WO2009017340A2 - Procédé d'émission de paquet permettant de réduire la surcharge d'en-tête - Google Patents

Procédé d'émission de paquet permettant de réduire la surcharge d'en-tête Download PDF

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Publication number
WO2009017340A2
WO2009017340A2 PCT/KR2008/004364 KR2008004364W WO2009017340A2 WO 2009017340 A2 WO2009017340 A2 WO 2009017340A2 KR 2008004364 W KR2008004364 W KR 2008004364W WO 2009017340 A2 WO2009017340 A2 WO 2009017340A2
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WO
WIPO (PCT)
Prior art keywords
header
packet
mobile station
information
base station
Prior art date
Application number
PCT/KR2008/004364
Other languages
English (en)
Other versions
WO2009017340A3 (fr
Inventor
Jeong Ki Kim
Yong Ho Kim
Ki Seon Ryu
Original Assignee
Lg Electronics Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from KR1020080006670A external-priority patent/KR101377961B1/ko
Application filed by Lg Electronics Inc. filed Critical Lg Electronics Inc.
Priority to US12/670,769 priority Critical patent/US20100208655A1/en
Publication of WO2009017340A2 publication Critical patent/WO2009017340A2/fr
Publication of WO2009017340A3 publication Critical patent/WO2009017340A3/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/04—Protocols for data compression, e.g. ROHC
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
    • H04L65/60—Network streaming of media packets
    • H04L65/70—Media network packetisation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/22—Parsing or analysis of headers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
    • H04L69/24—Negotiation of communication capabilities

Definitions

  • the present invention relates to a method of transmitting a packet in a wideband wireless access system, and more particularly, to a method of transmitting a packet, which is capable of reducing overhead of a header inserted into the packet when the packet is transmitted/received between a base station and a mobile station.
  • VoIP Voice over Internet Protocol
  • VoIP traffic is characterized in that it is generated with a fixed size having a fixed period in a VoIP codec.
  • VoIP communication may be divided into a talk-spurt period in which there is active conversation between users and a silence period in which a user listens to a speaker without speaking.
  • the silence period occupies more than 50% of a general call session.
  • various audio codecs are used for allocating different amounts of bandwidths to the talk- spurt period and the silence period.
  • AMR adaptive multi-rate
  • GSM global system for mobile communication
  • UMTS universal mobile telecommunications system
  • the VoIP supports silence suppression.
  • a vocoder for generating the VoIP traffic does not generate the traffic during the silence period and periodically generates conform noise in order to inform a counterpart that the call is continuously maintained.
  • the vocoder using the AMR codec generates a packet having a fixed size at an interval of 20 tns in the talk-spurt period and generates conform noise with an interval of 160 ms in the silence period.
  • the wideband wireless access system (for example, IEEE 802.16e) provides a new scheduling method such as an Extended real-time Polling service (Extended rtPS) for the VoIP traffic which supports the silence suppression.
  • the base station periodically allocates an uplink bandwidth used for bandwidth request or data transmission and does not change the size of the uplink (UL) allocation until a request for the change of the bandwidth is received from the mobile station. If the mobile station requests the change of the bandwidth and a bandwidth request size is set to 0, the base station allocates only a unicast bandwidth request (BR) opportunity for transmitting a BR header or does not allocate the bandwidth.
  • BR unicast bandwidth request
  • the base station may use a method of fixedly allocating a specified region to a specific mobile station. That is, a region having a predetermined size is initially allocated to a mobile station for supporting the VoIP service and the mobile station is informed of information on the allocated region via an UL- MAP which is initially transmitted. Period information of the regions which are subsequently allocated may be also included in the UP-MAP which is initially transmitted. Thereafter, in a next period, the base station may continuously allocate the region to the mobile station without informing the mobile station of the region which is initially informed via the UL-MAP. Then, the mobile station transmits the VoIP packet to the allocated region using the information on the region which is initially allocated in the map and transmits the VoIP region to the same region from the next period using the period information.
  • the VoIP packet is not transmitted to the region which is initially allocated. If the mobile station already has the allocation information for the VoIP connection when receiving an UL-MAP IE corresponding to the mobile station for the VoIP allocation or a UL-MAP IE for changing the position for the VoIP allocation, the VoIP packet is not transmitted to the region which is previously allocated and the VoIP packet is transmitted to a region which is newly allocated.
  • a method of persistently allocating a resource is called a persistent resource allocation method.
  • FIGs . 1 and 2 are views showing examples of a method of, at a base station, periodically allocating a resource to a mobile station for a VoIP service.
  • FIG. 1 shows an example of a case where the length of a frame is 5 ms in consideration of the
  • the VoIP service and the period of the frame which is allocated to the mobile station in order to transmit the VoIP packet is set to four frames.
  • the period of the frame which is allocated to the mobile station in order to transmit the VoIP packet varies according to the characteristics of the service.
  • the period of the frame which is allocated in order to transmit the VoIP packet may vary according to parameters such as the system characteristics (e.g., the system characteristics according to the length of the frame) and the status of the VoIP service (e.g., the talk-spurt period or the silence period) .
  • the base station informs the mobile station of the information on the allocated region for transmitting the VoIP packet via an UL-MAP at Frame 0 which is an initial frame, and allocates only a region for transmitting the VoIP packet without informing the mobile station of the information on the allocated region via the UL-MAP at Frame 4 and Frame 8 corresponding to next periods .
  • the period of the frame allocated for transmitting the VoIP packet is four frames (that is, 20 ms) . That is, the mobile station may store the information on the allocated region included in the UL-MAP received at Frame 0 and transmit the VoIP packet via the region at Frames 4 and 8 corresponding to the allocation periods even when the UL-MAP is not received.
  • the base station may allocate a region Pl for transmitting a VoIP packet of a specific mobile station at Frame 0 and transmit information on the allocated region via a UL-MAP.
  • the base station allocates a resource P2 for other mobile stations to a region Pl, which is allocated for the VoIP packet at Frame 0, and allocates a resource for the mobile station, which transmits the VoIP packet at Frame 0 , to another region Pl .
  • the mobile station, which transmits the VoIP packet at Frame 0 may check that the resource is allocated, to the region different from the region, which is initially allocated, at Frame 4, transmit the VoIP packet to the region Pl which is newly allocated instead of the region P2 which is initially allocated, and update parameters related thereto.
  • a new resource is allocated to the region Pl for the mobile station at Frame 4, it may be determined that the region which is previously allocated is allocated for the transmission of another packet and the VoIP packet may not be transmitted to the region which is previously allocated.
  • a method (group resource allocation method) of configuring mobile stations having the same attribute to a group and allocating a small number of resources to the mobile stations belonging to the group may be used .
  • FIG. 3 is a view showing an example of a medium access control protocol data unit (MAC PDU) defined in a wireless MAN mobile communication system based on the IEEE 802.16 system, which is generally used.
  • MAC PDU medium access control protocol data unit
  • protocols of the systems such as LAN, wireless LAN, 3GPP/3GPP2, and
  • the MAC header may include MAC addresses or link addresses of nodes for delivering data between the nodes of the link layer and include a header error check and link layer control information.
  • the MAC PDU 300 is started by a MAC header 301 having a predetermined length.
  • the generic MAC header 301 may be located in front of a payload 302 of the MAC PDU as shown in FIG. 3. If the header 301 is present, the payload 302 may be constituted by a subheader, a MAC SDU and a fragment . The length of the payload information may be changed so as to represent a variable byte. Accordingly, a MAC sub layer may transmit various traffic types of an upper layer without recognizing the format of a message or a bit pattern.
  • the MAC PDU 300 may include a cyclic redundancy check (CRC) 303.
  • CRC cyclic redundancy check
  • FIG. 4 is a view showing an example of the MAC header used in the wireless MAN mobile communication system based on the IEEE 802.16 system which is generally used.
  • the generic MAC header and six subheaders may be used in the MAC PDU.
  • the PDU-based subheaders are inserted next to the generic MAC header.
  • the fields included in the generic MAC header will be described in detail.
  • a HT field indicates a header type and indicates whether the MAC PDU is the generic MAC header including the payload next to the header or a signaling header for controlling a band request.
  • An EC field indicates encryption control and indicates whether the payload is encrypted.
  • a Type field indicates whether or not the subheader located next to the header is present or the type of the subheader.
  • An ESF field indicates whether or not an extended subheader located next to the header is present.
  • a CI field indicates whether or not the CRC is located next to the payload.
  • An EKS field indicates an encryption key sequence number used for encryption if the payload is encrypted.
  • a LEN field indicates the length of the MAC PDU.
  • a connection identifier (CID) indicates the connection identifier for delivering the MAC PDU.
  • connection is used as the identifier of the MAC layer for delivering data and a message between the base station and the mobile station, and the CID performs a function for identifying a specific mobile station or a specific service between the base station and the mobile station.
  • a numeral in parentheses located next to each of the fields indicates the bit number of each of the fields.
  • the base station may fixedly and persistently allocate the resource to one VoIP connection due to the VoIP traffic characteristics.
  • the VoIP packets which are periodically transmitted to the region allocated initially are packets for one VoIP connection and may be transmitted in a state in which all or a portion of the information included in the fields of the header structure shown in FIG. 4 has the same MAC header.
  • the repetitive transmission of the header having the same information as the header included in the packet which is previously transmitted or the header having partially overlapped information increases the header overhead and thus is not efficient in view of the resource operation.
  • An object of the present invention devised to solve the problem lies on a method of transmitting a packet including a compressed header by omitting a header including the same information as a header of a packet which is previously transmitted or omitting information overlapping with the header of the packet which is previously transmitted, such that header overhead is reduced when transmitting the packet.
  • Another object of the present invention devised to solve the problem lies on a detailed method of compressing or omitting the header when transmitting a VoIP packet, in which is further efficient in a method of transmitting a VoIP packet is significantly influenced by the header overhead .
  • a further object of the present invention devised to solve the problem lies on a method of coping with the case where the header should be updated in a base station or a mobile station in a specific situation even when header compression or omission is supported or the case where the transmission of a packet fails.
  • the object of the present invention can be achieved by providing a method of transmitting a packet, the method including: transmitting a first packet including a first header; and transmitting a second packet after the first packet is transmitted, the transmitting of the second packet is performed as, if a second header of the second packet includes the same information as information included in the first header, transmitting the second packet in a state of omitting the second header; or transmitting the second packet in a state of compressing the second header by omitting the same information of the second header as the information included in the first header. Accordingly, it is possible to reduce header overhead.
  • transmission packets including the first packet and the second packet may be the VoIP packets but are not limited thereto.
  • resources are allocated to the VoIP packets by a persistent resource allocation method or a group resource allocation method.
  • the first header may include an indicator (e.g., a next header indicator (NHI)) indicating whether or not the next header is omitted, or whether or not the header is compressed.
  • an indicator e.g., a next header indicator (NHI)
  • a detailed method for solving the header overhead by the header omission or the header compression and updating the header in a specific situation is provided.
  • the method may further include transmitting a header update request message, receiving a header update response message for the header update request message, and transmitting the updated header, if the update of header information of a subsequent packet next to the specific packet is required after a specific packet is transmitted.
  • the updated header information may be transmitted to the same region as the subsequent packet or a region different from the subsequent packet.
  • the method may further include transmitting a third packet including an updated third header after the header update is informed, or the header information which requires the update may be included in the header update request message.
  • the method may further include transmitting a channel quality indicator channel (CQICH) codeword which is previously allocated for the update of the header, and transmitting a third packet including a third header including header information which requires the update, if the update of header information of the subsequent packet subsequent to the specific packet is required after a specific packet is transmitted.
  • CQICH channel quality indicator channel
  • the method may further include transmitting a MAP information element (MAP IE) for informing the event, and performing any one of the update of the header information of the subsequent packet, the header omission or the header compression (e.g., uplink/downlink MAC header optimization IE) , if an event corresponding to any one of the update of the header information of the subsequent packet subsequent to the specific packet, header omission or header compression occurred a specific packet is transmitted.
  • MAP IE MAP information element
  • the header omission or the header compression e.g., uplink/downlink MAC header optimization IE
  • the method may further include retransmitting the second packet without omitting or compressing the second header if a NACK is received from a receiver with respect to the transmission of the second packet by a predetermined number of times.
  • the method may further include, at a mobile station, negotiating with a base station whether at least one of a header omission function and a header compression function is supported, and, at the mobile station, negotiating with the base station whether at least one of the header omission function and the header compression function is activated, before the above-described steps.
  • the second header may include a fixed part and a variable part, and the variable part may include information which varies according to a type field of the second header.
  • the variable part may include information which requires the update of the header when the second packet is transmitted.
  • the information which is omitted as the same information of the second header as the information included in the first header may include at least one of a connection ID (CID) and the length of the packet .
  • CID connection ID
  • a method of transmitting an uplink packet of a mobile station including: (a) receiving first indication information indicating header omission or header compression from a base station if a header omission event or a header compression event is generated in the mobile station or the base station; and (b) omitting or compressing a second header of a second packet subsequent to the reception of the first indication information according to the first indication information and transmitting the second packet to the base station.
  • the "header omission event” indicates the case where a packet including the same header as the header of a packet which is previously transmitted needs to be transmitted and the "header compression event” indicates the case where a header including the same information included in the header of a packet which is previously transmitted needs to be transmitted. Accordingly, the omission or the compression of the second header is performed with respect to information overlapping with a first header of a first packet which is transmitted before the second packet is transmitted.
  • the mobile station provides the header omission function and/or the header compression function. That is, in the present embodiment, a detailed method of exchanging information between the base station and the mobile station in order to reduce header overhead by the header omission or the header compression is provided.
  • the method may further include, if the header update event is generated in the base station or the mobile station, (c) receiving second indication information indicating the header update from the base station, and (d) updating a third header of a third packet subsequent to the reception of the second indication information according to the second indication information and transmitting the third header to the base station. Accordingly, it is possible to properly cope with the case where the header information is changed.
  • the method may further include, if the header omission event, the header compression event or the header update event are generated in the mobile station in the step (a) or (c) , reporting the generation of the event in the mobile station to the base station before the step ( a ) or ( c ) .
  • information indicating the header omission or the header compression and information indicating the header update may be received using at least one of a MAP information element (IE), a generic MAC header, a MAC signaling header, an extended subheader and a MAC management message.
  • IE MAP information element
  • IE MAP information element
  • IE generic MAC header
  • MAC signaling header an extended subheader
  • CQICH specific channel quality indicator channel
  • the MAP IE may includes information indicating whether or not the header of the second packet or the third packet transmitted just after the MAP IE is received is omitted or compressed, and information indicating whether or not a header format of a fourth packet next to the second packet or the third packet is equal to that of the second packet or the third packet.
  • the MAP EI may represent whether or not the header of the second packet or the third packet transmitted just after the MAP EI is received is omitted, compressed or updated (e.g., the uplink/downlink MAC header optimization IE) .
  • the method including: (a) omitting or compressing a second header of a second packet subsequent to the generation of a header omission event or a header compression event and transmitting the second packet, if the header omission event or the header compression event is generated in the base station or a mobile station, wherein the omission or the compression of the second header is performed with respect to information overlapping with a first header of a first packet which is transmitted before the second packet is transmitted.
  • the method may further include (b) , if a header update event is generated in the base station or the mobile station, updating a third header of a third packet subsequent to the generation of the header update event and transmitting the third packet to the mobile station.
  • the method may further include, if the header omission event, the header compression event or the header update event is generated in the mobile station in the step (a) or (b) , at the base station, receiving information on the generation of the event from the mobile station.
  • the information on the generation of the event may be received using at least one of an MAP information element
  • IE a generic MAC header, a MAC signaling header, an extended subheader, a specific channel quality indicator channel (CQICH) codeword and a MAC management message.
  • CQICH channel quality indicator channel
  • the MAP IE may include information indicating whether or not the header of the second packet or the third packet transmitted just after the MAP IE is received is omitted or compressed; and information indicating whether or not a header format of a fourth packet next to the second packet or the third packet is equal to that of the second packet or the third packet.
  • the MAP IE may represent whether or not the header of the second packet or the third packet transmitted just after the MAP IE is received is omitted, compressed or updated.
  • the packet transmitting method is further efficient in a VoIP packet transmitting method which is significantly influenced by the header overhead.
  • a detailed method of exchanging information between a base station and a mobile station is provided such that the header overhead is efficiently reduced.
  • FIGs . 1 and 2 are views showing examples of a method of, at a base station, periodically allocating a resource to a mobile station for a VoIP service.
  • FIG. 3 is a view showing an example of a medium access control protocol data unit (MAC PDU) defined in a wireless MAN mobile communication system based on the IEEE 802.16 system which is generally used.
  • FIG. 4 is a view showing an example of a MAC header used in the wireless MAN mobile communication system based on the IEEE 802.16 system which is generally used.
  • MAC PDU medium access control protocol data unit
  • FIG. 5 is a view showing an example of a generic MAC header for supporting a method of transmitting a packet in a state of omitting a MAC header, according to an embodiment of the present invention.
  • FIG. 6 is a view showing a method of transmitting a packet in a state of omitting a MAC header, according to an embodiment of the present invention.
  • FIG. 7 is a view showing a method of transmitting a packet in a state of omitting a MAC header, according to another embodiment of the present invention.
  • FIG. 8 is a view showing a method of transmitting a packet in a state of omitting a MAC header, according to another embodiment of the present invention.
  • FIG. 9 is a view showing a method of transmitting a retransmission packet including a header when the reception of a packet fails, according to an embodiment of the present invention.
  • FIGs. 10 and 11 are views showing a method of transmitting a retransmission packet including a header when the reception of a packet fails by a predetermined number of times, according to an embodiment of the present invention.
  • FIG. 12 is a view showing a method of transmitting a next packet including a generic header when a next packet transmission period is reached while a NACK is received due to the failure of the packet reception, according to another embodiment of the present invention.
  • FIG. 13 is a view showing an example of a MAC signaling header which may be used for updating the header, according to an embodiment of the present invention.
  • FIG. 14 is a view showing a method of omitting a header using an MAP IE when a downlink packet is transmitted, according to an embodiment of the present invention.
  • FIG. 15 is a view showing a method of omitting and updating a downlink header using an MAP IE, according to another embodiment of the present invention.
  • FIG. 16 is a view showing a method of omitting and updating a downlink header using an MAP IE, according to another embodiment of the present invention.
  • FIG. 17 is a view showing a method of omitting and updating a downlink header using a specific CQICH codword, according to another embodiment of the present invention.
  • FIG. 18 is a view showing a method of omitting a header using an UL_MAP IE when an uplink packet is transmitted, according to an embodiment of the present invention.
  • FIG. 19 is a view showing a method of omitting a header using an UL_MAP IE when an uplink packet is transmitted, according to another embodiment of the present invention.
  • FIG. 20 is a view showing a method of omitting a header using a specific CQICH codeword when an uplink packet is transmitted, according to another embodiment of the present invention.
  • FIG. 21 is a view showing a method of transmitting an uplink packet in a state in which a header is omitted, by- informing whether or not the header is updated using an UL_MAP IE, according to another embodiment of the present invention.
  • FIG. 22 is a view showing a method of transmitting an uplink packet in a state of omitting a header, by informing whether or not the header is updated using a header update request message, according to another embodiment of the present invention.
  • FIG. 23 is a view showing a method of transmitting an uplink packet in a state of omitting a header, by informing whether or not the header is updated using a specific CQICH codeword, according to another embodiment of the present invention.
  • FIG. 24 is a view showing an example of a compressed MAC header according to an embodiment of the present invention.
  • FIG. 25 is a view showing examples of fields which may be included in a variable part of a compressed MAC header according to an embodiment of the present invention.
  • FIG. 26 is a view showing an example of a method of transmitting a VoIP packet using a compressed header according to an embodiment of the present invention.
  • FIG. 27 is a view showing a method of transmitting a packet using a compressed header according to another embodiment of the present invention.
  • FIG. 28 is a view showing a method of transmitting a packet using a compressed header according to another embodiment of the present invention.
  • FIG. 29 is a view showing a method of transmitting a packet using a compressed header according to another embodiment of the present invention.
  • FIG. 30 is a view showing an embodiment of deciding a time point when a header is omitted by a system information message (e.g., DCD, UCD).
  • a system information message e.g., DCD, UCD
  • FIG. 31 is a view showing an embodiment of deciding a time point when a header is omitted when a service is generated.
  • FIG. 32 is a view showing an embodiment of adjusting downlink traffic using map information elements suggested in the present invention.
  • FIG. 33 is a view showing an embodiment of adjusting downlink traffic using map information elements suggested in the present invention.
  • a method of transmitting a packet including a compressed header by omitting a header including the same information as a header of a packet which is previously transmitted or omitting information overlapping with the header of the packet which is previously transmitted, such that header overhead is reduced when transmitting the packet.
  • an indicator indicating whether or not the MAC header is omitted from a MAC message or a compressed MAC header is used may be included.
  • FIG. 5 is a view showing an example of a generic MAC header for supporting a method of transmitting a packet in a state of omitting a MAC header, according to an embodiment of the present invention.
  • one reserved bit located next to the EKS field of the generic MAC header shown in FIG. 4 may be used as a next header indicator (NHI) bit.
  • the NHI may indicate which MAC header is attached to a next MAC PDU with respect to a service corresponding to a current CID.
  • the same MAC header as the existing packet is located if the NHI bit is set to 0 and the MAC header is omitted with respect to the next MAC header if the NHI bit is set to 1.
  • FIG. 6 is a view showing a method of transmitting a packet in a state of omitting a MAC header, according to an embodiment of the present invention.
  • a mobile station negotiates with a base station for a basic service capability in a process of registering the mobile station in the base station (e.g., an SBC-REQ/RSP message exchange step) , it may be determined whether the mobile station supports header omission.
  • a service is generated
  • a DSA-REQ/RSP message exchange step e.g., a DSA-REQ/RSP message exchange step
  • a parameter related to the service e.g., a DSC-
  • a header omission operation may be activated or inactivated.
  • header omission support information indicating whether or not the mobile station supports the header omission. It is assumed that, if this parameter is 1, the mobile station supports the head omission function and, if this parameter is 0, the mobile station does not support the head omission function.
  • header omission operation information indicating whether or not the header omission operation is activated between the base station and the mobile station. It is assumed that, if this parameter is 1, the header omission operation is activated and, if this parameter is 0, the header omission operation is inactivated.
  • the header omission operation 1
  • the mobile station transmits a VoIP packet including a generic MAC header to an allocated region at a current frame (S603) .
  • the mobile station transmits the NHI of the generic MAC header, which is set to 1 as described with reference to FIG. 5, and informs the base station that the packet is transmitted in a state of omitting the header at a frame corresponding to a next period.
  • the mobile station may transmit the VoIP packet in a state of omitting the header at the next periods (2 P ) (S604 to S605) .
  • information which should be changed or updated e.g., EKS, LEN or the like
  • information which should be changed or updated e.g., EKS, LEN or the like
  • a method of, at the mobile station, informing the base station that the header information should be updated is provided.
  • the mobile station transmits a header update request message including a target CID to be changed to the base station (S607) .
  • the base station may transmit a header update response message to the mobile station in response thereto (S608) .
  • the mobile station may transmit the VoIP packet including the generic MAC header at a frame corresponding to a next VoIP transmission period (S609) .
  • the packet may be transmitted in a state of omitting the header again at a frame corresponding to a next period (S610) .
  • the NHI of the header of the packet transmitted in the step S609 is set to 1.
  • FIG. 7 is a view showing a method of transmitting a packet in a state of omitting a MAC header, according to another embodiment of the present invention.
  • FIG. 7 The embodiment of the present invention shown in FIG. 7 is equal to the embodiment of FIG. 6 except for the process which is performed when the header information is updated or changed. Thus, only a step S706 related to the update or the change of the header information will be described in detail.
  • the mobile station may- transmit a CQICH codeword, which is previously allocated for changing the header information of the mobile station, via a fast feed-back channel, and inform the base station of the change of the header (S707) .
  • a codeword which is previously specified for changing the header information between the mobile station and the base station may be used as the CQICH codeword.
  • the base station which receives the specific CQICH codeword recognizes that the header needs to be updated and transmits a response message to the mobile station in a step S708.
  • This response message may be transmitted in the format of, but not limited to, an UL_MAP IE.
  • the mobile station may transmit the VoIP packet including the generic MAC header at a frame corresponding to a next VoIP transmission period (S709) .
  • the packet may be transmitted in a state of omitting the header again at a frame corresponding to a next period (S710) .
  • the NHI of the header of the packet transmitted in the step S709 is set to 1.
  • FIG. 8 is a view showing a method of transmitting a packet in a state of omitting a MAC header, according to another embodiment of the present invention.
  • the mobile station transmits the header update request message including the header information which needs to be updated, such that the header is not updated by additionally transmitting the generic MAC header.
  • FIG. 8 is equal to the embodiment of FIG. 6 except for the process which is performed when the header information is updated or changed.
  • a step S806 related to the update or the change of the header information will be described in detail.
  • the mobile station may transmit a header update request message to the base station (S807) .
  • the mobile station requests the header update to the base station, information to be updated is included in the header update request message.
  • the header update request message including the header information to be updated is transmitted, as described above, it is advantageous that the packet transmitted just after the header update request message is transmitted may be transmitted in a state of omitting the header.
  • the base station may receive the header update request message, update the information and transmit a header update response message to the mobile station (S808) . At this time, the base station may transmit the header update response message including the information which is updated by the base station.
  • the mobile station may transmit the VoIP packet in a state of omitting the header at a frame corresponding to a next VoIP transmission period (S809) .
  • the packet can be transmitted in a state of omitting the header including the same information as the header of the packet which is previously transmitted, and the packet can be transmitted in a state of including an indicator indicating whether or not the header is omitted in a next packet .
  • the method of, at the mobile station, informing the base station that the header should be updated using the header update request message or the CQICH codeword if the header needs to be updated is suggested.
  • an example of the header update request message which may be used for informing the base station that the header should be updated by the mobile station is as follows.
  • 2 may include or may not include the changed header information, depending on whether or not the changed header information is included in the header update request message.
  • a retransmission packet including the header is transmitted so as to increase a reception probability, which will now be described in detail.
  • FIG. 9 is a view showing a method of transmitting a retransmission packet including a header when the reception of a packet fails, according to an embodiment of the present invention.
  • FIG. 9 shows a detailed example of the method of transmitting the retransmission packet including the header when the reception of the packet fails by a predetermined number of times, that is, the method of transmitting the retransmission packet including the header when the reception of the packet fails one time.
  • a packet error may occur in a receiver.
  • the receiver may transmit a NACK to a transmitter in a step S902.
  • the transmitter retransmits the packet including the header like the initial transmission (S903) .
  • the reception probability can be increased.
  • the mobile station may define a NACK count in order to decide a time point, when the generic MAC header is transmitted, according to the number of NACKs which are continuously received. That is, when the initial VoIP packet is transmitted, the NACK count value is set to an initial value and the NACK count is decreased one by one whenever the mobile station receives the NACK. When the NACK count value becomes 0, the mobile station can transmit the retransmission packet including the generic header in order to increase the reception probability.
  • FIGs. 10 and 11 are views showing examples of a method of transmitting a retransmission packet including a header when the reception of a packet fails by a predetermined number of times, according to an embodiment of the present invention.
  • FIGs. 10 and 11 show examples which are more generalized than FIG. 9, that is, examples of the method of maintaining the header omission until the reception of the packet fails by a predetermined number of times corresponding to the NACK count value and transmitting a retransmission packet including the header when the reception of the packet fails by the predetermined number of times corresponding to the NACK count value.
  • FIGs. 10 and 11 show the examples of the method of transmitting the retransmission packet including the header when the mobile station continuously receives the NACK two times.
  • a step SlOOl it is assumed that the NACK count value is set to 2 and the reception of the packet fails when the mobile station transmits a first VoIP packet in a state of omitting the header.
  • the base station may transmit a NACK in order to inform the mobile station that the reception of the packet fails (S1002) .
  • the mobile station which receives the NACK decreases the NACK count value by 1 and checks whether the NACK count value is 0. In the present example, if the NACK is received one time, the NACK count value is not 0 and thus the mobile station transmits the first VoIP packet without the header again in a step S1003.
  • the mobile station may transmit a second VoIP packet without the header at a frame corresponding to a next period (S1005) .
  • FIG. 11 shows an example in which the NACK is received two times with respect to the transmission of the packet without the header (S1102 and S1104) and the NACK count value is 0. If the NACK count value is 0, the retransmission packet may be transmitted in a state of including the header therein in order to increase the reception probability (S1105) .
  • the next packet may be transmitted in a state of including the generic header therein so as to increase the reception probability.
  • FIG. 12 is a view showing a method of transmitting a next packet including a generic header when a next packet transmission period is reached while a NACK is received due to the failure of the packet reception, according to another embodiment of the present invention.
  • the base station may transmit a NACK to the mobile station (S1202) .
  • the mobile station transmits a first packet indicating that the header is omitted (S1203) .
  • FIG. 12 shows the case where the reception of the first VoIP packet which is retransmitted also fails.
  • a second VoIP packet may be transmitted without omitting the header of the next packet so as to increase the reception probability (S1205) .
  • the present invention is limited to the uplink packet transmission and the description of the above- described embodiments may be directly or indirectly used in the downlink packet transmission by the same principle.
  • a method of informing a counterpart of a header update state is described in the above-described embodiments, the present invention is limited to the uplink packet transmission and the description of the above- described embodiments may be directly or indirectly used in the downlink packet transmission by the same principle.
  • a header e.g., a signaling header, a subheader, an extended header or the like
  • a MAC management message like the above- described embodiments in order to update the header
  • FIG. 13 is a view showing an example of a MAC signaling header which may be used for informing the header update, according to an embodiment of the present invention.
  • the type of the header shown in FIG. 13 includes an additional 4-bit type field (a "Feedback Type" field shown in FIG. 13) as a feedback header.
  • a CID inclusion indication (CII) field indicates whether or not the CID is included. If the CII is 1, it is indicated that the CID is included and, if the CII is 0, it is indicated that the CID is not included.
  • the "Feedback Type" field is specified to ObIIlO so as to indicate that the feedback header is used for updating the header.
  • Table 3 shows an example of a list of extended subheaders used for the downlink (DL) .
  • the index described in "description" of Table 3 indicates the index of the IEEE 802.16e standard document.
  • the extended subheader for informing the downlink header update is added to the ES type 6 of “Description of extended subheaders type (DL) " of the IEEE 802.16e standard document. That is, according to the present embodiment, the downlink header update may be informed using the extended subheader corresponding to the ES type 6. It is apparent to those skilled in the art that the extended subheader which can be used for the downlink header update may be added as any type of the reserved ES type 7 to 27 as well as the ES type 6 in Table 3.
  • Table 4 shows an example of a list of the extended subheaders used for the uplink. Table 4
  • the index described in "description" of Table 4 also indicates the index of the IEEE 802.16e standard document.
  • the extended subheader for informing the uplink header update is added to the ES type 5 of "Description of extended subheaders type (UL) " of the IEEE 802.16e standard document. That is, according to the present embodiment, the uplink header update may be informed using the extended subheader corresponding to the ES type 5.
  • the extended subheader which can be used for the uplink header update may be added as any type of the reserved ES type 6 to 27 as well as the ES type 5 in Table 4.
  • An example of the format of the extended subheader for the header update may be expressed as follows in association with Table 3 and Table 4. Table 5
  • the above-described embodiments relate to the method of changing the generic MAC header and informing whether or not the header is updated.
  • the base station may inform the mobile station whether or not the header is omitted or instruct the omission of the header via the DL/UL-MAP IE.
  • Table 6 shows an example of the extended DIUC code which is available when the base station informs the mobile station whether or not the header is omitted with respect to the downlink VoIP service according to an embodiment of the present invention.
  • Table 6 shows an example in which the extended DIUC 05 is defined for the downlink MAC header omission (VoIP_DL_MAC_HO (header omission) _IE) for the VoIP service.
  • VoIP_DL_MAC_HO_IE may be defined in the extended DIUC (e.g., 06, 09-OA, OD-OE) represented by "reserved”.
  • the extended DIUC is specified in order to define VoIP_DL_MAC_HO_IE in the above-described example, it may be allocated in the basic DIUC or the extended DIUC 2.
  • the mobile station may determine whether or not the header is omitted with respect to the VoIP packet transmission when the extended DIUC is 05.
  • VoIP_DL_MAC_HO_IE of Table 7 it is indicated whether or not the header of the packet which is currently transmitted is omitted or whether or not the header is omitted for the update using the HT field. In addition, it is indicated whether or not the header of a next frame will be omitted using the HM field.
  • FIG. 14 is a view showing a method of omitting a header using an MAP IE when a downlink packet is transmitted, according to an embodiment of the present invention.
  • FIG. 14 shows an example in which the base station generates a header omission event.
  • the base station If the base station generates the header omission event (S1402) while the base station transmits a VoIP packet using a generic MAC header (GM) (S1401) , the VoIP packet without the MAC header may be transmitted (S1403) .
  • GM generic MAC header
  • the base station may transmit VoIP_DL__MAC_HO
  • VoIP_DL_MAC_HO IE in which a HT is set to ObI, to the mobile station at the same frame in order to inform the mobile station of the header omission, and may transmit VoIP_DL_MAC_HO IE, in which a HM is set to ObO, when the current header type is maintained even in the next frame .
  • the mobile station which receives VoIP_DL_MAC_HO IE determines that the header is not present in the current VoIP packet, using the HT which is set to ObI. It is determined that the same header as the current frame is used with respect to the VoIP packet transmitted at a next frame, using the HM which is set to ObO. Thereafter, the base station transmits the VoIP packet in a next period in a state of omitting the header (S1404) .
  • FIG. 15 is a view showing a method of omitting and updating a downlink header using an MAP IE, according to another embodiment of the present invention.
  • FIG. 15 shows another example in which the base station generates a header update event.
  • the HM of the VoIP_DL_MAC_HO IE transmitted in the step S1503 is set to ObI in order to indicate that the header is omitted at a next frame unlike the packet which is currently transmitted.
  • the mobile station recognizes that the header is not omitted at the current frame for the header update, using the HT of the received VoIP_DL_MAC_HO IE which is set to ObO and recognizes that the header type of the packet transmitted at the current frame is not maintained in the header of the packet transmitted at the next frame, that is, the header is omitted, using the HM of the received VoIP_DL_MAC_HO IE which is set to ObI. Thereafter, the base station transmits the VoIP packet without the header to the mobile station at a frame corresponding to a next period (S1504) .
  • FIG. 16 is a view showing a method of omitting and updating a downlink header using an MAP IE, according to another embodiment of the present invention.
  • FIG. 16 shows another example in which the mobile station generates a header update event.
  • the mobile station may inform the base station that the header update event is generated by a header update request message (S1603) . That is, in the present embodiment using the MAP IE, if the header update event is generated by the mobile station instead of the base station, an additional process of enabling the mobile station to inform the base station that the header update event is generated is required. Then, the base station may- transmit the MAP IE indicating the header update.
  • the base station transmits a header update response message to the mobile station in response to the header update request message of the mobile station (S1604) and transmits the VoIP packet including the generic MAC header therein (S1605) .
  • the HT is set to ObI in order to represent that the generic MAC header is included and the HM is set to ObI in order to represent that the next VoIP packet without the header is transmitted because the header update is completed.
  • the mobile station which receives the VoIP_DL_MAC_HO IE recognizes that the current VoIP packet includes the header and the next VoIP packet does not include the header, and receives the VoIP packet without the header in a step S1606.
  • FIG. 17 is a view showing a method of omitting and updating a downlink header using a specific CQICH codword, according to another embodiment of the present invention.
  • FIG. 17 shows a method of informing the base station whether or not the header update event is generated using a specific CQICH codeword when the mobile station generates a header update event, instead of the method of transmitting the header update request message shown in FIG. 16. If a header should be updated (S1702) while the mobile station receives a packet without a MAC header
  • the specific CQICH codeword is transmitted to the base station such that the base station is informed that the header update event is generated (S1703) .
  • the specific CQICH codeword used at that time a codeword which is previously decided between the base station and the mobile station in order to represent the generation of the header update event may be used.
  • the mobile station determines that the MAC header transmitted at a current frame is applied to only the current frame. Accordingly, the mobile station may transmit the VoIP packet without the header to the mobile station at a frame corresponding to a next period (S1705) .
  • Table 8 shows an example of an extended UIUC code which can be used for representing whether or not the header is omitted with respect to the uplink VoIP service.
  • Table 8 shows an example of defining "VoIP UL MAC header omission IE" such that the extended UIUC OB represents the uplink MAC header omission for the VoIP service.
  • the VoIP UL MAC header omission IE may be defined in the extended UIUC OC to OF represented by "reserved" .
  • the extended UIUC is specified in order to define the VoIP UL MAC header omission IE, the VoIP UL MAC header omission IE may be allocated in a basic UIUC or an extended UIUC 2.
  • the mobile station determines that OB of the extended UIUC includes the information element indicating whether or not the header is omitted with respect to the uplink VoIP packet transmission.
  • HT field indicates whether or not the header of the packet which is currently transmitted is omitted or whether or not the header is omitted for update and a HM field indicates whether or not the header of a next frame is omitted.
  • FIG. 18 is a view showing a method of omitting a header using an UL_MAP IE when an uplink packet is transmitted, according to an embodiment of the present invention.
  • the mobile station may transmit the
  • FIG. 19 is a view showing a method of omitting a header using an UL_MAP IE when an uplink packet is transmitted, according to another embodiment of the present invention.
  • FIG. 19 shows an example of informing the base station that a header omission event is generated by a header omission request message when the mobile station generates the header omission event. That is, when the header omission event is generated by the mobile station instead of the base station, a separate process of informing the base station that the header omission event is generated by the mobile station is required. Then, the base station may instruct the mobile station to omit the UL_MAP IE. That is, when the header omission event is generated
  • the mobile station transmits a header omission request message to the base station (S1903) .
  • the base station transmits a header omission response message to the mobile station in response to the header omission request message (S1904) .
  • the base station may transmit the VoIP_UL_MAC_HO IE, in which a HT is set to ObI and a HM is set to ObO, to the mobile station before the transmission of a next period (S1905) .
  • FIG. 20 is a view showing a method of omitting a header using a specific CQICH codeword when an uplink packet is transmitted, according to another embodiment of the present invention.
  • FIG. 20 shows a method of informing the base station whether or not the header update event is generated using a specific CQICH codeword when the mobile station generates a header update event, instead of the method of transmitting the header update request message like FIG. 19, and, at the base station, informing the mobile station whether or not the header is omitted using the UL_MAP IE.
  • the header omission event is generated (S2002) while the mobile station transmits a VoIP packet including a generic MAC header (S2001)
  • the specific CQICH codeword which is previously decided between the base station and the mobile station in order to represent the generation of the header update event is transmitted to the base station (S2003) .
  • the base station which receives the CQICH codeword can know that the mobile station omits the header in a next period. Accordingly, the base station may transmit a VoIP_UL_MAC__HO IE, in which a HT is set to ObI and a HM is set to ObO, to the mobile station before the transmission of a next period (S2004) .
  • FIG. 21 is a view showing a method of transmitting an uplink packet in a state in which a header is omitted, by informing whether or not the header is updated using an UL_MAP IE, according to another embodiment of the present invention.
  • FIG. 21 shows an example of informing the mobile station that a header update event is generated using the UL_MAP IE when the base station generates the header update event .
  • the base station transmits VoIP_UL_MAC_HO IE, in which a HT is set to ObI and a HM is set to ObI, to the mobile station (S2103) .
  • FIG. 22 is a view showing a method of transmitting an uplink packet in a state of omitting a header, by informing whether or not the header is updated using a header update request message, according to another embodiment of the present invention.
  • FIG. 22 shows a method of, at the mobile station, informing the base station whether or not the header update event is generated using a header update request message when the mobile station generates the header update event and, at the base station, informing the mobile station whether or not the header is updated and omitted using the UL_MAP IE.
  • the mobile station transmits a header update request message to the base station (S2203) .
  • the base station transmits a header update response message to the mobile station in response to the header update request message (S2204) . Thereafter, the base station transmits a VoIP_UL_MAC_HO IE, in which a HT is set to ObO and a HM is set to ObI, to the mobile station before the transmission of a next period (S2205) .
  • the mobile station which receives the VoIP_UL_MAC_HO
  • FIG. 23 is a view showing a method of transmitting an uplink packet in a state of omitting a header, by informing whether or not the header is updated using a specific CQICH codeword, according to another embodiment of the present invention.
  • FIG. 23 shows an example of informing the base station that the header update event is generated using the specific CQICH codeword when the mobile station generates the header update event and, at the base station, informing the mobile station whether or not the header is updated and omitted using a UL_MAP IE. That is, if the header update event is generated (S2302) while the mobile station transmits a VoIP packet without a MAC header (S2301) , in the present embodiment, the mobile station transmits the specific CQICH codeword, which is previously decided between the base station and the mobile station in order to indicate whether or not the header is updated, to the base station (S2303) .
  • the base station which receives the specific CQICH codeword knows that the mobile station will update the header in a next period. Then, the base station transmits a VoIP_UL_MAC_HO IE, in which a HT is set to ObO and a HM is set to ObI, to the mobile station before the transmission of the next period (S2304) .
  • the mobile station which receives the VoIP_UL_MAC_HO
  • the mobile station may transmit the VoIP packet without the header in the next period (S2306) .
  • a method of representing the header omission and update using the MAP IE may be equally applied to a method of transmitting a packet by the compression of a header according to an embodiment of the present invention, which will be described later.
  • a one reserved bit located next to the existing EKS is allocated as a NHI bit in the generic MAC header shown in FIG. 5. If the NHI is set to 0, the same MAC header as the existing header is located and, if the NHI is set to 1, the header is compressed unlike the above-described embodiment in which the header is omitted.
  • FIG. 24 is a view showing an example of a compressed MAC header according to an embodiment of the present invention.
  • the compressed MAC header may be divided into a fixed part and a variable part.
  • the fixed part may have a length of any one of 1 byte or 2 bytes .
  • the length of the variable part is decided according to a header type and may have a variable length of 0 to 4 bytes .
  • the lengths of the fixed part and the variable part may be changed .
  • a receiver which receives a MPDU may first read the fixed part and then read the variable part according to the header type.
  • the fields of the compressed header of FIG. 24 will be described as follows. -
  • a header update (HU) flag is a flag bit indicating whether a generic MAC header or a compressed MAC header is used in a next header. If this bit is set to 0, the next header may be transmitted as the same header as a current header. If the HU bit is set to 1, the receiver may be informed that the generic MAC header is transmitted at a next frame .
  • a header type field indicates the type of a current compressed MAC header.
  • the length of the MAC header and the contents of the variable part may be decided by the header type field.
  • a length (LEN) field indicates the length of the MPDU.
  • variable part or a variable header body field of which the contents may be changed according to the header type value and may selectively include at least one of the fields of the generic MAC header (e.g., a CI, an EKS, a type, a HCS, or the like) .
  • a transmitter may transmit header change information.
  • the fields which may be included in the variable part of the compressed MAC header according to the present embodiment will be described as follows.
  • FIG. 25 is a view showing examples of fields which may be included in a variable part of a compressed MAC header according to an embodiment of the present invention.
  • FIG. 25 shows examples in which the header type has 3 bits and eight variable parts may be represented according to the 3 -bit header type.
  • the number of examples of the variable parts which are applied according to the length of the header type may be changed and the fields configuring the examples may be changed according to the requirements of the system.
  • no field is included in the variable part if the header type is "ObOOO"
  • a HCS field is included in the variable part if the header type is "ObOOl”
  • a type field, an EC field and an ESF field are included in the variable part if the header type is "ObOlO” .
  • the type field, the EC field, the ESF field and the HCS field is included in the variable part if the header type is "ObOIl”
  • the ESF field, the CI field and the EKS field are included in the variable part if the header type is "ObIOO".
  • the ESF field, the CI Field, the EKS field and the HCS field are included in the variable part if the header type is "ObIOl", the type field, the EC field, the ESF field, the CI field and the EKS field are included in the variable part if the header type is "ObIlO", the type field, the EC field, the ESF field, the CI field and the EKS field are included in the variable part if the header type is "ObIlO", and the type field, the EC field, the ESF field, the CI field, the EKS field and the HCS field are included in the variable part if the header type is "Oblll".
  • FIG. 26 is a view showing an example of a method of transmitting a VoIP packet using a compressed header according to an embodiment of the present invention.
  • the mobile station transmits the VoIP packet using the generic MAC header in a step S2601.
  • the mobile station may set the NHI to 0 in a next packet in order to represent that the packet including the generic MAC header will be transmitted, and transmit the VoIP packet.
  • the mobile station transmits the packet using the generic MAC header at a frame corresponding to a next period (S2602) .
  • the mobile station may- set the NHI to 1 in a packet transmitted in a next period and transmit the packet, in order to represent that the packet will be transmitted using the compressed header.
  • the mobile station may transmit the VoIP packet using the compressed header at a frame corresponding to a next period (S2603) .
  • the mobile station may set the HU indicating whether or not the header is updated to 0 and transmit the packet, in order to transmit the VoIP packet using the compressed header even in the next period.
  • the mobile station may transmit the packet using the compressed header at a frame corresponding to a next period (S2604) .
  • the mobile station may set the HU field to 1 and transmit the packet, in order to transmit the packet including the generic MAC header without compressing the header at the frame corresponding to the next period.
  • the mobile station may transmit the packet using the generic MAC header at a frame corresponding to a next period (S2605) .
  • the mobile station may set the NHI field to 0 and transmit the packet, in order to transmit the packet including the generic MAC header at the frame corresponding to the next period.
  • FIG. 27 is a view showing a method of transmitting a packet using a compressed header according to another embodiment of the present invention.
  • a transmitter e.g., the mobile station (MS) transmits a VoIP packet using a generic MAC header.
  • the NHI may be set to 1, in order to the use the compressed header at a next frame (S2701) .
  • a receiver may not receive the packet.
  • the receiver may transmit a NACK to the transmitter in order to inform the transmitter of a packet reception error (S2702) .
  • the transmitter may retransmit the same packet to the receiver (S2703) .
  • the mobile station may transmit the VoIP packet using the compressed header in a next period (S2704) . If the mobile station uses the generic MAC header for updating the header while the VoIP packet is transmitted using the compressed header, the HU of the compressed header is set to 1 and the packet is transmitted (S2705) .
  • FIG. 28 is a view showing a method of transmitting a packet using a compressed header according to another embodiment of the present invention.
  • the transmitter (MS) transmits a VoIP packet using a generic MAC header.
  • the NHI may be set to 1 in order to use the compressed header (S2801) .
  • the receiver (BS) cannot receive the packet, the receiver transmits a NACK to the transmitter in order to inform the transmitter of a packet reception error (S2802) .
  • the transmitter which receives the NACK retransmits the same packet as the packet transmitted in the step S2801 to the receiver (S2803) . In the example of FIG. 28, even in the packet retransmission, a reception error occurs in the receiver. If the reception error occurs, the receiver transmits the NACK to the transmitter in order to inform the transmitter of the packet reception error (S2804) .
  • the mobile station transmits the packet using the generic MAC header in the packet transmission of a next period, without using the compressed header (S2805) . If the reception of the packet in which the NHI is set to 1 is successful, the transmitter may transmit the VoIP packet using the compressed header in a next period. In the example of FIG. 28, an example of setting the HU to 1 and transmitting the packet in order to use the generic MAC header at a next frame is shown (S2806) .
  • the receiver transmits the NACK to the transmitter (S2807) .
  • the transmitter which receives the NACK retransmits the same packet as the packet transmitted in the step S2805, that is, the VoIP packet using the compressed header (S2808) .
  • the receiver transmits the NACK to the transmitter in order to inform the transmitter of the packet reception error (S2809) .
  • the mobile station transmits the packet using the compressed header even in the packet transmission of a next period (S2810) .
  • FIG. 29 is a view showing a method of transmitting a packet using a compressed header according to another embodiment of the present invention.
  • the size of the packet transmitted by the mobile station is changed and the mobile station continuously transmits a VoIP packet using a compressed header.
  • the mobile station transmits the VoIP packet having a size A using the compressed header (S2901 and 2902) . If the size of the packet is changed to B, the mobile station transmits the VoIP packet using the compressed header of which the LEN value is changed (S2903) . If the size C of the packet and the EKS are changed, the EKS value is added to the variable part of the frame, and the packet of which the LEN value is changed is transmitted (S2904) .
  • the type and the header length may be decided according to the contents included in the header body.
  • a message e.g., a signaling header, a unicast (e.g., a MAC management message) /broadcast (e.g., an UL-MAP IE/DL- MAP IE) management message, or a CQICH codeword
  • a message e.g., a signaling header, a unicast (e.g., a MAC management message) /broadcast (e.g., an UL-MAP IE/DL- MAP IE) management message, or a CQICH codeword
  • the mobile station and the base station in order to decide a time point when the header is omitted or compressed, the mobile station and the base station exchange a predefined value before the packet transmission is started.
  • the base station may inform the mobile station of a time point when the header is omitted or compressed using a system information message (e.g., UCD, DCD, or the like) .
  • a system information message e.g., UCD, DCD, or the like
  • the base station and the mobile station may decide a time point when the header is omitted or compressed.
  • the mobile station and the base station may have a fixed value (global value) for omitting or compressing the header. That is, the system may fixedly set a count value for omitting the header.
  • the value exchanged between the mobile station and the base station using any one of the three methods is 1, after the service is started, the mobile station and the base station may transmit a VoIP packet using a generic MAC header and transmit the packet in a state of omitting or compressing the MAC header in the transmission of a next packet.
  • a method of, at the mobile station, acquiring a value for deciding a time point when the header is omitted will be described.
  • the methods of the following embodiments may be applied to a method of compressing the header.
  • FIG. 30 is a view showing an embodiment of deciding a time point when a header is omitted by a system information message (e.g., DCD, UCD or the like).
  • a system information message e.g., DCD, UCD or the like.
  • FIG. 30 shows a process of, at the base station, sending a downlink header omission (DHO) count and an uplink header omission (UHO) count to the mobile stations by a system information message.
  • DHO downlink header omission
  • UHO uplink header omission
  • the base station sends the header omission counts (e.g., the DHO count and the UHO count) to the mobile stations by the system information message (S3001) .
  • the system information message corresponds to the
  • DCD and the UCD of the 802.16d/e system may be included in the DCD in the 802.16d/e system and the UHO count may be included in the UCD.
  • the mobile station generates a VoIP service, checks that the UHO count value is 1 before a VoIP packet is transmitted, and transmits the VoIP packet using a generic MAC header (S3002) .
  • the UHO count value is decreased by 1 together with the packet transmission using the generic MAC header (S3003) . Thus, the UHO count value becomes 0.
  • the mobile station transmits the VoIP packet without the header
  • the mobile station sets an initial value of the UHO count value (that is, 1 in the present embodiment) (S3005) . Since the UHO value is 1 at a frame corresponding to a next transmission period, the mobile station transmits the VoIP packet including the generic MAC header (S3006) and decreases the UHO count value by 1 if the reception is successful (S3007) . If the mobile station receives the VoIP packet from the base station, since the DHO count value is set to 1, it is determined that the VoIP packet including the generic MAC header is received (S3008) . If the downlink VoIP packet is received, the mobile station decreases the DHO count value by 1 (S3009) . Thereafter, if a next VoIP packet is received from the base station, since the DHO count value is set to 0, it is determined that the VoIP packet without the header is received (S3010) .
  • FIG. 31 is a view showing an embodiment of deciding a time point when a header is omitted when a service is generated.
  • the mobile station and the base station may- exchange and decide the DHO count and the UHO count in order to generate a service or change QoS parameters related to the service (S3101) .
  • the initial values of the DHO and the UHO are set to 1.
  • a message for generating the service in a wideband wireless access system (IEEE 802.16 d/e system) is DSA-REQ/RSP and a message for changing the QoS parameters related to the service is a DSA-REQ/RSP.
  • the mobile station Since the UHO count value is set to 1 at the time of the initial transmission, the mobile station transmits the VoIP packet including the generic MAC header (S3102) . If the VoIP packet transmission is successful, the mobile station decreases the UHO count value by 1 (S3103) . Since the UHO count value is set to 0 in a next transmission period, the VoIP packet without the header is transmitted (S3104) .
  • the information elements may be constituted by different information elements according to the used headers (header omission, header compression or the generic
  • All information indicating which header will be used may be included using one map information element
  • MAP IE maps the map information elements representing whether or not the MAC header is omitted with respect to the downlink traffic.
  • the base station may transmit the downlink MAC header omission IE (DL_MAC Header Omission IE) shown in Table 10 to the mobile station in order to inform the mobile station whether or not the header is omitted with respect to the downlink traf f ic .
  • DL_MAC Header Omission IE downlink MAC header omission IE
  • Table 11 shows map information elements representing whether or not the MAC header is omitted with respect to the uplink traffic.
  • the base station may transmit the uplink MAC header omission IE (UL_MAC Header Omission IE) shown in Table 11 to the mobile station in order to inform the mobile station whether or not the header is omitted with respect to the uplink traf f ic .
  • UL_MAC Header Omission IE uplink MAC header omission IE
  • Table 12 shows map information elements representing whether or not the compressed MAC header is used with respect to the downlink traffic.
  • the base station may transmit the downlink MAC header compression IE (DL_MAC Header Compression IE) shown in Table 12 to the mobile station in order to inform the mobile station whether or not the compressed MAC header is used with respect to the downlink traffic.
  • DL_MAC Header Compression IE downlink MAC header compression IE
  • Table 13 shows map information elements representing whether or not the compressed MAC header is used with respect to the uplink traffic.
  • the base station may transmit the uplink MAC header compression IE (UL_MAC Header Compression IE) shown in Table 13 to the mobile station in order to inform the mobile station whether or not the compressed MAC header is used with respect to the uplink traffic.
  • UL_MAC Header Compression IE uplink MAC header compression IE
  • a header omission information element or a header compression information element may be used.
  • FIG. 32 is a view showing an embodiment of adjusting downlink traffic using map information elements suggested in the present invention.
  • the base station if the base station wants to omit the header (S3202) while a downlink VoIP packet is transmitted using a generic MAC header (S3201) , the base station transmits a DL_MAC_header Omission IE, in which a HT is set to ObI (header omission) and a HM is set to ObO
  • the base station transmits a downlink MAC header compression IE, in which a HT is set to ObI (header compression) and a HM is set to ObI (the header type is applied to only a current frame) , to the mobile station (S3207) .
  • a HT is set to ObI (header compression)
  • a HM is set to ObI (the header type is applied to only a current frame)
  • the base station When the base station wants to use the generic MAC header (S3210) while the packet without the header is transmitted (S3208 to S3209) , the base station transmits a downlink MAC header compression IE, in which a HT is set to ObO (the generic header is used) and a HM is set to ObI (the header type is applied to only a current frame) , to the mobile station (S3211) .
  • a HT is set to ObO
  • ObI the header type is applied to only a current frame
  • FIG. 33 is a view showing an embodiment of adjusting downlink traffic using map information elements suggested in the present invention.
  • FIG. 33 shows the case where a header omission/compression event is generated in the mobile station. If a header use event is generated in the base station, map information elements (UL_MAC_Header Omission IE/UL_MAC_Header Compression IE) are transmitted to the mobile station such that the mobile station may be informed of the header use event .
  • map information elements UL_MAC_Header Omission IE/UL_MAC_Header Compression IE
  • a header omission event is generated in the mobile station and the header is desired to be omitted (S3302) while the mobile station transmits an uplink VoIP packet using a generic MAC header (S3301)
  • the mobile station transmits a header omission request signal to the base station in order to inform the base station of the header omission (S3303) .
  • the mobile station may use various signals such as a MAC management message, a MAC header and a CQICH codeword, for the header omission request.
  • the base station may immediately respond to the header omission request (S3304) .
  • the base station may transmit a header omission map information element (UL_MAC_Header Omission IE) to the mobile station and respond to the request (S3305) .
  • the mobile station which receives the header omission map information element (UL_MAC_Header Omission IE) properly omits the header according to the set parameters and transmits the packet (S3306 to S3307) .
  • the mobile station transmits a header compression request signal to the base station (S3309) .
  • the mobile station may use various signals such as a MAC management message, a MAC header and a CQICH codeword, for the header compression request.
  • the base station immediately responds to the header compression request (S3310) .
  • the base station may transmit a header compression map information element (UL_MAC_Header Compression IE) to the mobile station and respond to the request (S3311) .
  • the mobile station which receives the header compression map information element (UL_MAC_Header Compression IE) properly compresses the header according to the set parameters and transmits the packet (S3312) .
  • information to be updated may be included in the request signal.
  • the mobile station wants to transmit a header compression request signal
  • compression header type information may be included in a header compression request signal.
  • Tables 14 and 15 show examples of defining information elements (IEs) in which the header omission and the compressed header can be used by one MAP IE.
  • IEs information elements
  • Table 14 shows a downlink MAC header optimization IE (DL_MAC header optimization IE) representing which MAC header is used with respect to downlink traffic.
  • DL_MAC header optimization IE downlink MAC header optimization IE
  • Table 15 shows an uplink MAC header optimization IE (UL_MAC header optimization IE) representing which MAC header is used with respect to uplink traffic.
  • UL_MAC header optimization IE uplink MAC header optimization IE
  • Information included in the map information elements suggested in the present invention may be included in a new map information element (DL/UL MAP IE) , in the existing map information elements, or in other map information elements which are newly defined according to the embodiments of the present invention.
  • HT and HM fields may be included in a persistent VoIP resource allocation map information element (e.g., a DL_Persistent allocation IE or an UL_Persistent allocation IE) so as to inform the mobile station whether or not the MAC header is present or the compression is performed.
  • a generic MAC header which is corrected according to one embodiment of the present invention in association with FIG. 5 may be used.
  • Such a generic MAC header is available in both the base station and the mobile station.
  • a MAC signaling header according to one embodiment of the present invention in association with FIG. 13 may be used.
  • Such a MAC signaling header is available in the mobile station when a specific event is generated in the mobile station.
  • An extended subheader according to one embodiment of the present invention in association with Tables 3 to 5 may be used. Such an extended subheader is available in the base station when a specific event is generated in the base station.
  • a MAC management message such as the header omission/compression/update request/response message of the above-described embodiments may be used.
  • This may be used in an embodiment in which the mobile station transmits a request message when the mobile station generates a specific event, and the base station transmits a response message in response thereto.
  • a specific CQICH codeword which is previously decided between the base station and the mobile station may be used for the header omission/compression/update.
  • the specific CQICH codeword may be used for transmitting the specific CQICH codeword and informing the base station of the specific CQICH codeword when an event such as header omission/compression/update is generated.
  • the MAP IE (e.g., UL-MAP IE or DL-MAP IE) may be used in association with Tables 10 to 15. This may be used as a response for a request message of the mobile station or may be used for informing the base station of an event when a specific event is generated in the mobile station or the base station. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
  • a packet including a compressed header is transmitted by omitting a header including the same information as a header of a packet which is previously transmitted or information overlapping with the header of the packet which is previously transmitted, it is possible to solve header overhead.
  • the packet transmitting method is further efficient in a VoIP packet transmitting method which is significantly influenced by the header overhead.
  • a detailed method of exchanging information between a base station and a mobile station is provided such that those skilled in the art readily embody the packet transmitting method according to the present invention.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Computer Security & Cryptography (AREA)
  • Multimedia (AREA)
  • Data Exchanges In Wide-Area Networks (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

L'invention concerne un procédé d'émission de paquet permettant de réduire la surcharge d'en-tête. Plus spécifiquement, l'invention concerne un procédé détaillé d'émission de paquet comprenant un en-tête compressé par omission d'un en-tête incluant la même information qu'un en-tête de paquet qui a été préalablement émis ou par omission d'informations se superposant avec l'en-tête du paquet qui a été préalablement émis.
PCT/KR2008/004364 2007-07-27 2008-07-25 Procédé d'émission de paquet permettant de réduire la surcharge d'en-tête WO2009017340A2 (fr)

Priority Applications (1)

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US12/670,769 US20100208655A1 (en) 2007-07-27 2008-07-25 Method of transmitting packet for reducing header overhead

Applications Claiming Priority (4)

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KR10-2007-0076069 2007-07-27
KR20070076069 2007-07-27
KR1020080006670A KR101377961B1 (ko) 2007-07-27 2008-01-22 헤더 오버헤드 감소를 위한 패킷 전송 방법
KR10-2008-0006670 2008-01-22

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WO2012110958A1 (fr) * 2011-02-14 2012-08-23 Telefonaktiebolaget L M Ericsson (Publ) Approche par rétro-compatibilité des champs d'une couche protocolaire
GB2503711A (en) * 2012-07-05 2014-01-08 Quixel Holdings Ltd Video data communication including sending new header information upon completion of transmission, and simultaneous encoding and transmission

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WO2012110958A1 (fr) * 2011-02-14 2012-08-23 Telefonaktiebolaget L M Ericsson (Publ) Approche par rétro-compatibilité des champs d'une couche protocolaire
US8750333B2 (en) 2011-02-14 2014-06-10 Telefonaktiebolaget Lm Ericsson (Publ) Backwards-compatible approach to fields of a protocol layer
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US9781450B2 (en) 2012-07-05 2017-10-03 Quixel Holdings Limited Simultaneous encoding and sending of a video data file

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