KR20040036226A - Method For Allocating Forward Code Channel In Mobile Communication System - Google Patents

Abstract

PURPOSE: A forward code channel allocating method in a mobile communication system is provided to effectively manage a Walsh code by changing a Walsh code for a corresponding voice call to allocate an available Walsh code with a speed requested by a data call. CONSTITUTION: A mobile terminal requests a 16 speed Walsh code allocation for a data call(S41), a base station checks whether the Walsh code with the requested speed is available(S42). If the Walsh code with the requested speed is not available, the base station allocates the maximum speed of Walsh code to the data call to receive a corresponding data service(S43). The base station searches a Walsh tree to check whether the Walsh code with the requested speed can be allocated(S44). If the Walsh code with the requested speed can be allocated, the base station changes the Walsh code for a corresponding voice call to make the Walsh code with the requested speed available(S45). The available Walsh code is re-allocated to provide the data service at the data transmission rate of the initially requested speed(S46).

Description

Method for allocating forward code channel in mobile communication system {Method For Allocating Forward Code Channel In Mobile Communication System}

The present invention relates to a forward code channel allocation in a mobile communication system, and in particular, in a code division multiple access (CDMA) mobile communication system, a forward radio channel is distinguished to simultaneously accommodate a voice call and a data call. The present invention relates to a forward code channel allocation method in a mobile communication system capable of providing a high-speed data service in allocating Walsh codes.

In general, a code division multiple access (CDMA) mobile communication system based on the IS-95 standard, which is a wireless section protocol, has a predetermined spread spectrum code (PN) for a wireless section between a base station and a terminal. Code and Walsh code) to separate channels.

Here, PN (Pseudorandom Moise) code is a code having a characteristic of a random number generated by hardware, and the purpose of classifying a logical channel using a spreading purpose on one physical channel or a Walsh code in a forward channel. Used as

Unlike the PN code, the Walsh code is generated not by hardware but by a predetermined table. The Walsh code is a logical channel that allows a plurality of terminals to transmit data in a forward wireless channel from a base station to a terminal. That is, it is a finite resource for distinguishing a pilot channel, a synchronization channel, a quick paging channel, a common control channel, a traffic channel, etc.).

Meanwhile, in the conventional CDMA mobile communication system, a plurality of terminals are divided into voice calls (FCH calls) and data calls (SCH calls) for each sector of the base station through the distribution of finite resources using Walsh codes for the forward wireless sections between the terminals and the system. Enable).

These Walsh codes are generated through the Hadamard Matrix, each of 64 and 128 bit rows with a '64 X 64 'matrix in the IS-95 standard and a maximum' 128 X 128 'matrix in the IS-2000 standard. It was created by numbering it.

For example, according to the RC (Radio Configuration) defined in the IS-2000 standard, in case of RC 4 by RC 1 to 5 supported by the CDMA mobile communication system, as shown in the Walsh tree shown in FIG. It supports up to 128 Walsh codes and the rest supports 64 Walsh codes, where 64 or 128 Walsh codes refer to resources excluding Quasi-Orthogonal Functions (QOFs) as described in the IS-2000 standard. Say.

In addition, the Walsh tree illustrated in FIG. 1 is an extension of the tree based on the orthogonality of the Walsh code, which cannot be used simultaneously due to a collision with the higher level Walsh code when the lower level Walsh code is used. For example, when the Walsh code '16' of the Walsh-64 series is used in FIG. 1, the Walsh code '0' cannot be used in the higher level Walsh-16 series.

In addition, the higher level Walsh tree means that a higher rate call allocation is possible for each RC. Therefore, when assigning a Walsh code, it is important to assign a Walsh code from a lower level on the Walsh tree to ensure the highest data rate.

In the conventional CDMA mobile communication system, when a terminal requests a voice call based on RC 3, an overhead channel among 64 Walsh codes (that is, a channel shared to all terminals located in one sector of the system) is used. Except for Walsh codes for allocation, one of the remaining Walsh codes is selected and assigned, and the Walsh codes used for data call allocation are assigned to the Walsh tree according to the double speed (1X, 2X, 4X, 8X, 16X, 32X). The level of the statue has different characteristics.

For example, if there is a data call request at 16x (16X), that is, 153.6 Kbps data rate, one Walsh code should be allocated among '0,2,1,3' in 'Walsh-4' series. In this case, if the Walsh code used as the overhead channel is one of the pilot channel, synchronization channel, and paging channel defined in the IS-2000 standard, only the Walsh code '2,3' can be used. If the Walsh code is not in use, one of the corresponding Walsh codes '2,3' can be selected and assigned.

Here, if there is any Walsh code in the Walsh tree belonging to the lower level of the Walsh code '2,3' in the 'Walsh-4' series, the data transfer rate of 16x cannot be guaranteed.

This will be described in more detail with reference to FIG. 2. In the case of FIG. 2, a higher level Walsh code (') is used as' 0,32,16,1' of the Walsh-64 series as a current overhead channel. Part (a, b) is not available.

In addition, Walsh code '8' of the Walsh-64 series and Walsh code '2' of the Walsh-4 series, which are used for the FCH call, are used for the current SCH 16x (153.6kbps) call in RC 3. For the SCH 4x (38.4kbps), the FCH call uses the Walsh-code of Walsh-64 and the Walsh-code of Walsh-16. have.

In this case, Walsh codes ('da, d') existing on the upper or lower level of the Walsh code being used by the two SCH calls described above may not be allocated.

As described above, in the conventional CDMA mobile communication system, a predetermined Walsh code is allocated to a high-speed data service for a SCH call supported from the IS-2000 standard. When assigning Walsh codes necessary for FCH allocation using -64 'series, only a small number of Walshtrees, that is, lower level Walsh codes, are allocated and used.

However, because each subscriber has a different time to terminate the call, the voice call subscriber's use of the Walsh code, i.e., the voice call currently on the call continues to occupy the Walsh code existing at a lower level of the high-speed Walsh code, thereby ensuring that the subscriber is within the same sector area. There is a problem that a Walsh code having a lower data rate can be allocated without accepting a data rate required by a subscriber who wants to use a SCH call, which is a data call. Therefore, the efficiency of Walsh code assignment is deteriorated. .

For example, a conventional Walsh code assignment scenario based on RC 3 will be described with reference to FIG. 3.

FIG. 3 illustrates a SCH call that is a data call while another subscriber is currently receiving voice service without releasing a call while randomly attempting or releasing multiple subscribers existing in the same sector. As a Walsh code allocation scenario, a subscriber station receiving voice service is assigned Walsh codes '58' and '7' of the 'Washy-64' series, and must be occupied in each sector. The head channel occupies the Walsh-64 Walsh code '0,32,16,1'.

At this time, if the Walsh code '8' of the 'walsh-64' series is allocated to the FCH call for signaling processing of the data call, the Walsh codes '58' and '7' of the 'walsh-64' series will be described. You cannot use the Walsh code in the 'a' or 'a' section, you can't use the 'da,' section in the 'walsh-64' Walsh code '0,32,16,1'. The Walsh code '8' of Walsh-64 for call signaling is not available, so the Walsh code of Walsh-4, a high-speed Walsh code for the SCH call, is not available. You will not be able to assign code.

That is, in the current CDMA mobile communication system, data call subscribers do not attempt a call after voice call subscribers complete call release, and a plurality of voice call subscribers and data call subscribers existing in the same sector attempt to call each other. Because of the small number of voice call subscribers, a small number of voice call subscribers do not assign high-speed Walsh codes to data call subscribers, even though few voice call subscribers are currently in service. There was a problem, which caused the Walsh code allocation to be inefficient, such as failing to provide a subscriber with a high data rate.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems described above, and an object thereof is to provide a Walsh code, which is a forward code channel of a double speed required in a data call due to the Walsh code occupancy of a voice call existing in the same sector of a base station in a CDMA mobile communication system. If the assignment is not possible, the Walsh code for the corresponding voice call is changed to make the assigned Walsh code available for the data call so that it can be allocated.

Another object of the present invention is to more efficiently manage Walsh code resources by assigning available Walsh codes required for data calls through Walsh code changes for voice calls, and also for data call subscribers. The purpose is to provide a high speed data service.

It is still another object of the present invention to change a Walsh code for a voice call, by performing the Walsh code change only on a voice call having two or more active sets, thereby making it possible to change the data quality of the voice call without affecting the call quality of the voice call. In order to provide the required high speed data service.

1 illustrates a Walsh tree without QOF in a typical CDMA mobile communication system.

FIG. 2 is a diagram illustrating a Walsh code assignment state for a Walsh tree in the case of RC 3 in FIG. 1. FIG.

3 illustrates a Walsh code allocation scenario for a Walsh tree based on RC 3 in a conventional CDMA mobile communication system.

4 is a flowchart illustrating Walsh code assignment in a CDMA mobile communication system in accordance with the present invention.

5 is a diagram illustrating a Walsh code allocation scenario for a Walsh tree when RC 3 is used in a CDMA mobile communication system according to the present invention.

FIG. 6 is a flow chart detailing the procedure of FIG. 4 for changing the Walsh code for a voice call to make the Walsh code available at the data call available.

A feature of the present invention for achieving the above object is that, in the mobile communication system, if the forward code channel of the double speed required for the data call cannot be allocated, the forward code channel in use is changed by changing the forward code channel in use. Making the forward code channel of the available state; The present invention provides a method for allocating a forward code channel in a mobile communication system comprising assigning a forward code channel made available to the data call to provide a data service of a required double speed.

The method for allocating a forward code channel in the above-described mobile communication system may further include a step of allocating a forward code channel having a maximum double speed assigned to the data call to accommodate a data service.

In this case, the process of making the forward code channel available includes: searching a forward code channel tree for a lower level of the forward code channel of the required double speed in the data call and selecting a forward code channel tree to which only voice calls are assigned; ; And changing the forward code channel assigned to the voice call in the forward code channel tree selected above to make the forward code channel of the double speed required for the data call available.

The selecting of the forward code channel tree may include selecting a forward code channel tree having the smallest number of voice calls currently being serviced among lower forward code channel trees of the requested double speed in which only voice calls are assigned.

The step of selecting a forward code channel tree may include selecting a forward code channel tree of at least two active sets of voice call subscribers currently being serviced among lower forward code channel trees of the requested double speed, in which only voice calls are assigned. Characterized in that, if there is no forward code channel tree having two or more active sets of all voice call subscribers, the lower forward code channel of the required double speed has a small number of voice calls currently in service and a small number of voice calls having one active set. It is characterized by selecting a tree.

On the other hand, the step of making the forward code channel available comprises: checking an active set of voice call subscribers currently in service in the forward code channel tree selected above to determine whether there are two or more; When the voice call subscribers have two or more active sets, changing the forward code channel assigned to all corresponding voice calls to make the forward code channel of the required double speed in the data call available. If there is a voice call subscriber having only one active set as a result of checking the active set, after performing soft or soft handoff on the corresponding voice call, the forward code channel assigned to the voice call is changed. Making the forward code channel of the required double speed in the data call available.

In this case, the forward code channel allocated to the voice call may be changed by performing a forward code channel handoff using a handoff message.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The CDMA mobile communication system according to the present invention solves the problem of inefficient allocation of Walsh code resources, which can occur when multiple voice and data calls are randomly attempted and released, without affecting the call quality of the voice call subscriber. To ensure high data rates for data call subscribers, this is achieved by changing the Walsh code of the voice call if the data call is unable to allocate the Walsh code, which is the high-speed forward code channel, due to the voice call currently in service. .

That is, in allocating a Walsh code managed for each sector of each base station in the CDMA mobile communication system according to the present invention, in order to accommodate a plurality of data calls and voice calls simultaneously, the lowest level, that is, the smallest size, on the Walsh tree is basically used. The Walsh code is searched for and assigned from that in the branch of.

However, when the corresponding data call and voice call occur randomly, especially when the call occupancy time of the voice call subscriber is long, the required high-speed Walsh code despite the fact that there are not many voice calls currently in service for the terminal to attempt data service. In this case, the present invention first allocates a Walsh code of the maximum assignable speed to the terminal requesting the data call and then requests the data call by changing the Walsh code of a specific voice call. Will assign a high-speed Walsh code.

In this case, the Walsh code change of the voice call may be performed by soft or soft handoff for voice calls having two or more active sets, that is, two or more sectors or cells, in order to prevent the call quality from being degraded when the Walsh code is changed. It is desirable to only perform voice calls that perform soft or softer handoff, and if it is necessary to change the Walsh code of a voice call with one active set, the base station controller It is desirable to change the Walsh code after having performed a soft or softer handoff.

In the following description, a case in which Walsh code resources are allocated based on RC 3 used in a 1x CDMA mobile communication system will be described as an example.

The Walsh code allocation operation in the CDMA mobile communication system according to the present invention will be described with reference to FIG. 4 as follows.

First, in order to provide a voice call or data service to terminals existing in each base station in a system, a Walsh code managed by a tree structure is searched and assigned. At this time, a random call attempt and a release of a voice call or a data call occur randomly. Occupancy times are also different, so if the Walsh code assignment for the data call is required from the terminal during the actual system operation, the Walsh code is assigned to the data call due to the Walsh code assigned to the voice call currently in service within the same sector as the Walsh code management criteria. There is a case where Walsh code, which is a high-speed forward code channel, cannot be assigned to.

For example, as illustrated in FIG. 5, four Walsh codes (“Walsh-64” series Walsh codes '0,32,16,1') are defined for an overhead channel in a specific sector. The mobile terminal assigned the Walsh code '8' for the data call while the voice call currently using the Walsh code '50, 58,9,7 'is used at 16x (156.3kbps) for the data call. When Walsh code assignment is requested (step S41), the base station searches for the Walsh code assignment state for the sector requesting the current data call to confirm whether the required Walsh code is available (step S42).

At this time, if the requested Walsh code is found to be available, the corresponding Walsh code is assigned to the data call to provide the corresponding data service (step S47).

However, due to the Walsh codes '0,32,16,1' used by the overhead channel and the Walsh codes '8,50,58,9,7' being used by the call currently in service, as shown in FIG. If all of the required Walsh codes are found to be unusable, then the Walsh codes with the highest available Walsh codes among the currently available available Walsh codes (i.e. By assigning the Walsh code of any one of 6, 5, and 3 'as the Walsh code of the requested data call, the corresponding data service is first accepted (step S43).

After allocating the Walsh code of the maximum assignable rate to accommodate the data service, the Walsh tree is searched to change the Walsh code for the voice call currently in service to ensure that the originally requested Walsh code is available. That is, it is checked whether the Walsh code of the requested double speed can be assigned (step S44).

If the Walsh code change for the voice call confirms that the Walsh code required for the required data rate cannot be allocated, it indicates that there is no Walsh code resource of the required double speed currently available. The data service is provided using the assigned Walsh code (step S48).

However, if it is confirmed that the Walsh code change for the voice call can allocate the Walsh code necessary for the required data rate, the Walsh code change for the corresponding voice call is performed. The Walsh code in the double speed is made available (step S45).

As described above, after the Walsh code of the double speed required for the data call is made available through the Walsh code change for the voice call, the low Walsh code assigned to the current data call is Walsh for the voice call. By reassigning the Walsh code made available through the code change, that is, the Walsh code of the initially requested double speed, the data service is then provided at a data transfer rate of the initially required double speed (step S46).

Meanwhile, in the above-described embodiment, the procedure for changing the Walsh code for the voice call to make the Walsh code at the double speed required for the data call available will be described in detail with reference to FIG. 6.

First, the Walsh tree is searched for the lower level of the required double speed to confirm that the Walsh code of the required double speed can be allocated in the data call by changing the Walsh code for the voice call (step S61), and only the voice call is allocated. It is checked whether the Walsh tree is present (step S62).

At this time, if the Walsh tree for the lower level of the requested double speed is searched and there is no Walsh tree to which only a voice call is assigned, it indicates that there is no available Walsh code of the required double speed as described above. Walsh code is used to provide data services.

However, as a result of searching the Walsh tree for the lower level of the requested double speed, if there is a Walsh tree to which only voice calls are assigned, the Walsh tree having the smallest number of voice calls currently serving is selected among the corresponding Walsh trees. Step S63).

For example, in the case of FIG. 5, the Walsh code of 16 times required in the data call is '0,2,1,3' of the 'Walsh-4' series, and the Walsh tree for the lower level of each Walsh code is shown. Walsh code '0,1' lower level Walsh tree corresponding to 'A, B' is excluded because Walsh code '0,32,16,1' used for overhead channel is assigned. Since the Walsh tree of the Walsh code '2,3' lower level is assigned only the voice call, the tree of the Walsh code '3' having the smallest number of voice calls is requested from the data call by changing the Walsh code for the voice call. The Walsh tree will be selected to assign the Walsh code of the double speed.

Thereafter, the active set of the voice call subscribers currently in service in the previously selected Walsh tree is checked to determine whether there are two or more (step S64), which is to prevent the call quality from being degraded when the Walsh code is changed. If there is more than one active set of subscribers, i.e., for voice call subscribers in which soft or soft handoffs are performed for two or more sectors or cells, the call is normally made over another sector while changing the Walsh code of the voice call in the current sector. This is because the service is available.

If there are two or more active sets of all voice call subscribers currently in service in the previously selected Walsh tree, a Walsh code change is performed through handoff of the Walsh code assigned to the corresponding voice call, thereby requiring the required speed in the data call. To make the Walsh code available (step S65). At this time, the base station performs a handoff on the Walsh code using the Universal Handoff Direction Message (UHDM) message defined in the IS-2000 standard, as in the normal handoff process. do.

However, as a result of checking the active set of the voice call subscribers currently serving in the Walsh tree selected above, if there is a voice call subscriber having only one active set, the number of voice calls currently being served among the Walsh trees assigned only the voice call is present. Next, after selecting the small Walsh tree (step S66), the operation of step S64 which checks whether two or more active sets of voice call subscribers are performed is repeated, so that voices for voice call subscribers having two or more active sets are repeated. Only the Walsh code of the call is changed to make the double Walsh code required for the data call available.

In addition, as a result of checking the active set of voice call subscribers currently in service for all Walsh trees assigned only voice calls through the above-described operation, there is a Walsh tree having two or more active sets of all voice call subscribers. If not, select a Walsh tree among Walsh trees that are assigned only voice calls and have a small number of voice calls that are currently in service but have only one active set, and then change the Walsh codes of the voice calls assigned in the corresponding Walsh tree. In this case, the voice call of the voice call subscriber having two or more active sets performs the Walsh code change through the Walsh code handoff as described above, in order to prevent the call quality of the voice call from being degraded. The voice call of a private voice call subscriber is routed to another section through the Or it is performing a Walsh code changing after it performs a soft or softer handoff in the cells.

For example, if there are two or more active sets of voice call subscribers currently serving in the tree of the 16X speed Walsh code '3' selected in the above-described embodiment with reference to FIG. 5, the Walsh code assigned to the corresponding voice call ' By changing 7 'to a Walsh code that is available in another Walsh tree, we make the Walsh code' 3 ', which is 16x in the' Walsh-4 'family available, and then' walsh-8 ', which is currently assigned to the current data call. By changing the 8x Walsh code belonging to the series to the 16x Walsh code '3' made available previously, it is possible to provide the data subscriber with the 16x required data service.

However, if there are not two or more active sets of voice call subscribers currently in service in the tree of 16x Walsh code '3', the number of voice calls currently in service is the next smaller in the tree of 16x Walsh code '2'. It is checked whether there are two or more active sets of voice call subscribers. In this case, if two or more active sets of voice call subscribers are identified, the Walsh codes '50, 58 'assigned to the corresponding voice calls are different from each other. By changing from the Walsh code to the available Walsh code, the 16x Walsh code '2' belonging to the Walsh-4 series is made available, and the 8x speed belonging to the Walsh-8 series currently assigned to the current data issue. By changing the Walsh code to the 16x Walsh code '2', which was made available earlier, it was possible to provide the data subscriber with the 16x required data service initially.

On the other hand, the embodiment according to the present invention is not limited to the above, it can be carried out by various alternatives, modifications and changes within the scope obvious to those skilled in the art with respect to the present invention, for example For example, when the Walsh code change for the voice call determines that the Walsh code required for the required data rate can not be allocated, the above-described embodiment uses the Walsh code of the maximum assignable speed to provide the data service. It is operating to provide, but instead, the data call is terminated by repeatedly checking whether the Walsh code of the required double speed can be allocated by changing the Walsh code for the voice call periodically until the data call ends. Required by changing the Walsh code for a voice call, for example, because another data call is terminated before In the case where the double speed Walsh code is enabled, the same Walsh code change is performed for the voice call as in the above-described operation to make the required double speed Walsh code available and then reassign it to the Walsh code of the data call. It may be possible to ensure that data services are initially provided at the required speed.

And such alternatives, modifications and variations will be considered to be within the scope of the following claims.

As described above, the present invention relates to a voice call corresponding to a Walsh code, which is a forward code channel of a double speed required for a data call due to the Walsh code occupancy of the voice call existing in the same sector of the base station in the CDMA mobile communication system. By changing the Walsh code for the data call, the Walsh code required for the data call is made available and allocated, thereby enabling efficient management of the Walsh code, which is the forward radio channel resource, as well as the high-speed data required for the data call subscriber. To provide services.

In addition, the present invention changes the Walsh code for the voice call to make the assigned Walsh code available in the data call available and assigns it, by performing the Walsh code change only for the voice call having two or more active sets. As a result, it is possible to provide a high speed data service required for a data call without affecting the call quality of a voice call.

Claims (9)

Changing the forward code channel being used in the mobile communication system to make the forward code channel of the required double speed available in the data call if the forward code channel of the double speed required for the data call cannot be allocated; And assigning a forward code channel made available to the data call to provide a data service of a required double speed. The method of claim 1, And assigning a forward code channel of a maximum double speed that can be allocated to the data call to accommodate a data service. The method of claim 1, The process of making the forward code channel available includes: searching the forward code channel tree for a lower level of the forward code channel of the required double speed in the data call to select a forward code channel tree to which only voice calls are assigned; Changing the forward code channel assigned to the voice call in the selected forward code channel tree to make the forward code channel of the double speed required for the data call available. How to assign code channels. The method of claim 3, The selecting of the forward code channel tree may include selecting a forward code channel tree having the smallest number of voice calls currently being serviced among lower forward code channel trees of the requested double speed in which only voice calls are assigned. Forward code channel allocation method The method of claim 3, The selecting of the forward code channel tree may include selecting a forward code channel tree having at least two active sets of voice call subscribers currently in service from among the lower forward code channel trees of the requested double speed in which only voice calls are assigned. A forward code channel allocation method in a mobile communication system. The method of claim 5, If there is no forward code channel tree in which all of the voice call subscribers have two or more active sets, the lower forward code channel tree of the required double speed may be selected while the number of voice calls currently in service is small and the number of voice calls having one active set is small. The forward code channel allocation method in a mobile communication system, characterized in that. The method of claim 3, The making of the forward code channel in an available state may include: checking an active set of voice call subscribers currently in service in the selected forward code channel tree to determine whether there are two or more; When the voice call subscribers have two or more active sets, changing the forward code channel assigned to all corresponding voice calls to make the forward code channel of the double speed required in the data call available. Forward Code Channel Allocation Method in Mobile Communication System. The method of claim 7, wherein As a result of checking the active set, if there is a voice call subscriber having only one active set, after performing soft or soft handoff for the corresponding voice call, the forward code channel assigned to the voice call is changed and And making the forward code channel of the required double speed in the data call available. The method according to claim 7 or 8, The forward code channel assignment method of the mobile communication system, characterized in that for performing the forward code channel handoff using a handoff message.