KR100606009B1 - Method for transmitting voice packet data in code division multiple access mobile communication system - Google Patents

Abstract

The present invention relates to a method for transmitting voice packet data by applying the AAL2 method to a base station and a base station control period in a code division multiple access method using an ATM technology. The present invention relates to a single ATM connection for PCM coded voice packet data. By multiplexing the data, the bandwidth between the base station and the base station controller can be efficiently used, and the real-time demands of the voice data can be satisfied.

IMT, ATM, VOICE PACKET, TRANSMISSION, AAL2

Description

METHODS FOR TRANSMITTING VOICE PACKET DATA IN CODE DIVISION MULTIPLE ACCESS MOBILE COMMUNICATION SYSTEM}             

1 is a block diagram of an ATM cell when transmitting voice packet data using the conventional AAL5 technology.

2 is a block diagram of an ATM cell when transmitting voice packet data using AAL2 technology according to the present invention.

3 illustrates a CSP-PDU and CPS-PK format of an AAL2 cell according to the present invention.

4 is a transmission configuration diagram of an AAL2 driver according to an embodiment of the present invention.

5A-5C are transmission control flow diagrams for multiplexing voice packets of an AAL2 task in accordance with an embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a code division multiple access (CDMA) mobile communication system, and more particularly, to a method for transmitting voice packet data by applying the AAL2 technique in a base station and a base station control period. .

Conventional CDMA mobile communication systems have provided voice-oriented services, but gradually developed to the IMT-2000 standard that enables high-speed data transmission as well as voice. In the IMT-2000 standard, services such as high quality voice, moving picture, and internet search are possible. Therefore, the quality of service requirements for satisfying each of these services are different, so quality management is required for each voice and data. For example, even if some loss occurs, there is no problem with the service, but if the delay occurs, the call quality is degraded. On the other hand, data has no problem in service against delay, but loss can have a big impact on service quality.

On the other hand, Asynchronous Transfer Mode (hereinafter referred to as ATM) technology is a transmission means for satisfying the service needs according to the characteristics of the voice and data can be regarded as suitable for the IMT-2000 network for multimedia services. In order for end users to benefit from this ATM technology, AAL types that segment and reassemble ATM cells must be considered according to the characteristics of voice and data. In general, in case of voice, AAL1 technology having real-time characteristics and constant bit rate is used in the prior art, and data and signaling traffic have a variable bit rate and a cell loss rate. Has been tailored to service needs with AAL5.

However, when the voice service is provided using AAL1 in the current IMT-2000 network and the E1 / T1 channel is used as the physical link during the base station and base station control period, the following problems occur. Assigning a peak rate to one subscriber call increases the bandwidth occupancy for the link between the base station and the base station controller, and transmits a low bit rate according to the current voice coding scheme. Delay problem occurs. In addition, since one virtual connection is allocated to one subscriber call, the link is wasted during the silent period. This is a problem caused by the constant-bit rate characteristic of AAL1 and is not suitable for the transmission method of voice packet data of the IMT-2000 network. Another alternative method is to send both voice and data using AAL5, but this method is also suitable for large data such as LAN data. Therefore, the short and variable size characteristics of voice packet data are used. Violation

1 shows a configuration when transmitting a voice packet to an ATM cell using the conventional AAL5.

Referring to FIG. 1, since voice has a small size, a lot of space is padded in one ATM cell (transmitted by filling the unused space with “0”), which is wasteful. If voice packet # 1 is transmitted at 21 bytes (5 headers + 16 fading bytes) of 13k QCELP coded half rate, 19 bytes of the first ATM cell becomes useless space. In addition, if voice packet # 2 is transmitted in 8 bytes (5 headers + 3 payload bytes) of 13k QCELP coded silence, 32 bytes of the second ATM cell become useless. In addition, the number of ATM cells can be transmitted only by using two ATM cells that can be used as one ATM cell, and there is a problem that a transmission delay as much as the number of fragments increases.

As described above, a short and variable length of voice information having real time is transmitted. However, the existing AAL5 or AAL1 technology causes problems of bandwidth and transmission delay.

Accordingly, an object of the present invention is to provide a method for transmitting voice packet data that efficiently uses bandwidth in consideration of characteristics of voice information in a code division multiple access mobile communication system.

Another object of the present invention is to provide a method of transmitting voice packet data which maintains real-time and reduces transmission delay as much as possible in a code division multiple access mobile communication system.

In order to achieve the above object, the present invention is characterized in that voice packet data is transmitted between a base station and a mobile station using AAL2 technology for multiplexing and transmitting a plurality of channels in one ATM connection in a code division multiple access mobile communication system. do.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Specific details appear in the following description, which is provided to help a more general understanding of the present invention, and it is understood that the present invention may be practiced without these specific matters. Will be self-evident. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The AAL2 technology applied to the present invention is an AAL2 CSP Spec. Of I.363.2 in September 1997 and an AAL2 SAR SSCS Spec of I.366.1 in June 1998 at the International Telecommunication Union (ITU-T). Although it is recommended as a recommendation, details have not been established so far. Since AAL2 technology is currently being standardized, there is no dedicated hardware chip for AAL2 processing, so that AAL2 cells can be transmitted in software and follow international standards as far as possible.

2 illustrates the configuration of an ATM cell when transmitting a voice packet using AAL2 technology according to the present invention.

1 and 2, the AAL2 technology according to the present invention is different from the conventional AAL5 technology. As shown in Fig. 1, voice packet # 1 occupies 21 bytes, voice packet # 2 occupies 8 bytes and uses 29 bytes (actually CPS-PDU.STF [1 byte] and CPS- of voice packets). Adding PH [3 bytes] results in 36 bytes.) There are still 12 more bytes left. If voice packet # 3 exceeds the extra space, it is overlapped with the next ATM cell and transmitted. Using AAL2, voice packet data can be multiplexed and transmitted in one ATM connection, thereby efficiently using bandwidth. Here, the size of voice packet data according to the PCM scheme to which the present invention is applied is as described in Table 1 below.

QCELP Voice packet data size silence quarter half full 8k 2 5 10 22 13k 3 7 16 34

In the present invention, AAL2 technology is used as a transmission method of voice packet data between a base station and a base station control period, and a method implemented by software without using a dedicated hardware chip is used. The AAL2 driver implemented in software according to the present invention uses the AAL2 transmission task, the channel control block 420 and the connection table to multiplex voice packets to the AAL2 cell and implement the AAL2 transmission function as shown in FIG. connection table 430 and a buffer memory 440.

The main functions according to the present invention are as follows.

1. AAL2 CPS-PK Transmission Function

One subscriber voice call is composed of one CPS-PK, and implements the function of multiplexing each CPS-PKs to AAL2 VC, and the AAL2 cell (the maximum multiplexing time) within a preset timer value (maximum multiplexing allowance time). CPS-PDUs are multiplexed and transmitted. If the CPS-PK overlaps two or more AAL2 cells, the timer value is reset and multiplexed.

2. AAL2 timer function

The transmission delay can be reduced by setting the maximum multiplexing allowance time when the CPS-PK is multiplexed to the CPS-PDU. If the allowable time is reached when the AAL2 cell is partially full, the remaining space is padded with "0" and transmitted.

The format of AAL2 CPS-PDU and CPS-PK used in the present invention is as shown in FIG. 3 and described in detail in ITU-T I.363.2.

The user information delivered from the user application, that is, the CPS-SDU (voice packet) is composed of a CPS packet (CPS-PK) by attaching a CPS packet header (CPS-PH). In addition, one CPS-PDU is generated by multiplexing one or more CPS-PKs together with a start field in a CPS-PDU (AAL2 cell). The CPS-PDU is ready to be sent immediately with only the ATM cell header attached.

The header of the CPS-PK, CPS-PH, is configured as follows.

Channel InDentifier (CID) is used to distinguish channels of AAL2 users when multiplexing CPS-PK to CPS-PDU, and is represented by 8 bits. CID = 0 is not used (since all padding information is 0), and CIDs 1 to 7 are reserved for AAL2 management.

Length Indentifier (LI) indicates the size of a CPS-PK payload (CPS-PP), that is, a CPS-SDU, and uses 6 bits.

User-to-User Indication (UUI) classifies and delivers user specific information, and is used to distinguish when classes of services are different, and uses 5 bits.

HEC (Header Error Control) checks the fields of the CPS-PK header.

According to the packet size of the CPS-PK, one or more CPS-PKs are combined with the CPS-PDU and configured up to the stage immediately before the ATM cell. If one CPS-PK size exceeds 47 bytes, it shall be possible to overlap the next CPS-PDU. If padding is present, the STF contains information indicating the padding start point and also the start point of the next CPS-PK. The start field (STF), which is a header of the CPS-PDU, is configured as follows.

The OSF (OffSet Field) is represented by 6 bits and indicates the start position of the first CPS-PK.

SN (Sequence Number) is represented by 1 bit and numbers the CPS-PDUs.

P (Parity) parity checks the fields of the STF.

A configuration for AAL2 cell transmission according to the present invention is as shown in FIG.

Referring to FIG. 4, the AAL2 transmission task receives a voice packet from an application program (user application) every time a subscriber's voice call is requested, creates an AAL2 CPS-PDU, and transmits it using a SAR driver. In addition, the AAL2 send task is generated and started using an OS system call as the driver is initialized. The channel control block 420 has the number of connections set in the AAL2 driver. The channel control block 420 has an AAL2 processing state as a configuration field and has information of a CPS-PK when overlapping. In addition, the channel control block 420 points to the unit buffer of the CPS-PDU (ptrTx_PDU) and also points to the free address in each unit buffer (ptrBUF). That is, the channel control block 420 is used by pointing to the connection table 430. The connection table 430 uses a connection table of an existing SAR driver. The buffer memory 440 allocates a predetermined size of the buffer pool TX_BUF for each channel and sets the size of the unit buffer to the size of the CPS-PDU. The pointing of these buffers is made at the corresponding channel control block 420.

Hereinafter, a process of transmitting voice packet data of the AAL2 driver according to the present invention will be described. 5A to 5C illustrate a process of multiplexing and transmitting a voice packet to an AAL2 CPS-PDU according to an embodiment of the present invention. Here, four states, AAL2 buffers and parameters are required to process the voice packet data transmission process of the AAL2 driver according to the present invention. Each state according to the present invention is as follows.

First, the IDLE state is a state where the CPS-PDU (TX-BUF) has no CPS-PK (if OSF is "0"), and the timer is not started (the timer is generated and assigned a timer ID from the OS). )to be.

Next, the PART state is when the CPS-PK is multiplexed to one or more CPS-PDUs, and there is still free space, and the timer is starting, and if it receives an expire message (maximum multiplexing time) from the timer, Transition to the EXPIRE state.

Next, the FULL state is a state where the CPS-PDU is full, and if the last CPS-PK overlaps the next CPS-PDU, the timer is reset and restarted.

Next, the EXPIRE state receives an expire message from the timer and pads the remaining space of the CPS-PDU to the AAL0 device. It is in the IDLE state immediately after being sent to the device in a temporary state.

Terms according to the present invention are as follows.

TX_BUF is a buffer (48 bytes) needed to fill the CPS-PDU before sending it to the AAL0 driver.

ptrBUF is a pointer to the next free octet in each unit TX_BUF, and the next CPS-PK or Padding starts here.

ptrTx_PDU is a pointer pointing to each unit TX_BUF.

ucPart is the size of the CPS-PP located in the next TX_BUF when the CPS-PK payload overlaps, and ucSplit is the size of the CPS-PH located in the next CPS-PDU when the CPS-PK header is overlapped.

ucSeqNo represents a sequence number of consecutive CPS-PDUs and represents a next expected sequence number.

u4timer is an id indicating the time when the CPS-PK is multiplexed.

ucState represents the state of the current AAL2 receive task.

u4Remain is the size remaining in the TX_BUF currently being multiplexed.

TX_PH_BUF is a temporary buffer that temporarily stores the overlapped CPS-PK header, and TX_PP_BUF is a temporary buffer that temporarily stores the overlapped CPS-PK payload.

When the AAL2 transmission task (Tx_Task) according to the present invention is in the IDLE state and one voice packet is received, the process is as follows. When the AA2 send task is in the IDLE state and receives one voice packet, the timer starts, configures the STF and CPS-PH of the CPS-PDU, and copies it to the CPS-PDU (TX_BUF). The information of the CPS-PK header is received from an application program (user application). Before copying the CPS-PK payload, the remaining space u4Remain of the buffer memory TX_BUF is compared with the CPS-PK payload size, and if the payload size is smaller than the remaining space, the CPS-PK payload is copied, and the state transitions to the PART state. Otherwise, copy only the remaining space and if there are no more payloads, copy to TX_PP_BUF and wait for the next CPS-PK.

In contrast, the AAL2 transmission task (Tx Task) is in the PART state, and when a new voice packet is received, the CPS-PK header is configured by comparing the header space and the remaining space in TX_BUF. If the remaining space is larger than the header size 3, the remaining space is copied, and after the transition to the PART state, CPS-PK payload processing is performed. Otherwise, copy only the remaining space and process the CPS-PK payload, if there are more headers (ucSplit), copy to TX_PH_BUF, copy the next TX_BUF as much as ucSplit, and process the CPS-PK payload.

On the other hand, the AAL2 transmit task (Tx Task) transitions to the EXPIRE state when the expire message is received from the timer in the PART state, pads the remaining part of TX_BUF to 0, transmits the CPS-PDU to the AAL0 device, and sends the IDLE state. Transition to.

2 to 5C, in operation 501, an AAL2 transmission task receives one CPS-PDU and performs operation AAL2 multiplexing in operation 503. When the AAL2 transmission task receives one voice packet in the IDLE state, the AAL2 transmission task configures the CPS-PDU.STF in step 505, configures the CPS-PK header in step 507, and configures the CPS-PDU payload.

In step 509, the AAL2 transmission task configures the CPS-PK header under the PART state, and in step 511, the size of the space (u4Remain) remaining in the transmission buffer TX_BUF that is currently multiplexed is smaller than the CPS-PK payload size. Judge whether If the remaining space of the transmission buffer TX_BUF is smaller than the payload size, the transmission buffer TX_BUF is copied as much as the remaining size u4Remain from the TX_BUF currently multiplexed on the PtrBUF. In step 515, ucSplit of the current CPS-PK header is copied to TX_PP_BUF and then transitioned to the FULL state.

On the contrary, if the remaining space of the transmission buffer TX_BUF is not smaller than the payload size, if the size (u4Remain) of the space remaining in the transmission buffer TX_BUF currently multiplexed in step 517 is equal to the CPS-PK payload size, Determine whether or not. If the size of the space (u4Remain) remaining in the transmission buffer TX_BUF that is currently multiplexed is equal to the CPS-PK payload size, the remaining size (u4Remain) of the transmission buffer TX_BUF currently multiplexed to PtrBUF in step 519. ) Is copied to the transmit buffer TX_BUF and transferred to the FULL state.

On the contrary, if it is determined that the size of the space (u4Remain) remaining in the transmission buffer TX_BUF that is currently multiplexed is not the same as the CPS-PK payload size, the transmission buffer is larger than the CPS-PK payload size in the PtrBUF in step 521. Copy to (TX_BUF) and transition to the PART state to configure the CPS-PK payload.

When the CPS-PK head overlaps in step 523 under the FULL state, it is determined whether the size (ucSplit) of the CPS-PH located in the next CPS-PDU is '0'. When the CPS-PK Head Is Overlapping If it is determined that the size (ucSplit) of the CPS-PH located in the next CPS-PDU is '0', the current CPS-PDU is copied to the AAL0 driver in step 525. In step 527, the CPS-PDU.STF is configured, and in step 529, the CPS-PDU.STF is copied into the transmission buffer TX_BUF in the PtrBUF by the CPS-PK payload size, and then transitions to the PART state. When the CPS-PK Head Overlaps If it is determined that the size (ucSplit) of the CPS-PH located in the next CPS-PDU is not '0', the current CPS-PDU is copied to the AAL0 driver in step 531. If the CPS-PDU.STF is configured in step 533, and the CPS-PK header of TX_PH_BUF is overlapped with the PtrBUF in step 535, the transmit buffer TX_BUF corresponding to the size (ucsplit) of the CPS-PH located in the next CPS-PDU. ) And construct the CPS-PK payload.

Here, the CPS-PK payload configuration is as follows.

In step 537, it is determined whether the value of the space u4Remain remaining in the transmission buffer TX_BUF currently multiplexed is smaller than the size of the CPS-PK header. If the remaining space of the transmission buffer TX_BUF is smaller than the size of the header, in step 539, the transmission buffer TX_BUF is copied by the remaining size u4Remain from the TX_BUF currently multiplexed on the PtrBUF. In step 541, the ucpart of the current CPS-PK payload is copied to TX_PP_BUF and then transitioned to the FULL state.

On the contrary, if the remaining space of the transmit buffer TX_BUF is not smaller than the size of the header, whether the size of the space (u4Remain) remaining in the transmit buffer TX_BUF currently multiplexed in step 543 is equal to the size of the CPS-PK header. Determine whether or not. If the size of the space (u4Remain) remaining in the transmission buffer TX_BUF that is currently multiplexed is equal to the size of the CPS-PK header, the remaining size (u4Remain) of the transmission buffer TX_BUF currently multiplexed to PtrBUF is determined in step 545. ) Is copied to the transmit buffer TX_BUF and transferred to the FULL state.

In contrast, if it is determined that the size of the space (u4Remain) remaining in the currently multiplexed transmission buffer TX_BUF is not the same as the size of the CPS-PK header, it is determined that the size of the transmission buffer is equal to the size of the CPS-PK header in PtrBUF in step 547. After copying to (TX_BUF), it transitions to the PART state.

When the CPS-PK payload overlaps in step 549 under the FULL state, it is determined whether the size (ucPart) of the CPS-PP located in the next transmission buffer TX_BUF is '0'. When the CPS-PK Payload Overlaps If it is determined that the size (ucPart) of the CPS-PP located in the next transmission buffer TX_BUF is '0', the current CPS-PDU is copied to the AAL0 driver in step 551. Transition to IDLE state.

In contrast, when the CPS-PK payload overlaps, if it is determined that the size (ucPart) of the CPS-PP located in the next transmission buffer TX_BUF is not '0', in step 553, the current CPS-PDU is AAL0 driver. Copy to In step 555, the CPS-PDU.STF is configured, and in step 557, when the PS-PK payload of TX_PP_BUF overlaps the PtrBUF, it transmits as much as the size (ucPart) of the CPS-PP located in the next transmission buffer TX_BUF. After copying to the buffer TX_BUF, the device transitions to the PART state.

If a u4Timer event is received in step 559, the timer is processed in step 561. In step 563, the data is processed as "0" by the remaining size (u4Remain) in the transmission buffer TX_BUF currently multiplexed with PtrBUF. In step 565, the current CPS-PDU is copied to the AAL0 driver, and the state transitions to the IDLE state.

In addition, in the detailed description of the present invention has been described with respect to specific embodiments, various modifications are possible without departing from the scope of the 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 configures the IMT-2000 network using ATM technology, thereby efficiently using the bandwidth between the base station and the base station controller and satisfying real-time demands of voice data.                     

Claims (11)

delete A method for transmitting voice packet data in a mobile communication system of a code division multiple access method, Receiving a voice packet under the first standby state, driving a timer, constructing a CPS-PDU.STF and a CPS-PK header, and copying the CPS-PDU; Before copying the CPS-PK payload, the remaining space of the transmission buffer and the CPS-PK payload size are compared. If the payload size is smaller than the remaining space of the transmission buffer, the process is performed. Characterized in that the method. The method of claim 2, The information of the CPS-PK header is received from an application program. The method of claim 2, If the payload size is larger than the remaining space of the transmission buffer, copy as much as the remaining space and then copy to the first temporary buffer if there are more payloads. The method of claim 2, And receiving a new voice packet under the second state, and configuring a CPS-PK header by comparing the header size with the space remaining in the transmission buffer. The method of claim 5, If the space remaining in the transmission buffer is larger than the header size, copying the CPS-PK header and processing the CPS-PK payload. The method of claim 5, If the space remaining in the transmission buffer is smaller than the header size, copy the CPS-PK header by the remaining space and process the CPS-PK payload. The method of claim 7, wherein If there are more headers, copying to the second temporary buffer and copying back to the next transmission buffer by the size of the CPS-PH located in the next CPS-PDU and processing the CPS-PK path. The method of claim 5, When the expiration message is received from the timer in the second state, the terminal transitions to the third state (EXPIRE), pads the remaining portion of the transmission buffer to '0', and transmits a CPS-PDU. How to. A method for transmitting voice packet data in a mobile communication system of a code division multiple access method, One subscriber voice call is composed of one CPS-PK, and each CPS-PK is multiplexed to AAL2 VC to multiplex and transmit the CPS-PK to the CPS-PDU within a preset maximum multiplexing allowance time. Way. The method of claim 10, If the CPS-PK overlaps two or more CPS-PDUs, resetting and multiplexing a timer value.

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