JP2004363950A - Cdma terminal and multipath synchronizing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CDMA terminal and a multipath synchronizing method that eliminate the need to always perform multipath searching operation, make a path search at an adequate time, and suppress a circuit scale as much as possible. <P>SOLUTION: A hand-over destination is predicted according to results of level measurement and/or quality of a peripheral cell and the cell at the hand-over destination is previously synchronized. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a CDMA terminal and a multipath synchronization method.
[0002]
[Prior art]
An example of a conventional CDMA receiver and a path search is described in Japanese Patent Application Laid-Open No. 2000-050338 of Patent Document 1.
The standardized specifications such 3GPP ⁽³ rd Generation Partnership Project) has to be performed in time specified measurements of the N neighboring cells. In addition, a result of measuring a neighboring cell and a change in the state of the cell are determined as an event and reported to the network. On the network side, a handover cell is specified for the mobile device (terminal) according to the event type and the report level. In addition, there is a provision that a mobile station instructed to perform handover adds a communication cell within T time.
[0003]
For this reason, the function has conventionally been realized using one of the following two methods.
As a first method, the multipath of the N neighboring cells is measured so that the N neighboring cells can be measured at the same time and the path of the communication finger can be synchronized immediately in response to a request for adding a communication cell from the network. There is a method of always performing a search operation.
[0004]
As a second method, the N peripheral cells are sequentially measured in a time-division manner with a hardware unit less than N, which is the number of peripheral cells, and after the network issues an instruction to add a communication cell, the N peripheral cells are measured. There is a method of performing a multipath search at high speed and determining the assignment of communication fingers. In this second conventional example, the path detection range is narrowed to detect the path at high speed.
[0005]
Japanese Patent Laid-Open Publication No. Hei 9-512141 of Patent Document 2 discloses that a reception level of a signal of a cell adjacent to a service cell is measured, and at least one adjacent cell is set as a candidate cell for handover based on the measurement. A handover method with the step of selecting as is described.
[0006]
Further, as one of the conventional techniques, for example, Japanese Patent Application Laid-Open No. 2000-321371 of Patent Document 3 can be cited. This publication describes a handover process in a terminal and a base station that constitute a wireless communication system. In this process, it is also described that intermittent open search is performed.
[0007]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2000-050338 [Patent Document 2]
Japanese Patent Publication No. 9-512141 [Patent Document 3]
JP 2000-321371 A
[Problems to be solved by the invention]
In the first method, since it is necessary to always perform a multipath search operation for N peripheral cells, the circuit scale becomes large. Further, in the second method, since it is necessary to perform a path search in a short time, fading and noise averaging may not be performed sufficiently, and an erroneous finger may be assigned. Performance may be degraded. In addition, since the path search is performed in a short time, there is a problem that the circuit scale of the corresponding portion also increases.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present invention uses the following method. In order to measure the levels of the N peripheral cells, the levels of the N peripheral cells are measured by appropriately using time-division hardware units less than N in the peripheral cell measuring unit. For this reason, it is not necessary to always perform a path search for all N cells. If the judgment condition to add to the communication cell among the measured cells is satisfied and an event occurrence is reported to the network as specified in the standardized specifications, before the network gives an instruction to add the cell to the communication, , Of the reported cells, the path synchronization of the cell satisfying the condition for adding to the communication cell (the cell determined to be added to the communication cell) is started. Upon receiving an instruction to add the cell to the communication cell from the network, path synchronization information is assigned to the communication finger. If a cell addition instruction has not been received from the network even after a certain period of time has elapsed, the operation of constantly performing a path search for the cell is stopped.
[0010]
With the above operation, it is possible to perform high-speed and stable handover with a small circuit scale (for example, a circuit scale smaller than the number N of peripheral cells).
[0011]
In other words, the invention of the CDMA terminal according to claim 1 predicts a handover destination based on a result of level measurement and / or quality of a neighboring cell, and performs synchronization of the cell of the handover destination in advance. It is characterized by having done.
[0012]
An invention of a CDMA terminal according to claim 2 is a CDMA terminal having a communication unit, a peripheral cell measuring unit, and a cell addition condition determining unit, wherein the peripheral cell measuring unit measures a delay profile of the peripheral cell. A measurement delay profile generation unit, a measurement path assignment unit that notifies the multipath timing to the measurement finger unit, a measurement finger unit and a measurement rake combining unit, and the measurement finger unit and The measurement rake combining unit measures the reception level and / or reception quality of the target cell and outputs it to the cell addition condition determination unit. It is characterized in that it is determined whether or not there is, and a handover destination is predicted, and synchronization of the cell of the handover destination is performed in advance.
[0013]
According to a third aspect of the present invention, in the second aspect, the CDMA terminal includes a communication delay profile generating unit, a communication path allocating unit, a communication finger, and a communication RAKE combining unit. Further comprising a communication unit, wherein the communication delay profile generation unit creates a delay profile of a cell under communication, and the communication path assignment unit includes a multipath with a good reception level based on the created delay profile. And notifies the communication finger of the path timing, and the communication finger despreads the received data A / D-converted via the antenna unit and the radio unit by the notified path timing. The demodulation is performed, and the communication rake (RAKE) combining unit performs rake combining of demodulated data for each multipath.
[0014]
The invention of a CDMA terminal according to a fourth aspect is the CDMA terminal according to the third aspect, further comprising a communication control unit for controlling the communication unit, wherein the communication control unit is notified of the target cell.
[0015]
According to a fifth aspect of the present invention, in the CDMA terminal according to the fourth aspect, the peripheral cell measurement unit has a timer unit, and the measurement control unit that controls the peripheral cell measurement unit is connected to the CDMA terminal by a network. Before being notified from, the time is executed by the timer for the target cell determined to be used for communication, the measurement kindergarten profile unit and the measurement not being used for measurement of the peripheral cells and the It is characterized in that the unit of the measurement path allocator is notified to continue the delay profile creation and path allocation for the cell.
[0016]
According to a sixth aspect of the present invention, in the CDMA terminal according to any one of the second to fifth aspects, the communication delay profile generator and the measurement delay profile generator are provided in common. I do.
[0017]
In the invention of the multipath synchronization method according to claim 7, a handover destination is predicted based on a result of level measurement and / or quality of neighboring cells, and synchronization of the handover destination cell is performed in advance. It is characterized by.
[0018]
The invention of the multipath synchronization method according to claim 8 measures a reception level and / or reception quality of a target cell, determines whether the target cell is a cell to be used for communication, and determines a handover destination. In this case, the handover destination cell is synchronized in advance.
[0019]
In the multipath synchronization method according to the ninth aspect, the reception level and / or the reception quality of the target cell is measured to determine whether the target cell is a cell to be used for communication. When the condition is added to the target cell by transmitting to the network, the path synchronization of the target cell for which the additional condition is satisfied is started and time counted.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
According to the present invention, in a CDMA mobile terminal, a handover destination is predicted on the mobile device (mobile terminal) side based on a level measurement result of a neighboring cell, and path synchronization of the handover destination cell is performed in advance. An object of the present invention is to provide a CDMA terminal and a multipath synchronization method capable of performing handover at high speed with a small circuit scale.
[0021]
FIG. 1 is a configuration diagram of a CDMA terminal of the present invention used in a path synchronization system. As shown in this figure, the measurement delay profile generation unit (13) measures the delay profile of the neighboring cell, and the measurement path allocation unit (14) notifies the multipath timing to the measurement finger unit (15). . The measuring finger unit (15) and the measuring RAKE combining unit (measuring rake combining unit) (16) measure the reception level and the reception quality. A cell addition condition determination unit (17) determines whether the cell is a cell to be used for communication based on the measured reception quality and reception level of the cell. The measurement result and the condition determination result of the cell are notified to the network via the transmission unit (11). In addition, for a cell that satisfies the cell addition condition, empty units of the measurement delay profile generating unit (13) and the measurement path allocating unit (14) are set before the network is instructed to add a cell. The multipath synchronization is started in advance by using this. When a handover instruction is received from the network, the communication finger (8) can be notified of the finger assignment information whose path has been synchronized in advance, so that the communication finger (8) can be activated without initial path synchronization. As described above, handover can be realized at high speed with a small circuit scale.
[0022]
Referring to FIG. 1, a CDMA terminal according to the present invention includes an antenna (1), a radio unit (2), an A / D (analog / digital) conversion unit (3), a communication unit (4), and a transmission unit (11). It comprises a D / A converter (12). The peripheral cell measurement unit (5), the cell addition condition determination unit (17), the measurement control unit (18), and the communication control unit (10) are computers (central processing units; processors; data processing units) that operate under the control of programs. May be implemented.
[0023]
The communication unit (4) includes a communication delay profile generation unit (6), a communication path assignment unit (7), a communication finger (8), and a communication RAKE combining unit (9).
[0024]
The peripheral cell measuring unit (5) includes a measuring delay profile measuring unit (13), a measuring path allocating unit (14), a measuring finger (15), a measuring RAKE combining unit (16), and a timer unit (19). And
[0025]
A CDMA terminal having such a configuration operates as follows.
Radio waves from the base station are received as analog data by the antenna (1) and the radio unit (2). The received analog data is converted into a digital signal by the A / D converter (3). This digital signal is input to the communication unit (4) and the peripheral cell measurement unit (5).
[0026]
The communication unit (4) is controlled by the communication control unit (10). The communication delay profile generation unit (6) has k units, and creates a delay profile of up to k communication cells based on the digital signal input by the A / D conversion unit (3).
The communication path allocating unit (7) selects a multipath with a good (high) reception level based on the created delay profiles up to k, and sets a maximum of one for each unit of the communication finger (8). Notify j path timings. Each unit of the communication finger (8) performs despreading and demodulation of the received data (digital signal input by the A / D conversion unit (3)) at designated timings. The communication RAKE combining unit (9) RAKE-combines the demodulated data for each of the multipaths up to j at the maximum, whereby a path diversity effect can be obtained.
[0027]
The peripheral cell measurement unit (5) is controlled by the measurement control unit (18), and periodically monitors the reception level and reception quality of the peripheral cells not used for communication.
The measurement delay profile generation unit (13) is composed of a plurality of units. Each unit receives the digital signal input by the A / D conversion unit (3), and transmits a spreading code specified by a network and a base station. Using the timing, a delay profile of each peripheral cell is created. Based on the respective delay profiles, the measurement path allocator (14) having the number of units corresponding to the number of units of the measurement delay profile generator (13) detects the top m peak positions of the delay profile. Thus, the position of the multipath (delay amount: path timing amount) is estimated, and a maximum of m path timings are notified to each unit of the measuring finger (15) having m units.
[0028]
As shown in FIG. 1, a measurement finger (15) composed of a maximum of m units is input by an A / D conversion unit (3) at a maximum of m path timings notified to a measurement RAKE combining unit (16). The obtained digital signal is output, and the measuring RAKE combining unit (16) combines the received signals to measure the reception level and the reception quality.
The measurement delay profile generator (13) and the measurement path allocator (14) are configured to be able to simultaneously measure n cells by n units. For example, when it is necessary to measure 32 cells in 800 ms and it takes 20 ms to measure one cell, only one of the delay profile measuring unit and the path allocating unit is used for time-division measurement of peripheral cells.
[0029]
The measured reception levels and reception qualities of the neighboring cells are compared by the cell addition condition determination unit (17) with the levels and qualities of the cells being communicated, and determination is made as to whether or not a certain threshold is exceeded. Is In addition, the level and quality of the cell under communication are measured by the communication unit (4) and notified to the communication control unit (10).
The reception level and quality (for example, energy per bit, C / N ratio, SNR, FER, etc.) measured by the neighboring cell measurement unit (5) and the determination result determined by the cell addition condition determination unit (17) are measured control signals. The section (18) is notified. At the same time, the communication control unit (8) is notified, and the cell quality, level information, and condition determination are performed via the transmission unit (11), the D / A conversion unit (12), the radio unit (2), and the antenna (1). The result is notified to the base station.
[0030]
If there is a cell that satisfies the cell addition determination condition, the measurement control unit (18) causes the timer unit (19) to start counting, and the measurement delay profile unit (13) and the measurement path allocation unit (14) A unit that is not used for the measurement of the neighboring cell is notified so as to continuously execute the creation of the delay profile and the path assignment of the cell. Hereinafter, this operation is expressed as “perform path synchronization (execute path synchronization)”. When the communication control unit (10) receives an instruction to add the cell from the network via the communication unit (4), the measurement control unit (19) transmits the path timing information of the cell to the communication control unit (10). ) To stop the path synchronization of the cell. The communication control unit (10) notifies the communication finger (8) of the path timing of the cell, and controls to use the cell for communication.
If the timer unit (19) times out before an instruction to add the cell is received from the network, the continuation of the path synchronization of the cell is stopped (the execution of the path synchronization is stopped).
[0031]
<Description of Operation of Embodiment>
Next, the overall operation of the present embodiment will be described in detail with reference to the configuration diagram of the CDMA terminal shown in FIG. 1 and the flowcharts of FIGS. For the sake of explanation, hereinafter, the maximum number k of cells that can communicate simultaneously is set to 6, and the number n of units of the measurement delay profile generation unit (13) and the measurement path allocation unit (14) is set to 7. Also, it will be described that 32 peripheral cells are measured within 800 ms, and it takes 20 ms to measure around one cell. However, these values are values used for description, and other values are set. And may be performed under different conditions.
[0032]
First, an operation example shown in FIG. 2 will be described.
From the network (base station), via the antenna (1), the radio unit (2) and the A / D conversion unit (3), the communication unit (4) and the peripheral cell measurement unit (5) Receive designation of surrounding cells to monitor level and quality. Cell information of # 1 to # 32 is notified to the communication control unit via the communication unit (STEP 1-1).
The communication control unit (10) notifies the measurement control unit (18) of the designation of the cell to be measured (STEP1-2).
The measurement controller (18) operates the measurement delay profile generator (13) and the measurement path allocator (14) of the unit to determine the level and quality of the cell, and assigns 1 to m to the measurement finger (15). Of the multipath positions (delay timing amount), and for the measurement fingers, m measurement fingers constituting the measurement finger are replaced by a maximum of m measurement fingers notified to the measurement RAKE combining unit (16). A maximum of m output signals from the digital signal input by the A / D converter (3) are output to the measurement RAKE combiner (16) at the path timing of, and the measurement RAKE combiner (16) The received signals are combined to measure the received level and the received quality (STEP 1-3). This operation is repeated by the number of target cells (measurement target cells) to measure 32 cells over 32 × 20 ms = 640 ms.
[0033]
When the measurement of all cells is completed, the cell addition / deletion condition determination unit (17) determines whether there is a cell to be added to the communication, and the level of the cell (target cell) determined by the measurement control unit (18). , Quality and determination (STEP 1-4).
The measurement control unit (18) notifies the communication control unit (10) of the measurement result of the level and quality of 32 cells and the determination result of the cell addition condition to the communication control unit (STEP 1-5). The communication control unit transmits the measurement result and the condition determination result to the base station via the transmission unit (11), the D / A conversion unit (12), the radio unit (2), and the antenna (1).
If the cell addition condition is not satisfied, the measurement control unit (18) returns to STEP 1-3 and repeats the operation (STEP 1-6).
[0034]
When the additional condition of the cell is satisfied, the measurement control unit (18) determines the continuation of the path synchronization of the upper six cells from the cell with the higher level or higher quality among the cells for which the additional condition is satisfied, from the units 2 to 7. It notifies the measurement delay profile generation unit (13) and the measurement path allocation unit (14). At the same time, the timer section (19) starts counting by the timer (STEP 1-7). The timer value is a preset value. Thereafter, the measurement delay profile generation unit (13) and the measurement path allocation unit (14) of the units 2 to 7 operate continuously until a stop request is issued from the measurement control unit (18). After performing the processes up to this point, the process returns to STEP 1-3, and this process (measurement) is repeated until all 32 cells have been processed.
[0035]
Next, an operation when a change of a communication cell and a monitored peripheral cell is instructed from the network based on the measurement result of the peripheral cell reported by the mobile device will be described with reference to FIG.
[0036]
A change designation of a communication cell and a peripheral cell to be monitored is received from the network. For the designation, cell information of # 1 to # 32 is notified to the communication control unit from the base station via the communication unit (STEP 2-1).
The communication control unit (10) notifies the measurement control unit (18) of the designation of the cell to be measured and the designation of the added communication cell (STEP 2-2).
[0037]
The measurement control unit (18) determines the path position where the path synchronization of the added communication cell is performed by the units 2 to 7 performed in STEP 1-7, via the communication control unit (10). The assignment unit is notified (STEP 2-3). Thereby, the communication unit can add a communication cell at high speed without performing initial synchronization of path detection. When the communication control unit is notified of the path synchronization of the units 2 to 7, the path synchronization of the units 2 to 7 is stopped, and the counting of the timer unit (19) is also stopped. Thereafter, the operation returns to STEP1-3.
[0038]
The case where the timer count of the timer section (19) has expired will be described with reference to FIG.
The measurement control unit (18) is notified that the timer count of the timer unit (19) has expired (STEP 3-1).
The path synchronization of the units 2 to 7 is stopped (STEP 3-2).
[0039]
Further, an example of the cell addition / deletion determination method described in STEPs 1-4 will be described with reference to FIG. In the present embodiment, a simple method will be described for simplifying the description. In 3GPP (3 ^rd Generation Partnership Project), this determination method may be a determination method based on a standardized specification of an event determination method for notifying a network of a change in cell state.
[0040]
The determination of the measured neighboring cells is started (STEP 4-1).
It is determined whether the measured level or quality of the neighboring cell #i has become better than the level or quality of the cell in communication (determination result A) (STEP 4-2).
It is determined whether or not the measured level or quality of the neighboring cell #i is equal to or higher than a preset threshold (determination result B) (STEP 4-3).
If at least either the determination result A or the determination result B is true (STEP4-4), the cell is set as an addition target cell (STEP4-5). That is, if either the determination result A or the determination result B is true, or if both the determination result A and the determination result B are true, the cell becomes an addition target cell, and otherwise, it is determined that the cell is not an additional cell. You.
The processing of STEP4-2 to STEP4-5 is repeated for the number of measured cells (STEP4-6 to STEP4-7). Either STEP4-2 or STEP4-3 may be the previous step, and the order shown in FIG. 5 may be reversed.
[0041]
As for the operation when the communication cell is deleted, the communication unit (4) measures the reception level and the quality, the communication control unit (10) determines the deletion condition, and notifies the network.
[0042]
By the above operation, the number of units for the delay profile generation unit and the path allocation of the peripheral cell measurement unit is smaller than the number of cells to be measured, so that the circuit scale can be reduced. Furthermore, for cells that are likely to be added to communication, path synchronization can be started before designation from the network, so that high-speed and accurate multipath finger assignment can be performed.
[0043]
<Other embodiments>
Next, another embodiment of the present invention will be described.
In the above-described embodiment, the measurement unit (4) and the delay profile generation unit of the neighboring cell measurement unit (5) are prepared independently. However, these resources can be shared and managed. This can further reduce the required circuit scale. Further, an operation example using the CDMA terminal having such a configuration is the same as the operation example of the above-described embodiment, and thus the description of the operation will be omitted.
[0044]
【The invention's effect】
According to the present invention, a condition is determined in accordance with the measured level and quality of a neighboring cell, and it is predicted in advance that a cell addition is required from the network, and a path search process is performed on the corresponding neighboring cell. Control is performed so that the multipath timing of a cell added as a handover destination can be quickly and accurately assigned, thereby improving communication performance.
[0045]
The reason is that before the handover instruction from the network is received, the mobile terminal can anticipate the handover and start detecting the path timing.
[0046]
Further, according to the present invention, since the above-described control is possible, the circuit scale can be reduced even when it is necessary to measure a plurality of peripheral cells.
[0047]
The reason is that hardware resources are preferentially allocated to cells having a high probability of being used for communication.
[Brief description of the drawings]
FIG. 1 is a block diagram showing one embodiment of a configuration example of a CDMA terminal according to the present invention.
FIG. 2 is a flowchart showing an operation using the CDMA terminal according to one embodiment of the present invention.
FIG. 3 is a flowchart showing an operation when a change of a communication target cell is notified from a network.
FIG. 4 is a flowchart illustrating an operation when a timer expires.
FIG. 5 is a flowchart illustrating an example of an additional condition determination.
[Explanation of symbols]
Reference Signs List 1 antenna 2 radio unit 3 A / D conversion unit 4 communication unit 5 peripheral cell measurement unit 6 communication delay profile generation unit 7 communication path assignment unit 8 communication finger 9 communication RAKE combining unit 10 communication control unit 11 transmission unit 12 D / A conversion unit 13 Measurement profile generation unit 14 Measurement path allocation unit 15 Measurement finger unit 16 Measurement RAKE combining unit 17 Cell addition condition determination unit 18 Measurement control unit 19 Timer unit

Claims (9)

A CDMA terminal, wherein a handover destination is predicted based on a result of level measurement and / or quality of neighboring cells, and synchronization of the cell of the handover destination is performed in advance. A CDMA terminal including a communication unit, a peripheral cell measurement unit, and a cell addition condition determination unit,
The peripheral cell measurement unit, a measurement delay profile generation unit for measuring the delay profile of the peripheral cell, a measurement path allocation unit that notifies the multipath timing to the measurement finger unit, a measurement finger unit and a measurement Rake synthesis part,
Has,
The measurement finger unit and the measurement rake combining unit measure the reception level and / or reception quality of the target cell and output the measurement level to the cell addition condition determination unit, and the target cell communicates with the cell addition condition determination unit. A CDMA terminal which judges whether the cell is a cell to be used, predicts a handover destination, and performs synchronization of the cell of the handover destination in advance. The CDMA terminal further includes a communication unit including a communication delay profile generation unit, a communication path assignment unit, a communication finger, and a communication RAKE combining unit,
The communication delay profile generation unit creates a delay profile of a cell in communication,
The communication path allocator selects a multipath having a good reception level based on the created delay profile, and notifies the communication finger of path timing,
The communication finger performs despreading and demodulation of the A / D-converted received data via the antenna unit and the radio unit according to the notified path timing,
The CDMA terminal according to claim 2, wherein the communication rake (RAKE) combining unit performs rake combining of demodulated data for each multipath. The CDMA terminal according to claim 3, further comprising a communication control unit that controls the communication unit, wherein the communication control unit is notified of the target cell. Further, the peripheral cell measurement unit has a timer unit, and it is determined that the measurement control unit that controls the peripheral cell measurement unit should be used for communication before the CDMA terminal is notified from the network. The timer performs the time count for the target cell, and the unit of the measurement kindergarten profile unit and the measurement path allocating unit that is not used for the measurement of the peripheral cell creates a delay profile of the cell and passes the path. The CDMA terminal according to claim 4, wherein the CDMA terminal is notified to continue the assignment. The CDMA terminal according to any one of claims 2 to 5, wherein the communication delay profile generator and the measurement delay profile generator are provided in common. A multipath synchronization method, wherein a handover destination is predicted based on a result of level measurement and / or quality of neighboring cells, and synchronization of the handover destination cell is performed in advance. The reception level and / or the reception quality of the target cell is measured to judge whether the target cell is a cell to be used for communication, a handover destination is predicted, and synchronization of the handover destination cell is performed in advance. A multipath synchronization method characterized by the above. The reception level and / or the reception quality of the target cell is measured to determine whether the target cell is a cell to be used for communication, and the result of the determination is transmitted to the network to satisfy the additional condition of the target cell. In this case, a path synchronization of the target cell in which the additional condition is satisfied is started and time counting is performed.

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