KR20010081204A - Assignment method for common packet channel - Google Patents

Abstract

PURPOSE: A method for allocating a CPCH(Common Packet CHannel) is provided to map a CA-ICH(Channel Allocation Indicator CHannel) signature and an OVSF(Orthogonal Variable Spreading Factor) code in order to efficiently use channel resources to the maximum. CONSTITUTION: A mobile station receives the status information of a desired CPCH from a system. The mobile station attempts access to the system in order to use the CPCH according to the received status information. The system maps the signature of a CA-ICH for the CPCH to a scrambling code and transmits it to the mobile station. The mobile station transmits a message through a relevant physical channel according to the CA-ICH.

Description

Assignment method for common packet channel

The present invention relates to a next generation mobile communication, and more particularly, to a method for allocating a common packet channel, which is suitable for allocating a common packet channel (CPCH) by efficiently utilizing channel resources in a wideband code division multiple access communication system.

1 is a diagram illustrating a transmission structure of a conventional common packet channel.

Referring to FIG. 1, the conventional Common Packet Channel (CPCH) is abbreviated as a Common Packet Channel Status Channel (CPCH), which the BS transmits whether the common packet channel of the current cell can be serviced. ), An access preamble (hereinafter abbreviated as AP) transmitted by the mobile station receiving the CSICH to request the use of a common packet channel (CPCH) of maximum transmission rate, and the base station transmits a response to the AP. Collision detection to detect and avoid collisions of an Access Preamble Acquisition Indicator Channel (AP-AICH) and a common packet channel generated when a plurality of mobile stations require the same common packet channel. Preamble (hereinafter, abbreviated as CD-P), and a collision detection preamble indication channel through which the base station transmits a response to the CD-P ( And a channel allocation indication channel (CA-ICH) for allocating a specific common packet channel (CPCH) and zero or eight slots in length to set the transmission power level prior to transmission of the message part. Transmits a power control preamble (hereinafter abbreviated to PC-P), a downlink-specific physical control channel (DL-DPCCH) for performing closed-loop power control (CL-PC), and user packet data It consists of a message part. The message part is composed of a data part and a control part.

Hereinafter, a transmission procedure of a common packet channel will be described.

First, a mobile station intended to transmit packet data receives a CSICH broadcast from a base station to identify a channel that is currently available (or unavailable). At this time, the mobile station checks the maximum rate available and then attempts to access the base station when the common packet channel that can support the desired transmission data rate is empty.

At this time, the mobile station selects an AP signature and an access slot one by one, and transmits the AP including the selected AP signature and the access slot to the base station according to the start time of the access slot.

As such, the mobile station informs the base station of the maximum data rate or minimum spread rate (SF) of the message portion required to transmit data by transmitting the AP signature and access slot to the base station in the access phase.

Thereafter, when the acquisition response for the transmitted AP is not received by a predetermined time, the mobile station raises the transmit power and retransmits the AP at the start of the access slot. This retransmission is repeated up to the threshold number of times.

The base station receives the AP from the mobile station and detects the maximum data rate or minimum spread rate required by the mobile station.

Then, the base station determines whether the common packet channel required by the mobile station can be allocated in consideration of the resources of the current common packet channel and the total amount of traffic. If the common packet channel can be allocated according to the determination result, the same signature as the received AP signature is transmitted as an ACK signal at the beginning of the access slot. If the allocation is not possible, the received AP signature is accessed with the inverted signature. Transmit with the NAK signal at the beginning of the slot.

Here, if a plurality of mobile stations simultaneously transmit APs with the same signature, the base station does not distinguish the mobile stations from the same signature and transmits an ACK signal to all mobile stations. Thus, the mobile station receiving the ACK signal has a CD- to reduce the collision. Send P to the base station. This CD-P also uses any one of the same 16 signatures as the AP.

The base station receiving the CD-P determines that no collision has occurred when only one CD-P is received, and transmits the same signature as the signature of the received CD-P to the mobile station through the CD-ICH. However, when a plurality of CD-Ps are received, it is determined that a collision has occurred, and the CD-P is transmitted by selecting the CD-P having the highest power among the received CD-Ps.

In addition, the base station transmits the CA-ICH including the channel information to be allocated in the form of a signature to the mobile station. At this time, the channel information included in the CA-ICH is a channelization code and a scrambling code of a downlink-dedicated physical control channel (DL-DPCCH) and a physical common channel (PCPCH). This CD-ICH and CA-ICH are simultaneously transmitted to the mobile station.

Thereafter, the mobile station receiving the CD-ICH and CA-ICH starts transmitting the message.

In transmitting this message, the mobile station transmits a PC-P to adjust its transmit power, and the base station transmits a downlink-only physical control channel (DL-DPCCH). Here, the mobile station transmits the PC-P for a predetermined time of 0 or 8 slots before transmitting a message consisting of a data part and a control part to a physical channel allocated through the signature information of the CA-ICH.

However, in the conventional common packet channel allocation method, a mapping method between a signature of CA-ICH for channel allocation and an orthogonal variable spreading rate code (OVSF code) that is a channelization code of a common packet channel has not been proposed.

Therefore, since channel resources cannot be efficiently used, a mapping method between signature of CA-ICH and orthogonal variable spreading rate code (OVSF code) is required.

Accordingly, an object of the present invention has been devised in view of the above-mentioned problems of the prior art, and assigns a common packet channel for mapping a CA-ICH signature and an orthogonal variable spreading rate code so that channel resources can be used as efficiently as possible. It is to provide a method.

According to an aspect of the present invention for achieving the above object, the mobile station receives the state information of the common packet channel from the system, and attempts to access the common packet channel to the system according to the received state information. do.

Then, the system maps the signature of the channel allocation indication channel for the common packet channel to be allocated to the scrambling code, and transmits a message to the corresponding physical channel according to the channel allocation indication channel.

Preferably, the system maps different scrambling codes for each common packet channel capable of assigning each signature of the channel allocation indication channel, or divides a specific scrambling code at predetermined chip intervals, and divides each of the divided scrambling codes. It is mapped to each signature of the channel allocation indication channel.

In addition, the mobile station selects any one of codes located in an upstream branch from a node having a spread rate of 2 in the code tree of the scrambling code as a channelization code of the data portion, and selects a code placed at the end of the downlink branch as a control part. A channelization code of the control portion, or a code located at the end of an upstream branch from a node having a diffusion rate of 2 in the code tree of the scrambling code, and a branch of a code located at a lower portion of the node. One of the codes located in the upstream branch of the code is selected as the channelization code of the data portion.

1 is a diagram showing a transmission structure of a conventional common packet channel.

2 is a diagram illustrating a mapping structure between a signature and a scrambling code of a CA-ICH according to the first embodiment of the present invention.

3A-3B illustrate a method of determining a channelization code of a message portion in accordance with the present invention.

4 is a diagram illustrating a mapping structure between a signature and a scrambling code of a CA-ICH according to a second embodiment of the present invention.

5 is a diagram illustrating a mapping structure between a signature of a CA-ICH and a scrambling code according to a third embodiment of the present invention.

Hereinafter, a configuration and an operation according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

The present invention proposes a new mapping method between a signature of a channel assignment indication channel (CA-ICH) and an orthogonal variable spreading rate code (OVSF code) to efficiently use channel resources.

To this end, the present invention maps the signature of CA-ICH to the scrambling code of the message part, and proposes four types of mapping methods. In addition, when mapping to the scrambling code, the mobile station proposes two methods of selecting channelization codes for data and control parts of the message part.

These three mapping methods and two channelization code selection methods will be described in detail in the following embodiments.

First embodiment

2 is a diagram illustrating a mapping structure between a signature and a scrambling code of a CA-ICH according to the first embodiment of the present invention.

In the first embodiment, a method of mapping 16 different scrambling codes SC # i to 16 signatures CA # i of 16 CA-ICHs will be described.

Referring to FIG. 2, the base station maps 16 CA-ICH signatures to one another in different scrambling codes.

That is, each signature of CA # 0 to CA # 15 is mapped to indicate the scrambling codes SC # 0 to SC # 15 of the message portion, respectively. Since SC # 0 to SC # 15 are different scrambling codes, 16 scrambling codes are additionally required to implement the present invention. However, since there are 2 ²⁵ -1 scrambling codes, no code shortage problem occurs.

As described above, when the CA-ICH signature is mapped to the scrambling code, since 16 scrambling codes are different from each other, each scrambling code SC # i has a channelization orthogonal variable spreading rate code tree. Thus, the channelization codes for the data and control portions in the message portion are selected from the channelized orthogonal variable spreading rate code tree each scrambling code has.

At this time, two methods are used as the channelization code selection method as shown in Figs. 3A to 3B.

Referring to FIG. 3A, the first method is an uplink branch C _{SF, 0} or C _{SF, SF /} at a node C _2,0 or C _2,1 having a spreading factor of 2 for an orthogonal variable spreading rate code tree. ₂ ) select one of the codes having a spreading factor from 4 to 256 (ie, C _{SF, 0} or C _{SF, SF / 2} ) as the channelization code (C _d ) of the data part, and The last code (C _256,127 or C _256,255 ) located in the direction of the branch, that is, a code having a spreading rate of 256, is selected and used as the channelization code (C _c ) of the control part.

Referring to FIG. 3B, in the second method, the code (C _256,0 or C _256,128 ) located at the end of the uplink branch at the node having a spreading rate of 2 is selected as the channelization code (C _c ) of the control part. Select a lower node from two nodes having a spreading factor of 4 and generate a spreading factor of 2, and select any one of codes from 4 to 256 in the upstream direction of the selected node. C _{SF, SF / 4} , C _{SF, 3 * SF / 4} ) is selected and used as the channelization code (C _d ) of the data portion.

Second embodiment

4 is a diagram illustrating a mapping structure between a signature and a scrambling code of a CA-ICH according to a second embodiment of the present invention.

In the second embodiment, several CA-ICH signatures describe a method of sharing and mapping one scrambling code. This mapping method takes into account the minimum spread rate (SF _min ) of a common packet channel that can be serviced by a cell, and assumes that the minimum spread rate (SF _min ) is 8 in FIG. 4.

Referring to FIG. 4, the mapping method proposed in the second embodiment is a method in which the number of scrambling codes mapped to the signature of the CA-ICH is determined according to the minimum spreading rate SF _{min that} can be serviced by the cell. That is, the number of scrambling codes is determined according to the following equation (1).

In more detail, one orthogonal variable spreading code tree has two nodes having a spreading rate of two. That is, C _2,0 or C _2,1 . Therefore, considering that the spreading rate used in the common packet channel is 4 to 256, it can be seen that two scrambling codes can share one orthogonal variable spreading rate code tree.

For example, if CA # 0 to CA # 7 map to point to C _2,0 nodes of SC # 0 to SC # 7, and CA # 8 to CA # 15 map to point to C _2,1 nodes, A total of eight scrambling codes can be mapped to 16 CA-ICH signatures.

Therefore, if the minimum spread rate SF _min supported by the cell is greater than 4, fewer than 8 scrambling codes may be used according to the minimum spread rate SF _min .

In FIG. 4, since the minimum diffusion rate SF _min is 8, the number of scrambling codes required by Equation 1 is four. 4 shows an example of mapping each of 16 CA-ICHs to four scrambling codes.

In this case, since each of the divided scrambling codes SC # 0, SC # 1, SC # 2, and SC # 3 has four nodes having a spreading factor of 4, CA # 0, CA # 4, CA # 8, CA # 12 Maps to each node on SC # 0, CA # 1, CA # 5, CA # 9, CA # 13 maps to each node on SC # 1, CA # 2, CA # 6, CA # 10, CA # 14 maps to each node of SC # 2, and CA # 3, CA # 7, CA # 11, and CA # 15 map to each node of SC # 3.

In this manner, if the minimum spreading ratio SF _min is 16, two scrambling codes are used by Equation 1, and 16 of each 8 nodes having a spreading ratio of 8 in two scrambling codes according to the method described above. The signature of CA-ICH is mapped.

As a result, when the minimum diffusion rate is 32 or less, only one scrambling code may be used.

In this second embodiment, the channelization code of the message portion is selected according to the two methods described in the first embodiment.

Third embodiment

FIG. 5 is a diagram illustrating a mapping structure between a signature of a CA-ICH and a scrambling code according to a third embodiment of the present invention.

In the third embodiment, a method of dividing one scrambling code and mapping it to the signature of each CA-ICH will be described.

Referring to FIG. 5, there are 2 ²⁵ -1 scrambling codes used for uplink in a wideband code division multiple communication system as long codes. And each scrambling code has a length of 2 ²⁵ -1 = 33554431 Chip.

However, since the message portion of the common packet channel has a length of 38400 × N, it is understood that only 38400 chips are required as the scrambling code of the message portion, so that one scrambling code can be divided.

In this case, since the divided scrambling codes are different from each other, they have the same result as the first embodiment of mapping to 16 different scrambling codes or the second embodiment of allocating eight different scrambling codes.

In this case, since the message part has a length of 4096 chips in the access preamble (AP) part and the collision detection preamble (CD-P) part, the remaining part except the AP part and the CD-P part in one scrambling code. Is divided into lengths of 38400 chips, and the divided scrambling codes are mapped to the signature of each CA-ICH. Therefore, one scrambling code can map the signatures of each of 16 CA-ICHs.

In addition, when one scrambling code is divided into lengths of 38400 chips, each of the divided scrambling codes SC # i has an orthogonal variable spreading rate code tree, and accordingly the method described in the second embodiment is the same in the cell. The number of codes mapped to the signature of the CA-ICH may be adjusted according to the minimum spreading rate (SF _min ).

That is, when the minimum spreading rate SF _min is 8, four scrambling codes among the divided scrambling codes are mapped to signatures of 16 CA-ICHs.

In this third embodiment, the channelization code of the message portion is selected according to the two methods described in the first embodiment.

Fourth embodiment

The fourth embodiment describes a mapping method between a CA-ICH and a scrambling code when allocating 16 or more common packet channels.

First, the base station assigns a common packet channel to a certain number of groups, and also specifies a scrambling code to a certain number of groups. The group information is then broadcasted to the mobile station through the CSICH.

After acquiring the group information of the common packet channel through the CSICH, the mobile station informs the base station through the AP of the group to which the desired common packet channel belongs. At this time, the mobile station informs the base station of the desired maximum data rate through the AP.

Then, the base station maps and transmits the CA-ICH for the common packet channel included in the group indicated by the AP to the scrambling code of the corresponding group.

At this time, the mapping method between the CA-ICH and the scrambling code is applied to the mapping method described in the first, second and third embodiments. Thus, one group consists of 16 or 8 scrambling codes. At this time, when the number of scrambling codes is small, it consists of 16 or less or 8 or less.

As described above, when the common packet channel is divided into groups and the scrambling codes to be mapped to the CA-ICH are divided into groups, the AP transmitted by the mobile station designates a scrambling code group as shown in Tables 1 to 3 below.

AP signature number Common packet channel group AP # 0 to AP # i SC # 0 to SC # 15 AP # (i + 1) to AP # j SC # 16 to SC # 31 AP # (j + 1) to AP # 15 SC # 32 to SC # 47

Table 1 shows an example when the mapping method in the first embodiment is applied.

Therefore, 16 scrambling codes are configured in one group, the AP of the mobile station designates a group, and the signature of the CA-ICH of the common packet channel belonging to each group is mapped to the 16 scrambling codes of the group, respectively.

AP signature number Common packet channel group AP # 0 to AP # i C _2,0 and C _2,1 nodes in SC # 0 through SC # 7 AP # (i + 1) to AP # j C _2,0 and C _2,1 nodes in SC # 8 through SC # 15 AP # (j + 1) to AP # k C _2,0 and C _2,1 nodes in SC # 16 through SC # 23 AP # (k + 1) to AP # 15 C _2,0 and C _2,1 nodes in SC # 24 to SC # 31

Table 2 shows an example when the mapping method in the second embodiment is applied.

Therefore, one scrambling code is configured in one group, the AP of the mobile station designates a group, and the signature of the CA-ICH of the common packet channel belonging to each group is C _2,0 and C of the eight scrambling codes of the group. Mapped to _2,1 nodes respectively.

AP signature number Common packet channel group AP # 0 to AP # i C _2,0 nodes in SC # 0 through SC # 15 AP # (i + 1) to AP # j C _2,0 nodes in SC # 16 through SC # 31 AP # (j + 1) to AP # k C _2,1 nodes in SC # 0 through SC # 15 AP # (k + 1) to AP # 15 C _2,1 nodes in SC # 16 to SC # 31

Table 3 shows another example when the mapping method in the second embodiment is applied.

In Table 3, 16 scrambling codes are configured in one group, the AP of a mobile station designates a group, and the signature of CA-ICH of the common packet channel belonging to each group is C _2,0 of 8 scrambling codes of the group. Or C _2,1 nodes, respectively.

In the first, second and third embodiments described so far, the base station transmits the maximum data rate of each common packet channel or the respective data rates available through the CSICH.

In particular, in the fourth embodiment, the base station broadcasts group information of the common packet channel in addition to the maximum transmission rate of the common packet channel or the respective data rates that can be serviced through the CSICH.

The transmission structure of the common packet channel to which the mapping method according to the present invention is applied will now be described.

First, a mobile station intended to transmit packet data receives a CSICH broadcast from a base station to identify a channel that is currently available (or unavailable). At this time, the mobile station checks the group information when it is designated as a group of the maximum usable data rate and common packet channel, and attempts to access the base station when the common packet channel capable of supporting the data rate is empty.

At this time, the mobile station selects one AP signature and an access slot from among 16 AP signatures and access slots, and matches the selected AP signature and access slot to the start point of the access slot. Transmit to base station.

As such, the mobile station informs the base station of the maximum data rate or minimum spread rate (SF) of the message portion required to transmit data by transmitting the AP signature and access slot to the base station in the access phase.

Thereafter, when the acquisition response for the transmitted AP is not received by a predetermined time, the mobile station raises the transmit power and retransmits the AP at the start of the access slot. This retransmission is repeated up to the threshold number of times.

The base station receives the AP from the mobile station to check the maximum data rate or minimum spread rate required by the mobile station.

Then, the base station determines whether the common packet channel required by the mobile station can be allocated in consideration of the resources of the current common packet channel and the total amount of traffic. If the common packet channel can be allocated according to the determination result, the same signature as the received AP signature is transmitted as an ACK signal at the beginning of the access slot. If the allocation is not possible, the received AP signature is accessed with the inverted signature. Transmit with the NAK signal at the beginning of the slot.

Here, if a plurality of mobile stations simultaneously transmit APs with the same signature, the base station does not distinguish the mobile stations from the same signature and transmits an ACK signal to all mobile stations. Thus, the mobile station receiving the ACK signal has a CD- to reduce the collision. Send P to the base station. This CD-P also uses any one of the same 16 signatures as the AP.

The base station receiving the CD-P determines that no collision has occurred when only one CD-P is received, and transmits the same signature as the signature of the received CD-P to the mobile station through the CD-ICH. However, when a plurality of CD-Ps are received, it is determined that a collision has occurred, and the CD-P is transmitted by selecting the CD-P having the highest power among the received CD-Ps.

In addition, the base station transmits the CA-ICH including the channel information to be allocated in the form of a signature to the mobile station. At this time, the signature of the CA-ICH is mapped to the scrambling code and transmitted. The method of mapping the signature of the CA-ICH to the scrambling code is performed according to the first to fourth embodiments as described above.

The channel information included in the CA-ICH is a channelization code and a scrambling code of a downlink-dedicated physical control channel (DL-DPCCH) and a physical common channel (PCPCH). This CD-ICH and CA-ICH are simultaneously transmitted to the mobile station.

Thereafter, the mobile station receiving the CD-ICH and CA-ICH starts transmitting the message.

In transmitting this message, the mobile station transmits a PC-P to adjust its transmit power, and the base station transmits a downlink-only physical control channel (DL-DPCCH). In this case, the mobile station transmits a message part to the allocated physical channel according to the scrambling code mapped to the signature of the CA-ICH, and the channelization codes for the data part and the control part are selected and used according to the method shown in FIGS. 3A and 3B. do.

As described above, the method for allocating a common packet channel according to the present invention has the following effects.

First, considering that 16 CA-ICH signatures support spreading rates between 4 and 256, other CAs are not affected when a particular mobile station is transmitting a high data rate by mapping the CA-ICH to a scrambling code. The remaining CA-ICH signature can be used instead, thereby effectively using channel resources.

Second, the channelization code of the message portion is allocated in the form of RACH or DPCH, so that implementation is easy.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the examples, but should be defined by the claims.

Claims (4)

A first step of the mobile station receiving status information of the common packet channel from the system, A second step of the mobile station attempting to access a common packet channel to the system according to the received state information; A third step of mapping a signature of a channel allocation indication channel for a common packet channel to be allocated by the system to a scrambling code and transmitting the same; And a fourth step of the mobile station transmitting a message to a corresponding physical channel according to the channel allocation indication channel. The method of claim 1, wherein in the third step, The system maps the common packet channel to a different scrambling code for each common packet channel capable of allocating signatures of the channel allocation indication channel. The method of claim 1, wherein in the second step, And the system divides a specific scrambling code into predetermined chip intervals and maps each of the divided scrambling codes to signatures of the channel allocation indication channel. A first step of the mobile station receiving group information of a common packet channel from a system; A second step of the mobile station instructing a group to use according to the received group information and attempting an access to inform a desired transmission rate; Selecting, by the system, a common packet channel to be allocated from the channel group indicated by the mobile station, and transmitting a signature of a channel allocation indication channel for the selected common packet channel by mapping it to a scrambling code; And a fourth step of the mobile station transmitting a message to a corresponding physical channel according to the channel allocation indication channel.