KR20030071957A - Method for transmitting/receiving information of orthogonal variable spreading factor code assigned to user data in high speed data packet access communication system - Google Patents

Abstract

PURPOSE: A method for transceiving orthogonal code information assigned to user data in an HSDPA(High Speed Downlink Packet Access) communication system is provided to transmit OVSF(Orthogonal Variable Spreading Factor) code information by using fewer bits, thereby efficiently transceiving the information. CONSTITUTION: A base station assigns 4 OVSF codes to a UE(User Element) B of a code set from an utmost left side on an entire code space, and removes the UE B. The base station assigns one OVSF code of an utmost right side to a UE C of the code set, and removes the UE C. The base station assigns 4 OVSF codes to a UE D of the code set from the utmost left side on a remaining code space, and removes the UE D. The base station assigns one OVSF code of the utmost right side to the UE C of the code set, and removes the UE C.

Description

{METHOD FOR TRANSMITTING / RECEIVING INFORMATION OF ORTHOGONAL VARIABLE SPREADING FACTOR CODE ASSIGNED TO USER DATA IN HIGH SPEED DATA PACKET ACCESS COMMUNICATION SYSTEM}

The present invention relates to a fast forward packet access communication system, and more particularly to a method for transmitting and receiving OVSF code information to be assigned to user data.

In general, the High Speed Downlink Packet Access (High Speed Downlink Packet Access) method is a high speed downlink shared channel, which is a forward data channel for supporting forward high speed packet data transmission in a universal mobile terrestrial system (UMTS) communication system. : General term for a data transmission method including an HS-DSCH) and related control channels. Adaptive Modulation and Coding (hereinafter referred to as "AMC"), Hybrid Automatic Retransmission Request (hereinafter referred to as "HARQ"), and fast cell selection to support the fast forward packet access. Fast Cell Select (hereinafter, referred to as "FCS") has been proposed.

Next, the AMC scheme, the FCS scheme, and the HARQ scheme, which are schemes for supporting the fast forward packet access, will be described.

First, the AMC method will be described.

The AMC scheme modulates different data channels according to channel conditions between a specific base station (Node B, hereinafter referred to as "Node B") and a user terminal (UE: User Element, hereinafter referred to as "UE"). A data transmission method of determining a method and a coding method to improve the use efficiency of the entire Node B. Accordingly, the AMC scheme has a plurality of modulation schemes and a plurality of coding schemes, and modulates and codes a data channel signal by combining the modulation schemes and coding schemes. Typically, each of the combinations of modulation schemes and coding schemes is referred to as a modulation and coding scheme (hereinafter, referred to as "MCS"), and level n to level n depending on the number of MCSs. Up to a plurality of MCSs can be defined. That is, the AMC scheme is a scheme for adaptively determining the level of the MCS according to a channel state between the UE and a Node B which is currently wirelessly connected, thereby improving overall Node B overall system efficiency.

Second, the FCS scheme will be described.

The FCS scheme is a method of quickly selecting a cell having a good channel state among a plurality of cells when the UE using the fast forward packet access scheme is located in a cell overlap region, that is, a soft handover region. Specifically, the FCS scheme includes: (1) when a UE using the fast forward packet access scheme enters a cell overlap region of any first Node B and any second Node B, the UE includes a plurality of cells. That is, a radio link (hereinafter referred to as "Radio Link") with a plurality of Node Bs is set. In this case, a set of cells configured with the UE and a radio link is called an active set. (2) Receive the packet data for the fast forward packet access method only from the cells maintaining the best channel state among the cells included in the active set to reduce the overall interference. In this case, the cell in which the channel state is the best in the active set is transmitted, and a cell transmitting high-speed forward packet access packet data is called a best cell, and the UE 130 periodically checks channel states of cells belonging to the active set. When a cell having a better channel state is generated than a current best cell, a best cell indicator is transmitted to cells belonging to the active set to replace the current best cell with a cell having a better channel state. do. The best cell indicator includes an identifier of a cell selected as a best cell and is transmitted. Accordingly, cells in the active set receive the best cell indicator and examine a cell identifier included in the best cell indicator. Thus, each of the cells in the active set checks whether the best cell indicator corresponds to its best cell indicator, and the corresponding cell selected as the best cell is a packet to the UE using a fast forward common channel (HS-DSCH). Send the data.

Third, an HARQ scheme, in particular, a multi-channel Stop And Wait Hybrid Automatic Retransmission Request (hereinafter referred to as "n-channel SAW HARQ") will be described.

The HARQ scheme newly applies the following two methods to increase the transmission efficiency of the ARQ (Automatic Retransmission Request) scheme. The first scheme is to perform the retransmission request and response between the UE and the Node B. The second scheme is to temporarily store the data in error and combine it with the retransmission data of the corresponding data. will be. In addition, the fast forward packet access scheme has introduced the n-channel SAW HARQ scheme to compensate for the shortcomings of the conventional Stop and Wait ARQ (SAW ARQ) scheme. In the SAW ARQ scheme, the next packet data is transmitted only after receiving an ACK for the previous packet data. However, since the next packet data is transmitted only after receiving the ACK for the previous packet data, there may occur a case where the ACK should be waited even though the packet data may be transmitted at present. In the n-channel SAW HARQ scheme, a plurality of packet data may be continuously transmitted without receiving an ACK for the previous packet data, thereby improving channel usage efficiency. That is, if n logical channels are established between the UE and the Node B, and each of the n channels can be identified by a specific time or channel number, the UE, which receives the packet data, at any point in time It is possible to know which channel the received packet data is transmitted through, and to take necessary measures such as reconstructing the packet data in the order to be received or soft combining the packet data.

The fast forward packet access communication system, which supports the AMC scheme, the FCS scheme, and the HARQ scheme to increase communication efficiency, is a system in which a plurality of UEs share transmission resources of some forward transmission resources. The forward transmission resources include a transmission output and an orthogonal variable orthogonal variable spreading factor (OVSF) code. In the case of the OVSF code, as discussed in the current standard, a spreading factor (SF) is spread. 10 OVSF codes are used for the fast forward packet access communication system when the factor is 16 (SF = 16), and 20 OVSF codes are used for the fast forward packet access communication when the spreading factor is 32 (SF = 32). Consideration for use in the system is under consideration.

Multiple OVSF codes available in the fast forward packet access communication system may be used simultaneously by multiple UEs at a particular time. That is, OVSF code multiplexing is possible between a plurality of UEs at a specific same time in the fast forward packet access communication system. Such OVSF code multiplexing will be described with reference to FIG. 1.

1 is a diagram illustrating an example of assigning an OVSF code in a typical high speed forward packet access communication system. In FIG. 1, in particular, the diffusion coefficient of 16 (SF = 16) will be described as an example.

Referring to FIG. 1, each OVSF codes are shown as C (i, j) according to the location of the code tree. In C (i, j), the variable i represents the spreading coefficient value, and the variable j represents the order from the leftmost in the OVSF code tree. For example, C (16,0) indicates that the spreading factor is 16, and the spreading factor is 16 when the spreading factor is 16 in the OVSF code tree. FIG. 1 assigns 10 OVSF codes to the fast forward packet access communication system from 7th to 16th, that is, C (16.6) to C (16,15) in the OVSF code tree when the spreading factor is 16. The case is shown. The 10 OVSF codes may be multiplexed to a plurality of UEs. For example, OVSF codes may be multiplexed as shown in Table 1 below.

Time t0 t1 t2 A C (16,6) to C (16,7) C (16,6) to C (16,8) C (16,6) to C (16,10) B C (16,8)-C (16,10) C (16,9) to C (16,10) C (16,11)-C (16,14) C C (16,11) to C (16,15) C (16,11) to C (16,15) C (16,15)

In Table 1, A, B, and C are any users, i.e., any UEs, using the fast forward packet access communication system. As shown in Table 1 above, at any time point t0, t1, t2, the users A, B, C are code multiplexed using OVSF codes assigned to the high speed forward packet access communication system. The number of OVSF codes to be allocated to each UE and the location on the OVSF code tree are determined by the Node B, which is the amount of user data of each of the UEs stored in the Node B, and the Node B and the UEs. The decision is made in consideration of the channel conditions set for each.

The high speed forward packet access communication system, which is currently under standardization, proposes to convey the OVSF code information to each UE through a forward control channel. To explain this in detail, first, a channel structure of the fast forward packet access communication system will be described.

The high speed forward packet access communication system includes a high speed downlink shared channel (HS-DSCH), a forward control channel, and a reverse control channel for transmitting forward user data. The HS-DSCH is a channel for transmitting user data to users using OVSF codes assigned to the fast forward packet access communication system. In order to support the AMC scheme, the HARQ scheme, and the FCS scheme of the fast forward packet access communication system, control information (exchange of control information) is required between the Node B and the UE, and the control information includes the forward control channel and the reverse control channel. Is sent through.

As control information transmitted through the reverse control channel, channel quality information periodically reported by the UE to the Node B, acknowledgment (ACK) signal reporting whether an error occurs in the user data received by the UE, and the UE There is a best cell information for reporting the cell providing the best channel by comparing the channel status of the cells within the receivable range. In addition, the control information transmitted through the forward control channel includes information for notifying any UE that user data is to be transmitted through HS-DSCH, information regarding an MCS level to be used for transmitting user data to the UE, OVSF code information to be allocated to user data transmission to the UE.

Next, a transmitter structure for transmitting OVSF code information allocated to user data in a typical high speed forward packet access communication system will be described with reference to FIG. 2.

2 is a block diagram illustrating a transmitter structure for transmitting OVSF code information allocated to user data in a typical high speed forward packet access communication system.

Referring to FIG. 2, the transmitter exists in a base station of the fast forward packet access communication system to perform user data transmission through HS-DSCH and forward control information transmission through a forward control channel, and AMC (Adaptive Modulation and Coding). Controller 201, scheduler 202, transmission buffer 203, turbo encoder 204, user data transmitter 205, control information generator 206, It consists of a channel encoder 207 and a control data transmitter 208. The transmission buffer 203 receives and buffers user data generated in an upper layer, and the user data buffered in the transmission buffer 203 is scheduled under the control of the scheduler 202 and the turbo encoder. Is output to 204. The turbo encoder 204 inputs user data output from the transmission buffer 203 and turbo codes the control by the AMC controller 201 to output the user data to the user data transmitter 205. The user data transmitter 205 modulates the turbo coded user data output from the turbo encoder 204 and channelizes the user data and transmits the channel data to the corresponding UE through a radio link.

Here, the information on the modulation scheme performed by the user data transmitter 205 is controlled by the AMC controller 201, and the information about the OVSF code used for the channelization is controlled by the scheduler 202. In this case, the AMC controller 201 determines appropriate MCS level and modulation scheme for the corresponding UE by using control information received from the UE. In addition, the scheduler 202 considers the amount of user data or the type of user data of other UEs using the fast forward packet access communication system, and selects an OVSF code to be used for user data transmission and user data transmission of the UE. Decide

MCS level information determined by the AMC controller 201 and OVSF code information determined by the scheduler 202 are respectively output to the control information generator 206. The control information generator 206 converts the MCS level information and the OVSF code information into a format suitable for a wireless channel. For example, if the control information is transmitted through a dedicated physical control channel (DPCCH), the control information generator 206 transmits the control information to the transmission format of the dedicated physical control channel (DPCCH). ) And outputs it to the channel encoder 207. The channel encoder 207 performs channel coding on the control information output from the control information generator 206 and outputs the channel coded control information to the control data transmitter 208. In this case, the channel coding is performed by selecting one of coding schemes such as convolutional coding or turbo coding. The control data transmitter 208 modulates and channelizes the channel coded control information output from the channel encoder 207 and transmits the channel coded control information to the corresponding UE through a radio link.

In FIG. 2, a transmitter structure for transmitting control information such as OVSF code information to be allocated to a UE has been described. Next, a receiver structure for receiving OVSF code information allocated to user data will be described with reference to FIG. 3.

3 is a block diagram illustrating a receiver structure for receiving OVSF code information allocated to user data in a typical high speed forward packet access communication system.

Referring to FIG. 3, the receiver is provided with a control data receiver 301 and a channel decoder to receive user data transmitted through the HS-DSCH and forward control information transmitted through the forward control channel. ) 302, control information decoder 303, user data receiver 304, turbo decoder 305, and reception buffer 306. Same as

First, when control data is received by the control data receiving unit 301 of the receiver via a wireless link, the control data receiving unit 301 de-spreads and demodulates the input received control data. After the modulation) process, the signal is output to the channel decoder 302. Here, the radio link is a channel for transmitting pre-regulated forward control data between the UE and the Node B, and may be, for example, a dedicated physical control channel (DPCCH).

The channel decoder 302 channel decodes the despread and demodulated signal output from the control data receiver 301, and the control data on which the channel decoding is completed is output to the control information decoder 303. . In this case, the control information decoder 303 extracts the information about the MCS level and the OVSF code allocated to the user data transmission from the control data output from the channel decoder 302 and the channel decoding is completed. Here, the information on the MCS level from the information on the MCS level and the OVSF code extracted by the control information decoder 303 is transmitted to the user data receiving unit 304 and the turbo decoder 305, the OVSF Information about the code is transmitted to the user data receiving unit 304.

On the other hand, the user data received via the wireless link is input to the user data receiving unit 304, the user data receiving unit 304 despreads and demodulates the received user data and then despreading and The demodulated user data is output to the turbo decoder 305. Here, the despreading performed by the user data receiver 304 is performed using the OVSF code information received from the control information decoder 303, and the demodulation performed by the user data receiver 304 is performed by the despreading. Similarly, the MCS level information received from the control information decoder 303 is used.

The turbo decoder 305 inputs the despread and demodulated user data output from the user data receiver 304 and performs turbo decoding on the input despread and demodulated user data. Output to the receive buffer 306. Here, the turbo decoder 305 performs turbo decoding on the despread and demodulated user data using MCS level information received from the control information decoder 303. The user data buffered in the reception buffer 306 is transferred to a higher layer at a corresponding point in time according to a predetermined control. Accordingly, when the receiver, that is, the UE, recognizes the OVSF code information and the MCS level allocated to the user data, the receiver can receive the user data transmitted from the Node B through the wireless link.

As described above, in the fast forward packet access communication system, the transmitter should transmit the OVSF code information to be allocated to the user data from the transmitter to the receiver. Then, the receiver will transmit the OVSF code information to be allocated to the user data transmitted from the transmitter. It is possible to detect user data received from the transmitter side by using the same. Thus, in the fast forward packet access communication system currently discussed in the standard, the starting point of the OVSF code and the OVSF code of the OVSF code to be allocated to the user data so as to efficiently inform the receiver side, that is, the UE, of the OVSF code information. A way of telling the count is being considered.

Here, a method of informing OVSF code information to be allocated to the user data by informing a starting point of the OVSF code and the number of OVSF codes will be described.

First, the situation shown in Table 1, that is, a situation in which C (16,5) to C (16,15) is allocated to the high speed forward packet access communication system will be described as an example. In order to forward user data by allocating OVSF codes of C (16,5) and C (16,6) to any UE A at any time t0, the UE A may be received at any time earlier than the time t0. It is only possible for the UE A to receive the user data at the time point t0 by transmitting OVSF code information to be allocated to the user data. As described above, OVSF code information to be transmitted through the forward control channel prior to user data transmission through the HS-DSCH is shown in Table 2 below.

Time t0 t1 t2 A C (16,6) ~ C (16,7) SP: 0110NC: 0010 C (16,6) ~ C (16,8) SP: 0110NC: 0011 C (16,6) ~ C (16,10) SP: 0110NC: 0100 B C (16,8) ~ C (16,10) SP: 1000NC: 0011 C (16,9) ~ C (16,10) SP: 1001NC: 0010 C (16,11) ~ C (16,14) SP: 1011NC: 0100 C C (16,11) ~ C (16,15) SP: 1011NC: 0101 C (16,11) ~ C (16,15) SP: 1011NC: 0100 C (16,15) SP: 1111NC: 0001

In Table 2, the SP (Start Point) indicates the starting point of the OVSF code allocated to the actual user data transmission on the OVSF code tree, and as described in FIG. 1, the leftmost side is 0000 on the OVSF code tree. Is represented by 1111. In Table 2, the number of codes (NC) represents the number of OVSF codes allocated to the user data transmission, and the number of OVSF codes is represented by a binary number. Thus, as shown in Table 2, as an example, in a situation in which 10 codes having a spreading factor of 16 are allocated to a high speed forward packet access communication system (see FIG. 1), the SP and NC are used to allocate user data to the UE. In order to transmit OVSF code information, 4 bits are needed to represent the SP, and 4 bits are needed to represent the NC, and thus 8 bits are required.

When generalizing this, the number of bits required to represent the SP is R (log ₂ n), and the number of bits required to represent the NC in the situation where NH codes having a spreading coefficient n are allocated to the fast forward packet access communication system. Becomes R (log ₂ NH). Wherein R (x) means a minimum integer equal to or greater than any real number x. In the case of allocating a plurality of OVSF codes to one UE, it is assumed that only consecutive OVSF codes are allocated in the OVSF code tree.

The OVSF code information represented by the SP and the NC is one of the control information described with reference to FIGS. 2 and 3, and the transmitter side of the fast forward packet access communication system, i. Is sent to the UE. However, since the OVSF code information to be allocated to the user data must be transmitted to the UE through a forward control channel such as the dedicated physical control channel (DPCCH) whenever the user data is transmitted through the HS-DSCH, the size of the OVSF code information. The smaller is, the more preferable. However, the method of notifying the start point SP of the OVSF code and the number of OVSF codes NC about the OVSF code to be allocated to the user data is more than necessary to indicate the starting point of the OVSF code and the number of OVSF codes. There has been a problem that many bits have to be allocated to the OVSF code information.

Accordingly, an object of the present invention is to provide a method for transmitting and receiving OVSF code information to be allocated to user data in a high speed forward packet access communication system.

Another object of the present invention is to provide a method for transmitting / receiving information on all OVSF codes that can be allocated to user data in a high speed forward packet access communication system using only a separate logical identifier.

Method according to the first aspect of the present invention for achieving the above objects; A method for transmitting orthogonal code information assigned to user data in a high speed forward packet access communication system having an orthogonal code information table in which one or more logical identifiers correspond to all orthogonal code information allocable to user data in one-to-one correspondence. When the user data to be transmitted to the user terminal is generated, determining an orthogonal code to be allocated to the user data to be transmitted to the specific user terminal in consideration of the amount of user data transmitted to other user terminals and the type of the user data; Determining a logical identifier having information corresponding to the determined orthogonal code by searching the orthogonal code information table, and generating and transmitting the detected logical identifier as control information for the specific user terminal. artillery Characterized in that.

According to a second aspect of the present invention for achieving the above objects; A method of receiving orthogonal code information assigned to user data in a high speed forward packet access communication system having an orthogonal code information table in which one or more logical identifiers correspond to all orthogonal code information allocable to user data in one-to-one correspondence; Despreading the channel data by despreading the control data received through the channel, detecting a logical identifier for the orthogonal code information allocated when transmitting the user data from the channel decoded control data, and transmitting the logical identifier And detecting the orthogonal code information corresponding to the detected logical identifier by searching the orthogonal code information table after the detection.

Method according to the third aspect of the present invention for achieving the above objects; In the high speed forward packet access communication system, orthogonal code information that can be generated in real channel conditions is calculated for orthogonal codes that can be allocated to user data, and corresponding logical identifiers are stored for each of the calculated orthogonal code information. A method of transmitting orthogonal code information allocated to user data in a fast forward packet access communication system having one orthogonal code information table, wherein user data is transmitted to other user terminals when user data to be transmitted to a specific user terminal is generated. Determining an orthogonal code to be allocated to user data to be transmitted to the specific user terminal in consideration of the amount and the type of the user data; and determining the orthogonal code and searching an orthogonal code information table to obtain information corresponding to the determined orthogonal code. Branch Detecting a logical identifier, and generating and transmitting the detected logical identifier as control information for the specific user terminal.

Method according to the fourth aspect of the present invention for achieving the above objects; In the high speed forward packet access communication system, orthogonal code information that can be generated in real channel conditions is calculated for orthogonal codes that can be allocated to user data, and corresponding logical identifiers are stored for each of the calculated orthogonal code information. A method of receiving orthogonal code information allocated to user data in a fast forward packet access communication system having an orthogonal code information table, the method comprising: despreading and channel decoding a control data received through a specific channel; Detecting a logical identifier for orthogonal code information allocated when transmitting user data from the decoded control data; and detecting the orthogonal code information table after detecting the logical identifier to correspond to the detected logical identifier. Ortho code information check It is characterized by including the process of delivery.

Method according to the fifth aspect of the present invention for achieving the above objects; A high speed forward packet shared with a plurality of user terminals and having a fast forward common channel for spreading and transmitting the user data with orthogonal code information determined in consideration of the amount and type of user data transmitted to a specific user terminal. In the method for allocating orthogonal code information to the user data in an access communication system, user terminals connectable to the fast forward common channel in any one transmission time period and orthogonal code information allocated to each of the user terminals. A first process of generating a code set consisting of elements corresponding to the number of orthogonal codes included in the first order; and sequentially reconstructing from a first element having a maximum number of orthogonal codes allocated among the elements constituting the code set A second process of generating a reconstruction code set, and the reconstruction code The first element is sequentially assigned from an orthogonal code located at the leftmost side of the entire code space, which is a set of orthogonal codes that can be allocated to the fast forward common channel by the number of orthogonal codes corresponding to the first element among the elements of. A third process of removing from the reconstruction code set and the number of orthogonal codes corresponding to a second element having a minimum number of orthogonal codes allocated among the remaining elements of the reconstruction code set after removing the first element; And a fourth process of sequentially assigning orthogonal codes located at the rightmost side of the code space and removing the second element from the reconstruction code set.

1 is a diagram illustrating an example of allocating an OVSF code in a typical high speed forward packet access communication system;

2 is a block diagram showing a transmitter structure for transmitting OVSF code information assigned to user data in a typical high speed forward packet access communication system.

3 is a block diagram showing a receiver structure for receiving OVSF code information assigned to user data in a typical high speed forward packet access communication system.

4 is a block diagram illustrating a transmitter structure for transmitting OVSF code information allocated to user data in a fast forward packet access communication system according to another embodiment of the present invention.

FIG. 5 is a block diagram illustrating a receiver structure for receiving OVSF code information allocated to user data in a fast forward packet access communication system according to another embodiment of the present invention.

6 illustrates an example of OVSF code allocation according to another embodiment of the present invention.

7 is a diagram schematically showing an example of OVSF code allocation according to another embodiment of the present invention;

8 schematically illustrates an example of OVSF code allocation according to another embodiment of the present invention.

9 schematically illustrates an example of OVSF code allocation according to another embodiment of the present invention.

10 is a diagram schematically showing an example of OVSF code allocation according to another embodiment of the present invention;

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted so as not to distract from the gist of the present invention.

First, in the present invention, as described above, orthogonal variable spreading factor (OVSF) code information to be allocated to user data in a high speed downlink packet access communication system is described above. Instead of separately configuring the OVSF code starting point (SP) and the number of OVSF codes (NC), logical identifiers are assigned to all assignable OVSF codes in consideration of all the OVSF codes that can be allocated to the user data. Use the way.

The Spreading Factor (SF) described in FIG. 1 is 16 for a method of assigning logical identifiers to all assignable OVSF codes in consideration of all OVSF codes allocable to user data of the present invention. In the case of 10 OVSF codes from the 7th OVSF code to the 16th OVSF code in the OVSF code tree, that is, 10 OVSF codes from C (16,6) to C (16,15) An example of the case allocated to the access communication system will be described. In this case, the number of possible cases according to the number of allocated OVSF codes is shown in Table 3 below.

OVSF Code Count The number of possible cases Remarks 10 One [C (16,6) to C (16,15)] 9 2 [C (16,6) to C (16,14)], [C (16,7) to C (16,15)] 8 3 [C (16,6) to C (16,13)], [C (16,7) to C (16,14)], [C (16,8) to C (16,15)] 7 4 [C (16,6) to C (16,12)], [C (16,7) to C (16,13)], [C (16,8) to C (16,14)], [C (16,9) to C (16,15)] 6 5 [C (16,6) to C (16,11)], [C (16,7) to C (16,12)], [C (16,8) to C (16,13)], [C (16,9) to C (16,14)], [C (16,10) to C (16,15)] 5 6 [C (16,6) to C (16,10)], ..... [C (16,11) to C (16,15)] 4 7 [C (16,6) to C (16,9)], ..... [C (16,12) to C (16,15)] 3 8 [C (16,6) to C (16,8)], ..... [C (16,13) to C (16,15)] 2 9 [C (16,6) to C (16,7)], ..... [C (16,14) to C (16,15)] One 10 [C (16,6)], ........, [C (16,15)]

The remarks column in Table 3 shows examples of possible cases. As shown in Table 3, the number of OVSF codes allocated to one user terminal (UE) (hereinafter referred to as "NU") is the number of OVSF codes allocated to the fast forward packet access communication system ( In the same case as "NH"), only one case can be generated. When the NU is 1 less than the NH, that is, the number of OVSF codes allocated to one UE in Table 3 is 9, the number of possible cases is [C (16,6) to C (16,14)]. Or 2 in the case of [C (16,7) to C (16,15)]. If the NU is 2 less than the NH, the number of possible cases becomes 3.

In other words, if the NU value is repeated until the NU value is equal to the NH value, the number of all cases that can occur in the high speed forward packet access communication system, that is, the TNC, is calculated. The TNC calculation process is represented by Equation 1 below.

Therefore, the number of bits used for transmitting the OVSF code information is R (log ₂ TNC).

Thus, the number of bits used for transmitting the OVSF code information according to the present invention and the number of bits used for transmitting the OVSF code information described in the related art will be compared with reference to Table 4 below.

Number of bits required for conventional OVSF code information transmission Number of bits required for OVSF code transmission according to an embodiment of the present invention SF: 16 and NH: 10 R (log ₂ 16) + R (log ₂ 10) = 8 R (log ₂ 55) = 6 SF: 32, NH: 20 R (log ₂ 32) + R (log ₂ 20) = 10 R (log ₂ 210) = 8 SF: 64, NH: 40 R (log ₂ 64) + R (log ₂ 40) = 12 R (log ₂ 820) = 10

As shown in Table 4, in the present invention, it is possible to transmit OVSF code information allocated to user data using fewer bits than in the prior art. That is, in the related art, OVSF code information to be allocated to user data is composed of information about each of the start point SP of the OVSF code and the number of allocated OVSF codes NC. However, in the present invention, after calculating all the OVSF code information that can be generated for the OVSF code to be allocated to the user data, the calculated OVSF code information is stored in advance in the form of an OVSF code information table. Here, the process of calculating all the OVSF code information that can be generated for the OVSF code to be allocated to the user data is the same as the conventional OVSF code information calculation method, and a detailed description thereof will be omitted. When the user data is actually transmitted from the transmitter side to the receiver side, OVSF code information to be allocated to the user data is expressed as a logical identifier on the OVSF code information table.

Here, the OVSF code information table is generated by calculating OVSF code information in all cases that can be allocated to user data in the high-speed forward packet access communication system and mapping a logical identifier to each of the calculated OVSF code information. The process is as follows.

As described above, the method of mapping the calculated OVSF code information in all cases to the logical identifier is not limited to one method, and it is only necessary to correspond the OVSF code information in all cases to a specific logical identifier in any way. . For example, since the NU corresponds to the logical identifier 0 from the case where the NU is the same as the NH, the remaining cases may be increased by 1 to correspond to the logical identifier, or vice versa.

Table 5 shows an example in which logical identifiers are mapped to each of the OVSF code information in all cases. In Table 5, the spreading factor is 16 in the fast forward packet access system and 10 from the 7th OVSF code to the 16th OVSF code on the OVSF code tree, that is, C (16,6) to C (16,15). Assume that OVSF codes are allocated.

SP NC Logical identifier SP NC Logical identifier C (16,6) 10 000000 C (16,6) 3 011100 C (16,6) 9 000001 C (16,7) 3 011101 C (16,7) 9 000010 C (16,8) 3 011110 C (16,6) 8 000011 C (16,9) 3 011111 C (16,7) 8 000100 C (16,10) 3 100000 C (16,8) 8 000101 C (16,11) 3 100001 C (16,6) 7 000110 C (16,12) 3 100010 C (16,7) 7 000111 C (16,13) 3 100011 C (16,8) 7 001000 C (16,6) 2 100100 C (16,9) 7 001001 C (16,7) 2 100101 C (16,6) 6 001010 C (16,8) 2 100110 C (16,7) 6 001011 C (16,9) 2 100111 C (16,8) 6 001100 C (16,10) 2 101000 C (16,9) 6 001101 C (16,11) 2 101001 C (16,10) 6 001110 C (16,12) 2 101010 C (16,6) 5 001111 C (16,13) 2 101011 C (16,7) 5 010000 C (16,14) 2 101100 C (16,8) 5 010001 C (16,6) One 101101 C (16,9) 5 010010 C (16,7) One 101110 C (16,10) 5 010011 C (16,8) One 101111 C (16,11) 5 010100 C (16,9) One 110000 C (16,6) 4 010101 C (16,10) One 110001 C (16,7) 4 010110 C (16,11) One 110010 C (16,8) 4 010111 C (16,12) One 110011 C (16,9) 4 011000 C (16,13) One 110100 C (16,10) 4 011001 C (16,14) One 110101 C (16,11) 4 011010 C (16,15) One 110110 C (16,12) 4 011011

Thus, as shown in Table 5, the OVSF code information table is generated by allocating logical identifiers for all OVSF code information that can be allocated during user data transmission in the fast forward packet access system. The OVSF code information table may be generated directly in the transmitter of the fast forward packet access system, that is, Node B, or may be generated in the upper layer of the Node B or higher and used as it is in the Node B.

As described above, when the total code space to be used in the communication system using the HSDPA method is determined, all assignable cases can be identified. Here, the "overall code space" means a set of OVSF codes allocated for the HS-DSCH in the entire communication system using the HSDPA scheme. The starting point of the entire code space is defined as the overall starting point (OSP), and the end point of the entire code space is called the overall end point (OEP). If a code is assigned to a certain UE, the starting point is called an individual starting point (ISP: Individual Starting Point, hereinafter referred to as an "ISP"). When is referred to as an individual end point (IEP: hereinafter referred to as "IEP"), the following steps are repeated starting from the case where NU and NH are the same and until NU is 1. Assuming that NU is any integer n between 1 and NH, if NU is n, starting with the case where ISP and OSP are the same, and sequentially moving the codes backward one by one until ESP and OSP are the same All cases where NH is n are calculated.

This will be described with reference to FIG. 10.

10 is a diagram schematically showing an example of OVSF code allocation according to another embodiment of the present invention.

In FIG. 10, five codes from C (16, 11) to C (16, 15) are allocated to the HS-DSCH. In the description of FIG. 10, for convenience of description, C (16,11) to C (16,15) will be defined as C1 to C5. As shown in FIG. 10, possible code allocation cases are as follows.

First, if NU and NH are the same, there is only one case because ISP and OSP, IEP and OEP are the same (case 1). Next, when NU is 1 smaller than NH, there is one case where ISP and OSP are the same (case 2), and two cases exist because OEP and IEP are the same when case one moves backwards ISP (case 3). . When the NU is 2 smaller than NH, there is one case where the ISP and the OSP are the same (case 4), there is a case where the ISP exists one code after the OSP (case 5), and the case where the OEP and the IEP are the same. Therefore, there are three possible cases when NU is less than NH. Repeating the above process until NU becomes 1, all possible cases are identified as shown in FIG. In the above case, what identifier is assigned to case 1 to case 15 is determined depending on the case. As described in Table 5, the identifiers may be assigned in the order of the largest to the smallest NU, and conversely, the identifiers may be assigned in the order of the smallest to the largest NU, or may be assigned by the ISP. For example, in FIG. 10, the ISP of [case 1, case 2, case 4, case 7, case 11] is C1, the case of [case 3, case 5, case 8, case 12] is C2, and [case] 6, Case 10, Case 13] is ISP C3, Case 9, Case 14 ISP is C4, and Case 15 ISP C5. In the cases shown in FIG. 10, logical identifiers are assigned as shown in Table 6 below.

Next, a description will be given with reference to FIGS. 4 to 5 for transmitting and receiving OVSF code information to be allocated to user data using the OVSF code information table in the fast forward packet access communication system.

4 is a block diagram showing a structure of a transmitter for transmitting OVSF code information allocated to user data in a fast forward packet access communication system according to another embodiment of the present invention.

Referring to FIG. 4, the transmitter is present in a base station of the fast forward packet access communication system to perform user data transmission through HS-DSCH and forward control information transmission through a forward control channel, and AMC (Adaptive Modulation and Coding). Controller 501, scheduler 502, transmission buffer 503, turbo encoder 504, user data transmitter 505, control information generator 506, A channel encoder 507, a control data transmitter 508, and an OVSF code information table storage 509 are described in more detail as follows.

The transmission buffer 503 buffers user data generated in an upper layer, and the user data buffered in the transmission buffer 503 is scheduled under the control of the scheduler 502 to provide the turbo encoder 504. Will be printed). The turbo encoder 504 inputs user data output from the transmission buffer 503, turbo codes the control by the AMC controller 501, and outputs the turbo data to the user data transmitter 505. The user data transmitter 505 modulates the turbo coded user data output from the turbo encoder 504 and channelizes the user data and transmits the channel data to the corresponding UE through a radio link.

Here, the information on the modulation scheme performed by the user data transmitter 505 is controlled by the AMC controller 501, and the information about the OVSF code used for the channelization is controlled by the scheduler 502. In this case, the AMC controller 501 determines appropriate MCS level and modulation scheme for the corresponding UE by using control information received from the UE.

In addition, the scheduler 502 considers the amount of user data or type of user data of other UEs using the fast forward packet access communication system, and the OVSF code to be used for user data transmission time and user data transmission of the corresponding UE. Determine. The scheduler 502 then searches the OVSF code information table storage 509 to detect a logical identifier corresponding to the OVSF code to be used for the determined user data transmission, and converts the detected logical identifier into the control information generator ( 506). In addition, the MCS level information determined by the AMC controller 501 is also output to the control information generator 506.

The control information generator 506 converts a logical identifier corresponding to the MCS level information and the OVSF code information into a format suitable for a wireless channel. For example, if the control information is transmitted through a dedicated physical control channel (DPCCH), the control information generator 506 transmits the control information to the transmission format of the dedicated physical control channel (DPCCH). format) to output to the channel encoder 207. The channel encoder 507 performs channel coding on the control information output from the control information generator 506, and outputs the channel coded control information to the control data transmitter 508. In this case, the channel coding is performed by selecting one of coding schemes such as convolutional coding or turbo coding. The control data transmitter 508 modulates and channelizes the channel coded control information output from the channel encoder 507 and transmits it to the corresponding UE through a radio link.

4 illustrates a structure of a transmitter for transmitting control information such as OVSF code information to be allocated to a UE. Next, a receiver structure for receiving OVSF code information allocated to user data will be described with reference to FIG. 5.

5 is a block diagram illustrating a receiver structure for receiving OVSF code information allocated to user data in a fast forward packet access communication system according to another embodiment of the present invention.

Referring to FIG. 5, the receiver is provided with a control data receiver 601 and a channel decoder to receive user data transmitted through the HS-DSCH and forward control information transmitted through the forward control channel. 602, control information decoder 603, user data receiver 604, turbo decoder 605, receive buffer 606, and OVSF code information table storage 607. It is composed.

First, when control data is received by the control data receiver 601 of the receiver through a wireless link, the control data receiver 601 de-spreads and demodulates the input received control data. And then outputs to the channel decoder 602. Here, the radio link is a channel for transmitting pre-regulated forward control data between the UE and the Node B, and may be, for example, a dedicated physical control channel (DPCCH).

The channel decoder 602 channel decodes the despread and demodulated signal output from the control data receiver 601, and the control data on which the channel decoding is completed is output to the control information decoder 603. . At this time, the control information decoder 603 extracts information on the MCS level and information on the OVSF code from the control data output from the channel decoder 602 and the channel decoding is completed. That is, the information about the MCS level in the information on the MCS level and the OVSF code extracted by the control information decoder 603 is transmitted to the user data receiving unit 604 and the turbo decoder 605, the OVSF Information about the code is transmitted to the user data receiving unit 604.

Here, the control information decoder 603 first detects a logical identifier representing the OVSF code information on the received control data in order to extract information about the OVSF code. The control information decoder 603 searches the OVSF code information table stored in the OVSF code information table storing unit 607 to determine the OVSF code information corresponding to the detected logical identifier, that is, the starting point and code on the OVSF tree. The detected OVSF code information is converted into a number of and the detected OVSF code information is transmitted to the user data receiver 604. When the receiver, i.e., the UE, recognizes the OVSF code information and MCS level allocated to the user data extracted by the control information decoder 603, the receiver receives the user data transmitted from the Node B through a radio link.

The user data received through the radio link is input to the user data receiving unit 604. The user data receiving unit 604 despreads and demodulates the received user data, and then despreads and demodulates the received user data. The user data is output to the turbo decoder 605. Here, the despreading performed by the user data receiver 604 is performed using the OVSF code information received from the control information decoder 603, and the demodulation performed by the user data receiver 604 is performed by the despreading. In the same manner, the MCS level information received from the control information decoder 603 is used. The turbo decoder 605 inputs the despread and demodulated user data output from the user data receiver 604 and performs turbo decoding on the input despread and demodulated user data. Output to the receive buffer 606. Here, the turbo decoder 605 performs turbo decoding on the despread and demodulated user data using the MCS level information received from the control information decoder 603. The user data buffered in the reception buffer 606 is transferred to a higher layer at a corresponding point in time according to a predetermined control.

In the above-described embodiments of the present invention, that is, the first preferred embodiment of the present invention, orthogonal code information in which one-to-one correspondence of logical identifiers corresponding to all orthogonal code information allocable to user data in a high speed forward packet access communication system is provided. A table having fewer bits than the conventional OVSF code information to be allocated to user data in a high speed forward packet access communication system by transmitting and receiving orthogonal code information allocated to actual user data with a logical identifier on the orthogonal code information table. Efficient transmission and reception of the information is made possible by using the data transmission scheme.

Next, a method of transmitting and receiving orthogonal code information to be allocated to user data in a fast forward packet access communication system according to a second embodiment of the present invention will be described. In the second embodiment, orthogonal code information to be allocated to user data is transmitted and received in a similar manner to the method described in the first preferred embodiment of the present invention. However, in the first embodiment, an orthogonal code information table is generated by mapping all orthogonal code information assignable to the user data one-to-one with a logical identifier, whereas in the second embodiment, the orthogonal code information can be assigned to the user data. Orthogonal code information when there is no possibility in the channel environment is excluded, and orthogonal code information is generated by mapping only the orthogonal code information when possible in the real channel environment to a logical identifier. As a result, in the second embodiment, only the orthogonal code allocation information is transmitted among all orthogonal code information allocable to the user data except for the case where there is no possibility of occurrence in the actual channel situation, thereby reducing the number of necessary bits. Unlike the first embodiment, only the rules applied when the base station Node B allocates the orthogonal code to be allocated to the user data are different, and the rest of the operations are the same.

Then, in the second embodiment of the present invention, when the base station allocates an orthogonal code to user data of the user terminal, code assignment rule 1 as described below is followed.

[Code Allocation Rule 1]

First, when the number of orthogonal codes allocated to HSDPA is n, the set is C = [C_1, C_2,, C_n], and the element C_1 of the set is allocated to the HSDPA on the OVSF code tree described in FIG. Defined as the leftmost code among the code. That is, in FIG. 1, C_1 becomes a code located at the leftmost of the codes allocated to the HSDPA on the OVSF code tree, that is, C (16,6). The set of OVSF codes assigned to any user terminal (UE) X is called C (X), and the number of OVSF codes is defined as N (X). That is, if the code assigned to any UE X is C (16,6) and C (16,7), then C (X) = [C (16,6), C (16,7)] And N (X) = 2.

In allocating OVSF codes to one or more user terminals at any point in time, the base station Node B allocates the leftmost OVSF codes to the user terminals to which the most OVSF codes are allocated. The OVSF code allocation to the remaining user terminals is not restricted. When there is only one user terminal, the OVSF code is allocated from the leftmost side of the OVSF code tree. For example, C = [C (16,6), .C (16,15)] in any HSDPA system, and 5, 2, respectively, in any user terminal A, B, C at any time, If one OVSF code needs to be allocated, five OVSF codes to be allocated to the user terminal A are allocated from C (16,6) to C (16,10), which are the leftmost on the HSDPA OVSF code tree. The OVSF codes for the user terminal B and the user terminal C are freely assigned without any limitation.

Hereinafter, code assignment according to the second preferred embodiment of the present invention will be described with reference to FIG.

6 illustrates an example of OVSF code allocation according to another embodiment of the present invention.

Referring to FIG. 6, first, for convenience of description, a series of OVSF codes is defined as a code section, and the number of OVSF codes belonging to the code section and the size of the code section are defined to have the same meaning.

Using the OVSF code allocation rule 1 as described in the second embodiment reduces the number of OVSF codes to be assigned to any user terminal, i.e. to occur in any user terminal. For example, when 10 OVSF codes are allocated from C (16,6) to C (16,15) in any HSDPA system, and assigns 4 OVSF codes to any user terminal, the first embodiment In the example of FIG. 6, the number of OVSF codes that can be assigned to any user terminal is seven. That is, as shown in FIG. 6, case 1 [C (16,6), C (16,7), C (16,8), C (16,9)] and case

2 [C (16,7), C (16,8), C (16,9), C (16,10)]

3 [C (16,8), C (16,9), C (16,10), C (16,11)]

4 [C (16,9), C (16,10), C (16,11), C (16,12)]

5 [C (16,10), C (16,11), C (16,12), C (16,13)]

6 [C (16,11), C (16,12), C (16,13), C (16,14)]

7 (C (16,12), C (16,13), C (16,14), C (16,15)).

However, if the same code allocation rule 1 as in the second embodiment is applied, OVSF code assignment like case 2, case 3, and case 4 cannot occur. The reason for this is that the code assignment like 2 is possible when C (16,6) is assigned to another user terminal. However, C (16,6) is the leftmost code section to which the largest code section should be allocated, and since the code section of size 4 exists on the right side of C (16,6), the case 2 for any user terminal OVSF code assignment like For the same reasons as in case 2, the OVSF code allocation as in case 3 and case 4 does not hold.

As described above, when the code allocation rule 1 proposed in the second embodiment is applied, the case in which the OVSF code is not allocated to the arbitrary user terminal is generalized as follows.

When the number of OVSF codes allocated to the HSDPA is N, when the K OVSF codes are allocated to any user terminal, the following cases may occur.

Case (1, K): [C_1, C_2,, C_K]

Case (2, K): [C_ (K + 1), C_ (K + 2),, C_2K]

Case (3, K): [C_ (K + 2), C_ (K + 3),, C_ (2K + 1)]

.

.

Case (last, K): [C_ (N-K + 1), C_ (N-K + 2),, C_N]

Therefore, if it can occur when there are K OVSF codes assigned to any user terminal, the number TNC (K) when assignable to any user terminal is given by Equation 2 below.

In Equation 2, the first term "1" is a value for case (1, K), and the other term N-K + 1- (K + 1) +1 is case (2, K) and (last, K) represents the number of cases existing between cases. Equation (2) holds only when K is less than or equal to N / 2, and when K is greater than N / 2, there is always only one number. For example, the case of N = 10 and K = 6 is as follows. Case (1,6) may be present as [C (16,5),, C (16,10)]. Case (2,6) is [C (16,11),, C (16,16)] and does not exist because the last code is out of the entire code section. Even when K is 7,8,9,10, only 1 is possible for the same reason as in the case of K = 6.

Therefore, in the second embodiment, when N OVSF codes are allocated in the HSDPA system to allocate K OVSF codes to any user terminal, the number of OVSF codes that can be allocated in an actual channel environment is represented by Equation 3 below.

TNC (K) = N-2 (K-1), provided K is less than or equal to N / 2

TNC (K) = 1 when K is greater than N / 2

In Equation 3, N is the total number of OVSF codes allocated to the HSDPA system, K is the number of OVSF codes to be assigned to any user terminal at any time, and TNC (K) is the OVSF assigned to any user terminal. The number of cases that can occur in an actual channel environment corresponding to the number of codes.

An orthogonal code information table in which one-to-one correspondence of logical identifiers corresponding to orthogonal code information according to code assignment rule 1 to user data of an arbitrary user terminal according to the second embodiment is shown in Table 7 below.

In the orthogonal code information table shown in Table 7, it is assumed that 10 OVSF codes having a spreading factor (SF) of 16 are allocated to the HSDPA system. Table 7 can generate the first embodiment, but in the second embodiment, Information on an orthogonal code that cannot occur, that is, cannot occur in a real channel environment is also shown. Orthogonal codes that cannot be generated in the actual channel environment are separately shown in italics.

Unlike Table 7, the logical identifier can be given from the case where the code space is small, as shown in Table 8 below. Table 8 below illustrates an example in which an arbitrary code interval [C_1,, C_15] is allocated for the HS-DSCH.

In Table 8, for convenience, the identifier is expressed in decimal not in binary. As shown in Table 7 or Table 8 above. If the size of the entire code interval is 10, the number of OVSF codes to be allocated to user data for any user terminal according to the second embodiment can be represented using 6 bits, and the size of the entire code interval is 15 In the case of 7 bits is possible. Of course, the first embodiment also indicates OVSF code information to be allocated to the user data using 6 bits when the entire code section is 10, but in the second embodiment, the first embodiment is determined according to the number of OVSF codes allocated to the HSDPA system. It represents the OVSF code information to be allocated to the user data more efficiently than the example. That is, when the NC is 11, at least 7 bits are required in the first embodiment to indicate OVSF code information to be allocated to the user data. In the second embodiment, unlike the first embodiment, since only the OVSF code information to be allocated to the user data, which can occur in the actual channel situation, is represented, the six bits can be represented as it is.

As a result, when the OVSF code information to be allocated to the user data is represented according to the second embodiment, the number of bits required to represent the OVSF code information is reduced by at least one bit or in some cases according to the size of the entire code section.

Next, a third embodiment of the present invention will be described.

The third embodiment of the present invention modifies the code allocation rule 1 of the second embodiment described above to minimize the number of code allocation cases. In the following description of the third embodiment, it is assumed that the maximum number of UEs capable of receiving the HS-DSCH during a certain TTI is fixedly set, and the maximum number of UEs capable of receiving the HS-DSCH during the TTI is fixed. The number is defined as "M" and the following code allocation rule 2 is proposed.

[Code Allocation Rule 2]

When the base station needs to allocate an OVSF code to one or more UEs at any point in time, a code set consisting of a number of OVSF codes to be allocated with the UE will be defined as follows. Create The structure of the code set is as follows.

code set = [UE A = 2, UE B = 4, UE C = 1, UE D = 3]

In the above, it is assumed that an OVSF code is allocated to four UEs A, B, C, and D at any time. The base station reconstructs the code set from the leftmost to the right in order of the number of OVSF codes allocated, and looks at the structure of the reconstructed code set as follows.

code set = [UE B = 4, UE D = 3, UE A = 2, UE C = 1]

Upon completion of the code set reconfiguration according to the number of OVSF codes allocated to the base station, the base station allocates the OVSF codes from the leftmost side of the entire code space to the UE on the leftmost side of the code set, and identifies the UE assigned the OVSF codes. Remove from code set. The base station then again assigns OVSF codes from the rightmost side of the entire code space to the UE located at the rightmost side in the code set and also removes the UE from the code set. And assigns OVSF codes from the leftmost of the entire code space to the UE on the leftmost side in the code set and also removes the UE from the codeset. The above steps are repeated until the code set becomes empty, that is, until there are no UEs constituting the code set. In the above example, the OVSF code allocation process must be repeated four times until the code set becomes empty by allocating OVSF codes to four UEs. If an ONSF code is assigned to only one UE at any time, if the number of OVSF codes to be allocated to the UE is 1/2 or more of the entire code space, the base station allocates corresponding OVSF codes at the leftmost of the entire code space. When the number of OVSF codes to be allocated to the UE is less than 1/2 of the total code space, the base station allocates corresponding OVSF codes at the rightmost side of the entire code space.

Meanwhile, referring to the order in which the ONSF codes are allocated in the above example, the OVSF code is assigned to the UE B located on the leftmost side of the code set, that is, the most OVSF code is allocated, and the second rightmost on the code set. The OVSF code is assigned to UE C located at ie, the smallest code assigned, and the OVSF code is sequentially assigned to UE D and fourth to UE A. If the code set is a set consisting of one element of [UE B = 4], since the number of OVSF codes allocated to the UE B is less than 1/2 of the number of OVSF codes in the entire code space, the total code space All four OVSF codes are allocated at the right side of.

Next, the OVSF code allocation process according to the code allocation rule 2 described above will be described with reference to FIG. 7.

7 is a diagram schematically showing an example of OVSF code allocation according to another embodiment of the present invention.

Referring to FIG. 7, as described above, the base station first allocates four OVSF codes from the leftmost side in the entire code space to UE B of the code set, and then removes the UE B, and secondly, Allocating one OVSF code on the rightmost side to UE C of the code set, then removing the UE C, and thirdly assigning four OVSF codes from the leftmost to the remaining code space for UE D of the code set. After the UE D is removed, the UE C of the code set is finally allocated after the OVSF code is assigned to the rightmost OVSF code.

When the code allocation rule 2 described above is followed, only NUM of the maximum number of UEs is generated from the leftmost side of the entire code space among the cases where NU is 1 in the code allocation rule 1 described in the second embodiment of the present invention. It is possible. For example, if any OVSF codes of the entire code space are [C_1, C_2, ..., C_N], the possible occurrence when the NU is 1 is [C_N-M + 1], [C_N-M + 2]. ], .., [C_N]. As described above, when the code allocation rule proposed in the third embodiment of the present invention is applied, a case in which OVSF code allocation for any UE is possible is generalized as follows. When the number of OVSF codes allocated to the communication system using the HSDPA scheme is N and the maximum number of UEs capable of allocating OVSF codes in one TTI is M, when allocating K OVSF codes to any UE Possible occurrences in the OVSF code assignment are as follows.

(1) When K> 1

Case (1, K): [C_1, C_2,, C_K]

Case (2, K): [C_ (K + 1), C_ (K + 2),, C_2K]

Case (3, K): [C_ (K + 2), C_ (K + 3),, C_ (2K + 1)]

.

.

Case (last, K): [C_ (N-K + 1), C_ (N-K + 2),, C_N]

(2) When K = 1

Case (1,1): [C_N-M + 1]

Case (2,1): [C_N-M + 2]

.

.

Case (last, 1): [C_N]

As shown above, when the number of OVSF codes allocated to any UE is K, the number TNC (K) that can occur is expressed by Equation 4 below.

TNC (K) = M, provided K is 1

TNC (K) = N-2 (K-1), provided If

TNC (K) = 1

In Equation 4, N denotes the total number of OVSF codes allocated to the communication system using the HSDPA scheme, M denotes the maximum number of UEs that can be simultaneously assigned OVSF codes within one TTI, and K denotes The number of OVSF codes to be assigned to any UE at any time point, and the TNC (K) refers to the number of cases that can occur in the actual channel environment corresponding to the number of OVSF codes assigned to any UE.

In the third embodiment of the present invention, a code set is generated when the maximum number of UEs that can be simultaneously assigned an OVSF code in any one TTI is generated, and the entire code space starts from the UE located at the leftmost of the code set. OVSF codes are assigned to UEs present in the code set sequentially by assigning the OVSF codes at the leftmost side of the code set, and assigning the OVSF codes existing at the rightmost side of the entire code space from the UE existing at the rightmost side of the code set. Minimize the number of possible cases in OVSF code assignment by assigning

Next, a fourth embodiment of the present invention will be described.

As described in the third embodiment of the present invention, the fourth embodiment of the present invention also modifies the code allocation rule 1 of the second embodiment described above to minimize the number of code allocation cases. A code allocation rule 3 according to the fourth embodiment is proposed.

[Code Allocation Rule 3]

If a base station needs to allocate OVSF codes to one or more UEs at any point in time, it first generates a code set consisting of the number of OVSF codes to be allocated with the UE as follows. Same as

code set = [UE A = 2, UE B = 4, UE C = 1, UE D = 3]

It is assumed that the code set also allocates OVSF codes to four UEs A, B, C, and D at any time. The base station reconfigures the code set from left to right in ascending order of the number of allocated OVSF codes. A code set reconstructing the code set is as follows.

code set = [UE B = 4, UE D = 3, UE A = 2, UE C = 1]

As described above, the base station reconfigures the code set from left to right in ascending order of the number of allocated OVSF codes, and then allocates the OVSF codes from the leftmost side of the entire code space to the UE on the leftmost side of the codeset. Remove from code set. The OVSF codes are then allocated to the next UE of the code set, that is, the leftmost UE of the current code set, from the leftmost of the remaining code spaces of the entire code space and then removed from the code set. And, no special restriction is placed on OVSF code assignments for the remaining UEs. In the above example, referring to the order in which the OVSF codes are allocated, the base station firstly allocates the OVSF code from the leftmost part of the entire code space to the UE B located on the leftmost side, that is, the most allocated OVSF code, and the second. The OVSF code is allocated to the UE DUE D, which is allocated the OVSF code next to the UE B. Next, the base station freely allocates the corresponding number of OVSF codes to the UE C and the UE A without any restriction among the code spaces remaining in the entire code space.

Next, the OVSF code allocation process according to the code allocation rule 3 described above will be described with reference to FIG. 8.

8 is a diagram schematically showing an example of OVSF code allocation according to another embodiment of the present invention.

Referring to FIG. 8, as described above, the base station first allocates four OVSF codes from the leftmost side in the entire code space to UE B of the code set, and then removes the UE B, and secondly, After assigning one leftmost OVSF code to UE A of the code set, the UE A is removed, and thirdly, UE C and UE D of the code set have one and three OVSF codes, without restriction. And remove the UE C and the UE D. That is, the fourth embodiment of the present invention is different from the third embodiment of the present invention in that the OVSFs in which the UEs assigned the first and second many OVSF codes in the code set are always located at the leftmost in the entire code space Codes are allocated, which reduces the number of additional cases that can occur.

For example, an OVSF code allocation process according to the above-described code allocation rule 3 when NU is K and NH is N will be described with reference to FIG. 9.

9 is a diagram schematically showing an example of OVSF code allocation according to another embodiment of the present invention.

Referring to FIG. 9, when the code assignment rule 3 is used, the number of cases that can be generated depends on the relationship between the NU and the NH. First, when K is greater than or equal to RU (N / 2) as shown in FIG. There is always one case that can occur in an OVSF code assignment. This case is the same as the case of using the code assignment rule 2 described above. Secondly, as shown in FIG. 9 (b) The number of cases that can occur in OVSF code allocation is always two cases. In the case of using the code assignment rule 2, the situation shown in FIG. Although the number of cases that may occur at may be two or more, the code allocation rule 3 may cause two cases where a code section smaller than K cannot be located at the leftmost side of the entire code space. Thirdly, as shown in FIG. In this case, the number of possible cases is one case on the leftmost side of the entire code space, one case on the rightmost side of the entire code space, and N-3K + 2 cases between the code spaces of the two cases.

That is, when there are K OVSF codes assigned to any UE, the number TNC (K) when assignable to any UE is expressed by Equation 5 below.

If

TNC (K) = 2 If

TNC (K) = 1

A code assignment table according to the fourth embodiment of the present invention described above is shown in Table 9 below.

In Table 9, it is assumed that NH is 15, and the code allocation table as shown in Table 9 is variable according to a method of assigning the value and identifier of the NH. The shaded parts in Table 9 refer to the OVSF codes allocated in the corresponding row. For example, in Table 9, since the identifier 2 is shaded from 1 to 14, this indicates that the identifier, that is, the identifier 2 means C_1 to C_14.

In the above, the code allocation scheme proposed in the first, second, third, and fourth embodiments of the present invention has been described. Next, the first, second, and second embodiments of the present invention are described. An operation of a UE and a base station when a set of OVSF codes allocated to an arbitrary UE to an arbitrary time point by logical identifiers according to the code allocation schemes proposed in the third and fourth embodiments will be described. .

First, the operation of the base station will be described.

The base station manages a user buffer for each of the UEs establishing the HSDPA call. Each of the user buffers buffers data to be transmitted to the corresponding UE. The base station assigns an OVSF code to corresponding ones of the UEs every TTI. Here, since the base station determines how many OVSF codes are allocated to which UEs in allocating OVSF codes, the detailed description thereof will be omitted here. The base station determines the number of OVSF codes to be allocated to each of the UEs, and then configures a code set as described above. In the first embodiment of the present invention, the code set is used as it is, and it is defined as "code set_1". In the second embodiment of the present invention, the most OVSF codes are allocated among the elements of the code set. The receiving UEs use an ordered code set from the leftmost to the right, and define this as "code set_2". The third and fourth embodiments of the present invention are the same as the second embodiment. A code set rearranged left-to-right from the UEs assigned the most OVSF codes among the elements of the code set is defined as "code set_3" and "code set_4".

After generating or rearranging the code set as described above, an OVSF code is allocated for each element of the code set according to a code allocation rule. In other words, the corresponding SP and NC for the UE is obtained. For example, if a code interval [C_1 to C_5] is allocated to any UE A, the SP of the UE A is C_1 and the NC is 5. Then, the code allocation rules according to the first to fourth embodiments of the present invention described above are summarized as follows.

(1) First embodiment

The code allocation rule, which is not particularly limited, is not defined. When the base station determines the UEs and the number of codes to be assigned at any point in time, the base station determines the SPs and NCs of the determined UEs according to the allocated number of codes. .

(2) Second Embodiment

In the code set_2 configured above, a code is allocated to the UE located at the leftmost side from the leftmost side of the entire code space, and the code is allocated at the remaining code space of the entire code space without particular limitation for the remaining UEs. The code assignment rule used at this time becomes "code assignment rule 1" described above.

(3) Third embodiment

In the code set_3 described above, 1) a code is assigned to the UE located at the leftmost side from the leftmost side of the entire code space, and then the UE is removed from the code set_3, and 2) the rightmost side of the entire code space is assigned to the UE located at the rightmost side. After the code is allocated, the UE is removed from the code set_3, and the code is allocated to the remaining UEs without any particular limitation. In this case, the code assignment rule 2 described above is used as the code assignment rule.

(4) Fourth Embodiment

In the code set_4 described above, 1) a code is assigned to the UE located at the leftmost side from the leftmost side of the entire code space, and then the UE is removed from the code set_4, and 2) the next left UE is assigned the minimum of the entire code space. After allocating the code from the right side, the UE is removed from the code set_4, and the other UEs are assigned the code without any particular limitation. In this case, the code assignment rule 3 described above is used as the code assignment rule.

As described above, when the code assignment for the corresponding UEs is completed, that is, the base station completes the code assignment for the corresponding UEs in one of the methods described in the first to fourth embodiments of the present invention. As the code assignment is completed, a code information table is generated, and the generated OVSF code information table is stored in the OVSF code information table storage unit 509. Of course, it is also possible to use information calculated using a direct equation without generating the OVSF code information table. This will be described with reference to Table 6 described in the second embodiment of the present invention. Meanwhile, the OVSF code information table storage unit 509 described in FIG. 5 is replaced by a logical identifier calculator, and the OVSF code described in FIG. 6 is replaced by the OVSF code information table. The information table storage 607 is replaced with a logical identifier inverse calculator. In addition, in the drawing, the logical identifier calculator or the logical identifier inverse calculator is not separately displayed, and operates by replacing the OVSF code information table storage unit 509 and OVSF code information table storage unit 607 of FIGS. 5 and 6. Consider that.

First, the logical identifier generator will be described.

First, the logical identifier calculator receives SP and NC, which are code interval information allocated to a certain UE, and NH, which is an entire code interval size, to calculate a logical identifier as described in the second embodiment of the present invention as follows. do. The logical identifier calculator determines whether SP is C_1 and NC is less than or equal to RD (NH / 2) ( Check it. That is, it is checked whether the starting point ISP of any code allocation interval for which the logical identifier is to be calculated is the same as the OSP. If the ISP is the same as the OSP, the logical identifier is calculated using Equation 6 below.

In Equation 6, RD (x) is a numerical value obtained by rounding down a random real number x.

On the other hand, if the ISP and the OSP is not the same as a result of the test, the correlation between the NC and RD (NH / 2) is examined. If the above test results In the case of Equation 7, a logical identifier is calculated.

On the other hand, the ISP and OSP is not the same as the test result, In one case, the logical identifier is calculated using Equation 8 below.

Second, the logical identifier inverse calculator will be described.

The logical identifier inverse calculator calculates SP and NC by receiving a logical identifier and NH. The logical identifier inverse calculator calculates SP and NC by using Equation 9 when it is assumed that the input logical identifier is X as an example.

In the logical identifier inverse calculator, the first SP is 1 in Equation 9, and any integer nc is less than or equal to RD (NH / 2) ( Assuming that nc satisfying Equation 9 exists. When nc satisfying Equation 9 is present, the logical identifier inverse calculator detects that SP is 1 for the corresponding logical identifier X and that nc is the number NC of codes.

On the other hand, if there is no nc that satisfies Equation (9), the logical identifier inverse calculator checks whether there is an nc that satisfies the condition shown in Equation (10).

When there is an nc that satisfies the condition shown in Equation 10, the logical identifier inverse calculator detects nc as NC and SP as in Equation 11 for the corresponding logical identifier X.

SP = X- (nc-1) (NH-nc +3)

On the other hand, if the NC and the SP for the logical identifier X is not calculated during the above-described calculation process, the SP of the logical identifier X is 1, and the NC is calculated as shown in Equation 12 below.

As a result, the OVSF code information table configurable through the first to fourth embodiments of the present invention has a size of NH, a code assignment rule and a rule for assigning a logical identifier (for example, the SP is fast). , Or from NC to large, or from NC to small), and when the OVSF code information table is changed, logical identifier calculation using the above-described formula algorithm and NC and SP using the logical identifier Of course, the calculation method is also variable.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, the present invention generates the OVSF code information table by mapping the OVSF code information for all cases allocable to the user data in the fast forward packet access communication system into logical identifiers, and then assigns the user data to be transmitted to the corresponding user terminal. The OVSF code information to be allocated is transmitted and received with a logical identifier on the OVSF code information table. Therefore, in the fast forward packet access communication system, it is possible to transmit OVSF code information to be allocated to user data using fewer bits than in the related art, which has an advantage of enabling efficient information transmission and reception. In addition, the resource efficiency is increased by reducing the number of bits required to transmit the OVSF code information.

In addition, the present invention generates the OVSF code information table by mapping the OVSF code information in the case of assignable to the user data in a real channel situation in a high speed forward packet access communication system with a logical identifier, and then assigns the user data to be transmitted to the corresponding user terminal. The OVSF code information to be allocated is transmitted and received with a logical identifier on the OVSF code information table. Thus, in the fast forward packet access communication system, it is possible to transmit OVSF code information to be allocated to user data using fewer bits, thereby enabling efficient information transmission and reception.

Claims (23)

A method for transmitting orthogonal code information allocated to user data in a high speed forward packet access communication system, the method comprising: When the user data to be transmitted to a specific user terminal is generated, determining an orthogonal code to be allocated to the user data to be transmitted to the specific user terminal in consideration of the amount of user data transmitted to other user terminals and the type of the user data; Detecting a logical identifier having information corresponding to the determined orthogonal code by searching an orthogonal code information table after determining the orthogonal code; And generating and transmitting the detected logical identifier as control information for the specific user terminal, and transmitting the orthogonal code information allocated to user data in the fast forward packet access communication system. The method of claim 1, The orthogonal code information table; After calculating all orthogonal code information that can be generated for orthogonal codes assignable to user data in the fast forward packet access communication system, corresponding logical identifiers are stored for each of the calculated orthogonal code information. And orthogonal code information allocated to user data in a high speed forward packet access communication system. The method of claim 1, The orthogonal code information may be assigned to a code start point indicating at which position an orthogonal code for corresponding user data starts on an orthogonal code tree generated for a spreading coefficient used in the fast forward packet access communication system, and assigned to the corresponding user data. A method for transmitting orthogonal code information assigned to user data in a high speed forward packet access communication system, characterized in that it represents a number of orthogonal codes. The method of claim 1, And the orthogonal code is an OVSF code, and transmits orthogonal code information allocated to user data in a fast forward packet access communication system. A method for receiving orthogonal code information assigned to user data in a high speed forward packet access communication system, the method comprising: Despreading and channel decoding the control data received through a specific channel; Detecting, from the channel decoded control data, a logical identifier for orthogonal code information allocated at the time of transmission of user data by the transmitter; Orthogonal code allocated to user data in a fast forward packet access communication system, comprising: detecting orthogonal code information corresponding to the detected logical identifier by searching an orthogonal code information table after detecting the logical identifier How to receive the information. The method of claim 5, The orthogonal code information table; After calculating all orthogonal code information that can be generated for orthogonal codes assignable to user data in the fast forward packet access communication system, corresponding logical identifiers are stored for each of the calculated orthogonal code information. And orthogonal code information assigned to user data in a high speed forward packet access communication system. The method of claim 5, The orthogonal code information may be assigned to a code start point indicating at which position an orthogonal code for corresponding user data starts on an orthogonal code tree generated for a spreading coefficient used in the fast forward packet access communication system, and assigned to the corresponding user data. A method for receiving orthogonal code information assigned to user data in a high speed forward packet access communication system, characterized in that it indicates the number of orthogonal codes. The method of claim 5, And the orthogonal code is an OVSF code, and receives orthogonal code information allocated to user data in a fast forward packet access communication system. A method for transmitting and receiving orthogonal code information allocated to user data in a high speed forward packet access communication system, Determining the orthogonal code to be allocated to the user data to be transmitted to the specific user terminal in consideration of the other user data serviced by the base station detecting the occurrence of user data for the specific user terminal; Determining, by the base station, the orthogonal code, detecting a logical identifier having information corresponding to the determined orthogonal code from an orthogonal code information table, generating the control information for the specific user terminal, and transmitting the control information through a specific channel; Receiving, by the base station, control information transmitted from the base station through the specific channel, detecting a logical identifier for orthogonal code information allocated by the base station when transmitting user data from the control information; The user terminal detecting the logical identifier includes searching the orthogonal code information table to detect orthogonal code information corresponding to the detected logical identifier and assigning the user data to the high speed forward packet access communication system. How to send and receive orthogonal code information. The method of claim 9, The orthogonal code information table; After calculating all orthogonal code information that can be generated for orthogonal codes assignable to user data in the fast forward packet access communication system, corresponding logical identifiers are stored for each of the calculated orthogonal code information. And orthogonal code information allocated to user data in a high speed forward packet access communication system. The method of claim 9, The orthogonal code information includes a code starting point indicating at which position an orthogonal code for corresponding user data starts on an orthogonal code tree generated for a spreading coefficient used in the fast forward packet access communication system, and assigning to the corresponding user data. A method for transmitting and receiving orthogonal code information allocated to user data in a fast forward packet access communication system, characterized in that it represents the number of orthogonal codes. The method of claim 9, The orthogonal code is a method of transmitting and receiving orthogonal code information allocated to user data in a fast forward packet access communication system, characterized in that the OVSF code. In the high speed forward packet access communication system, orthogonal code information that can be generated in real channel conditions is calculated for orthogonal codes that can be allocated to user data, and corresponding logical identifiers are stored for each of the calculated orthogonal code information. A method of transmitting orthogonal code information allocated to user data in a high speed forward packet access communication system having an orthogonal code information table, the method comprising: When the user data to be transmitted to a specific user terminal is generated, determining an orthogonal code to be allocated to the user data to be transmitted to the specific user terminal in consideration of the amount of user data transmitted to other user terminals and the type of the user data; Detecting a logical identifier having information corresponding to the determined orthogonal code by searching an orthogonal code information table after determining the orthogonal code; And generating and transmitting the detected logical identifier as control information for the specific user terminal, and transmitting orthogonal code information allocated to user data in a high speed forward packet access communication system. The method of claim 13, Orthogonal codes that can be generated in an actual channel environment in the high-speed forward packet access communication system sequentially allocate as many orthogonal codes as are allocated to the user data from the leftmost orthogonal code on the orthogonal code tree, and the leftmost orthogonal code. And generating the orthogonal codes as many as the number of orthogonal codes to be allocated to the user data from the next orthogonal code allocated from the next orthogonal code. The method of claim 13, The orthogonal code information may be assigned to a code start point indicating at which position an orthogonal code for corresponding user data starts on an orthogonal code tree generated for a spreading coefficient used in the fast forward packet access communication system, and assigned to the corresponding user data. A method for transmitting orthogonal code information assigned to user data in a high speed forward packet access communication system, characterized in that it represents a number of orthogonal codes. The method of claim 13, And the orthogonal code is an OVSF code, and transmits orthogonal code information allocated to user data in a fast forward packet access communication system. In the high speed forward packet access communication system, orthogonal code information that can be generated in real channel conditions is calculated for orthogonal codes that can be allocated to user data, and corresponding logical identifiers are stored for each of the calculated orthogonal code information. A method of receiving orthogonal code information assigned to user data in a fast forward packet access communication system having an orthogonal code information table, the method comprising: Despreading and channel decoding the control data received through a specific channel; Detecting, from the channel decoded control data, a logical identifier for orthogonal code information allocated at the time of transmission of user data by the transmitter; Orthogonal code allocated to user data in a fast forward packet access communication system, comprising: detecting the orthogonal code information corresponding to the detected logical identifier by searching the orthogonal code information table after detecting the logical identifier How to receive code information. The method of claim 17, Orthogonal codes that can be generated in an actual channel environment in the high-speed forward packet access communication system sequentially allocate as many orthogonal codes as are allocated to the user data from the leftmost orthogonal code on the orthogonal code tree, and the leftmost orthogonal code. And generating orthogonal codes as many as the number of orthogonal codes to be allocated to the user data from the next orthogonal code allocated from the next orthogonal code. The method of claim 17, The orthogonal code information may be assigned to a code start point indicating at which position an orthogonal code for corresponding user data starts on an orthogonal code tree generated for a spreading coefficient used in the fast forward packet access communication system, and assigned to the corresponding user data. A method for receiving orthogonal code information assigned to user data in a high speed forward packet access communication system, characterized in that it indicates the number of orthogonal codes. The method of claim 17, And the orthogonal code is an OVSF code and receives orthogonal code information allocated to user data in a high speed forward packet access communication system. A high speed forward packet shared with a plurality of user terminals and having a fast forward common channel for spreading and transmitting the user data with orthogonal code information determined in consideration of the amount and type of user data transmitted to a specific user terminal. In the method for allocating orthogonal code information to the user data in a connected communication system, Generate a code set consisting of elements corresponding to the number of orthogonal codes included in orthogonal code information allocated to each of the user terminals and user terminals accessible to the fast forward common channel in any one transmission time period. The first process A second process of generating a reconstruction code set by sequentially reconstructing from a first element having the largest number of orthogonal codes allocated among the elements constituting the code set; Sequentially assigning the first orthogonal codes corresponding to the first element among the elements of the reconstruction code set from orthogonal codes located at the leftmost part of the entire code space, the orthogonal codes allocable to the fast forward common channel; A third process of removing the first element from the reconstruction code set; After removing the first element, the orthogonal codes are sequentially located from the rightmost side of the entire code space by the number of orthogonal codes corresponding to the second element having the minimum number of orthogonal codes allocated among the remaining elements of the reconstruction code set. And a fourth process of removing the second element from the reconstruction code set after allocating to. The method of claim 21, And removing the second element and repeating the third process and the fourth process with respect to the remaining elements of the reconstruction code set until there are no elements of the reconstruction code set. Said method. A high speed forward packet shared with a plurality of user terminals and having a fast forward common channel for spreading and transmitting the user data with orthogonal code information determined in consideration of the amount and type of user data transmitted to a specific user terminal. In the method for allocating orthogonal code information to the user data in a connected communication system, Generate a code set consisting of elements corresponding to the number of orthogonal codes included in orthogonal code information allocated to each of the user terminals and user terminals accessible to the fast forward common channel in any one transmission time period. Process, Generating a reconstructed code set by sequentially reconstructing from the first element having the maximum number of orthogonal codes allocated among the elements constituting the code set; Sequentially assigning the first orthogonal codes corresponding to the first element among the elements of the reconstruction code set from orthogonal codes located at the leftmost part of the entire code space, the orthogonal codes allocable to the fast forward common channel; Removing the first element from the reconstruction code set; After removing the first element, the number of orthogonal codes corresponding to the second element having the maximum number of orthogonal codes allocated among the remaining elements of the reconstruction code set is located at the rightmost side of the remaining code space of the entire code space. And sequentially removing the second element from the reconstruction code set after sequentially assigning orthogonal codes.