CN1134921C - Method for Allocating Traffic Channel Frequency in Code Division Multiple Access Mobile Communication System - Google Patents

Abstract

The invention relates to a method for selecting the frequency of a channel when allocating channels for services in a code division multiple access mobile communication system. According to the total load on a frequency point, it is determined whether the frequency point is connected to a new service; and the load on each frequency point is balanced. Including: setting N load thresholds from small to large for each frequency point, and correspondingly setting N+1 priorities from large to small; the base station periodically measures the current load of each frequency point, and the load threshold value Compare and determine the priority of each frequency point; the base station selects the frequency point with the highest priority for the user, and the user who switches to this frequency point establishes a service channel with the base station; the base station counts the number of failures of the selected frequency point and adjusts priority.

Description

Method for Allocating Traffic Channel Frequency in Code Division Multiple Access Mobile Communication System

technical field

The invention relates to the technical field of mobile communication, in particular to a resource allocation technology in a Code Division Multiple Access (CDMA) mobile communication system, that is, a method for selecting the frequency of a channel when realizing channel allocation for a service in the CDMA mobile communication system.

Background technique

With the rapid growth of business demand and number of users in the field of mobile communication technology, system capacity has always been a matter of great concern to designers. The current code division multiple access (CDMA) mobile communication system adopts a new multiple access method, including using orthogonal codewords to distinguish users, using spread spectrum technology to reduce interference, etc., so that the number of access users can be greatly increased on limited spectrum resources. The system capacity is no longer limited by the specific number of frequency points or time slots, but by the total interference of the system. In other words, to make the system have the maximum capacity, the interference should be reduced to the lowest value, that is, to achieve the overall goal of reducing system interference from all aspects. Therefore, how to reduce system interference has become an important content of expanding the capacity of CDMA mobile communication system.

In frequency division multiple access (FDMA) and time division multiple access (TDMA) communication systems, since the same-channel interference and adjacent-channel interference between channels have a significant impact on system capacity, the system interference can be reduced by planning frequencies reasonably. There are correspondingly more researches done on this basis. However, in the CDMA communication system, since the frequency reuse coefficient of CDMA can be considered to be 1 in theory, that is, the same-channel interference can be ignored, so the frequency planning problem can be simplified, and the corresponding engineering and related technical documents are rarely involved. To further optimize the performance of the CDMA system by planning and allocating frequencies (frequency points). However, the reality is that due to the incomplete orthogonality of pseudo-random codes, there is reverse interference between cells at the same frequency point, so the frequency reuse coefficient of the CDMA mobile communication system is greater than 1, that is, the frequency reuse coefficient between the same frequency The interference cannot be ignored, and this kind of interference shows that the capacity of adjacent cells when sharing frequency points is lower than that of different frequency points.

Looking at the existing CDMA mobile communication systems, in order to facilitate soft handover, generally at least one common frequency is used in all cells. However, as mentioned above, co-channel interference still exists in the CDMA communication system, so when the number of users is relatively large and the amount of switching is relatively large, it is necessary to allow users with a high possibility of switching to occupy the shared frequency first to reduce hard Switching times, reducing the drop rate.

In the code division multiple access mobile communication system, the current method of selecting the frequency of the channel when assigning the channel for the service is: the mobile station searches for all pilot signals on a common frequency point in the idle state, so as to have a good enough wireless transmission condition. The base stations keep in touch, and only when all the pilot signals on the common frequency point are lower than a certain threshold value, the mobile station will select another different frequency point (also called different frequency point) for pilot signal search . That is to say, as long as channel access can be realized on the current shared frequency point, other frequency points will not be searched. After the mobile station initiates a request on the access channel, the base station will allocate a traffic channel to the mobile station on the frequency point where it is located.

In this current method, the mobile station does not distinguish between common frequency points and different frequency points when selecting frequency points. Users and edge users use different frequency points, resulting in frequent hard handovers during calls, which greatly limits the advantages of CDMA soft handovers.

At the same time, when there are multiple frequency points in the cell, the load of each frequency point cannot be the same, and the interference on the frequency point with heavy load is also large. In the current method, the mobile station cannot independently select the optimal frequency point with light load, but keeps searching for the pilot signal on the frequency point that can be accessed, that is, the frequency point remains unchanged as long as it can be accessed, so the mobile station It is possible to select a frequency point with heavy load and large interference, and this frequency point may not be able to provide a large traffic service for this mobile station due to the heavy load. Taking a step back, even if this frequency point can Providing services also consumes more transmit power of base stations and mobile stations than selecting other frequency points, increasing interference to other users.

From the above analysis, it can be seen that when the mobile station accesses, the system does not compare the load between frequency points, and the final allocated traffic channel may be on the frequency point with heavy load, because the frequency point with heavy load has large interference , the mobile station and the base station have to transmit with greater power, which in turn increases the interference to other users of the frequency point (including the interference of users of the same frequency point in the cell and adjacent cells), and deteriorates the channel condition. Other frequency points with lighter loads are idle and unused, resulting in a waste of resources. It is unavoidable that the idle frequency point is not selected, and the selected frequency point can only be accessed but cannot provide services. In severe cases, it is very likely that the cell cannot provide services to users even though there are idle frequency points in the cell. Analyzing the above-mentioned situations, in the final analysis, this is because the base station did not carry out overall measurement when allocating frequency points to the mobile station, and lacked adjustment functions, resulting in uneven service distribution.

To sum up, for a CDMA mobile communication system whose capacity is limited by interference, the capacity depends on the interference, and the interference depends on the business load. Therefore, it is possible to maximize the system capacity only when the load is evenly distributed.

Contents of the invention

The purpose of the present invention is to design a method for allocating service channel frequencies in a code division multiple access mobile communication system, which is a method for selecting the frequency of the channel when realizing allocating channels for services, and solves the problem of uneven distribution of frequency points in existing methods Defects, realize the optimal frequency point selection, in order to reduce the transmission power, reduce interference, and increase the system capacity.

The method of the present invention is based on the frequency allocation principle of load balancing at each frequency point, including deciding whether to access new services at a frequency point according to the total load on a frequency point, and balancing the load on each frequency point.

The technical scheme that realizes the object of the present invention is such: a kind of method for allocating service channel frequency in the code division multiple access mobile communication system, it is characterized in that comprising following logic processing steps:

A. Set N load thresholds lower than full load for each frequency point, and set N+1 priorities from large to small for the N load thresholds from small to large;

B. The base station periodically measures the current load of each frequency point, and determines the priority of each frequency point according to the comparison results between the current load of the frequency point and the N load thresholds;

C. The base station selects the frequency point with the highest priority for the mobile station user, and the mobile station user switched to the frequency point establishes a service channel with the base station;

D. The base station counts the number of failures of the frequency points selected for allocation, and when there are continuous service access failures at a certain frequency point, the priority of the frequency point is reduced or the use of the frequency point is prohibited.

In the step A, the frequency points include shared frequency points and non-shared frequency points. When setting the load threshold value, the load threshold values of each priority level of the shared frequency points are lower than those of the non-shared frequency points. The load threshold of the corresponding priority.

The non-shared frequency points are respectively less than 50% of full load, 50-70% of full load, 70-90% of full load, 90-95% of full load, and greater than full load at the load threshold 95% of the time, the corresponding priority levels are 1 to 5; the shared frequency point, the load threshold value is less than 40% of the full load, 40-60% of the full load, 60% of the full load -80%, 80-90% of full load, and greater than 90% of full load, the corresponding priority levels are 1 to 5 respectively.

In the step B, the base station periodically measures the current load of each frequency point, including measuring the forward signal load and reverse signal load of each frequency point; determining the priority of each frequency point includes determining the priority of the forward signal load The priority of the forward signal load and the reverse signal load; the load on a certain frequency point is the ratio of the forward signal load priority to the reverse signal load priority on the frequency point.

The described periodic measurement of the current load of each frequency point by the base station is to periodically measure the forward signal load and the reverse signal load of each frequency point by the base station transceiver, and report to the base station controller; then the base station controller performs priority determination.

The forward signal load of a frequency point is based on the ratio of the total transmit power of the base station at the frequency point to the maximum transmit power of the base station; the reverse signal load of a frequency point is based on the Based on the total received interference (RSSI) on the frequency point.

The above is based on the total interference (RSSI) received by the base station at this frequency point, which is calculated by using the formula 1/(1-M/M _max ), where M is the current mobile station user at this frequency point M _max is the maximum number of mobile station users that can be supported by this frequency point.

In the step C, the base station selects and allocates the frequency point with the highest priority for the mobile station user, which is to preferentially select the frequency point with high priority for allocating the forward signal load; the priority of the forward signal load at the two frequency points is equal At the same time, a frequency point with a high priority for allocating the reverse signal load is preferentially selected.

In the step C, the base station selects and allocates the frequency point with the highest priority for the mobile station user, and also includes selecting and allocating the shared frequency point and the non-shared frequency point according to the type of the mobile station user.

The determination of the user type of the mobile station further includes: the base station controller monitors the reverse access channel, and when receiving the paging response message when the mobile station user is called or the call initiation message when the mobile station user is calling, The user type of the mobile station is judged according to the strength of the pilot signal and the fading rate of the pilot.

The described judgment of mobile station user type according to pilot signal strength and pilot frequency fading rate includes: respectively setting the threshold of pilot frequency signal strength and pilot frequency fading rate; pilot signal strength is reported by mobile station user, base station The strength of the pilot signal is calculated, and the pilot fading rate reflecting the amount and rate of change of the pilot signal is calculated; it is compared with the preset pilot signal strength threshold and pilot fading rate threshold; the mobile station user who meets any threshold is judged It is a switching user, otherwise it is a resident user.

The determination of the mobile station user as a handover user or a resident user further includes using a parameter Tuser of 0 or 1 to indicate that the mobile station user is a handover user or a resident user, respectively.

The selection and allocation of shared frequency points and non-shared frequency points according to the type of mobile station users further includes: when the shared frequency points and non-shared frequency points are at the same priority level, preferentially select and allocate shared frequency points for handover mobile station users Frequency point, when the priority of the shared frequency point is low, randomly select and allocate the remaining frequency point with the highest priority, and the resident mobile station users preferentially choose to allocate non-shared frequency points; When the levels are different, the users of the handover type or the resident type mobile station will choose the frequency point with the highest allocation priority first.

In the step D, the base station counts the number of failures of the selected allocated frequency points, and also includes setting two parameters of the number of business failures and the number of business failure thresholds.

In the step D, the priority of the frequency point is lowered when there are continuous service access failures at a certain frequency point, which further includes: adding 1 to the number of business failures every time a service access fails or a call is dropped, and When the number of failures is greater than the threshold number of service failures, the priority of the corresponding frequency point will be lowered by one level.

The said lowering the priority of the corresponding frequency point by one level includes lowering the priority of the forward signal load of the frequency point by one level, and lowering the priority of the reverse signal load of the frequency point by one level.

Realize the method for allocating service channel frequency in the code division multiple access mobile communication system of the present invention, it is characterized in that comprising the following steps:

a. The base station periodically measures the current load of each frequency point, including forward signal load and reverse signal load;

b. Determine the priority of the forward signal load and the priority of the reverse signal load at each frequency point;

c. The base station judges the accessed mobile station user as a handover user or a resident user;

d. The base station selects the shared frequency point with the highest priority for handover users, and selects the non-shared frequency point with the highest priority for resident users;

e. The base station allocates the traffic channel on the selected frequency point to the user;

f. The base station updates the priority of the selected frequency point according to the number of service failures.

The method for allocating traffic channel frequencies in a code division multiple access mobile communication system of the present invention is a frequency allocation method based on load balancing. The method also takes into account the convenience of soft handover for users, and treats shared frequency points and different frequency points differently. Points, assigning frequency points and other technologies according to the probability of user switching. Including: in order to achieve frequency point load balancing, when assigning service channels to users, frequency points are selected according to the reverse load before the frequency point; in order to facilitate the realization of soft handover, the number of hard handovers is reduced, and priority is allocated to users with high handover probability Shared frequency points; determine the frequency point load including forward load and reverse load, based on the ratio of the total transmission power of the base station at a certain frequency point to the maximum transmission power and the total interference received; and according to the frequency point load The method of judging the priority, and the priority needs to be continuously adjusted according to the service completion rate after the frequency point is actually allocated.

The method for allocating service channel frequency in the code division multiple access mobile communication system of the present invention has simple algorithm realization, can be closely combined with the protocol, and is convenient for realization. Compared with the current algorithm, in principle, it can balance the load of frequency points, reduce the transmission power of base stations and mobile stations, reduce interference, increase system capacity, and also reduce the possible number of hard handovers and optimize system performance .

Description of drawings

Fig. 1 is the system structural block diagram of the CDMA mobile communication system that adopts the method of the present invention.

Fig. 2 is a block diagram of the processing flow for selecting and allocating frequency points by the method of the present invention.

Detailed ways

The technology of the present invention will be further described through embodiments and accompanying drawings in combination with a CDMA2000 mobile communication system.

Referring to Fig. 1, the code division multiple access mobile communication system shown in the figure adopts a frequency allocation scheme based on load balancing. It includes a mobile station 20 and a base station 10. Wherein, the mobile station 20 includes a transmitter receiver, and the base station 10 includes several (assumed to be 3) transmitter receivers (also known as base station transceivers, including frequency processing units) 101, 102, 103, respectively working in three frequency bands. Points f1, f2, and f3, and set the common frequency point as f1, and each frequency point can support multiple user access. In the figure, 104 is a base station controller, and 105 is a mobile switching center. The system work includes the reverse link from the mobile station 20 to the base station 10 and the forward link from the base station 10 to the mobile station 20. Whether a certain frequency point can access new services depends on the total load on the frequency point.

Referring to Figure 2, the process of the system allocating traffic channel frequencies is:

Step 21, periodically measure the load of each frequency point, and the base station transceivers 101 to 103 take Tch as a cycle to periodically measure the reverse signal strength RSSI (reflecting the reverse signal strength RSSI of the frequency point f1-f3) reported by the mobile station 20 on the frequency point Loads) Rload1-Rload3 and forward loads Fload1-Fload3 of corresponding frequency points f1-f3. The base station transceivers 101 to 103 report the measured forward loads Fload1-Fload3 and reverse loads Rload1-Rload3 on frequencies f1-f3 to the base station controller 104, and the base station controller 104 makes a priority determination.

To measure the load on each frequency point, the forward and reverse loads should be considered comprehensively. Among them, the forward load can be measured based on the ratio of the total transmission power of the above-mentioned base station at a certain frequency point to the maximum transmission power, expressed as: forward Load Fload = forward transmission power/total transmission power of the base station; measuring the reverse load can be based on the total interference (RSSI) received by the above-mentioned base station at a certain frequency point, which can be expressed as: reverse load Rload = RSSI = 1 /(1-M/Mmax), M is the current number of users, and Mmax is the maximum number of supported users.

The above-mentioned base station has been periodically measuring the load of each frequency point, and the measurement object includes the forward and reverse load on a frequency point.

It should be noted that in the third generation (3G) code division multiple access mobile communication system, the load asymmetry usually manifests as heavy forward load and light reverse load (such as when multiple users download high-speed data services at the same time) ; At the same time, the business itself usually has the same amount of forward and reverse traffic (such as voice service) or the forward is larger than the reverse traffic (such as data service), so the forward load should be the bottleneck when considering the frequency load.

Step 22, determine the priority of each frequency point, the base station controller 104 according to the corresponding relationship between the preset frequency point load and priority, the forward load Fload1-Fload3 on the f1-f3 frequency points reported by the base station controller 104 Perform priority determination with reverse loads Rload1-Rload3 to obtain forward frequency point priority Fpri and reverse frequency point priority Rpri respectively.

The specific method of determining the priority of each frequency point is as follows:

When the forward and reverse load of a frequency point is lower than the first threshold value Th1, the priority of the frequency point is set to 1; when the forward and reverse load of a frequency point is lower than the second threshold value Th2 but higher than When the first threshold value is Th1, the priority of the frequency point is set to 2, and so on. N thresholds can be set, correspondingly there are (N+1) priority levels. It is assumed here that there are 4 thresholds, which are 50% (Th1), 70% (Th2), 90% (Th3), and 95% (Th4) of full load, and the corresponding 5 priority levels are from high to low. is 1 to 5. Since the shared frequency point f1 is more used for soft handover, and more shared frequency point resources should be reserved for soft handover in adjacent cells, the priority decision threshold of the shared frequency point f1 is selected as 40% of the full load (Th1) , 60% (Th2), 80% (Th3), 90% (Th4). Corresponding to the common frequency point f1 and the different frequency points f2 and f3, each frequency point priority generates five levels: G1 (frequency point load<Th1), G2 (Th1<frequency point load<Th2), G3 (Th2<frequency point load <Th3), G4 (Th3<frequency load<Th4), G5 (frequency load>Th4).

And because the forward and reverse frequency points are used symmetrically, the load of a frequency point on the forward and reverse links must not exceed a certain threshold, that is, the service can only be admitted when the forward and reverse links are allowed to access services. Therefore, when measuring the frequency load and determining the priority, the front and reverse loads must also be considered comprehensively. Therefore, the forward and reverse loads of a frequency point each have a priority value. As mentioned above, when measuring the load of a certain frequency point and judging that its priority is G4 (Th3<frequency point load<Th4), call barring and handover access should be performed; when measuring the load of a certain frequency point, judging its When the priority is G5 (frequency point load > Th4), the service should be banned.

For each frequency point load (including shared frequency point load and different frequency point load), the ratio of the forward load Fload to the reverse load Rload is the frequency load, and the corresponding relationship with the priority can be expressed in the following table: Measured load value priority 1 priority 2 Priority 3 Priority 4 Priority 5 Fload/Rload (different frequency points) <50% 50-70% 70-90% 90-95% >95% Fload/Rload (shared frequency point) <40% 40-60% 60-80% 80-90% >90%

Step 23, access mobile station user, base station controller 104 is monitoring reverse access channel all the time, if mobile station 20 initiates a call, then according to the pilot frequency selected during its idle state on the reverse (enhanced) access channel Send a call initiation message; if mobile station 20 is called, then above-mentioned base station 10 sends a paging message up and down the forward (fast) paging channel, and mobile station 20 is monitoring the forward (fast) paging channel all the time, judges paging Whether the paging message matches its own address, if it matches, the mobile station 20 will report a paging response message on the reverse access channel after certain processing, if not, continue to execute until it matches.

After the base station controller 104 receives the paging response message that the mobile station 14 is called or the call initiation message that the mobile station 14 is calling, it first judges the user type of the mobile station according to the pilot strength and the pilot fading rate, and determines the user type of the mobile station. It is a switch-type user or a resident user, and is represented by the parameter Tuser (here, a switch-type user refers to a new user who initiates a call, indicating that the user has a higher probability of switching in the future, which is different from a user in the process of switching). If it is a switching user, the parameter Tuser is 1, and if it is a resident user, the parameter Tuser is 0.

The so-called handover mobile station users refer to users with a higher handover probability. After a rough analysis, it can be considered that handover users are mobile station users whose connection status with the reference base station wireless link is not good enough, that is, the pilot strength is relatively low. Low users, or mobile station users who are moving fast and moving away from the current base station, can be characterized by the pilot fade rate.

The specific judgment can be realized by setting two thresholds, one is the threshold for judging the pilot signal strength (Pilot_stre_th), and the other is the threshold for judging the pilot fading rate (Pilot_chanrate_th), and the threshold for judging the pilot fading rate is switching Among the fast-moving users, the threshold of the pilot signal strength is used to judge that it is a marginal user among the handover users. When any one of the two thresholds is satisfied (or reached), it can be judged as a handover user, Tuser=1; otherwise, it is a resident user Tuser=0.

The pilot strength can be reported by the mobile station; the pilot fading rate should be within a certain time range (in the access state), and the pilot frequency is calculated by the base station controller (BTS) according to several pilot strengths continuously reported by the mobile station. The amount of change and the rate of change are compared with the threshold of the preset pilot fading rate, and the unit of the measurement value can be dB/ms.

Step 24 to step 27, select the frequency point for the mobile station, the base station controller 104 selects the frequency point for the mobile station user according to the determination result of the mobile station user type, that is, the parameter Tuser and the load status of each frequency point, that is, the priority Fpri/Rpri, The selection goal is to select the frequency point f with the highest priority for the mobile station user, and the selection principle is:

If the user type of the mobile station is switching type Tuser=1 (fast mobile user or edge user), the shared frequency point is given priority in the frequency point with the highest priority, and if the priority of the shared frequency point is low, the remaining priorities are randomly selected The highest frequency point is assigned (step 24, step 25, step 27); correspondingly, if the mobile station user type is a resident type Tuser=0 (non-fast mobile user or edge user), the non-shared frequency point is preferred. Frequency points are allocated, and shared frequency points are reserved (step 26); only when shared frequency points and other frequency points are at the same priority level, then the shared frequency points are preferentially selected according to user type, if the shared frequency points and other frequency points If the priorities are different, the frequency point with the highest priority is selected first.

When determining the priority according to the load, since the forward and reverse loads of each frequency point have a priority, select the frequency point with a higher forward priority when allocating frequency points for services. If the forward priority of two frequency points is the same , select the frequency point with higher reverse priority.

Step 28, allocate the traffic channel on the selected frequency point for the mobile station user, the base station controller 12 sends the selected frequency point to the mobile station 20 through the FCCH, and the mobile station 20 is switched to the frequency specified by the base station controller 104 point, and then establish a traffic channel with the base station transceiver on the corresponding frequency point.

In step 29, the priority is updated according to the number of service failures, and the base station controller 104 adjusts the priority of the selected frequency point according to whether the service access after frequency point allocation is successful or not. Including: once the service access fails or the call is dropped once, then add 1 to the flag Cfail, Cfail=Cfail+1; within a certain period of time, if the flag Cfail is greater than a threshold flag Thfail, Cfail>Thfail, then the corresponding frequency The priority value Fpri/Rpri of the point is lowered by 1 level, that is, Fpri/Rpri=Fpri/Rpri+1. The priority value of each frequency point should be updated according to the periodic measurement results. It can be characterized by setting parameters during implementation: including the number of business failures and the business failure threshold, which can be expressed as Ser_fail_num and Ser_fail_th respectively.

The number of service failures is the number of service access failures caused by hardware, network and other non-access parts, or the algorithm is not well considered, and the business load of the unexpected cell is too large, and the service cannot be accessed. In short, the statistical service The purpose of updating the number of failures and updating the priority of frequency points is to make up for and correct the wrong allocation of frequency points, and reduce the possibility of future allocation errors.

If there are several consecutive service failures at a certain frequency point, it can be recorded. On the one hand, the priority of this frequency point is lowered or even banned, so as to avoid communication failures after accessing services in the future; on the other hand, the detection part can be triggered to check the frequency point. Check whether components such as the channel processor are abnormal.

When implementing the method of the present invention, on the basis of the current CDMA mobile communication system design, the base station transceiver is required to increase two measured values: the pilot decay rate and the number of business failures, and the requirement to set the frequency point load in the background database Measurement cycle.

Claims (16)

1. the method for distribution service channel frequency in the CDMA mobile communication systems is characterized in that comprising following logical process step:

A. be lower than fully loaded load door limit value and a descending N+1 priority be set for each frequency point setting N for N ascending load door limit value correspondence;

B. periodic measurement each frequency in base station is worked as preload, and determines the priority of each frequency when the comparative result of preload and N load door limit value according to this frequency;

C. the base station is that user of mobile station is selected to distribute the highest frequency of priority, and Traffic Channel is set up in the user of mobile station and the base station that switch on this frequency;

D. the base station reduces the priority of this frequency or bans use of this frequency when the service access failure appears in certain frequency continuously fail number statistics of the frequency of selected distribution.

2. the method for distribution service channel frequency in a kind of CDMA mobile communication systems according to claim 1, it is characterized in that: in the described steps A, described frequency comprises shared frequency and non-shared frequency, when the load door limit value is set, allow the load door limit value of shared each priority of frequency all be lower than the load door limit value of non-shared each respective priority of frequency.

3. the method for distribution service channel frequency in a kind of CDMA mobile communication systems according to claim 2, it is characterized in that: described non-shared frequency, be respectively less than fully loaded 50%, fully loaded 50-70%, fully loaded 70-90%, fully loaded 90-95% at the load door limit value, and during greater than fully loaded 95%, pairing priority is respectively 1 to 5 grade; Described shared frequency is respectively less than fully loaded 40%, fully loaded 40-60%, fully loaded 60-80%, fully loaded 80-90% at the load door limit value, and during greater than fully loaded 90%, pairing priority is respectively 1 to 5 grade.

4. the method for distribution service channel frequency in a kind of CDMA mobile communication systems according to claim 1, it is characterized in that: among the described step B, periodic measurement each frequency in base station is worked as preload, comprises the forward signal load and reverse signal load of measuring each frequency; The priority of determining each frequency comprises the priority of definite forward signal load and the priority of reverse signal load; Load is the ratio of forward direction signal load priority and reverse signal load priority on this frequency on certain frequency.

5. according to the method for distribution service channel frequency in claim 1 or the 4 described a kind of CDMA mobile communication systems, it is characterized in that: describedly work as preload by each frequency of base station periodic measurement, be forward signal load and reverse signal load by each frequency of base station transceiver periodic measurement, and the reporting base station controller; Carrying out priority by base station controller again judges.

6. the method for distribution service channel frequency in a kind of CDMA mobile communication systems according to claim 4 is characterized in that: the forward signal of described frequency load is that the ratio with the total transmitting power of base station on this frequency and the maximum transmission power of base station is a foundation; The reverse signal of described frequency load is to be foundation with base station received total interference volume on this frequency.

7. the method for distribution service channel frequency in a kind of CDMA mobile communication systems according to claim 6 is characterized in that: described is foundation with base station received total interference volume on this frequency, is to utilize formula 1/ (1-M/M _Max) the calculating acquisition, M is the current mobile station number of users of this frequency, M _MaxIt is the supported maximum user of mobile station number of this frequency.

8. the method for distribution service channel frequency in a kind of CDMA mobile communication systems according to claim 1, it is characterized in that: described step C, the base station is that user of mobile station is selected to distribute the highest frequency of priority, is the preferential high frequency of priority of selecting to distribute the forward signal load; When the priority of the forward signal of two frequencies load is identical, the then preferential high frequency of priority of selecting to distribute the reverse signal load.

9. the method for distribution service channel frequency in a kind of CDMA mobile communication systems according to claim 2, it is characterized in that: among the described step C, the base station is that user of mobile station is selected to distribute the highest frequency of priority, also comprises the selection distribution of carrying out shared frequency and non-shared frequency according to the type of user of mobile station.

10. the method for distribution service channel frequency in a kind of CDMA mobile communication systems according to claim 9, it is characterized in that: the judgement of described user of mobile station type, further comprise: monitor Reverse Access Channel by base station controller, during call initiation message when page-response message when receiving that user of mobile station is exhaled or user of mobile station master exhale, carry out the type of this user of mobile station according to pilot signal strength and pilot tone rate of fading and judge.

11. the method for distribution service channel frequency in a kind of CDMA mobile communication systems according to claim 10, it is characterized in that: describedly carry out the user of mobile station type according to pilot signal strength and pilot tone rate of fading and judge, comprising: the thresholding that pilot signal strength and pilot tone rate of fading are set respectively; Pilot signal strength is reported by user of mobile station, and the base station calculates the pilot tone rate of fading of reflection pilot signal variable quantity and rate of change according to the pilot signal strength that reports continuously; Compare with default pilot signal strength thresholding and pilot tone rate of fading thresholding; The user of mobile station that satisfies any thresholding is judged to be the switch type user, otherwise is resident type user.

12. the method for distribution service channel frequency in a kind of CDMA mobile communication systems according to claim 11, it is characterized in that: describedly user of mobile station is judged to be the switch type user or for resident type user, also comprises with parameter Tuser being 0 or being 1 to represent that respectively it is the switch type user or is resident type user.

13. the method for distribution service channel frequency in a kind of CDMA mobile communication systems according to claim 9, it is characterized in that: the selection that described type according to user of mobile station is carried out shared frequency and non-shared frequency distributes, further comprise: when shared frequency and non-shared frequency are in same priority, for the switch type user of mobile station preferentially selects to distribute shared frequency, when the priority of shared frequency is hanged down, select at random to distribute the highest frequency of all the other priority, for resident type user of mobile station preferentially selects to distribute non-shared frequency; In the priority of shared frequency and non-shared frequency not simultaneously, switch type or resident type user of mobile station are all preferentially selected the highest frequency of priority for use.

14. the method for distribution service channel frequency in a kind of CDMA mobile communication systems according to claim 1, it is characterized in that: among the described step D, the base station also comprises service fail number and two parameters of service fail threshold number are set to fail number statistics of the frequency of selected distribution.

15. the method for distribution service channel frequency in a kind of CDMA mobile communication systems according to claim 1, it is characterized in that: among the described step D, when appearring in certain frequency continuously, the service access failure reduces the priority of this frequency, further comprise: the every failure of service access once or call drop once, the service fail number is added 1, and at the service fail number during, the priority of corresponding frequency is reduced one-level greater than the service fail threshold number.

16. the method for distribution service channel frequency in a kind of CDMA mobile communication systems according to claim 15, it is characterized in that: described priority with corresponding frequency reduces the priority reduction one-level that one-level comprises that the priority that the forward signal of this frequency is loaded reduces one-level and the reverse signal of this frequency is loaded.