KR100678309B1 - Medium access control frame processing method based code division multiple access mode - Google Patents

Abstract

The present invention defines a forward structure and a reverse structure of a medium access control frame used in a wireless communication system based on a code division multiple access (CDMA) scheme and provides a mobile multimedia service using a defined medium access control frame. A method for processing a medium access control (MAC) frame based on a split multiple access (CDMA) scheme, the base station comprising: at least one first access point for transmitting traffic and control information and at least one random access channel for a channel allocation request from a mobile station; Receiving a request for channel allocation through a reverse media access control (MAC) frame including a shared channel; Determining a service type and reserving a channel by a medium access control (MAC) scheduler of the base station; And a third step of the base station assigning a channel to the mobile station using a forward medium access control (MAC) frame comprising a signal channel, a paging channel and at least one second shared channel, wherein the random access channel Includes a service type field for indicating a service type of a channel requested by the mobile station, a mobile identifier field, and a dynamic parameter field for use in transmitting cell information of the mobile station necessary for the base station to perform scheduling; The paging channel may include an access control field used for access control, a response field for allocating a code to the mobile station to which the channel is assigned, and IDLE / division in a current frame for each code assigned to the mobile station. Channel bitmap field for expressing (BUSY) information and code for remaining resources after allocating network resources Contains an available code field for transmission.

Media access control, frame structure, code division multiple access, broadband communication

Description

MEDIUM ACCESS CONTROL FRAME PROCESSING METHOD BASED CODE DIVISION MULTIPLE ACCESS MODE}             

1 is an exemplary configuration diagram of a wireless communication system to which the present invention is applied.

2 is a diagram illustrating an embodiment of a forward channel for processing a media access control frame based on a code division multiple access (CDMA) scheme according to the present invention;

3 is a diagram illustrating an embodiment of a reverse channel for media access control frame processing based on a code division multiple access (CDMA) scheme according to the present invention;

4A and 4B illustrate an exemplary state transition diagram for packet transmission in a media access control frame processing method based on a code division multiple access scheme according to the present invention.

5 is a flowchart illustrating a method for processing a medium access control frame based on a code division multiple access scheme according to the present invention.

* Explanation of symbols for the main parts of the drawings

11 mobile station 12 base station

13: exchanger

The present invention relates to a method for processing a media access control frame based on a code division multiple access scheme, and more particularly, to a medium access for providing a mobile multimedia service based on a wideband code division multiple access (CDMA) scheme in a wireless communication system. Control method (MAC: Medium Access Control) frame processing.

Media Access Control (MAC) is an access control method that is required for multiple users to efficiently share the same communication medium, and ultimately manages how to allocate an effective capacity of a channel to each user. Therefore, the MAC frame for wireless asynchronous transfer mode (ATM) should be applicable to the wireless section by extending the advantages of statistical multiplexing of the existing asynchronous transfer mode (ATM) network. Constant Bit Rate (CBR), Variable Bit Rate (VBR), Available Bit Rate (ABR) and Unspecified Bit Rate (UBR) defined in Asynchronous Transfer Mode (ATM) It must be able to support traffic classes such as Bit Rate. However, since wireless network resources are limited and have high error characteristics in a wireless network, a medium access control (MAC) frame for broadband mobile multimedia should be designed in consideration of these characteristics.

Therefore, the MAC frame for providing a broadband mobile multimedia service is different from the MAC frame of a digital mobile communication system that provides voice or low-speed data transmission service using a conventional circuit switched method. It must be able to maintain high frequency efficiency and satisfy various quality of service (QOS) requirements of users.

The MAC frame may be classified into a fixed allocation method, a random access method, a centralized request allocation method, a distributed request allocation method, and the like according to a method used. In the existing broadband wireless asynchronous delivery mode (ATM) network, a mixture of these methods is used depending on the service characteristics. For example, each method uses a time division multiple access (TDMA) method.

Until now, there have been few studies on the wireless medium access control method for the wireless asynchronous transfer mode (ATM) using the code division multiple access (CDMA) method.

Therefore, in the related art, it is difficult to easily provide a mobile multimedia service based on a wideband code division multiple access (CDMA) scheme using a medium access control (MAC) frame.

The present invention has been made to solve the above problems, and defines a forward structure and a reverse structure of a medium access control frame used in a wireless communication system based on a code division multiple access (CDMA) scheme, and a defined medium. An object of the present invention is to provide a method for processing a Media Access Control (MAC) frame based on a code division multiple access (CDMA) scheme that provides a mobile multimedia service using an access control frame.

In order to achieve the above object, the present invention provides a method for processing a medium access control frame based on a code division multiple access scheme applied to a code division multiple access (CDMA) wireless communication system, the base station for requesting channel allocation from a mobile station. Receiving a channel allocation request through a reverse medium access control (MAC) frame including at least one random access channel and at least one first shared channel for transmitting traffic and control information; Determining a service type and reserving a channel by a medium access control (MAC) scheduler of the base station; And a third step of the base station assigning a channel to the mobile station using a forward medium access control (MAC) frame comprising a signal channel, a paging channel and at least one second shared channel, wherein the random access channel Includes a service type field for indicating a service type of a channel requested by the mobile station, a mobile identifier field, and a dynamic parameter field for use in transmitting cell information of the mobile station necessary for the base station to perform scheduling; The paging channel may include an access control field used for access control, a response field for allocating a code to the mobile station to which the channel is assigned, and IDLE / division in a current frame for each code assigned to the mobile station. Channel bitmap field for expressing (BUSY) information and code for remaining resources after allocating network resources Contains an available code field for transmission.

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The present invention proposes a logical structure of a reverse link and a forward link of a wideband code division multiple access (CDMA) medium access control (MAC) frame. By using the proposed medium access control (MAC) frame, it supports reserved and random services according to the characteristics of the service, and extends the advantages of statistical multiplexing in the Asynchronous Transfer Mode (ATM) network to the wireless section. It supports packet services.

In the present invention, while designing a wireless medium access control (MAC) frame suitable for a wideband code division multiple access (CDMA) scheme, the designed medium access control (MAC) frame should be able to provide services by reservation and random access according to the service characteristics do. In addition, in order to satisfy various quality of service (QOS) of broadband multimedia services, an access control and resource allocation structure must be adopted.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is an exemplary configuration diagram of a wireless communication system to which the present invention is applied.

A wireless communication system based on the code division multiple access (CDMA) scheme is composed of a mobile station 11, a base station 12, a switch 13, and the like. The user is provided with a multimedia service through the mobile station 11, and for this service, communication is performed using a medium access control (MAC) frame.

The present invention is directed to a medium access control (MAC) frame for communication between mobile station 11 and base station 12.

2 is a diagram illustrating an embodiment of a forward channel for media access control frame processing based on a code division multiple access (CDMA) scheme according to the present invention.

The logical channel structure constituting the forward channel is shown in FIG. As shown in FIG. 2, the forward logical channel structure includes a signal channel (SCH), a paging channel (PCH) 22, and a shared channel 23 (DCH).

The paging channel (PCH) 22 broadcasts control information necessary for access and transmission to the mobile station, and includes an access control field (ACF), a channel bit map field 223, and a response ( ACK) field 222, available code field 224, and the like. The meaning of each field is as follows.

Access control field (ACF): used for access control, and the inside is divided into code information 225, status information 226, and data access probability (DAP) information 227 necessary for random access. The status information 226 consists of IDLE, BUSY, COLLISION, etc. to indicate the status of the random access channel.

ACK field: A code is allocated to a terminal corresponding to a case where a random access succeeds. This field consists of mobile ID information 228 and code information 229.

Channel Bitmap field: Represents information such as IDLE / BUSY in the current frame for each code assigned to the UE in bit units and transmits the information. This field is used by the scheduler to control the priority of the terminal.

Available Code field: Allocates the current network resource and sends the available code if there is any remaining resource. This field is mainly used by a terminal that receives a non-regulated bit rate (UBR) service.

The shared channel (DCH) 23 is composed of a shared traffic channel (DTCH: Dedicated Trafic Channel, 232) and a shared signal channel (DSCH: Dedicated Signal Channel, 231), which transmits traffic again. The number of is adjusted.

3 is a diagram illustrating an embodiment of a reverse channel for media access control frame processing based on a code division multiple access (CDMA) scheme according to the present invention.

3 shows a logical channel structure of a reverse link. In FIG. 3, the logical channel of the reverse link is composed of a random access channel (RACH) 31 and a shared channel (DCH) 32. The random access channels RACH 31 are used for random access, and the number of channels is adjusted by the number of collisions occurring in the random access channel 31. The fields required for the random access channel (RACH) 31 are as follows.

Service Type (ST) field 311: Indicates a type of service requesting a channel. That is, information identifying whether a service requested by the terminal is a communication service having an identity bit rate (CBR), a variable bit rate (VBR), an available bit rate (ABR), or an undefined bit rate (UBR) is included.

Mobile ID field 312: indicates an identifier of a terminal requesting random access.

Dynamic Parameter (DP) field 313: Used by a base station (BS) to transmit cell information of a terminal required to perform scheduling. The cell information of the terminal includes the number of cells currently waiting in the terminal and the remaining time, and is transmitted to the base station through the dynamic parameter (DP) field.

The shared channel (DCH) 32 is divided into a shared traffic channel (DTCH) 321 used to transmit traffic and a shared signal channel (DSCH) 322 used to transmit control information, and the number of channels is every frame. The number of channels is adjusted by the scheduling method.

4A and 4B are exemplary state transition diagrams for packet transmission in a method for processing a media access control frame based on a code division multiple access scheme according to the present invention.

Each terminal can be classified into a method of transmitting a packet by random access and a method of transmitting a packet through random access.

The former case is called a reserved random access method, and only the first packet participates in the contention and the remaining packets are transmitted through the reservation. In the latter case, it is called an iterative random access method, and each packet is transmitted through contention, and a delay occurs when a collision occurs.

In the case of the constant bit rate (CBR), variable bit rate (VBR), and available bit rate (ABR) services, the reserved random access method is basically used, and in the case of an undefined bit rate (UBR) service, iterative random By using an access method, a service suitable for the characteristics of an unqualified bit rate (UBR) service is provided.

4A shows a state transition diagram when using the reserved random access method. In FIG. 4A, the UE attempts to make a call in an idle state 401 or when a cell arrives, transitions to a contention state 402 and receives a code assignment.

When a code is assigned through contention, the code transitions to an active state 403 to transmit data through the assigned code. If the cell no longer arrives in the active state 403, it transitions to the wait state 404. Wait state 404 is a state added to use a Media Access Control (MAC) frame based on code division multiple access (CDMA), where the wait state 404 has a reserved code and is transmitted. It means no data. If there is no data even after waiting for the waiting time T in the wait state 404, the state transitions back to the idle state 401.

In general, in time division multiple access (TDMA) or frequency division multiple access (FDMA), since network resources become slots or frequencies, it is appropriate to return resources when there is no data to transmit. However, in the code division multiple access (CDMA), a state different from the existing medium access control (MAC) is required because resources are available to other terminals if the terminal does not transmit data even if the terminal has a code.

Therefore, by adding a wait state, the state in which the code is retained even if there is no data for a certain period of time is set. The benefit of doing so is that you do not have to return the code immediately, which reduces the latency caused by re-joining when data arrives, and reduces the wait time T in the wait state 402. It is possible to provide a target service by setting the characteristics for each service. That is, when the waiting time T is infinity, the state transition diagram of the identity bit rate (CBR) service using the fixed band allocation scheme is used. When the waiting time T is 0, the bursting characteristics are appropriate. State transition diagram suitable for reserved data service. Therefore, it can be seen that FIG. 4A includes the function of the existing state transition diagram.

4B shows a state transition diagram of an iterative random access scheme. In this state transition diagram, when data to be transmitted in the idle state 451 arrives, the terminal transmits a cell through a common code. If the transfer is successful, the same process is repeated in the active state 452 until the end of the data transfer. If a collision occurs, the state transitions to the Blocked state 453 to retransmit the data. If the retransmission is successful, the state transitions back to the active state 452. If the buffer is empty due to the successful transmission in the active state 452 or in the blocked state 453, the idle state 451. To transition to.

The state of the random access channel is divided into three states, idle, busy, and collision, and the state information is broadcast in the cell area through the paging channel (PCH). The contents of each state are as follows.

IDLE: Indicates that the random access channel is not in use.

BUSY: means that the random access channel is being used.

Collision: Indicates that a packet transmitted on a random access channel has collided.

The random channel access of the terminal uses a slotted ALOHA scheme, and when a collision occurs, a method for quickly resolving the collision is considered in consideration of the priority of each service using information fed back.

5 is a flowchart illustrating a method for processing a medium access control frame based on a code division multiple access scheme according to the present invention.

5 shows a process flow diagram between a base station and a mobile station. The mobile station corresponds to the mobile station 11 in the wireless communication system to which the present invention shown in FIG. 1 is applied, thereby communicating with the base station 12.

Requesting a channel from the mobile station 11 to the base station 12 is a reverse link, and FIG. 3 shows a frame structure thereof, and assigning a channel to the mobile station 11 using a physical channel is a forward link. 2 shows a frame structure thereof.

This is shown as follows in the flow of the drawing.

First, a channel request comes from the mobile station to the base station (501). At this time, the reverse frame shown in FIG. 3 is used.

The medium access control (MAC) scheduler of the base station determines the service type (502). In this case, the service type in the reverse frame transmitted from the mobile station is determined to determine the corresponding type.

The base station reserves a channel using a medium access control (MAC) protocol in a medium access control (MAC) scheduler (503).

The channel to the mobile station is allocated using the physical channel (504). That is, channel allocation from the base station to the mobile station uses the forward frame shown in FIG. At this time, the channel is allocated in consideration of the service type and the like based on the physical channel.

The mobile station communicates with the base station using the assigned channel to provide a mobile multimedia service (505).

Such services are based on code division multiple access (CDMA).

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill in Esau.

As described above, the present invention defines a forward structure and a reverse structure of a medium access control frame used in a wireless communication system based on a code division multiple access (CDMA) scheme, and uses mobile media access control frames to define a mobile multimedia. By presenting a method capable of providing a service, it can be used in line and packet services and the like, and has an effect of enabling random and reservation access.

Claims (8)

delete delete A method for processing a medium access control frame based on a code division multiple access method applied to a code division multiple access (CDMA) wireless communication system, A first base station receiving a channel allocation request from a mobile station through a reverse medium access control (MAC) frame including at least one random access channel for a channel allocation request and at least one first shared channel for transmitting traffic and control information; step; Determining a service type and reserving a channel by a medium access control (MAC) scheduler of the base station; And A third step of the base station allocating a channel to the mobile station using a forward medium access control (MAC) frame comprising a signal channel, a paging channel and at least one second shared channel; The random access channel is, A service type field for indicating a service type of a channel requested by the mobile station, a mobile identifier field, and a dynamic parameter field for use in transmitting cell information of the mobile station necessary for the base station to perform scheduling; The paging channel is, Represents an access control field used for access control, a response field for assigning a code to the mobile station to which a channel is assigned, and IDLE / BUSY information in a current frame for each code assigned to the mobile station. And a channel bitmap field for releasing a channel and an available code field for transmitting a code for remaining resources after allocating network resources. The method of claim 3, wherein The access control field, A method for processing a medium access control frame comprising code necessary for channel allocation, status information, and data access probability information. The method of claim 3, wherein The response field is A method for processing a medium access control frame comprising mobile identifier information and code information. delete The method of claim 3, wherein After the third step, the mobile station waits without returning the assigned code for a predetermined time even when there is no data to be transmitted in an active state in which the code is allocated through competition and transmits data through the assigned code. Media access control frame processing method characterized in that it further comprises. delete

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