CN1852554A - Alien-frequency hard switching-over method in wide-band CDMA system - Google Patents

Abstract

The invention discloses a method for inter-frequency hard switching in a wideband code division multiple access system, which includes: setting a pseudo-pilot at the same frequency point as the main frequency point of the current cell in an adjacent cell. The UE obtains the pseudo-pilot of the neighboring cell, compares the frequency of the pseudo-pilot with the primary frequency of the current cell, and determines that the neighboring cell is a same-frequency cell. The UE uses the pseudo-pilot to measure the signal strength, quality and synchronization information of the neighboring cell with the same frequency as the current cell. When the measured signal strength and quality exceed the signal strength and quality of the current cell, the radio network controller RNC selects the neighboring cell as the target cell, and the UE uses the measured synchronization information to directly handover from the current cell to the neighboring cell. The present invention does not use dual receivers, does not start the compression mode, and uses pseudo-pilots to perform necessary measurements for switching during normal communication, completes hard switching between different frequencies, and ensures a high success rate of switching between different frequencies.

Description

A method of inter-frequency hard handoff in wideband code division multiple access system

technical field

The invention relates to wideband code division multiple access (WCDMA) system switching technology, in particular to an inter-frequency hard switching method in the WCDMA system.

Background technique

Handover in WCDMA system can be divided into two categories, one is soft or softer handover, and the other is hard handover. During the soft handover process, the user equipment (UE) first establishes a connection with the target cell, and then disconnects the connection with the current cell, that is, the soft handover is first connected and then disconnected. During the hard handover process, the connection between the UE and the current cell is interrupted first, and then a new link is established, that is, the hard handover is disconnected first and then reconnected.

For hard handoffs, there are three categories. Intra-frequency hard handover mainly refers to the use of hard handover at the same frequency; inter-frequency hard handover refers to handover between different frequencies; inter-system handover refers to handover between WCDMA and GSM systems.

For inter-frequency hard handover, it can be divided into measurement-based handover and blind handover in terms of implementation. Measurement-based handover means that the UE measures the signals of adjacent cells, reports the test results to the Radio Network Controller (RNC), and the RNC decides whether to perform handover.

For measurement-based inter-frequency hard handover, there are usually two implementation methods.

One is to enable the implementation method of compressed mode. In the process of inter-frequency hard handover, the UE needs to measure the carriers of adjacent cells, and this measurement requires a certain idle time. When the UE has only one radio frequency receiving unit, it can only decode a signal of one frequency at a time. Therefore, the UE in the communication process must start the compressed mode, acquire idle time, and perform measurements. In the compression mode, the base station compresses the data when sending certain downlink channel frames, and the UE can use the remaining time to perform inter-frequency measurement. The inter-frequency hard handoff method of initiating compressed mode has several disadvantages:

1. It takes a certain amount of time to start the compression mode, and it also takes a certain amount of time to report the measurement report. The signal may decline sharply during this period, resulting in dropped calls, so the handover success rate is relatively low;

2. The idle time obtained by starting the compression mode is not enough, so the measurement time is not enough, which affects the efficiency of system switching;

3. After the transmission data is compressed, the gain will decrease, and the signal quality will also decrease. In order to avoid a significant drop in signal quality, the same signal quality as the signal before compression can be obtained at the receiving end, and the compressed part of the data can be transmitted with a higher transmission power. However, when the transmit power is limited, the signal quality will still decrease;

4. Starting the compression mode will also bring a certain capacity loss.

The other is the implementation method using dual receivers. During the hard handover process, since the UE has two sets of receiving devices, it can still measure different frequencies through another receiver under the condition of ensuring normal communication. This kind of measurement does not adopt the compressed mode and can be carried out early, thereby avoiding the call drop caused by untimely measurement and switching. However, in this method, the UE uses two receivers, which increases the complexity and cost of the UE.

Soft handover is applicable to the handover between cells with the same frequency. Since the two cells use the same frequency, in the process of normal communication, the necessary measurements for handover can be performed without starting the compressed mode.

Contents of the invention

In view of this, the object of the present invention is to provide a method for inter-frequency hard handover in a wideband code division multiple access system, to ensure high-quality inter-frequency hard handover without using compressed mode and without using dual receivers Success rate.

In order to achieve the above object, the invention provides a kind of method utilizing pseudo-pilot to realize the inter-frequency hard handover in wideband code division multiple access system, and the method comprises:

Step a: Set a pseudo-pilot at the same frequency as the main frequency of the current cell in the adjacent cell;

Step b: The UE obtains the pseudo-pilot of the neighboring cell, compares the frequency of the pseudo-pilot with the primary frequency of the current cell, and determines that the neighboring cell is a same-frequency cell;

Step c: The UE uses the pseudo-pilot to measure the signal strength, quality and synchronization information of the neighbor cell that is the same frequency cell as the current cell;

Step d: When the measured signal strength and quality exceed the signal strength and quality of the current cell, the radio network controller RNC selects the neighboring cell as the target cell, and the UE uses the measured synchronization information to directly switch from the current cell to the neighboring cell.

Wherein, at least three channels are set for the pseudo-pilot described in step a: the common pilot channel CCPICH, the primary synchronization channel P-SCH, and the secondary synchronization channel S-SCH.

Wherein, the measurement method described in step c is: measure the signal strength and quality through the CCPICH of the pseudo-pilot, and obtain synchronization information through the CCPICH, P-SCH, and S-SCH of the pseudo-pilot.

Wherein, the power ratio setting of the three channels is the same as that of a conventional cell.

Wherein, the primary scrambling code spreading information of the false pilot described in step a is set to be identical with the primary scrambling code spreading information of the primary frequency point of the adjacent cell;

The method for measuring the synchronous information of adjacent cells described in step c is: measure and obtain the primary scrambling code spreading information in the synchronous information of adjacent cell pseudo-pilots, according to the primary scrambling code spreading information of pseudo-pilots and the primary frequency points of adjacent cells The spreading information of the primary scrambling code is the same, and the spreading information of the primary scrambling code of the primary frequency point of the adjacent cell is obtained.

Wherein, in step d, the synchronization information including the primary scrambling code spreading information of the primary frequency point of the adjacent cell is used to directly switch from the current cell to the traffic channel of the adjacent cell.

Wherein, setting the pseudo-pilot in step a is: setting the pseudo-pilot in the radio frequency device in the base station.

Wherein, the setting of the pseudo-pilot in the radio frequency device in the base station is: the frequency point of the pseudo-pilot and the main frequency point of the adjacent cell are set in the same multi-carrier radio frequency device.

Wherein, the setting of the pseudo-pilot in the radio frequency device in the base station is: the frequency point of the pseudo-pilot and the main frequency point of the adjacent cell are set in two different radio frequency devices.

To sum up, the present invention uses the set pseudo-pilot to perform inter-frequency hard handover. Due to the use of pseudo pilots, when the UE is a single receiver, inter-frequency measurement can be performed without starting the compression mode, and inter-frequency hard handover can be completed. In the normal communication process, the present invention can make full and timely measurement by using the pseudo-pilot frequency, thereby reducing the probability of call drop in the switching measurement process and ensuring a higher success rate of switching between different frequencies. The present invention utilizes the same frequency point and the same primary scrambling code spreading information as the current cell to obtain the information of the primary frequency point of the adjacent cell by obtaining the pseudo-pilot information of the adjacent cell, thereby simplifying the process for the UE to obtain the information of the adjacent cell.

Description of drawings

FIG. 1 is a step diagram of the inter-frequency hard handover method of the present invention.

Detailed ways

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

The present invention uses pseudo-pilots to perform inter-frequency hard handover. The main idea is: firstly, the base station installs pseudo-pilot equipment, and sets pseudo-pilot channels and parameters, and then uses pseudo-pilots to complete necessary measurements with soft-handover measurement ideas, and finally Inter-frequency hard switching is completed.

Suppose cells S1 and S2 are adjacent cells, the primary frequency point of S1 cell is F1, and the primary frequency point of S2 cell is F2.

The method for implementing inter-frequency hard handover by using pseudo pilots will be described in detail below in conjunction with FIG. 1 .

Step 101, setting a pseudo-pilot with frequency F1 in cell S2.

The frequency point F1 of the pseudo-pilot is set in the radio frequency device. The two frequency points F1 and F2 of the S2 cell can be respectively set in two radio frequency devices, or can share a multi-carrier radio frequency device.

The main frequency point F2 carries all the channels required by the WCDMA system, including the common pilot channel (CCPICH), the primary synchronization channel (P-SCH), the secondary synchronization channel (S-SCH), the common control physical channel (CCPCH), and the dedicated Physical channel (DPCH), etc.

For the pseudo-pilot, only three channels are set: CCPICH, P-SCH and S-SCH. The power ratio of each channel is the same as that of a conventional cell.

The frequency point F1 of the pseudo-pilot is set to spread the same main scrambling code as the main frequency point F2.

As in the above steps, the S2 cell with the pseudo-pilot set is called a pseudo-pilot cell, and the S2 cell uses frequency points F1 and F2, wherein the F1 frequency point is a pseudo frequency point, and the F2 frequency point is a main frequency point. The S1 and S2 cells are adjacent cells, and the S1 cell is a non-pseudo-pilot cell, using the frequency point F1. The S2 cell is identified by its pseudo-frequency point F1, so that it is exactly the same as the main frequency point of the S1 cell.

Step 102, the UE obtains the pseudo-pilot of the S2 cell. Since the S2 cell has a pseudo-frequency point F1 with the same frequency as the S1 cell, compare the frequency point of the pseudo-pilot with the main frequency point of the S1 cell, and judge that the S2 cell is the one of the S1 cell. same frequency area. Therefore, when the UE is connected to the S1 cell, it can use the measurement idea of soft handover to perform measurement, specifically as in step 103 .

In step 103, the UE uses the pseudo-pilot to measure the information of the S2 cell. Measure the signal strength and quality through the CCPICH at the F1 frequency point, and obtain synchronization information through the CCPICH, P-SCH, and S-SCH at the F1 frequency point. Since the primary scrambling code information of the F1 frequency point of the S2 cell is the same as the primary scrambling code information of the F2 frequency point, the primary scrambling code information of the F2 frequency point can be obtained by obtaining the primary scrambling code information of the F1 pseudo frequency point. Since F1 and F2 of S2 are completely synchronized, the UE obtains synchronization with F1, and also obtains synchronization with F2.

In step 103, the measurement necessary for switching can be completed without starting the compression mode, thereby avoiding performance degradation caused by the compression mode.

In step 104, the UE switches from the S1 cell to the S2 cell. If the signal quality of the S1 cell drops, when the signal strength and quality measured in step 103 exceed the signal strength and quality of the S1 cell and the handover condition is met, the RNC selects the S2 cell as the target cell according to the measurement report reported by the UE, and Command the UE to switch to the F2 frequency of the S2 cell. The UE first disconnects from the F1 frequency of the S1 cell, and then uses the synchronization information obtained in step 103 including the primary scrambling code spreading information to directly switch to the traffic channel of the F2 frequency of the S2 cell.

If the UE needs to switch from the S2 cell to the S1 cell, according to the above pseudo pilot setting method, the pseudo pilot with the frequency point F2 is set in the S1 cell, and then the handover can be completed according to the above pseudo pilot inter-frequency hard handover method.

If you want to use pseudo-pilots for inter-frequency hard handover, multiple pseudo-pilots can be set in a base station, and the frequency points of each pseudo-pilot are the main frequency points of the surrounding adjacent cells. Among devices, multi-carrier radio frequency devices can also be shared.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (9)

1, the alien-frequency hard switching-over method in a kind of broadband CDMA system is characterized in that, this method comprises:

Step a: the pilot beacon of putting identical frequency with the current area dominant frequency is set in the adjacent area;

Step b:UE obtains the pilot beacon of adjacent area, and relatively the frequency of pilot beacon and the dominant frequency point of current area judge that obtaining the adjacent area is co-frequency cell;

Step c:UE utilizes pilot beacon to measure and signal strength signal intensity, quality and the synchronizing information of current area for the adjacent area of co-frequency cell;

Steps d: when the signal strength signal intensity that records and quality surpassed the signal strength signal intensity of current area and quality, it was Target cell that radio network controller (RNC) is selected the adjacent area, and UE utilizes the synchronizing information that records, and directly switches to the adjacent area from current area.

2, method according to claim 1 is characterized in that, the described pilot beacon of step a is provided with three channel: Common Pilot Channel CCPICH, primary synchronization channel P-SCH at least, from synchronizing channel S-SCH.

3, method according to claim 2 is characterized in that, the described method of measurement of step c is: by the CCPICH measure signal intensity and the quality of pilot beacon, CCPICH, P-SCH, S-SCH by pilot beacon obtain synchronizing information.

4, method according to claim 2 is characterized in that, the power ratio setting of described three channels is identical with conventional sub-district.

5, method according to claim 1 is characterized in that, the main scrambler spread spectrum information of the described pilot beacon of step a is provided with identical with the main scrambler spread spectrum information of adjacent area dominant frequency point;

The method of the synchronizing information of the described measurement of step c adjacent area is: measure the main scrambler spread spectrum information in the synchronizing information of adjacent area pilot beacon, main scrambler spread spectrum information according to pilot beacon is identical with the main scrambler spread spectrum information of adjacent area dominant frequency point, obtains the main scrambler spread spectrum information of adjacent area dominant frequency point.

6, method according to claim 5 is characterized in that, steps d is utilized the synchronizing information of comprising of adjacent area dominant frequency point of main scrambler spread spectrum information, directly switches on the Traffic Channel of adjacent area from current area.

7, method according to claim 1 is characterized in that, the described pilot beacon that is provided with of step a is: pilot beacon is set in the radio-frequency devices in the base station.

8, method according to claim 7 is characterized in that, the described pilot beacon that is provided with in the radio-frequency devices in the base station is: the frequency of described pilot beacon and adjacent area dominant frequency point are arranged in the same multicarrier radio-frequency devices.

9, method according to claim 7 is characterized in that, the described pilot beacon that is provided with in the radio-frequency devices in the base station is: the frequency of described pilot beacon is arranged in two different radio-frequency devices with adjacent area dominant frequency point.

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