KR100747525B1 - Method for transmitting a packet data communication system - Google Patents

Abstract

The present invention relates to a mobile communication system, and more particularly, to a method of transmitting packet data. The packet data transmission according to the present invention is a priority of Walsh codes to be used in a mobile communication system in which a time division scheme and a code division scheme are mixed. Generating a table mapped with a rank; Determining a Walsh code usage unit to be allocated to the terminals; Notifying the corresponding terminal of the location information in the table according to the determined Walsh code use unit; And transmitting the packet data by applying the assigned Walsh codes.

Walsh Code, Units Using Walsh Code

Description

Method for transmitting a packet data in a communication system

1 is a diagram illustrating an example of a TDM packet transmission used in the present invention.

2 is a diagram showing an example of a packet transmission of the CDM / TDM scheme used in the present invention.

3 is a diagram illustrating an example of a Walsh code information table used in the present invention.

The present invention relates to a mobile communication system, and more particularly, to a method of transmitting packet data.

Conventional wireless communication systems for packet data transmission use a physical channel such as a packet data channel (PDCH) and a packet data control channel (PDCCH) for packet data transmission.

The PDCH is actually a channel for transmitting packet data to be transmitted to the corresponding terminal (or user, hereinafter referred to as terminal). Several users divide the PDCH into a time division multiplexing (TDM) scheme or divide the PDCH into a code division multiplexing (CDM) scheme. Alternatively, the TDM scheme and the CDM scheme may be mixed.

The PDCCH includes control information that enables the terminal to properly receive data transmitted through the PDCH without error. One or more such control channels may be used in addition to the PDCCH.

In the method of transmitting the data by the base station to each terminal by TDM method and CDM method, packet data transmitted to each terminal is transmitted on different time axes or different on the same time axis. Is sent using the code. Here, the code distinguishes data of respective terminals, and a representative example is a Walsh code having excellent orthogonality.

In using the Walsh code, conventionally, when packet data transmitted to a terminal is transmitted from a base station using different codes on the same time axis by the CDM scheme, the corresponding terminal has a packet data transmitted to the terminal. You need to know which Walsh code you are using to get it right.

Thus, the base station transmits information on the Walsh code used to transmit each PDCH to the terminals (or each terminal) using the PDCCH.

Conventionally, many bits are used to represent all information of this Walsh code. However, in a situation where the available resources of the base station are limited, it is necessary to reduce the length of this information bit as much as possible.

 Accordingly, an object of the present invention is to provide a packet data transmission method in a communication system for reducing the length of an information bit for a Walsh code transmitted to a terminal.

According to an aspect of the present invention for achieving the above object, generating a table mapping the priority of Walsh codes to be used in a mobile communication system in which a time division scheme and a code division scheme are mixed; Determining a Walsh code usage unit to be allocated to the terminals; Notifying the corresponding terminal of the location information in the table according to the determined Walsh code use unit; And transmitting the packet data by applying the assigned Walsh codes.

Preferably, the Walsh code use unit to be allocated to any one terminal is determined as an integer multiple of a predetermined Walsh code minimum use unit.

Preferably, the Walsh code use unit to be allocated to any one terminal is determined by an increase multiple of (x + 1) times, (x + 2) times, etc., for x, which is a predetermined Walsh code minimum use unit.

Preferably, the Walsh code use unit to be allocated to any one terminal is determined according to the number of elements in the whole Walsh code space.

Advantageously, said location information is the location information of the beginning and ending location in said table of Walsh codes to be assigned to either terminal.

Preferably, points are designated at predetermined intervals in the table, and a combination of two points represents first and end position information of Walsh codes to be assigned to any one terminal. In this case, the points are represented by using some of the bits allocated to represent the location information.

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

Prior to describing the present invention, the parameters used in the present invention are described below.

In the present invention, the aforementioned Walsh code, PDCH, and PDCCH are used. Here, the Walsh codes, PDCH, and PDCCHs are not limited to the names, but represent codes or channels having the same function. In addition, a newly defined physical channel NPDCCH (hereinafter referred to as NPDCCH) is used to additionally transmit control information not included in the conventional control channel.

The Walsh code space is a collection of Walsh codes currently available when the base station transmits packet data. The components change over time.

Walsh_Max is the maximum number of Walsh codes that can be included in the Walsh code space, and the value changes over time.

Walsh (all) is a parameter indicating all Walsh codes in the Walsh code space.

PDCH (i) means the i-th PDCH when it is possible to use two or more PDCHs. In this case, each PDCH uses Walsh codes in Walsh code space separately.

For example, if up to four PDCHs are available in a system, PDCH (0), PDCH (1), PDCH (2), PDCH (3) are possible, and PDCH scheduled to transmit packet data at some point in time They share the Walsh code space. However, if only one PDCH is scheduled, the PDCH uses Walsh (all). On the other hand, when PDCH (0) and PDCH (3) are used at the same time, these two PDCHs divide Walsh code space, and the Walsh codes they use are defined as Walsh (0) and Walsh (3), respectively.

Walsh (i) is a set of Walsh codes used by PDCH (i) at a specific transmission time. This element consists of elements in the Walsh code space. Although the Walsh code space does not change, the Walsh code belonging to Walsh (i) changes over time. That is, Walsh (i) of the previous time and Walsh (i) of the current time have different constituent elements and number of elements. The Walsh code usage unit of Walsh (i) is x, and the number of elements of each Walsh (i) is a multiple of x. 1x, 2x, 3x, etc. The number of elements in Walsh (i) is independent of the number of Walsh (all).

N _{max_PDCH} is the maximum number of PDCH or PDCCH that the system or sector can use.

N _{real_PDCH} is the number of PDCH or PDCCH that the system or sector uses at a given time.

As shown in FIG. 1, the TDM packet data is transmitted in a time division manner by determining the order of data to be transmitted to each terminal. Here, the base station always uses all Walsh code space for the PDCH.

In FIG. 1, the length of time of the transmission unit on the PDCH and the PDCCH is fixed or variable. In addition, the transmission unit time lengths of the PDCH and the PDCCH do not necessarily have to match. user k implies packet data or control information for user k (or terminal k). Transmission of the PDCH and PDCCH for the user k is determined according to a specific rule, the transmission time and the transmission length. Here, the time interval between transmission of PDCH and PDCCH for each user may or may not exist depending on the system environment.

In the CDM / TDM packet data transmission, as shown in FIG. 2, the base station determines the order of data to be transmitted to each terminal (scheduling), and transmits the data in the time division (TDM) and code division (CDM) methods. In this manner, only one PDCH may be transmitted at a time of transmission, and several PDCHs may be transmitted.

When one PDCH is transmitted, Walsh (all) is used for this PDCH. When two or more PDCHs are transmitted, each PDCH uses Walsh codes in Walsh code spaces separately. That is, each PDCH (i) uses Walsh (i). PDCH (i) has PDCCH (i) which is a PDCCH having control information corresponding to each.

The terminal monitors the PDCCH (i), finds out what form of packet data is transmitted through which PDCH (i), and can receive the corresponding information. The transmission unit time lengths of the PDCH (i) and the PDCCH (i) do not necessarily need to match.

2 illustrates an example in which up to four PDCHs may exist in a CDM / TDM scheme. Here, the time lengths of the transmission units on the PDCH (i) and the PDCCH (i) are fixed or variable. There may or may not be a time interval between transmissions of PDCH or PDCCH for each user. In FIG. 2, the empty space is a case where PDCH or PDCCH is not used. In the transmission period (a), four PDCH (i) are transmitted, and four PDCCH (i) are used. In the transmission period (b), three PDCH (i) are transmitted, and three PDCCH (i) are used. In the transmission period (c), three PDCH (i) are transmitted, and three PDCCH (i) are used. In the transmission period (d), one PDCH (i) is transmitted and one PDCCH (i) is used. In the transmission period (e), four PDCH (i) are transmitted, and four PDCCH (i) are used.

In order to operate the TDM or CDM / TDM scheme of FIGS. 1 and 2, the present invention selectively informs terminals (or each terminal) of the following information.

First, the base station assigns a 'priority of use' to all Walsh codes that may be elements of the Walsh code space. In order to determine Walsh (i), this order is maintained. For example, if there are a total of 28 Walsh codes that can be elements of the Walsh code space, and each has an identification number representing itself, then their 'priority' order is determined. As shown in FIG. 3, the priority order may be determined. 3 shows the identification numbers of the Walsh codes from top to bottom in the order of high priority.                     

In the following description, the table as shown in FIG. 3 is referred to as a 'code priority usage table'.

For example, if there are 12 codes in the Walsh code space at any one time, you can use 12 at the top of the table.

If at any moment there are twelve codes in the Walsh code space, Walsh (0) and Walsh (1) are determined, with eight and four element counts respectively, Walsh (0) is eight down from the top of the table. Walsh (1) can use the four codes from the ninth code above the table.

At this time, the number of Walsh codes that Walsh (i) has may be a multiple of a specific number (ie, Walsh code use unit). In this case, the base station informs the terminals of this 'walsh code use unit' information. The base station informs the terminals of this information using a physical channel, a broadcasting method, or a signaling method.

In order for the Walsh code use unit information to be used, the minimum number of Walsh code use units must be standardized in the system. This is because the number of bits of the control channel is determined according to the 'minimum number of Walsh code use units'.

Here, the minimum number of Walsh code use units is one. Therefore, the number of elements in Walsh (i) can be any number.

If the minimum number of Walsh code units is greater than 1, i.e., the minimum number of Walsh code units is assumed to be x, the fixed number of elements of Walsh (i) can be used only in multiples. That is, x, 2x, 3x can be.

In the variable equation, the number of elements in Walsh (i) is a multiple of x, which can be a multiple of (x + 1), (x + 2), and the like.

The table expression defines the minimum unit of Walsh code usage according to the number of elements in the standard Walsh code space. Both variable and fixed expressions can be applied to this table system. For example, if the number of elements in the Walsh code space is 28, the minimum unit of Walsh code usage is four. In addition, when the number of elements in the Walsh code space is 27, the minimum unit of using the Walsh code is four. In addition, when the number of elements in the Walsh code space is 26, the minimum unit of using the Walsh code is three. In addition, when the number of elements in the Walsh code space is 10, the minimum unit of using the Walsh code is 2. On the PDCCH (i) or NPDCCH (i) tells the start position and the end position on the 'code priority priority table' of codes belonging to Walhs (i) used by the PDCH.

Hereinafter, information that teaches a start position and an end position on a code priority order table of codes belonging to Walsh (i) is called Walsh_start_end (i). This Walsh_start_end (i) can be expressed in the following two cases.

First, when it is assumed that the information bit of Walsh_start_end (i) is 6 bits, it may be expressed as Walsh_start_end (i) = ( 001 101 ) ₂ . The codes in Walsh (i) have a starting position of 001 and an ending position of 101 on the code priority list. Conversely, the start position may be 101 and the end position may be 001.

If Walsh_Max is 25 and information bits of Walsh_start_end (i) are represented in binary, the minimum unit of use of Walsh code is 1, and the maximum (2 * 5) requires 10 bits. If the minimum unit of use for Walsh code is 2, a maximum of (2 * 4) 8 bits are required. If the minimum unit of use for Walsh code is 3, a maximum of (2 * 3) 6 bits are required.

For example, the 'minimum unit of Walsh code usage' is x, the number of binary bits in Walsh_start_end (i) is 2y, and the front y and back y bits are the starting and ending positions on the code priority table, respectively. If we assume that the value of the first y bits of Walsh_start_end (i) is a, and the value of the last y bits is b, then the code belonging to Walsh (i) is (a * x) th through (b * x) th.

Second, points are determined by dividing the position of the code priority table in appropriate units, and then the value of Walsh_start_end (i) may be expressed to indicate a combination of the points.

If the combination of points and the value of Walsh_start_end (i) are matched 1: 1, and there is a remaining value of Walsh_start_end (i), it is used for a specific purpose.

For example, if Walsh_Max is 14, Walsh code usage unit is 3, and Walsh_start_end (i) has 4 bits, 6 points (P_0, P_1, ..., P_5). At this time, the combination of these 6 points is a total of ' ₆ C ₂ = (6 * 5) / 2 = 15'. The 15 combinations correspond to the values of Walsh_start_end (i).

In Table 1, Walsh_start_end (i) = (0000) ₂ is used for a specific purpose. Walsh_start_end (i) = (0001) ₂ means use Walsh code between P_0 and P_1. Walsh_start_end (i) = (0010) ₂ means use Walsh code between P_0 and P_2. Walsh_start_end (i) = (0011) ₂ means use Walsh code between P_0 and P_3. Walsh_start_end (i) = (0100) ₂ means use Walsh code between P_0 and P_4. Walsh_start_end (i) = (0101) ₂ means use Walsh code between P_0 and P_5. Walsh_start_end (i) = (0110) ₂ means use Walsh code between P_1 and P_2. Walsh_start_end (i) = (0111) ₂ means use Walsh code between P_1 and P_3. Walsh_start_end (i) = (1000) ₂ means use Walsh code between P_1 and P_4. Walsh_start_end (i) = (1001) ₂ means use Walsh code between P_1 and P_5. Walsh_start_end (i) = (1010) ₂ means use Walsh code between P_2 and P_3. Walsh_start_end (i) = (1011) ₂ means use Walsh code between P_2 and P_4. Walsh_start_end (i) = (1100) ₂ means use Walsh code between P_2 and P_5. Walsh_start_end (i) = (1101) ₂ means use Walsh code between P_3 and P_4. Walsh_start_end (i) = (1110) ₂ means use Walsh code between P_3 and P_5. Walsh_start_end (i) = (1111) ₂ means use Walsh code between P_4 and P_5.

As another example, Table 2 or Table 3 below shows 11 points (P_0) in the code priority table when Walsh_max is 28, Walsh code usage unit is 3, and Walsh_start_end (i) has 6 bits. , P_1, ..., P_10). In this case, a combination of the 11 points are present in a total of _{'11 C 2 = (11 *} 10) / 2 = 55' of. In addition, since the number of bits of Walsh_start_end (i) is 6, a total of '2 ⁶ = 64' types may be referred to. Therefore, the combination of 11 points and the value of Walsh_start_end (i) are matched 1: 1, and the values of Walsh_start_end (i) of the remaining '64 -55 = 9 'branches are used for a specific purpose.

On the other hand, if the remaining Walsh codes allocated above do not reach the minimum unit of Walsh code use, in particular, the number of bits for representing the remaining Walsh codes is greater than the number of bits for representing the beginning and end positions of the assigned Walsh codes. In case of exceeding, b may be named as a special character.

In all cases described above, the number of elements in Walsh (i) does not necessarily obey the rule of being an exact multiple of the "unit of Walsh code use" if it is necessary to achieve a particular case or purpose. For example, if the value of Walsh_Max is not an exact multiple of "Walsh code usage unit" as shown in Table 1, two Walsh codes between P_4 and P_5 may be assigned to Walsh (i).

As described above, the present invention may use fewer bits when representing Walsh code information.

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

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

Claims (8)

In a mobile communication system in which time division and code division are mixed, Creating a table that maps priorities of Walsh codes to use; Determining a Walsh code usage unit to be allocated to the terminals; Notifying the corresponding terminal of the location information in the table according to the determined Walsh code use unit; And transmitting the packet data by applying the assigned Walsh codes. The method of claim 1, wherein the information about the table and the Walsh code usage unit is provided to the terminals through one of a physical channel, a broadcasting scheme, and a signaling scheme. . The method of claim 1, wherein the Walsh code use unit to be allocated to the one terminal is determined as an integer multiple of a preset Walsh code minimum use unit. The method of claim 1, wherein the Walsh code use unit to be allocated to any one terminal is determined as an increase multiple of (x + 1) times, (x + 2) times, etc. for x, which is a predetermined Walsh code minimum use unit. Packet data transmission method in a communication system, characterized in that the. The method of claim 1, wherein the Walsh code usage unit to be allocated to the one terminal is determined according to the number of elements in the entire Walsh code space. 2. The method of claim 1, wherein the position information is position information of a first position and an end position in the table of Walsh codes to be assigned to any one terminal. 2. A communication system according to claim 1, wherein points are designated at predetermined intervals in the table, and a combination of two points represents first and end position information of Walsh codes to be assigned to any one terminal. Packet transmission method. 8. The method of claim 7, wherein the points are represented using some of the bits allocated to represent the location information.

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