. At the same time, through pilot search, the pilot frequency of base station 2 is found. The current pilot strength of base station 2 is The pilot strength difference relative to base station 1 is greater than a certain set value, the cluster terminal combines the forward shared channel information from base station 1 and base station 2, and if the combined forward frame FER cluster terminal does not meet the conditions, it sends The forward power adjustment application is sent to base station 1, and the forward shared channel transmit power of base station 1 is adjusted.

When the cluster terminal moves to position B, through pilot search, it is found that the difference between the pilot strengths of base station 1 and base station 2 is less than a certain set value. At this time, the cluster terminal combines the forward signals from base station 1 and base station 2. Shared channel information, if the combined forward frame FER cluster terminal does not meet the conditions, then send forward power adjustment requests to base station 1 and base station 2 at the same time, and adjust the forward shared channel transmission power of base station 1 and base station 2 at the same time.

When the cluster terminal is at point C, through the pilot search, it is found that the difference between the pilot intensity of base station 2 and the frequency intensity of base station 1 is greater than a certain set value. At this time, the cluster terminal combines the forward signals from base station 1 and base station 2. For shared channel information, if the combined forward frame FER cluster terminal does not meet the conditions, it sends a forward power adjustment application to base station 2, and adjusts the forward shared channel transmit power of base station 2.

Example 2

First, the same as Step 101 of Embodiment 1, determine the basic transmission power of the base station;

Then, after establishing the forward shared channel, each cluster terminal sends forward power control information to the base station. Since each power control, the base station has to receive forward power control messages from each terminal, and for cluster terminals, most of the terminals are in the state of listening but not talking, so the base station cannot know the current power control message. When comparing the power control information of multiple cluster terminals, how many cluster terminals are there in your own coverage area, it is likely to be incomplete. Therefore, the base station sets a time parameter after receiving the power control information sent by each cluster terminal. Any one of the cluster terminals expects to increase the transmit power value of the forward shared channel, then increase the transmit power value of the forward shared channel, if all the cluster terminals expect to reduce the transmit power value of the forward shared channel, then reduce the forward shared channel transmit power value.

One of the characteristics of the cluster system is that the number of cluster terminals in the same cluster group is not limited. If there are many cluster terminals in the current cell, all the cluster terminals will send power control information to the base station, which will cause a lot of reverse interference , within the timing time, the base station waits for more cluster terminals to report power control parameters, which consumes more reverse resources. Therefore, the method in embodiment 2 is applicable to the situation where the number of cluster terminals in the cluster group is small.

Claims (10)

1, a kind of method of CDMA colony communication system forward power control is characterized in that this method comprises:

Determine the basic transmitting power of base station, after colony terminal is set up forward shared channel, from described basic transmitting power, adjust the transmission power level of this current cluster group forward shared channel according to the situation that guarantees the correct reception of all colony terminals in the current cluster group.

2, method according to claim 1 is characterized in that, the transmission power level of the current cluster group of described adjustment forward shared channel comprises,

Each colony terminal is monitored the power control information from its forward shared channel simultaneously in the cluster group, whether the transmission power level of judging current forward shared channel meets the demands, if do not satisfy, then report forward power adjustment application by backward channel, the base station rules out the poorest terminal according to the parameter in the forward power adjustment application, determine the transmission power level adjustment step-length of current forward shared channel, adjust the transmission power level of current forward shared channel, otherwise the transmission power level of current forward shared channel is reduced a step-length.

3, method according to claim 2 is characterized in that, described step-length is dynamically determined according to the priority of the situation of current network, cluster group and the terminal number in the cluster group and density.

4, method according to claim 2, it is characterized in that whether the described transmission power level of judging current forward shared channel meets the demands is that whether whether correct or forward frame be frame or judged by the signal to noise ratio that frame error rate calculated according to the cyclic redundancy check (CRC) of the frame error rate of forward shared channel or forward frame.

5, method according to claim 2 is characterized in that, the parameter in the described forward power adjustment application comprises at least, the ratio of the ratio of frame error rate, end objectives chip energy and power spectral density and received signal chip energy and power spectral density.

6, method according to claim 5, it is characterized in that, the base station rules out the poorest terminal according to the parameter in the forward power adjustment application and further comprises, the end objectives chip energy of carrying in the forward power adjustment application that base station calculating reports and the ratio and the difference of received signal chip energy of power spectral density with the ratio of power spectral density, in all reporting terminals, select the terminal of difference maximum then, as the poorest terminal.

7, method according to claim 2 is characterized in that, described forward power adjustment application is reported by the colony terminal that expectation increases the transmission power level of forward shared channel.

8, method according to claim 1, it is characterized in that, the transmission power level of the current cluster group of described adjustment forward shared channel comprises, each colony terminal is sent to the base station with the forward power control information of current forward shared channel in the cluster group, at regular intervals at interval, the base station judges whether that according to the forward power control information of described current forward shared channel arbitrary colony terminal expectation increases the transmission power level of forward shared channel, if then increase the transmission power level of forward shared channel, otherwise the transmission power level of reduction forward shared channel.

9, method according to claim 1, it is characterized in that, this method further comprises, if colony terminal is in the overlapping region that a plurality of base stations cover, merging is from the information of the forward shared channel of each base station, whether the transmission power level of judging the current forward shared channel after merging meets the demands

If do not satisfy, then report the forward power adjustment to apply for to the strong base station of pilot frequency intensity, adjust the transmission power level of the forward shared channel of this base station, if the pilot frequency intensity of each base station is identical, then cover this regional base station and report forward power adjustment application, adjust the transmission power level that all cover the forward shared channel of this regional base station to all;

If the transmission power level of the current forward shared channel after merging meets the demands, then reduce the transmission power level of forward shared channel.

10, method according to claim 1 is characterized in that, described basic transmitting power is determined according to the colony terminal that the is in cell edge information that can receive.

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