CN1359207A - Method for distributing forward link initial emission power in CDMA system - Google Patents

Abstract

The present invention provides a method for allocating the initial transmission power of the forward link in a code division multiple access (CDMA) system. After entering the channel message, the access judgment is performed. If the access is allowed, the base station extracts the forward pilot strength item in the wireless environment measurement report, and assigns the forward link initial link according to the obtained forward pilot strength item. transmit power. By implementing the distribution method of the present invention, the test time can be shortened, the access speed can be accelerated, and the success rate of access can be improved at the same time.

Description

A Method for Allocating Initial Transmitting Power of Forward Link in Code Division Multiple Access System

The invention relates to the field of mobile communication, in particular to a method for distributing initial transmission power of a forward link from a base station to a mobile station in a mobile communication system using code division multiple access (CDMA).

In the CDMA communication system, there are two communication ends, the mobile station and the base station, and each end has a transmitting and receiving system. When there is an incoming call and needs to page the mobile station users in the cell, the base station will send a paging message on the forward (fast) paging channel. The called mobile station has been monitoring the paging channel. When a paging message matching its own address is found, the mobile station will report a paging response on the reverse (enhanced) access channel after a certain delay. Or, when the mobile station users in the cell need to actively communicate, they will also report the access request message on the reverse (enhanced) access channel. Both of the above two messages contain the measurement report on the forward pilot channel of the cell to which it belongs. After receiving the paging response message or access request message from the mobile station, the base station makes an access admission judgment. If the request is allowed, the base station decides to allocate various parameters of the forward and reverse channels (including forward and reverse channels). Reverse initial transmission power), and send the reverse channel parameters to the target mobile station through the forward assigned channel. Then the above-mentioned mobile station switches the channel to the above-mentioned specified reverse and forward channels to start transmitting and receiving signals, and the base station also switches to the specified channel unit at the same time, and starts transmitting and receiving signals on the above-mentioned specified forward and reverse channels. After a series of tests and information exchange, the mobile station and the base station start the business communication. The present invention relates to a method for the base station to determine its forward initial transmission power allocation before the dedicated channel allocation in the CDMA system, that is, how the base station determines its forward initial transmission power allocation after the mobile station user requests or is required to establish a wireless connection. Initial value of transmit power.

The method in the prior art is to assign a fixed value for the forward initial transmit power to transmit, and then pass a series of tests to start communication when the forward power reaches a long-term average value (stable value) under power allocation. In this way, since the assigned fixed value may be far from the stable value, if the power allocation method is not fast, the test time may be very long, and the access failure may be caused by the deterioration of the wireless environment.

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a method for distributing the initial transmission power of the forward link with fast access speed and high success rate in a CDMA system.

Another object of the present invention is to provide a method for calculating the initial transmission power of the forward link in a CDMA system.

The object of the present invention is achieved in this way, a method for distributing the initial transmission power of the forward link in a CDMA system, wherein the CDMA system includes a mobile station, a base station, and a reverse link from the mobile station to the base station Road and the forward link from the base station to the mobile station; the mobile station includes a transmitting and receiving system, the base station includes a transmitting and receiving system and several channel units; each channel unit is responsible for a specific channel, including the designated channel transmit power; it is characterized in that: before the dedicated channel is assigned, the base station receives the reverse access channel message of the mobile station (the paging response message when the mobile station is called, and the call initiation message when the mobile station is calling) message), the access judgment is performed, and if the access is allowed, the base station extracts the forward pilot strength item in the wireless environment measurement report, and allocates the forward link strength item according to the obtained forward pilot strength item Initial transmit power.

According to the distribution method of forward link initial transmission power in the CDMA system of the inventive method, it is characterized in that, the computing formula of described forward link initial transmission power is as follows: $P_{\mathrm{send}}=\min [P_{\mathrm{pilot}}\·{10}^{\frac{\mathrm{D.}+0.5m}{10}},P_{\mathrm{av}}]---\left(1\right)$

Among them, P _send is the specified forward initial transmit power;

P _pilot is the transmission power of the forward pilot channel;

D is the ratio of the information bit energy and the interference spectral density that the mobile station must satisfy in order to meet the quality of service requirements;

M is the extracted forward pilot strength;

P _av is the maximum power that can be allocated.

Implementing the method for allocating the forward link initial transmission power in the CDMA system of the present invention can dynamically determine the forward initial transmission power according to the current wireless environment conditions, so that the forward initial transmission power is as close as possible to the long-term average of the forward transmission power value, thereby shortening the test time, speeding up the access speed, and improving the success rate of the access.

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is the structural block diagram of the CDMA system applicable to the inventive method;

Fig. 2 is the internal structure logic diagram of the base station in the CDMA system shown in Fig. 1;

Fig. 3 is the calling flow chart of mobile station in the embodiment of the method of the present invention;

Fig. 4 is a flow chart of the mobile station being called in the embodiment of the method of the present invention.

The present invention is applicable to CDMA system, as shown in Figure 1, described CDMA system comprises a mobile station 100, a base station 110, the forward link of base station 110 to mobile station 100 and the reverse link of mobile station 100 to base station 110 . The mobile station 100 includes a transmitting and receiving system 101, and the base station 110 includes a transmitting and receiving system 111 and several channel units 112-114. Each channel unit is responsible for baseband spread spectrum signal processing of a specific channel, including the channel gain of the channel. As shown in FIG. 2, the transmitting and receiving system 111 of the base station 110 further includes a transmitter 115 and a receiver 116, and the transmitter 115 and the receiver 116 are respectively connected to a part of channel units. During communication, the base station 110 will send system signaling or service content etc. on the forward channel established on the forward link through the channel unit 112 connected to the transmitter 115 . The information bits of a specific channel are input into a specific channel unit 112 connected to the transmitter 115 of the base station 110, and the channel unit 112 performs baseband spread spectrum and channel gain processing, and outputs a spread spectrum signal. The frequency signals are multiplexed and input to the transmitter 115 of the transmitting and receiving system 111 for transmission. The mobile station 100 uploads the user request and service content through the reverse channel established on the reverse link to the channel unit 114 connected to the receiver 116 for processing. The radio frequency signal of the same frequency point received by the receiver 116 of the transmitting and receiving system 111 of the base station 110 is input to different channel units connected to the receiver 116 of the base station 110 through decorrelation for despreading and baseband processing to obtain information bit.

The feature of the present invention is that after receiving the reverse access channel message from the mobile station 100, the base station 110 makes an access judgment, and if the access is allowed, dynamically determines the forward initial transmit power according to the current wireless environment conditions, so that the forward The initial transmit power is as close as possible to the long-term average of the forward transmit power. The present invention uses the principle of similar closed-loop distribution to estimate the initial transmission power of the forward link, that is, the forward pilot strength in the wireless environment measurement report of the reverse access channel message measured by the mobile phone, calculates the path loss, and then calculates the path loss according to the Path loss, calculate the forward initial transmit power. Since the forward initial transmission power of the base station has an upper limit, we define: $P_{\mathrm{send}}=\min [P_{\mathrm{pilot}}\·{10}^{\frac{\mathrm{D.}+0.5m}{10}},P_{\mathrm{av}}]---\left(1\right)$

Among them, P _send is the specified forward initial transmit power;

P _pilot is the transmission power of the forward pilot channel, which can be obtained from the base station database;

D is the ratio of the information bit energy to the interference spectral density that the mobile station must meet in order to meet the service quality requirements, and can choose a long-term measurement value or a preset value, such as 5dB;

M is the extracted forward pilot strength;

P _av is the maximum power that can be allocated, which can be obtained from the base station database.

When the initial transmit power required by the service is greater than the forward power that the system can provide, transmit according to the maximum transmit power that can be allocated by the system. Therefore, in formula (1), the final forward initial transmit power of the base station used is the calculated P The minimum value among _send and P _av .

As shown in FIG. 3 , it is the calling process of the mobile station in one embodiment of the present invention. When a mobile station user in a cell needs to actively communicate, it will report a call initiation message on the reverse (enhanced) access channel, and the message includes a measurement report on the forward pilot channel of the cell it belongs to. The base station has been monitoring the reverse (enhanced) access channel. After receiving the call initiation message from the mobile station, the base station makes an access admission judgment. If the request is allowed, the base station decides to allocate the forward and reverse channels. Various parameters (including forward and reverse initial transmission power), at this time, the base station determines the forward initial transmission power according to formula (1) according to the received forward pilot strength measurement information. For example, for a typical CDMA system, the power of the forward pilot channel is 15% of the maximum transmit power; the ratio of the energy per bit required by the service quality to the interference spectral density is 6dB; the assignable power P _av is the forward maximum transmit power minus to the transmitted power. Then the forward initial transmit power is:

P _send ＝min[P _pilot ·10 ^0.6+0.05M ，P _av ]) (2)

And, the base station delivers the reverse channel parameters to the target mobile station through the forward assignment channel. Then the mobile station switches the channel to the specified reverse and forward channels to start transmitting and receiving signals, while the base station also switches to the specified channel unit, and starts transmitting and receiving signals on the specified forward and reverse channels. After a series of tests and information exchange, the mobile station and the base station start the business communication.

As shown in FIG. 4 , it is the called process of the mobile station in the embodiment of the present invention. When there is an incoming call and needs to page the mobile station users in the cell, the base station will send a paging message on the forward (fast) paging channel. The called mobile station has been monitoring the forward (fast) paging channel, and when it finds a paging message matching its own address, the mobile station will, after a certain delay, switch to the reverse (enhanced) access channel Report the paging response message, including the measurement report on the forward pilot channel of the cell to which it belongs. After the base station receives the paging response message from the mobile station, it makes an access admission judgment. If the request is allowed, the base station decides to allocate various parameters of the forward and reverse channels (including the initial transmission of the forward and reverse channels). Power), at this time, the base station determines the forward initial transmission power according to the received forward pilot strength measurement information according to the formula (1). For example, for a typical CDMA system, the power of the forward pilot channel is 15% of the maximum transmit power; the ratio of the energy per bit required by the quality of service to the interference spectral density is 6dB; the assignable power P _av is the forward maximum transmit power minus to transmit power. Then the forward initial transmit power is:

P _send ＝min[P _pilot ·10 ^0.6+0.05M ，P _av ]) (3)

And, the base station delivers the reverse channel parameters to the target mobile station through the forward assignment channel. Then the above-mentioned mobile station switches the channel to the above-mentioned specified reverse and forward channels to start transmitting and receiving signals, and the base station also switches to the specified channel unit at the same time, and starts transmitting and receiving signals on the above-mentioned specified forward and reverse channels. After a series of tests and information exchange, the mobile station and the base station start the business communication.

The present invention adopts the existing CDMA air interface protocol and corresponding structure, and the adopted hardware and most of the software are ready-made, so no detailed description is given here.

Claims (4)

1. the distribution method of forward link initial emission power in a code division multiple access (CDMA) system, wherein, described cdma system comprises a travelling carriage, a base station, and by travelling carriage to the reverse link of base station with by the forward link of base station to travelling carriage; Described travelling carriage comprises an emitting-receiving system; The base station comprises an emitting-receiving system and several Channel Elementss, and each Channel Elements is responsible for a concrete channel, comprises specifying this channel transmitting power; It is characterized in that: before dedicated channel allocation, described base station is after receiving the Reverse Access Channel message of described travelling carriage, insert judgement, insert if allow, forward pilot intensity item in the then described base station extraction radio environment measurements report wherein distributes forward link initial emission power according to the described forward pilot intensity item that obtains.

2. the distribution method of forward link initial emission power is characterized in that in the cdma system according to claim 1, and the computing formula of described forward link initial emission power is as follows: $P_{\mathrm{send}}=\min [P_{\mathrm{pilot}}\·{10}^{\frac{D+1.5M}{10}},P_{\mathrm{av}}]---\left(1\right)$

Wherein, P _SendForward direction Initial Trans for appointment;

P _PilotTransmitting power for Forward Pilot Channel;

D is the described travelling carriage information bit bit energy that must satisfy in order to satisfy quality of service requirement and the ratio of disturbance spectrum density;

The forward pilot intensity of M for extracting;

P _AvBe the maximum power that to distribute.

3. the distribution method of forward link initial emission power is characterized in that in the cdma system according to claim 2, and the master of described travelling carriage exhales flow process as follows:

Travelling carriage reports call initiation message on Reverse Access Channel, comprise the measurement report to the affiliated subdistrict Forward Pilot Channel in the message;

This Reverse Access Channel is being monitored in the base station always, after the base station receives the call initiation message of travelling carriage, insert access and judge,, then distribute the various parameters that comprise forward direction and reverse Initial Trans of forward direction and backward channel by the base station decision if this request is allowed to;

The base station is according to the forward pilot strength measurement message that receives, according to formula (1) decision forward direction Initial Trans.

4. the distribution method of forward link initial emission power is characterized in that in the cdma system according to claim 2, and during user of mobile station in incoming call needs the paging sub-district, the quilt of described travelling carriage exhales flow process as follows:

The base station is issuing page message on Forward Paging Channel;

The travelling carriage of being exhaled is being monitored this Forward Paging Channel always, when finding and during oneself the beep-page message of matching addresses, travelling carriage reports page-response message on Reverse Access Channel after certain time-delay, comprise the measurement report to the affiliated subdistrict Forward Pilot Channel;

After the base station receives the page-response message of travelling carriage, insert access and judge,, then distribute the various parameters that comprise forward direction and reverse Initial Trans of forward direction and backward channel by the base station decision if this request is allowed to;

The base station is according to the forward pilot strength measurement message that receives, according to formula (1) decision forward direction Initial Trans.

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