KR100332811B1 - Physical channel allocation mehtod for mobile telecommunication system - Google Patents

Abstract

The present invention is a 3GPP (3GPP: 3rd Generation Partnership Project) system, which is one of the next generation mobile communication standard in a cell is divided into a number of sectors of the uplink channel used for the terminal to transmit data to the base station A physical channel allocation method for more efficiently performing channel allocation for a PRACH (Physical Random Access Channel).

In the present invention, for the channel allocation of the PRACH in the mobile communication system, the scrambling code is determined using a node corresponding to a signature in which each signal is mapped to the corresponding scrambling code, and one OVSF code is assigned to one sector. Sector allocation is achieved by OVSF code in one cell, and channel classification in the same cell by scrambling code.

Description

PHYSICAL CHANNEL ALLOCATION MEHTOD FOR MOBILE TELECOMMUNICATION SYSTEM}

The present invention relates to an uplink channel allocation technology in a mobile communication system. In particular, one cell is divided into several sectors in a 3rd generation partnership project (3GPP) system, which is one of the next generation mobile communication standards. The present invention relates to a physical channel allocation method of a mobile communication system suitable for channel allocation for a PRACH (Physical Random Access Channel) among uplink channels used for transmitting data to a base station in a divided situation.

In general, a scrambling code and an Orthogonal Variable Spreading Factor (OVSF) code are used to allocate a PRACH channel among uplink channels used by a mobile station to transmit data to a base station in a 3GPP system. One of the signatures is carried on an AP (AP) and transmitted.

In the case of the PRACH channel allocation scheme in the related art, as shown in FIG. 1, each of 16 signatures corresponds to a node existing at a position of SF (SF) 16 in a one-to-one manner, and thus an OVSF code from a node corresponding to the signature. In this case, one scrambling code is used.

The OVSF code, which is the channelization code, determines the data part and the control part of the message to be transmitted. Each code is determined in the same manner as in FIG. 2 from the node determined in the above manner. Therefore, the OVSF code that can be assigned to 16 signatures is a section in which SF is 32 to 256.

In this case, channels in one cell are identified by OVSF codes, and a total of 16 different channels can be allocated.

This is prepared in the case where one cell is divided into several sectors. In general, 16 scrambling codes of a PRACH allocated to one cell are provided. Therefore, sectors are divided using a scrambling code, and channel divisions within the same sector are set to the 16 OVSFs. As a result, the total number of PRACHs that can be generated by using 16 scrambling codes in one cell becomes 256.

By improving the method of allocating 16 scrambling codes and OVSF codes, the number of PRACHs provided by one cell can be increased.

As described above, in the related art, it is not possible to increase the total number of channels of PRACHs that can be allocated in one cell without increasing the number of scrambling codes, which makes it difficult to allocate physical channels more efficiently.

Accordingly, a first object of the present invention is to provide a new type of PRACH channel allocation method considering sectorization in 3GPP system.

A second object of the present invention is to maximize the number of channels that can be allocated by optimizing the channel allocation method of PRACH according to sectors in one cell.

A third object of the present invention is to provide a channel allocation method for PRACH considering sectorization when the PRACH and PCPCH use the same 16 scrambling codes in the message part.

1 is a code tree for allocating an OVSF code of a PRACH having sixteen signatures in the prior art.

2 is an explanatory diagram showing a method for allocating an OVSF code which is a channelization code of a PRACH in the prior art;

3 is a code tree to which the PRACH channel allocation method of the present invention is applied.

4 is an explanatory diagram showing a control portion OVSF code allocation method of PRACH for each sector in the present invention.

5A and 5B are explanatory diagrams of a data portion OVSF code allocation method of a PRACH according to each sector in the present invention.

FIG. 6 is an explanatory diagram of a control portion OVSF code allocation method of a PRACH for each sector when the PCPCH and the PRACH use the same 16 scrambling codes in the present invention. FIG.

7A and 7B are explanatory diagrams of a data portion OVSF code allocation method of a PRACH for each sector when the PCPCH and the PRACH use the same 16 scrambling codes in the present invention.

*** Description of the symbols for the main parts of the drawings ***

SF: spreading factor SC: scrambling code

According to the first aspect of the present invention, the channel allocation of the PRACH determines the scrambling code by using the node corresponding to each signature.

According to a second aspect of the invention, each signature in the first aspect is a different signal and is mapped to a respective scrambling code.

According to a third aspect of the present invention, one OVSF code is assigned to one sector, the sector division is a OVSF code in a cell, and the channel division in the same cell is a scrambling code.

According to the fourth aspect of the present invention, the maximum number of sectors in a cell that can be obtained by the OVSF code is 28, and each sector can be divided into channels by 16 scrambling codes, so the maximum number of channels can be allocated in one cell. The number of is 448.

According to a fifth aspect of the present invention, in the case of using the same scrambling code as PCPCH in the message part, the channel allocation of the PRACH is in accordance with the above 1-3, wherein the number of sectors is 16 and the channel can be distinguished in one cell. The number of is 256. In this case, the number of scrambling codes for channel allocation of PCPCH and PRACH in one cell is reduced.

When described in detail with reference to Figures 3 to 7 attached to the operation of the present invention as follows.

In FIG. 3, AP # 0 to AP # 15 denotes a signature that a terminal carries on an access preamble and transmits. The AP # 0 to AP # 15 are mapped 1: 1 with nodes of a point where SF is 16 in the OVSF code tree.

Each access preamble signature is mapped to each scrambling code as follows.

---------- (Equation 1)

Here, SC means a scrambling code of PRACH.

According to the present invention, the scrambling code allocated when the terminal transmits a specific signature AP # s and is approved by the base station follows the mapping rule of Equation 1 above.

Channelization code of the control portion of the message to be sent using the approved signature AP # s Is allocated in the same manner as in FIG. 4, which is represented by the following equation (2).

------------ (Equation 2)

Where I is the index of the sector where the terminal is located.

Channelization code of the data part Can be any branch connected from the (I + 4) th node present at the position SF = 32 to the point SF = 256. If you follow only the highest branch, you can formulate it as follows:

------ (Eq 3)

At this time, SF has a range from 32 to 256.

In case of following only the lowest branch, it can be formulated as follows.

--- (Equation 4)

(Equation 3) corresponds to FIG. 5A, and (Equation 4) corresponds to FIG. 5B. Many other methods can be used. Is a code value assigned to each node in the OVSF code tree. It is defined as the following equation.

------------------------------------ (Equation 5)

-------------- (Eq. 6)

------ (Eq. 7)

The above process can be equally applied whenever each sector is added. The total number of nodes at the point where SF = 32 is 32, of which 4 nodes are used for the control part, so the maximum number of nodes that can be sectorized in one cell is 28. Thus, 12 sectors can be allocated while using the same number of scrambling codes as in the conventional method.

The above process can be used in the same way for channel assignment of PCPCH by sector. At this time, the PRACH and the PCPCH have 16 different scrambling codes.

6 shows a method for allocating an OVSF code of a PRACH when the PCPCH and the PRACH use the same scrambling code. The mapping rules of the signature and the scrambling code of each access preamble of the PRACH are the same as in the first embodiment. Follow (1).

The OVSF code of PCPCH is expressed by the following expression (8).

-------------- (Eq. 8)

here, Wow Are the OVSF codes of the control and data portions of the PCPCH, respectively.

OVSF code of the control part of the PRACH taking into account orthogonality to the OVSF code of the PCPCH Is Each sector can be allocated differently according to one sector. For example, the following sectors can be allocated as shown in Equation 9 below.

---------------- (Eq. 9)

Here, I means a sector to which the terminal belongs.

Channelization code of the data portion Can be any branch connected from the (I + 16) th node existing at the position SF = 32 to the point SF = 256. If you follow only the highest branch, you can formulate it as follows:

---- (Eq. 10)

At this time, SF has a range from 32 to 256.

If you follow only the lowest branch, you can formulate it as follows:

--- (Eq. 11)

Equation 10 corresponds to FIG. 7A, and Equation 11 corresponds to FIG. 7B.

According to this embodiment, the number of scrambling codes required for channel allocation of PCPCH and PRACH is reduced from 32 to 16 in the prior art, and the PRACH channel allocation supports 16 sectors as in the prior art.

As described in detail above, the present invention has an effect of efficiently utilizing resources by improving a channel allocation scheme of PRACH in a 3GPP system in which one cell is composed of several sectors.

In addition, the present invention has the effect of increasing the total number of channels of PRACH that can be allocated without increasing the number of scrambling codes in one cell.

In addition, the present invention can use only the same 16 scrambling codes for channel allocation of PRACH and PCPCH, but can allocate as many channels as the existing structure supports, thereby reducing the total number of required scrambling codes by half. have.

In addition, the present invention can efficiently perform common shared random access channel allocation in a mobile communication system, can efficiently use a given resource in a situation where the sectorization of PRACH used in 3GPP is considered, and the PCPCH is sectorized The same can be applied to the effect.

Claims (11)

In the mobile communication system, for the channel allocation of the PRACH, a scrambling code is determined using a node corresponding to a signature in which each signal is mapped to a corresponding scrambling code, and one OVSF code is assigned to one sector. A method of allocating a physical channel in a mobile communication system, characterized in that sector division in a cell is an OVSF code and channel division in a same cell is a scrambling code. The method of claim 1, wherein the maximum number of sectors that can be obtained by the OVSF code in one cell is 28, and each sector can be classified into 16 scrambling codes. The method of claim 1, wherein when using the same scrambling code as PCPCH in the message part, when the number of sectors is 16, the number of distinguishable channels in one cell is 256. . In the PRACH channel allocation method of a mobile communication system, signatures AP # 0 to AP # 15 carried by an MS in an access preamble are mapped 1: 1 with nodes at a point where SF is 16 in an OVSF code tree, After receiving approval from the base station, the channelization code of the control portion of the message to be sent using the approved signature AP # s Is assigned according to the formula below, and the channelization code of the data part The physical channel allocation method of the mobile communication system, characterized in that all branches connected from the (I + 4) th node existing at the position of SF = 32 to the point of SF = 256 are possible. I: Index of sector in which the terminal is located The channelization code of a data portion of claim 4. The physical channel allocation method of the mobile communication system characterized in that the following equation when only following the highest branch in the code tree. The channelization code of a data portion of claim 4. The physical channel allocation method of the mobile communication system characterized in that the following equation when following only the lowest branch in the code tree. The method according to claim 5 or 6, Is the value corresponding to each node in the OVSF code tree. When the PCPCH and the PRACH use the same scrambling code in the mobile communication system, the OVSF code of the PCPCH is defined by the following equation, and the OVSF code of the control part of the PRACH Is Channelization code of data part The physical channel allocation method of the mobile communication system, characterized in that all branches connected from the (I + 16) th node present at the position of SF = 32 to the point of SF = 256 possible. , here, : OVSF Codes in the Control Section of PCPCH : OVSF code of the data part of PCPCH 9. The OVSF code of claim 8, wherein a control portion of a PRACH The physical channel allocation method of the mobile communication system, characterized in that the allocation according to the following formula. here, SF: range from 32 to 256 9. The channelization code of claim 8, wherein the channelization code of the data portion The physical channel allocation method of the mobile communication system characterized in that the following formula when following the highest in the code tree. here, , SF: in the range of 32 to 256 9. The channelization code of claim 8, wherein the channelization code of the data portion The physical channel allocation method of the mobile communication system characterized in that the following equation when following only the lowest branch in the code tree. here,