KR20030027606A - Method for transmitting a packet data in Communication System - Google Patents

Abstract

PURPOSE: A method of transmitting packet data in a communication system is provided to assign a reference control channel, and to transmit control information on transmitted data through the reference control channel, then to transmit data to terminals through transmission channels corresponding to the assigned control channel, thereby improving resource efficiency. CONSTITUTION: A mobile communication system separates terminals into groups, and assigns a reference control channel to each group. The system transmits control information on transmitted data through the reference control channel. The system transmits the data to the terminals through transmission channels corresponding to the assigned control channel. The data or the control information is transmitted through a transmission channel or the reference control channel for one of the terminals at a certain time, when assigning the reference control channel to the groups. The data or the control information is transmitted through a transmission channel or the reference control channel only for one of the terminals at a certain time, when assigning one of the reference control channels to the groups.

Description

Method for transmitting a packet data in a communication system

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 by using Time Division Multiplexing (TDM) or divide the PDCH by Code Division Multiplexing (hereinafter, referred to as CDM). 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 the TDM scheme, the packet data transmitted to each terminal always uses all available resources allocated to the PDCH channel. As a result, even if only a part of the available resources is needed, the use of all of them may result in waste of resources.

In addition, in the CDM / TDM scheme, the length of the PDCH's time axis is always fixed for all terminals, which leads to many limitations in the efficient use of resources, and heavy use of PDCCHs used for one PDCH. There is a difficulty in utilizing efficient system resources.

Accordingly, the present invention has been made in view of the above-mentioned problems of the prior art, and is to provide a method for transmitting packet data to improve resource utilization efficiency.

According to an aspect of the present invention for achieving the above object, in a mobile communication system in which a time division scheme and a code division scheme are mixed, the terminals are divided into a predetermined number of groups, and the data is received for each group. Allocating either reference control channel; Transmitting control information on data to be transmitted through the reference control channel; And transmitting the data to the terminals through a transmission channel corresponding to the assigned control channel.

Preferably, a time division scheme in which one reference control channel is allocated to the groups so that data or control information is transmitted through a transmission channel or a reference control channel for any one of the terminals at an arbitrary transmission time point. Is operated.

Preferably, any one of a plurality of reference control channels is assigned to the groups, and at any transmission time, data or control information is transmitted only through a transmission channel or a reference control channel for any one of the terminals. Time division method is used.

Preferably, any one of a plurality of reference control channels is assigned to the groups, and at any time of transmission, reference control channels or transport channels for a plurality of terminals, or a transport channel for any one terminal or A time division scheme and a code division scheme in which data or control information is transmitted through a reference control channel are mixed.

Preferably, the control channel or transmission unit of the transmission channel transmitted at any transmission time is limited to a specific length so as not to overlap with other terminals on the time axis for the convenience of transmission scheduling.

Preferably, the terminal supports code multiplexing, the maximum number of control channels (or transport channels) available, the number of control channels (or transport channels) currently in use, and the maximum number of control channels (or transport channels) available. And providing Walsh code configuration information of.

Advantageously, the number of reference control channels assigned is equal to or less than the number of control channels (or transport channels) available in the system.

Preferably, when transmitting information bits for representing information on the Walsh code allocated to any one group to each terminal on a new control channel (NPDCCH), only one reference control channel is used, that is, code division scheme. If not used, this new control channel is not transmitted.

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 shows a first embodiment of a CDM / TDM scheme according to the present invention.

4 is a view showing a second embodiment of the CDM / TDM scheme according to the present invention;

5 is a view showing a third embodiment of the CDM / TDM scheme according to the present invention.

6a to 6b show a fourth embodiment of the CDM / TDM scheme according to the present invention.

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

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 the 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 informs terminals (or respective terminals) of the following information.

First, the base station informs the terminals (or each terminal) whether the CDM is supported. Whether this is supported tells the terminals by physical channel, signaling method, broadcast method, and the like. At this time, the base station informs the terminals from time to time according to its first operation or system operation.

Second, the base station determines the number N _{max_PDCH} of the maximum PDCH (or PDCCH) available. This N _{max_PDCH} information is a fixed value of the system or a value that informs the terminals by a signaling method or a broadcasting method. At this time, the base station informs the terminals from time to time according to its first operation or system operation. In addition, the base station _{informs the terminals} of the configuration information of the N _{max_PDCH} PDCCHs (for example, the type of walsh code used to transmit each PDCCH, _etc. ) together with the N _{max_PDCH} information (optional). The PDCCH configuration information is a fixed value of the system or a value reported by a physical channel, a signaling method, or a broadcasting method. At this time, the base station informs the terminals from time to time according to its first operation or system operation.

Third, the base station designates and informs each terminal of PDCCH (i) to refer to signal reception (reception of PDCH). This PDCCH (i) reference information informs each terminal in a signaling method or a broadcast method. As one example, this role may be performed by informing each UE of only PDCCH information (for example, a kind of walsh code used to transmit the corresponding PDCCH) to each UE. That is, the UE belonging to one group does not know the information of the PDCCH used by the other group, and only the information of the PDCCH to be referred to by itself. At this time, the base station informs the terminals from time to time according to its first operation or system operation. To this end, first, several terminals are divided into a plurality of groups, and then one PDCCH (i) is allocated to each group.

Group A = {terminal 1, terminal 3, terminal 11, ....}-> PDCCH (0)

Group B = {terminal 6, terminal 7, terminal 13, ....}-> PDCCH (1)

...

Group L = {terminal 17, terminal 26, terminal 37, ....}-> PDCCH (L)

...

The allocation method of the PDCCH for each terminal is determined according to each system operation situation, for example, how many PDCHs to use. Even if N _{max_PDCH} is 4, if only two PDCCHs are allocated to the terminals, the system can automatically use only two PDCHs simultaneously. That is, the maximum value of N _{real_PDCH} is determined to be 2.

The terminal continuously monitors its PDCCH (i), and if it finds that its packet is being transmitted, it receives data on the PDCH (i) transmitted to itself based on the contents of the PDCCH (i). At this time, if the information on the time length of the transmission unit of the PDCH (i) is not included in the information of the PDCCH (i), each terminal uses an additional means such as a cyclic redundancy check (CRC) code of the PDCCH (i) The time length of the transmission unit of PDCH (i) can be found. The purpose of determining the time unit of such a transmission unit is to perform blind rate detection.

Fourth, in order to implement the proposed scheme, the base station additionally informs each terminal of information on Walsh (i) used by the PDCH (i). At this time, information bits for representing the information on the Walsh (i) are added to the PDCCH (i), or transmitted to each terminal on a new control channel (NPDCCH) for this control information. If only one PDCCH is used, that is, the NPDCCH may not be transmitted when the CDM is not used.

The CDM / TDM scheme is operated between the terminal receiving the above information and the base station providing the same as illustrated in FIGS. 3 to 6.

3 is a diagram illustrating a first embodiment of a CDM / TDM scheme according to the present invention.

3 illustrates a case in which all terminals refer to a PDCCH (0) when receiving all data of a PDCH transmitted to them, and illustrates a method in which a base station allocates one PDCCH to all terminals. In this case, the packet data transmission according to the present invention is performed in the same manner as the packet data transmission of the conventional TDM scheme.

4 is a diagram illustrating a second embodiment of a CDM / TDM scheme according to the present invention.

4 illustrates a method of allocating N _{real_PDCH} PDCCHs smaller than or equal to N _{max_PDCH} to groups including at least one or more terminals, at which point one terminal receives data of a PDCH transmitted to itself. It refers to referring to only one PDCCH assigned to the. In transmitting the PDCCH, the base station transmits only one PDCCH for a specific user at the same time.

4 is an exemplary operation diagram when N _{real_PDCH} is 3 and the relationship between the terminal and the PDCCH is set as follows.

Group A = {terminal 1, terminal 2, terminal 3}-> refer to PDCCH (0) only

Group B = {terminal 4, terminal 5, terminal 6}-> refer to PDCCH (1) only

Group C = {terminal 7, terminal 8, terminal 9}-> refer to PDCCH (2) only

In this case, only one PDCCH is transmitted at the same time, and PDCH (i) corresponding to each PDCCH (i) always uses Walsh (all).

In this case, as in FIG. 3, the packet data transmission according to the present invention is performed in the same manner as the packet data transmission in the conventional TDM scheme.

3 to 4, the present invention prevents heavy use of the control channel that may occur in the CDM scheme by allowing the TDM scheme to operate as described above when necessary resources are available.

5 shows a third embodiment of a CDM / TDM scheme according to the present invention.

FIG. 5 illustrates a method of allocating N _{real_PDCH} PDCCHs smaller than or equal to N _{max_PDCH} to groups including at least one or more terminals, similarly to FIG. 4. At the time of receiving, it illustrates only referring to one PDCCH assigned to itself. In transmitting the PDCCH, unlike FIG. 4, the base station transmits a plurality of PDCCHs for a plurality of users at the same time.

5 is an exemplary operation diagram when N _{real_PDCH} is 3 and a relationship between the terminal and the PDCCH is set as follows.

Group A = {terminal 1, terminal 2, terminal 3}-> refer to PDCCH (0) only

Group B = {terminal 4, terminal 5, terminal 6}-> refer to PDCCH (1) only

Group C = {terminal 7, terminal 8, terminal 9}-> refer to PDCCH (2) only

In the above example, since the transmission interval (a) and the transmission interval (c) are used only in the TDM scheme according to the transmission scheduling of the base station, PDCH (i) corresponding to each PDCCH (i) always uses Walsh (all). do. Since the CDM scheme is used for the transmission interval (b), the PDCH (i) corresponding to each PDCCH (i) uses Walsh (i).

6a to 6b illustrate a fourth embodiment of the CDM / TDM scheme according to the present invention.

PDCH (i) being transmitted at one time point and PDCH (i) of next time point can overlap each other on the time axis as shown in FIG. 6A (a) transmission period.

Alternatively, in order to prevent overhead of transmission scheduling of the base station, PDCH (i) being transmitted at a certain time point and PDCH (i) at a next time point are changed so as not to overlap each other on the time axis as in the interval (a) of FIG. 6B. It is possible.

6A to 6B, as in FIG. 5, PDCH (i) corresponding to each PDCCH (i) always uses Walsh (all) in a transmission period in which only a TDM scheme is used according to transmission scheduling of a base station. However, the PDCH (i) corresponding to each PDCCH (i) uses Walsh (i) in a transmission period using only the CDM scheme.

6A to 6B, when the CDM scheme is used, the transmitted PDCH may be fixed to a transmission unit time of a specific length in order to speed up transmission scheduling of the base station. This transmission unit time is fixed to have a uniform length with the transmission unit time of the reference PDCH or to have a length smaller than the reference PDCH so that the PDCHs to be transmitted do not overlap each other on the time axis.

5, 6A and 6B, the present invention prevents waste of available resources according to the TDM scheme and prevents overuse of the control channel according to the CDM scheme.

As described above, the present invention can reduce the waste of available resources by operating the CDM / TDM. In addition, by operating the CDM / TDM according to the present invention, it is possible to reduce the heavy use of the packet data control channels used for one packet data channel.

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, Dividing the terminals into a predetermined number of groups, and assigning each of the groups with one reference control channel for data reception; Transmitting control information on data to be transmitted through the reference control channel; And transmitting the data to the terminals through a transmission channel corresponding to the assigned control channel. The method of claim 1, wherein one reference control channel is allocated to the groups so that data or control information is transmitted through a transmission channel or a reference control channel for any one of the terminals at an arbitrary transmission time point. A packet data transmission method in a communication system, characterized in that time division scheme is operated. 2. The apparatus of claim 1, wherein any one of a plurality of reference control channels is assigned to the groups, and at any transmission time, data or control only through a transport channel or a reference control channel for any one of the terminals. A packet data transmission method in a communication system, characterized in that a time division scheme for transmitting information is operated. 2. The apparatus of claim 1, wherein any one of a plurality of reference control channels is assigned to the groups, and at any time of transmission, reference control channels or transmission channels for a plurality of terminals, or for one terminal. A time division method and a code division method in which data or control information is transmitted through a transmission channel or a reference control channel are mixed. The communication system of claim 1, wherein the transmission control channel or transmission unit of the transmission channel at any transmission time is limited to a specific length so as not to overlap with other terminals on a time axis for convenience of transmission scheduling. Data transfer method. The method according to claim 1, wherein the terminal supports code multiplexing, the maximum number of control channels (or transmission channels) available, the number of control channels (or transmission channels) currently in use, and the maximum number of control channels (or channels) available. And providing Walsh code configuration information of a transport channel). 2. The method of claim 1, wherein the number of allocated reference control channels is less than or equal to the number of control channels (or transport channels) available in the system. The method according to claim 1, wherein when information bits for representing information about Walsh codes assigned to any one group are transmitted to each terminal on a new control channel (NPDCCH), only one reference control channel is used, that is, a code. The method of transmitting packet data in a communication system, characterized in that the new control channel is not transmitted when the partitioning scheme is not used.