CN100407853C - Adjustment Method of Primary and Secondary Carrier Frequency in Multi-carrier Frequency Cell in TD-SCDMA System - Google Patents

Abstract

A method for adjusting primary and secondary carrier frequencies in a multi-carrier frequency cell in a TD-SCDMA system. In a multi-carrier frequency cell, one carrier frequency is selected as the primary carrier frequency, and other carrier frequencies are used as secondary carrier frequencies; the cell is established and the primary carrier frequency is activated. TS0 and DwPTS time slots, shield the TS0 and DwPTS time slots of the auxiliary carrier frequency, configure the main common channel to the main carrier frequency; the P-CCPCH on the main carrier frequency adopts omnidirectional coverage, and all UEs receive Broadcast messages; measure the power, interference and load of the main and auxiliary carrier frequencies, and evaluate the available resources of the main and auxiliary carrier frequencies according to the measurement results. Initiate primary and secondary carrier frequency switching. Using the method of the present invention, users can be accepted on both the main and auxiliary carrier frequencies, the probability of collision is small, and the probability of success in admission is high.

Description

Adjustment Method of Primary and Secondary Carrier Frequency in Multi-carrier Frequency Cell in TD-SCDMA System

Technical field:

The invention relates to the adjustment of primary and secondary carrier frequencies in a multi-carrier frequency cell in a TD_SCDMA (Time Division-Synchronous Code Division Multiple Access) system.

Background technique:

In order to meet the continuous increase of traffic in a cell, it is usually necessary to use multiple carrier frequencies in a cell. However, if the cell is configured according to the current TD-SCDMA protocol, and several carrier frequencies with DwPTS and TS0 are used in one cell, then a UE (User Equipment, user) at the cell junction will face difficulties in cell search, Problems such as measurement complexity and switching difficulties.

In the multi-carrier frequency suggestion of the TD Alliance (hereinafter referred to as "suggestion"), for each cell, one of the allocated frequency points is determined as the main carrier frequency, and the remaining frequency points are used as auxiliary carrier frequencies. The main carrier frequency and auxiliary carrier frequency use the same scrambling code and basic midamble (intermediate code). In order to solve the problems of difficult cell search and handover, within the same cell range, DwPTS and TS0 are only sent on the main carrier frequency, and the frequency points of the main and auxiliary carrier frequencies are fixed, so it is necessary to broadcast information SIB11, The relevant secondary carrier frequency information is added to the SIB12, and the frequency information of the relevant secondary carrier frequency is provided in corresponding dedicated information (such as a measurement control message).

Since all users in the cell are admitted on the main carrier frequency and then allocated to each carrier frequency, the probability of admission collision is high. At the same time, users who switch to the local cell measure the information of the main carrier frequency, but may be finally allocated on the auxiliary carrier frequency, so the handover process is relatively complicated, and the probability of successful handover is not high.

Invention content:

The technical problem to be solved by the present invention is to provide a method for dynamically adjusting the main and auxiliary carrier frequencies in the cell multi-carrier frequency coverage mode. The primary and secondary carrier frequencies are dynamically adjusted according to the available resources of the primary and secondary carrier frequencies.

Technical scheme of the present invention is:

1.1 In a multi-carrier frequency cell, select one carrier frequency as the main carrier frequency, and other carrier frequencies as auxiliary carrier frequencies; the main carrier frequency and auxiliary carrier frequency use the same scrambling code and basic midamble (Midamble); among them, the main carrier frequency The selection is random, or it can be configured in the background;

1.2 Establish a cell, activate the TS0 and DwPTS time slots of the main carrier frequency, and send signals in the TS0 and DwPTS time slots of the main carrier frequency; shield the TS0 and DwPTS time slots of the auxiliary carrier frequency, and TS0 and DwPTS of the auxiliary carrier frequency do not send signals, Configure the main common channel on the main carrier frequency; there is no P-CCPCH on the auxiliary carrier frequency, and the P-CCPCH on the main carrier frequency adopts omnidirectional coverage mode, and all UEs receive broadcast messages on the main carrier frequency;

1.3 Measure the power, interference and load of the main and auxiliary carrier frequencies, and evaluate the available resources of the main and auxiliary carrier frequencies according to the measurement results; the higher the power of the carrier frequency, the higher the interference, and the heavier the load, the more resources it can use. Conversely, the less available resources the carrier frequency can use; the evaluation of the available resources can make the weighted value of these measurements; a delay time can be set, and every other delay time can be used for the power of the main and auxiliary carrier frequencies, The interference and load are measured once, and the available resources of the primary and secondary carrier frequencies are evaluated according to the measurement results.

1.4 If there is no auxiliary carrier frequency that can use more resources than the main carrier frequency, go to step 1.3; otherwise, broadcast the message that the main carrier frequency needs to be reconfigured, so that all UEs can receive broadcasts on the new main carrier frequency message, and go to step 1.5.

1.5 Initiate the main and auxiliary carrier frequency switching, switch the currently used main carrier frequency to the auxiliary carrier frequency, delete its common channel, switch the auxiliary carrier frequency with the most available resources to the main carrier frequency, and establish on the new main carrier frequency Public channel, go to step 1.2.

In the present invention, it is one of the conditions to determine that the available resources of the auxiliary carrier frequency are better than the available resources of the main carrier frequency:

(1) Q _{main_frequency} < Q _worst and Q _{sub_frequency} > Q _threshold

(2): Q _{sub_frequency} > Q _best and Q _{main_frequency} < Q _threshold

(3): Q _{main_frequency} < Q _{sub_frequency} -Q _hysteresis

in:

Q _{main_frequency} is the resource available on the main carrier frequency;

Q _{sub_frequency} is the resource available on the auxiliary carrier frequency;

Q _worst is the threshold at which the available resources on the main carrier frequency are lower than the worst value;

Q _best is the threshold at which available resources on the secondary carrier frequency are higher than the best value;

Q _threshold is a threshold of available resources on the main and auxiliary carrier frequencies;

Q _hysteresis A hysteresis parameter of resources on primary and secondary carrier frequencies.

Use method of the present invention, can bring following effect:

(1) Both the main and auxiliary carrier frequencies can be accepted, so the admission can be performed at several frequency points, and the collision probability is smaller than the method proposed in the "suggestion".

(2) The switched-over user and the newly switched-on user measure the information of the main carrier frequency, and at the same time, accept it on the main carrier frequency, which has a higher probability of successful admission than the method proposed in the "suggestion".

(3) Perform admission judgment on the primary carrier frequency and allocate resources on the secondary carrier frequency, requiring a handover process for the UE from the primary carrier frequency to the secondary carrier frequency.

(4) Since new users entering the cell are always admitted on the main carrier frequency, users who have already camped on the original carrier frequency can be admitted on the original carrier frequency if they are synchronized with the original carrier frequency. Reselection reduces the burden on the UE.

Description of drawings:

Figure 1: After the cell is established, the initial primary and secondary carrier frequency allocation diagram;

Figure 2: After the main and auxiliary carrier frequency switching, the distribution diagram of the main and auxiliary carrier frequency;

Fig. 3: the flow chart of the main steps of the dynamic adjustment of the main and auxiliary carrier frequencies in the present invention;

Figure 4: User distribution diagram of each carrier frequency at time T1;

Figure 5: At time T2, the user distribution diagram of each carrier frequency before handover;

Figure 6: At time T3, the user distribution diagram of each carrier frequency after handover;

Fig. 7: The detailed flowchart of the dynamic adjustment of the primary and secondary carrier frequencies in the present invention.

Detailed ways:

In a multi-carrier frequency cell, a cell is configured with multiple carrier frequencies (generally, carrier frequencies with the same coverage), and all carrier frequencies form a carrier frequency group G (F0, F1...Fn), and both primary and secondary carrier frequencies can receive new services. However, new user services in the current cell (referring to users who are newly powered on or switched to the cell) can only be accessed on the main carrier frequency. The main difference between the main carrier frequency and the auxiliary carrier frequency is that: the main carrier frequency TS0 (time slot 0) and DwPTS (downlink pilot time slot) time slots are active, and the auxiliary carrier frequency TS0 and DwPTS time slots are turned off. The UE reads broadcast messages and paging messages on the new main carrier frequency. That is to say, the signal is sent in the TS0 and DwPTS time slots of the main carrier frequency. The TS0 and DwPTS of the auxiliary carrier frequency do not send signals, and the main common channel is configured on the main carrier frequency. There is no P-CCPCH on the auxiliary carrier frequency, and the P-CCPCH on the main carrier frequency adopts omnidirectional coverage mode, and all UEs receive broadcast messages on the main carrier frequency.

The UE's initial cell search process can be divided into the following four steps: 1. Search for the cell with the best signal on a certain carrier frequency; 2. Detect the DwPTS of the cell and establish downlink synchronization; 3. Obtain the cell scrambling code and basic Midamble code (middle 4. Determine the position of P-CCPCH (Primary Common Control Physical Channel), obtain control multiframe synchronization, and read BCH (Broadcast Channel) information. From the above process, it can be seen that since only the DwPTS on the main carrier works, and the DwPTS time slot on the auxiliary into the main carrier frequency. When the user on the auxiliary carrier frequency loses downlink synchronization for any reason, it needs to perform the cell search process again, and finally can only access to the main carrier frequency.

The basic idea of the present invention is that the main carrier frequency and the auxiliary carrier frequency are not fixed, and the available resources on the main and auxiliary carrier frequency will change with the establishment of a new connection on the main carrier frequency and the release of the connection on the auxiliary carrier frequency. The RNC (Radio Network Controller) evaluates the quality of all carrier frequencies by comprehensively evaluating the power, interference, and load of the main and auxiliary carrier frequencies. The higher the power of the carrier frequency, the higher the interference, and the heavier the load, the more resources it can use. more; on the contrary, the carrier frequency can use less resources. The evaluation of the amount of available resources can make the weighted value of these measurement quantities; if there is an auxiliary carrier frequency whose available resources are better than the current main carrier frequency, switch the currently used main carrier frequency to an auxiliary The secondary carrier frequency that uses the most resources is switched to the primary carrier frequency. When the main carrier frequency is about to change, for the user service accepted on the carrier frequency, it is not necessary to notify the user to switch, but only need to tell it that the main carrier frequency has changed.

Fig. 3 describes the main steps of the present invention, and Fig. 7 describes the detailed process of the present invention in detail. Described below:

As shown in step 1 of Figure 3, the CRNC (controlling radio network controller, controlled radio network controller) identifies the cell through the C-ID (cell identifier), and uses the resources provided by the Node B through the local cell ID. Node B configures cells according to the messages received from CRNC. The configuration of the main and auxiliary carrier frequencies in the cell can be configured by the background database. If the background database is not configured, then a frequency point is randomly selected as the main carrier frequency, and all other frequency points are used as auxiliary carrier frequencies. Corresponding to the flow of the cell establishment and the previous part in Figure 7 . As shown in Figure 1 and Figure 4, cell C has four carrier frequencies in total: f1, f2, f3 and f4. Select the carrier frequency f1 as the main carrier frequency, and the other three carrier frequencies f2, f3 and f4 are auxiliary carrier frequencies.

According to step 2 in FIG. 3 , broadcast messages and downlink synchronization messages are only sent on the main carrier frequency, and the TS0 and DwPTS time slots of the auxiliary carrier frequency are closed. Corresponding to "turn on the TS0 and DwPTS of the main carrier frequency, turn off the TS0 and DwPTS of the auxiliary carrier frequency, and send broadcast messages and downlink synchronization codes on the main carrier frequency" in Fig. 7 . In this way, although there are multiple frequency points available in the cell, only the main carrier frequency has information on the DwPTS at any time. Since the newly powered-on users and the users handed over to the current cell can only detect the DwPTS information of the main carrier frequency during cell search, these UEs can only access the main carrier frequency.

According to the measurement information of the power, interference and load of the primary and secondary carrier frequencies, the available resources of the primary and secondary carrier frequencies are comprehensively evaluated, as shown in step 3 in FIG. 3 and corresponding steps in FIG. 7 . Obtain information about the current resource occupancy of each frequency point. The assessment of available resources can be performed based on power, interference and load, which is the weighting of these measurement quantities. The available resource quantity Q can be calculated by weighting Q=1-(F1+F2+F3+Fn) of the measured quantity. Among them: F1 is a function of power, which increases with the increase of power; F2 is a function of interference, which increases with the increase of interference; F3 is a function of load, which increases with the increase of load; Fn is the function of other factors A factor for comprehensive consideration, such as the number of users on the carrier frequency, business volume, number of successful receptions, and number of dropped calls. The definitions of the functions F1, F2, F3 and Fn are related to the specific implementation process and algorithm, and this patent only shows how to consider these factors related to the carrier frequency quality. It can be seen from the calculation expression that when the power is greater or the interference is stronger or the load is heavier, the amount of available resources will be less.

After a hysteresis time Thysteresis, if the available resources on the main and auxiliary carrier frequencies satisfy the following inequality 1, 2 or 3, the frequency point of the main carrier frequency is switched to an appropriate auxiliary carrier frequency point. A delay time is set here to prevent frequent switching of the main and auxiliary carrier frequencies.

If the number of available resources on the main carrier frequency and an auxiliary carrier frequency satisfies the following equation, then the main and auxiliary carrier frequencies are switched:

Inequality 1: Q _{main_frequency} < Q _worst and Q _{sub_frequency} > Q _threshold

Inequality 2: Q _{sub_frequency} > Q _best and Q _{main_frequency} < Q _threshold

Inequality 3: Q _{main_frequency} < Q _{sub_frequency} -Q _hysteresis

Among them, the definition of each parameter is as follows:

Q _{main_frequency} is the resource available on the main carrier frequency;

Q _{sub_frequency} is the resource available on the auxiliary carrier frequency;

Q _worst is the threshold at which the available resources on the main carrier frequency are lower than the worst value;

Q _best is the threshold at which available resources on the secondary carrier frequency are higher than the best value;

Q _threshold is a threshold of available resources on the main and auxiliary carrier frequencies;

Q _hysteresis A hysteresis parameter of resources on primary and secondary carrier frequencies.

According to the judgment criterion of the switching frequency point, if the current conditions do not meet the requirements of the switching frequency point, the main carrier frequency will still stay at the current frequency point. Otherwise, switch the main frequency point to an auxiliary frequency point with the best conditions. Users who have established downlink synchronization with the auxiliary carrier frequency do not need to switch to the main carrier frequency if they can maintain synchronization. When the UE initiates a call or is paged by the system, it can initiate an RRC connection on the current carrier frequency. process and allocate dedicated resources. After a period of time, the condition of the auxiliary carrier frequency f4 is better than that of the main carrier frequency f1 (f4 is also the best condition among the carrier frequencies f2, f3 and f4). At this time, the news that the main and auxiliary carrier frequencies will be reconfigured is broadcast, as shown in the figure Step 4 of 3 and the corresponding steps in Figure 7 enable the UE to receive broadcast information on the new main carrier frequency after a specific SFN or a specific time (in order for the UE to receive it, the broadcast may need to last for a period of time) .

According to step 5 in Fig. 3 and the last step in Fig. 7, switch the main carrier frequency of the cell from f1 to f4, and switch the carrier frequency f1 to the auxiliary carrier frequency. The specific handover process is as follows: as shown in Figure 4, before the handover, there are users Ui, 1, Ui, 2...Ui, ml on the carrier frequency fi, since the carrier frequency f1 is the main carrier frequency, after a period of time, as shown in Figure 5 It shows that the carrier frequency f1 camps and switches into some new users V1, V2...Vm. When in all carrier frequencies, when the condition of f4 becomes the best, carry out the switching of main and auxiliary carrier frequency, the currently used main carrier frequency f1 is switched to auxiliary carrier frequency, and auxiliary carrier frequency f4 is switched to main carrier frequency; after switching, Users U1, 1, U1, 2...U1, m1 and V1, V2...Vm on carrier frequency f1 continue to reside on carrier frequency f1; users residing on carrier frequency f2, f3 and f4 remain unchanged, and carrier frequency Users on f4 do not feel that they have switched from the auxiliary carrier frequency to the main carrier frequency. After a period of time, as shown in Figure 6, some new users W1, W2...Wn reside and switch in on the main carrier frequency f4. As time goes by, the main carrier frequency may switch from carrier frequency f4 to other carrier frequencies. During this process, it is assumed that no user turns off or switches out of the cell, otherwise the number of users camping on each carrier frequency will gradually decrease.

The method of the present invention only sends DwPTS and broadcast information (TS0) on the main carrier frequency, multiple frequency points use a common broadcast channel, and the common control channels DwPCH, P-CCPCH, PICH, etc. of the same cell are only configured on the main carrier frequency superior. At the same time, the configuration of the main and auxiliary carrier frequencies changes dynamically. According to the measurement of the available resources of the main and auxiliary carrier frequencies in the cell, when the available resources of the main and auxiliary carrier frequencies change greatly, changing the frequency point of the main carrier frequency will It switches to an auxiliary carrier frequency with more available resources. Since both the main and auxiliary carrier frequencies can be accepted, the acceptance can be performed at several frequency points, so the probability of collision is small. If the users who have camped on the original carrier frequency are synchronized with the original carrier frequency, they can be admitted on the original carrier frequency. Since no cell reselection is required, the burden on the UE is reduced. At the same time, since only the main carrier frequency has TS0 and the auxiliary carrier frequency does not, TS0 interference is also relatively small. The UE has a relatively high probability of successfully switching directly to the main carrier frequency by measuring the PCCPCH RSCP measurement of the main carrier frequency.

Claims (3)

1. the major-minor carrier frequency method of adjustment of multi-carrier frequency cell in the TD-SCDMA system may further comprise the steps:

1.1 in multi-carrier frequency cell, select a carrier frequency as main carrier frequency, other carrier frequency are as assistant carrier frequency; Main carrier frequency uses identical scrambler and the Midamble of basic midamble code with assistant carrier frequency;

1.2 set up the sub-district, activate the time slot 0 and the descending pilot frequency time slot of main carrier frequency, at the time slot 0 and the descending pilot frequency time slot transmission signal of main carrier frequency; The time slot 0 and the descending pilot frequency time slot of shielding assistant carrier frequency, the time slot 0 and the descending pilot frequency time slot of assistant carrier frequency do not send signal, and the Your Majesty is total to channel configuration to main carrier frequency;

1.3 power, interference and load to major-minor carrier frequency are measured, according to the stock number used of the major-minor carrier frequency of measuring of outcome evaluation;

If can use resource greater than a thresholding that can use resource on the major-minor carrier frequency less than using resource to be lower than on the thresholding of worst-case value and the assistant carrier frequency on the main carrier frequency 1.4 can use resource on the main carrier frequency, or can use resource can use resource less than a thresholding that can use resource on the major-minor carrier frequency on the assistant carrier frequency greater than using resource to be higher than on the thresholding of best values and the main carrier frequency on the assistant carrier frequency, or can use resource on the main carrier frequency less than using resource to deduct the sluggish parameter of resource on the major-minor carrier frequency on the assistant carrier frequency, then

Broadcast the message that major-minor carrier frequency will be reshuffled, make all users all on new main carrier frequency, receive broadcast, and forward step 1.5 to; Otherwise forward step 1.3 to;

Switch 1.5 initiate major-minor carrier frequency, current use main carrier frequency is switched to assistant carrier frequency, delete its common signal channel,, on new main carrier frequency, set up common signal channel, change step 1.2 using the maximum assistant carrier frequency of stock number to switch to main carrier frequency.

2. the major-minor carrier frequency method of adjustment of multi-carrier frequency cell in the described TD-SCDMA of claim 1 system is characterized in that, the selection of main carrier frequency be at random or backstage configuration.

3. the major-minor carrier frequency method of adjustment of multi-carrier frequency cell in the described TD-SCDMA of claim 1 system, it is characterized in that, a lag time is set, power, interference and load to major-minor carrier frequency in the described step 1.3 are measured, according to the stock number used of the major-minor carrier frequency of measuring of outcome evaluation, be to carry out once every a lag time.

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