KR20100073303A - Apparatus and method for transmitting/receiving voice packet in broadband wireless access system - Google Patents

Abstract

PURPOSE: A method for transmitting and receiving RTP packet through a RTP CS of protocol layer structure in a band wireless access system is provided to reduce a required bandwidth of a wireless part by 46% by forming OP header and UDP header according to a packet classification rule. CONSTITUTION: A higher layer transmits VoIP(Voice over Internet Protocol) packet to RTP(Real-time Transport Protocol) CS(Circuit Switching). MAC(Medium Access Control) SDU(Service Data Unit) corresponding to VoIP packet comprises IP header(Internet Protocol, 106), UDP header(User Datagram Protocol, 104), RTP header(Real-time Transport Protocol, 102) and VoIP payload(100). The RTP CS removes the IP header and the UDP header on the MAC SDU. The IP header comprises the information about a protocol, a source IP address, and a destination IP address. The UDP header comprises the information about a destination port number and a source port number.

Description

Apparatus and method for transmitting and receiving voice packet in broadband wireless access system {APPARATUS AND METHOD FOR TRANSMITTING / RECEIVING VOICE PACKET IN BROADBAND WIRELESS ACCESS SYSTEM}

The present invention relates to an apparatus and a method for transmitting and receiving a voice packet in a broadband wireless access system. In particular, when a transmitting side transmits a Realtime Transport Protocol (RTP) packet to a wireless section in a broadband wireless access system, an IP (Internet Protocol) header and UDP ( User Datagram Protocol (User Datagram Protocol) headers do not transmit over the wireless section, but only the RTP header and Voice over Internet Protocol (VoIP) payload are transmitted.When the receiving side receives the RTP packet over the wireless section, An apparatus and method for generating an IP header and a UDP header are provided.

In general, communication systems have been developed mainly for voice services, and are gradually developing into communication systems capable of not only voice but also data services and various multimedia services. However, the voice-oriented communication system did not meet the rapidly increasing service needs of users because of the relatively small transmission bandwidth and high usage fee. In addition, due to the development of the communication industry and increasing user demand for Internet services, there is an increasing need for a communication system capable of efficiently providing Internet services. As a result, it has been introduced into a broadband wireless access system for efficiently providing Internet services with broadband enough to meet the demand of rapidly increasing users.

The broadband wireless access system is a system for integrating and supporting not only voice but also various low speed and high speed data services and multimedia application services such as high definition video. The broadband wireless access system is based on a wireless medium using broadband such as 2GHz, 5GHz, 26GHz and 60GHz, in a mobile or fixed environment, public switched telephone network (PSTN), public switched data network (PSDN), internet network, IMT2000 network, It is a wireless communication system that can connect ATM (Asynchronous Transfer Mode) network and can support channel rates of 2Mbps or more. The broadband wireless access system may be classified into a broadband wireless subscriber network, a broadband mobile access network, and a high-speed wireless local area network (LAN) according to terminal mobility (fixed or mobile), communication environment (indoor or outdoor), and channel transmission rate. .

The wireless access method of the broadband wireless access system is being standardized by the International Organization for Standardization. The WiMAX system, one of the broadband wireless access systems, is an IEEE 802.16 standardization group of the Institute of Electrical and Electronics Engineers. Is being standardized on. The IEEE 802.16 standard has a wider bandwidth of data than conventional wireless technology, and thus can transmit a lot of data in a short time, and all users share a channel (or resource) to efficiently use the channel. It is possible. In addition, quality of service (QoS) is guaranteed so that users can receive different quality services according to the characteristics of the service.

The IEEE 802.16 protocol used in the WiMAX system provides MAC layer connectivity. Each Service Flow (SF) generated between the UE and the base station in the WiMAX system has a virtual circuit form divided by a connection ID (CID). The Convergence Sublayer (hereinafter referred to as 'CS') in the IEEE 802.16 protocol hierarchy determines the type of payload of a MAC PDU (Packet Data Unit) and transmits an IP (Internet Protocol) packet. IP CS, Ethernet CS for Ethernet packet transmission, and ROHC CS for transmission of an IP packet whose header is compressed by ROHC (RObust Header Compression).

Voice over Internet Protocol (VoIP) technology is a communication technology that transmits a voice packet generated by a voice codec into a Realtime Transport Protocol (RTP) packet and transmits it over a wireless section. In general, an RTP packet consists of [IP header + User Datagram Protocol (UDP) header + RTP header + voice packet]. By using the VoIP technology, a voice packet may be transmitted in real time even in an IP packet switched communication system such as a WiMAX system. Voice codecs used in the VoIP technology include AMR (Adaptive MultiRate), G.711, G.723.1, and G.729.

As described above, in order to transmit a voice packet in real time in the IP packet switched communication system, an IP header, a UDP header, and an RTP header are added to the voice packet. The IP header has fields such as a source IP address and a destination IP address, and occupies 20 bytes. The UDP header has fields such as a source port number and a destination port number, and occupies an 8 byte size. The RTP header has a field such as a sequence number and occupies a size of 12 bytes. The voice packet occupies a size of 20 bytes in the case of the G.729 codec having an 8 kbps bandwidth and a transmission period of 20 ms. Therefore, the sum of the IP header, UDP header, RTP header size, and voice packet size based on the G.729 voice codec adds up to 60 bytes. Of these, 28 bytes corresponding to the IP header and the UDP header form an additional amount of data used for forming a virtual circuit and delivering one voice packet to a VoIP application of a destination host, that is, header transmission overhead. do.

The WiMAX system generally proposes a Payload Header Suppression (PHS) technique and a ROburst Header Compression (ROHC) technique in order to reduce the header transmission overhead in forming the virtual circuit. In the PHS scheme and the ROHC scheme, fields that do not change well when a connection is established once among packet headers transmitted in a radio section through an appointment between a base station and a terminal in advance (ie, source IP address, destination IP address, source port number, Header compression scheme that omits the destination port number field). Although header transmission overhead can be partially reduced through such a header compression scheme, there is a problem in that the size of header transmission overhead that can be reduced is still limited because fields that are changed every packet must be transmitted.

An object of the present invention is to provide an apparatus and method for transmitting and receiving voice packets in a broadband wireless access system.

Another object of the present invention is to provide an apparatus and method for defining an RTP CS for transmitting an RTP packet to a CS on an IEEE 802.16 protocol hierarchy in a broadband wireless access system, and transmitting and receiving an RTP packet through the defined RTP CS. have.

Another object of the present invention is to transmit the voice packet by transmitting only the RTP header and the VoIP payload without transmitting the IP header and the UDP header to the wireless section when the transmitting side transmits the RTP packet to the wireless section in the broadband wireless access system. The present invention provides an apparatus and method for reducing the bandwidth required for the wireless section.

According to another object of the present invention, when a receiving side receives an RTP packet in a wireless section in a broadband wireless access system, an IP header and a UDP are used by using a packet classification rule even if the receiving header does not receive an IP header and a UDP header in a wireless section. An apparatus and method for generating a header are provided.

According to an aspect of the present invention for achieving the above object, the voice packet transmission method of CS in a broadband wireless access system, when receiving the MAC SDU from a higher layer, whether the received MAC SDU is a MAC SDU for voice packets Checking whether the MAC SDU is a MAC SDU for a voice packet, and removing an IP header and a UDP header from the received MAC SDU, thereby creating a new MAC SDU composed of an RTP header and a voice payload. Generating and transmitting the generated new MAC SDU to a MAC sublayer.

According to an aspect of the present invention for achieving the above object, the voice packet transmission method in a broadband wireless access system, the CS classifier, when the MAC SDU for the voice packet is received from a higher layer, RTP the received MAC SDU Transmitting to a CS, and generating, by the RTP CS, a new MAC SDU composed of an RTP header and a voice payload by removing an IP header and a UDP header from the received MAC SDU, and transmitting the same to a MAC sublayer. Characterized in that it comprises a.

According to an aspect of the present invention for achieving the above object, in a broadband wireless access system, a voice packet transmission apparatus, when a MAC SDU for a voice packet is received from a higher layer, and transmits the received MAC SDU to the RTP CS A CS classifier and the RTP CS for removing a IP header and a UDP header from a MAC SDU from the CS classifier, generating a new MAC SDU consisting of an RTP header and a voice payload, and transmitting the same to the MAC sublayer. It features.

According to an aspect of the present invention for achieving the above object, the voice packet receiving method of CS in the broadband wireless access system, when the MAC SDU for the voice packet is received from the MAC sublayer, generating an IP header and a UDP header Inserting the generated IP header and the UDP header into the received MAC SDU, generating a new MAC SDU comprising an IP header, a UDP header, an RTP header, and a voice payload; And transmitting the SDU to a higher layer.

According to one aspect of the present invention for achieving the above object, the voice packet receiving method of CS in the broadband wireless access system, the CS classifier, when the MAC SDU for the voice packet is received from the MAC sublayer, the received MAC Transmitting the SDU to the RTP CS, generating the IP header and the UDP header by the RTP CS, and inserting the generated IP header and the UDP header into the received MAC SDU, Generating a new MAC SDU comprising a header, a UDP header, an RTP header, and a voice payload; and transmitting, by the RTP CS, the generated new MAC SDU to an upper layer.

According to an aspect of the present invention for achieving the above object, the voice packet receiving apparatus of CS in the broadband wireless access system, when the MAC SDU for the voice packet is received from the MAC sublayer, the received MAC SDU RTP CS A new MAC composed of an IP header, a UDP header, an RTP header, and a voice payload by generating a CS classifier for transmitting the IP header and an UDP header, and inserting the generated IP header and the UDP header into the received MAC SDU. After generating the SDU, it characterized in that it comprises the RTP CS for transmitting the generated new MAC SDU to the upper layer.

According to the present invention, in the broadband wireless access system, by defining the RTP CS for the transmission of the RTP packet to the CS on the IEEE 802.16 protocol hierarchy, when the sender transmits the RTP packet to the radio section, the IP header and UDP header is a radio section Only the RTP header and the VoIP payload are transmitted, and when the receiving side receives the RTP packet over the radio section, the IP packet and the UDP header are generated using a packet classification rule, thereby transmitting the voice packet. There is an advantage that can reduce the required bandwidth of about 46%. For example, when transmitting an RTP packet over a wireless section using a G.729 codec having an 8 kbps bandwidth and a transmission period of 20 ms, when transmitting an RTP packet using a conventional IP CS, the MAC Service Data Unit (IP SDU) is [IP]. Header + UDP header + RTP header + voice packet], the MAC SDU size is 60 bytes (= 20 + 8 + 12 + 20). On the other hand, when the RTP packet is transmitted using the RTP CS as in the present invention, since the MAC SDU consists of [RTP header + voice packet], the MAC SDU size is 32 bytes (= 12 + 20).

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, when 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.

In the present invention, when the transmitting side transmits the RTP packet to the wireless section in the broadband wireless access system, the IP header and the UDP header do not transmit to the wireless section, but transmit only the RTP header and the VoIP payload, and the receiving side transmits the RTP packet. Will be described with respect to the apparatus and the law for generating the IP header and UDP header using a packet classification rule when receiving over a wireless section. To this end, the present invention defines the RTP CS for the transmission of the RTP packet to the CS on the IEEE 802.16 protocol hierarchy.

Meanwhile, an RTP CS type service flow (SF) is generated according to a dynamic service flow generation procedure of an existing WiMAX system. Accordingly, both terminal-initiated service flow generation and base station-initiated service flow generation are possible.

In addition, the CS specification TLV (Type / Length / Value) is included in the DSA request and response message transmitted and received to establish a new connection between the base station and the terminal, which is a service for the connection. Indicates which CS the flow is for. 14 or 15 may be set as a value of the CS specification TLV to indicate that the service flow for the connection is for an RTP CS according to the present invention.

Hereinafter, as an RTP packet transmitted using the RTP CS, a VoIP packet will be described as an example.

In addition, the packet classification rule of the RTP CS is a determination condition for distinguishing a general IP packet from a VoIP packet and represents a virtual circuit for transmitting a VoIP packet between a base station and a terminal. The packet classification rule of the RTP CS is composed of the same items as the packet classification rule of the IP CS. However, the RTP CS must include five packet classification rule items as shown in Table 1 below, and CS priority must always be higher than that of the IP CS.

Item Explanation example Protocol Transport protocol type UDP → 0x11 IP masked source address Source IP address band
(src, smask) 10.0.17.251/255.255.255.255
→ (0x0a0011fb, 0xffffffff) IP masked destination address Destination IP address band
(dst, dmask) 203.213.66.74/255.255.255.255
→ (0xcbd5424a, 0xffffffff) Protocol source port range Source port number band
(sportlow, sporthigh) Port 48765
→ (0xbe7d, 0xbe7d) Protocol destination port range Destination port number band
(dportlow, dporthigh) Port 50001
→ (0xc351, 0xc351)

As shown in Table 1, the RTP CS includes Protocol, IP masked source address, IP masked destination address, Protocol source port range, and Protocol destination port range items, among which Protocol is transmitted. Indicates the type of protocol. In addition, the IP masked source address represents a source IP address band, which is represented by an IP source address value src and a mask value of an IP source address. The IP masked destination address represents a destination IP address band, which is represented by an IP destination address value dst and a mask value dmask of the IP destination address. The protocol source port range represents a source port number band, which is represented by a sportlow and a sporthigh of the source port number. The protocol destination port range represents a destination port number band, which is represented by a dlowlow and a dporthigh of the destination port number.

The CS packet classification rule table is a table defining packet classification rules for each CS, and may be generated as shown in Table 2 below. Here, five packet classification rule items of the RTP CS are determined during the VoIP call setup process, and the packet classification rules of the RTP CS are generated according to the determination. That is, the IP masked destination address and the protocol destination port range among the five packet classification rule items of the RTP CS are SIP signaling processes (that is, the sender sends a session initiation protocol INVITE message to the receiver to request voice call setup, and receives The IP address and UDP port number of the called party obtained in the process of sending a session initiation protocol success message (SIP 200 OK) to the sender and responding to the request) are determined as the IP masked source address and the protocol source port range. The IP address and UDP port number of the calling party are determined. The protocol is set to 17 because it uses UDP-based RTP.

CS type CS
Priority SFID Scheduling Method protocol Source IP
address Source port number Destination IP
address Destination port number IP CS 0 0 0x4 BE 0 0.0.0.0/
0.0.0.0 0 0.0.0.0/
0.0.0.0 0 IP CS 1 One 0x67 nrtPS 6 0.0.0.0/
0.0.0.0 0 0.0.0.0/
0.0.0.0 80 RTP CS 0 7 0x109 ertPS 17 10.0.17.251/
255.255.255.255 48765 203.213.66.74/
255.255.255.255 50001

As shown in Table 2, the packet classification rule for each CS includes a CS priority, a Service Flow ID (SFID), a scheduling scheme, a protocol, a source IP address, a source port number, a destination IP address, and a destination port number. It is configured to include information about.

1 is a diagram illustrating a configuration of a corresponding MAC SDU when a transmitting side transmits a VoIP packet to a wireless section in a broadband wireless access system according to the present invention.

Referring to FIG. 1, the MAC SDU corresponding to the VoIP packet transmitted by the upper layer to the RTP CS is [IP header 106 + UDP header 104 + RTP header 102 + VoIP payload 100]. It consists of. The RTP CS removes an IP header 106 and a UDP header 104 from the MAC SDU received from an upper layer to generate a new MAC SDU consisting of only [RTP header 102 + VoIP payload 100]. Here, the IP header 106 includes information on protocols, source IP addresses, and destination IP addresses. In addition, the UDP header 104 includes information about a source port number and a destination port number.

2 is a diagram illustrating a protocol hierarchy of a transmitting side in a broadband wireless access system according to the present invention.

As shown, the protocol layer structure of the transmitting side is largely classified into a higher layer 200, a medium access control (MAC) layer, and a PHY (PHYsical) layer 240, and the MAC layer is a CS 210 and a MAC. It is configured to include a sub-layer 230. The CS 210 may include a CS classifier 212 and various types of CSs, for example, an IP CS 214, an RTP CS 216, an Ethernet CS 218, and an ROHC CS (as defined in the present invention). 220).

Referring to FIG. 2, the CS classifier 212 in the CS 210 may include header information extracted from an IP header and a UDP header in the received MAC SDU when the MAC SDU is received from the upper layer 200. The CS packet classification rules in the CS packet classification rule table are compared, a CS corresponding to a matching packet classification rule is selected, and the received MAC SDU is transmitted to the selected CS. Accordingly, when the CS classifier 212 receives the MAC SDU for the VoIP packet from the upper layer 200, the CS classifier 212 transmits the received MAC SDU to the RTP CS 216. That is, header information extracted from the IP header and the UDP header in the received MAC SDU and information obtained in the process of establishing a VoIP call for transmitting the VoIP packet (this is generated by the RTP CS packet classification rule and the CS packet Included in the classification rule table), and the MAC SDU for the received VoIP packet is transmitted to the RTP CS 216 according to the comparison result. In addition, the CS classifier 212 extracts an SFID from the packet classification rule of the selected CS, determines a CID using the extracted SFID and the SFID-CID mapping table, and determines the received MAC SDU with the selected CS. Together with the determined CID.

The IP CS 214 is a CS for transmission of an IP packet excluding a VoIP packet, the Ethernet CS 218 is a CS for transmission of an Ethernet packet, and the ROHC CS 220 is a header in an ROHC scheme. Is a CS for transmission of the compressed IP packet. The IP CS 214, the Ethernet CS 218, and the ROHC CS 220 perform the same operations as before. That is, the IP CS 214, the Ethernet CS 218, and the ROHC CS 220 process the MAC SDUs from the CS classifier 212, which together with the CIDs from the CS classifier 212 are MAC sublayers. Transmit to 230.

The RTP CS 216 according to the present invention is a CS for transmitting a VoIP packet, and is composed of [RTP header + VoIP payload] by removing an IP header and a UDP header from a MAC SDU from the CS classifier 212. A new MAC SDU is generated and the generated new MAC SDU and the CID from the CS classifier 212 are transmitted to the MAC sublayer 230.

The MAC sublayer 230 generates a MAC header using CIDs from various kinds of CSs 214 to 220 and inserts the generated MAC headers into MAC SDUs from various kinds of CSs 214 to 220. After generating the MAC PDU, the generated MAC PDU is transmitted to the radio section through the PHY layer 240.

3 is a diagram illustrating a protocol hierarchy of a receiving side in a broadband wireless access system according to the present invention.

As shown, the protocol layer structure of the receiving side is largely classified into a higher layer 300, a MAC layer, and a PHY layer 340, and the MAC layer includes a CS 310 and a MAC sublayer 330. It is composed. The CS 310 may include a CS classifier 312 and various kinds of CSs, for example, an IP CS 314, an RTP CS 316, an Ethernet CS 318, and an ROHC CS (as defined in the present invention). 320).

Referring to FIG. 3, the MAC sublayer 330 in the CS 310 extracts a MAC header from a MAC PDU received from a radio section through the PHY layer 340, and obtains a CID from the extracted MAC header. do. In addition, the MAC sublayer 330 removes the MAC header from the MAC PDU to generate a MAC SDU, and transmits the generated MAC SDU and the obtained CID to the CS classifier 312.

The CS classifier 312 obtains an SFID using the CID and the SFID-CID mapping table from the MAC sublayer 330, selects a CS including the obtained SFID from a CS packet classification rule table, and The MAC SDU from the MAC sublayer 330 is transmitted to the selected CS.

The IP CS 314 is a CS for receiving an IP packet excluding a VoIP packet, the Ethernet CS 318 is a CS for receiving an Ethernet packet, and the ROHC CS 320 is a header in an ROHC manner. Is the CS for reception of the compressed IP packet. The IP CS 314, the Ethernet CS 318, and the ROHC CS 320 perform the same operations as before. That is, the IP CS 314, the Ethernet CS 318, and the ROHC CS 320 process the MAC SDU from the CS classifier 312 and transmit it to the upper layer 300.

The RTP CS 316 according to the present invention uses information obtained in the process of establishing a VoIP call for transmission of the VoIP packet (which is generated as an RTP CS packet classification rule and included in a CS packet classification rule table). A new MAC composed of [IP header + UDP header + RTP header + VoIP payload] by generating an IP header and a UDP header and inserting the generated IP header and UDP header into a MAC SDU from the CS classifier 312. After generating the SDU, the generated new MAC SDU is transmitted to the upper layer 300.

4 is a flowchart illustrating a method of operating a CS classifier at a transmitting side for transmitting a VoIP packet to a wireless section in a broadband wireless access system according to an exemplary embodiment of the present invention.

Referring to FIG. 4, the CS classifier determines whether a MAC SDU is received from an upper layer in step 401. Here, the MAC SDU for the VoIP packet, which is received from the upper layer, is composed of [IP header + UDP header + RTP header + VoIP payload]. When the MAC SDU is received from the upper layer, the IP header and the UDP header information in the received MAC SDU are extracted in step 403. That is, information about a protocol, a source IP address, and a destination IP address is extracted from the IP header, and information about a source port number and a destination port number is extracted from the UDP header.

After that, the CS classifier selects a CS having the highest priority from the CS packet classification rule table previously generated in step 405, and checks whether the packet classification rule of the selected CS matches the extracted header information in step 407. do. If the packet classification rule of the selected CS and the extracted header information do not match, the CS classifier selects a CS having the next priority in step 409, and returns to step 407 to repeat the following steps.

On the other hand, when the packet classification rule of the selected CS and the extracted header information match, the CS classifier extracts the SFID from the packet classification rule of the selected CS in step 411 and the SFID-CID mapping predefined in step 413. Use the table to determine the CID for transmission of the VoIP packet. Here, the SFID-CID mapping table may be configured, for example, as shown in Table 3 below.

SFID CID 0x4 538 0x67 663 0x109 56

In step 415, the CS classifier transmits the determined CID and the received MAC SDU to the selected CS. Accordingly, the MAC SDU for the VoIP packet is transmitted to the RTP CS.

The CS classifier then terminates the algorithm according to the present invention.

5 is a flowchart illustrating a method of operating a RTP CS at a transmitting side for transmitting a VoIP packet to a wireless section in a broadband wireless access system according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the RTP CS checks whether a CID and a MAC SDU are received from the CS classifier in step 501. Here, the MAC SDU received from the CS classifier is composed of [IP header + UDP header + RTP header + VoIP payload].

Thereafter, the RTP CS removes an IP header and a UDP header from the received MAC SDU in step 503 to generate a new MAC SDU consisting of [RTP header and VoIP payload].

In step 505, the RTP CS transmits the received CID and the generated new MAC SDU to a MAC sublayer.

The RTP CS then terminates the algorithm according to the present invention.

6 is a flowchart illustrating a method of operating a CS classifier at a receiving side for receiving VoIP packets in a wireless section in a broadband wireless access system according to an exemplary embodiment of the present invention.

Referring to FIG. 6, the CS classifier determines whether a CID and a MAC SDU are received from the MAC sublayer in step 601. Here, the MAC SDU for the VoIP packet, which is received from the MAC sublayer, is composed of [RTP header + VoIP payload].

When the CID and the MAC SDU are received from the MAC sublayer, the CS classifier obtains an SFID using the received CID and a predefined SFID-CID mapping table in step 603.

Thereafter, the CS classifier selects a CS including the SFID from the CS packet classification rule table previously generated in step 605, and transmits the received MAC SDU to the selected CS in step 607. Accordingly, the MAC SDU for the VoIP packet is transmitted to the RTP CS.

The CS classifier then terminates the algorithm according to the present invention.

7 is a flowchart illustrating a method of operating a RTP CS at a receiving side for receiving a VoIP packet in a wireless section in a broadband wireless access system according to an exemplary embodiment of the present invention.

Referring to FIG. 7, the RTP CS checks whether a MAC SDU is received from the CS classifier in step 701. Here, the MAC SDU received from the CS classifier is composed of [RTP header + VoIP payload].

In step 703, the RTP CS generates an IP header and a UDP header that are not transmitted in the radio section using its packet classification rule. That is, the IP header is generated using the protocol in the packet classification rule, information on the source IP address, the destination IP address, and the like, and the UDP header is generated using the source port number and the destination port number. do.

Here, the items included in the IP header, including information on the protocol, the source IP address, and the destination IP address, are composed of the items as shown in Table 4 below.

Item Explanation Version version. Always 4 since IPv4 is used. Header Length Length of the IP header. Since IPv4 is used, it is always 5 (unit, 4 bytes). Type Of Service (TOS) Type of service. Set to zero or a value previously reserved for VoIP packets. That is, the length of the IP header is 4 bytes * 5 = 20 bytes. Total length Total length in bytes. It is calculated as [IP header 20 bytes + UDP header 8 bytes + RTP header 12 bytes + VoIP payload]. In this case, the size of the VoIP payload is a value obtained by subtracting the RTP header 12 bytes from the size of the MAC SDU received from the CS classifier. If the total length exceeds the maximum length, the data is fragmented and transmitted. Identification IP header delimited identifier. Set to 0 because fragmentation is not needed. Flags Flags related to fragmentation. Since fragmentation is not necessary, the DF (Don't Fragmentation) bit, which is a flag for not fragmenting, is set to 1, the MF (More Fragmentation) bit, which is a flag for fragmentation, is set to 0, and the reserved bit is set to 0. Fragment Offset Flag offset indicating the relative position of the fragmented packet to reassemble if fragmented. Set to 0 because fragmentation is not needed. Time To Live (TTL) Valid time. Set to a normal TTL initial value, such as 64 or 128. Protocol Transport protocol. Set to 17 because UDP is used as the transport protocol layer. Header Checksum Header checksum. Calculate according to the IP header checksum calculation method. Source IP address Source IP Address. Use the source IP address determined during the VoIP call setup process. Destination IP address Destination IP address. Use the destination IP address determined during the VoIP call setup process.

Next, an item included in the UDP header including information on the source port number and the destination port number is composed of items as shown in Table 5 below.

Item Explanation Source Port number Source port number. Use the source port number determined during the VoIP call setup process. Destination Port number Destination port number. Use the destination port number determined during the VoIP call setup process. Length Total length in bytes. [UDP header 8 bytes + RTP header 12 bytes + VoIP payload]. In this case, the size of the VoIP payload is a value obtained by subtracting the RTP header 12 bytes from the size of the MAC SDU received from the CS classifier. Checksum Checksum. Calculate according to the checksum calculation method.

In step 705, the RTP CS inserts the generated IP header and UDP header into the received MAC SDU to generate a new MAC SDU consisting of [IP header + UDP header + RTP header + VoIP payload].

In step 707, the RTP CS transmits the generated new MAC SDU to a higher layer.

The RTP CS then terminates the algorithm according to the present invention.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

1 is a diagram illustrating a configuration of a corresponding MAC SDU when a transmitting side transmits a VoIP packet to a wireless section in a broadband wireless access system according to the present invention;

2 is a diagram illustrating a protocol hierarchy of a transmitting side in a broadband wireless access system according to the present invention;

3 is a diagram illustrating a protocol hierarchy of a receiving side in a broadband wireless access system according to the present invention;

4 is a flowchart illustrating a method of operating a CS classifier at a transmitting side for transmitting a VoIP packet to a wireless section in a broadband wireless access system according to an embodiment of the present invention;

5 is a flowchart illustrating a method of operating a RTP CS at a transmitting side for transmitting a VoIP packet to a wireless section in a broadband wireless access system according to an embodiment of the present invention;

6 is a flowchart illustrating a method of operating a CS classifier at a receiving side for receiving VoIP packets in a wireless section in a broadband wireless access system according to an embodiment of the present invention;

7 is a flowchart illustrating a method of operating a RTP CS at a receiving side for receiving a VoIP packet in a wireless section in a broadband wireless access system according to an exemplary embodiment of the present invention.

Claims (30)

In the voice packet transmission method of the convergence sublayer (CS) in a broadband wireless access system, Checking whether the received MAC SDU is a MAC SDU for a voice packet when a Medium Access Control (MAC) Service Data Unit (MAD) is received from an upper layer; When the received MAC SDU is a MAC SDU for a voice packet, a Real Time Transport Protocol (RTP) header and a voice payload are removed by removing an Internet Protocol (IP) header and a User Datagram Protocol (UDP) header from the received MAC SDU. Creating a new MAC SDU consisting of: And transmitting the generated new MAC SDU to a MAC sublayer. The method of claim 1, The process of checking whether the received MAC SDU is a MAC SDU for a voice packet, Comparing header information extracted from at least one of an IP header and a UDP header in the received MAC SDU with information obtained when setting up a voice call for transmitting the voice packet; When the header information extracted from at least one of the IP header and the UDP header in the received MAC SDU and the information obtained during the voice call setup process for transmitting the voice packet coincide, the received MAC SDU is Determining that it is a MAC SDU for the voice packet. The method of claim 2, The header information extracted from the IP header may include at least one of a protocol, a source IP address, and a destination IP address. The method of claim 2, The header information extracted from the UDP header includes at least one of a source port number and a destination port number. The method of claim 2, wherein the voice call setup process comprises: The sender sends a session initiation protocol INVITE message to the receiver to request voice call setup, and the receiver sends a session initiation protocol success message (SIP 200 OK) to the sender to respond to the request. In the method of transmitting a voice packet in a broadband wireless access system, When the Convergence Sublayer (CS) classifier receives a Medium Access Control (MAC) Service Data Unit (SDU) for a voice packet from a higher layer, the Convergence Sublayer (CS) classifier sends the received MAC SDU to a Realtime Transport Protocol (RTP) CS. Transfer process, The RTP CS removes an Internet Protocol (IP) header and a User Datagram Protocol (UDP) header from the received MAC SDU to generate a new MAC SDU consisting of a Realtime Transport Protocol (RTP) header and a voice payload. Transmitting to the MAC sublayer. The method of claim 6, The CS classifier transmits the received MAC SDU to the RTP CS, Comparing header information extracted from at least one of an IP header and a UDP header in the received MAC SDU with information obtained in a voice call setup process for transmitting the voice packet; When the header information extracted from at least one of the IP header and the UDP header in the received MAC SDU and the information obtained during the voice call setup process for transmitting the voice packet coincide, the received MAC SDU is determined. Transmitting to the RTP CS. The method of claim 7, wherein The header information extracted from the IP header may include at least one of a protocol, a source IP address, and a destination IP address. The method of claim 7, wherein The header information extracted from the UDP header includes at least one of a source port number and a destination port number. The method of claim 7, wherein the call setup process, The sender sends a session initiation protocol INVITE message to the receiver to request voice call setup, and the receiver sends a session initiation protocol success message (SIP 200 OK) to the sender to respond to the request. An apparatus for transmitting a voice packet in a broadband wireless access system, CS classifier for transmitting the received MAC SDU to the Realtime Transport Protocol (RTP) Convergence Sublayer (CS) when a Medium Access Control (MAC) Service Data Unit (SDU) for a voice packet is received from an upper layer. Wow, By removing the Internet Protocol (IP) header and User Datagram Protocol (UDP) header from the MAC SDU from the CS classifier, a new MAC SDU consisting of a Realtime Transport Protocol (RTP) header and voice payload is generated, and the MAC sublayer Apparatus comprising the RTP CS for transmitting to. The method of claim 11, wherein the CS classifier, Means for comparing header information extracted from at least one of an IP header and a UDP header in the received MAC SDU with information obtained during a voice call setup process for transmitting the voice packet; When the header information extracted from at least one of the IP header and the UDP header in the received MAC SDU and the information obtained during the voice call setup process for transmitting the voice packet coincide, the received MAC SDU is determined. Means for transmitting to the RTP CS. 13. The method of claim 12, The header information extracted from the IP header includes at least one of a protocol, a source IP address, and a destination IP address. 13. The method of claim 12, The header information extracted from the UDP header includes at least one of a source port number and a destination port number. The method of claim 12, wherein the voice call setup process comprises: The sender sends a session initiation protocol INVITE message to the receiver to request voice call setup, and the receiver sends a session initiation protocol success message (SIP 200 OK) to the sender and responds to the request. In a convergence sublayer (CS) voice packet reception method in a broadband wireless access system, Generating an Internet Protocol (IP) header and a User Datagram Protocol (UDP) header when a MAC SDU for a voice packet is received from a medium access control (MAC) sublayer; Inserting the generated IP header and the UDP header into the received MAC SDU, generating a new MAC SDU comprising an IP header, a UDP header, a Realtime Transport Protocol (RTP) header, and a voice payload; And transmitting the generated new MAC SDU to an upper layer. The method of claim 16, wherein the IP header and UDP header, And generating information by using information acquired during a voice call setup process for transmitting the voice packet. The method of claim 17, wherein the voice call setup process comprises: The sender sends a session initiation protocol INVITE message to the receiver to request voice call setup, and the receiver sends a session initiation protocol success message (SIP 200 OK) to the sender to respond to the request. The method of claim 16, Wherein the IP header comprises at least one of a protocol, a source IP address, and a destination IP address. The method of claim 16, And the UDP header comprises at least one of a source port number and a destination port number. In a convergence sublayer (CS) voice packet reception method in a broadband wireless access system, When a Convergence Sublayer (CS) classifier receives a MAC Service Data Unit (SDU) for a voice packet from a Medium Access Control (MAC) sublayer, the received MAC SDU is converted into a Realtime Transport Protocol (RTP) CS. Transfer to, Generating, by the RTP CS, an Internet Protocol (IP) header and a User Datagram Protocol (UDP) header; The RTP CS inserting the generated IP header and the UDP header into the received MAC SDU to generate a new MAC SDU comprising an IP header, a UDP header, an RTP header, and a voice payload; And transmitting, by the RTP CS, the generated new MAC SDU to a higher layer. The method of claim 21, wherein the IP header and UDP header, And generating information by using information acquired during a voice call setup process for transmitting the voice packet. The method of claim 22, wherein the voice call setup process comprises: The sender sends a session initiation protocol INVITE message to the receiver to request voice call setup, and the receiver sends a session initiation protocol success message (SIP 200 OK) to the sender to respond to the request. The method of claim 21, Wherein the IP header comprises at least one of a protocol, a source IP address, and a destination IP address. The method of claim 21, And the UDP header comprises at least one of a source port number and a destination port number. An apparatus for receiving a voice packet of a convergence sublayer (CS) in a broadband wireless access system, A CS that transmits the received MAC SDU to a Realtime Transport Protocol (RTP) Convergence Sublayer (CS) when a MAC Service Data Unit (SDU) for a voice packet is received from a Medium Access Control (MAC) sublayer. Classifier, Generates an IP (Internet Protocol) header and a User Datagram Protocol (UDP) header, and inserts the generated IP header and UDP header into the received MAC SDU, and comprises an IP header, a UDP header, an RTP header, and a voice payload. And generating the new MAC SDU, and then transmitting the generated new MAC SDU to a higher layer. The method of claim 26, wherein the IP header and UDP header, And generating information by using information obtained during a voice call setup process for transmitting the voice packet. 28. The method of claim 27, wherein the call setup process comprises: The sender sends a session initiation protocol INVITE message to the receiver to request voice call setup, and the receiver sends a session initiation protocol success message (SIP 200 OK) to the sender and responds to the request. The method of claim 26, And the IP header includes at least one of a protocol, a source IP address, and a destination IP address. The method of claim 26, And the UDP header includes at least one of a source port number and a destination port number.

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