WO2011021866A2

WO2011021866A2 - Method and system for data transmission on an access link

Info

Publication number: WO2011021866A2
Application number: PCT/KR2010/005495
Authority: WO
Inventors: Anil Agiwal; Young-Bin Chang
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2009-08-21
Filing date: 2010-08-19
Publication date: 2011-02-24
Also published as: WO2011021866A3

Abstract

A method and system for data transmission on an access link is provided. The method includes receiving a media access control (MAC) packet data unit (PDU) from a base station (BS) using a relay link. The method also includes fragmenting the MAC PDU into two or more fragments by a relay station (RS) if available bandwidth in the RS is lesser than size of the received MAC PDU. Further the method includes adding a fragmented MAC PDU MAC header (FMMH) to each of the two or more fragments and transmitting each of the two or more fragments to a mobile station (MS) on the access link. The system includes a base station, a relay station, and a mobile station (MS).

Description

METHOD AND SYSTEM FOR DATA TRANSMISSION ON AN ACCESS LINK

The present disclosure relates generally to the field of wireless communication. More particularly, the present disclosure relates to a method and system for data transmission on an access link.

Typically, a wireless communication system communicates datathrough a wireless link between a base station and a mobile station. However, since the location of the base station is fixed, the wireless communication system has low flexibility and communication is ineffective when traffic distribution and call demands change. A fixed or a movable relay station, based on a multi hop relay scheme, is hence used between the base station and the mobile station to enhance data communication. The multi hop relay scheme includes transmitting a media access control (MAC) packet data unit (PDU) by the base station to the mobile station through the relay station. The wireless link between the base station and the relay station is referred to as a relay link and the wireless link between the relay station and the mobile station is referred to as an access link. Channel quality on the relay link is reliable compared to the access link and hence the base station sends a MAC PDU,for example thousand bytes, to the relay station through the relay link. However, the relay station is unable to fragment the MAC PDU and send the MAC PDU to the mobile station through the access link due to failure of encryption and decryption processes.

In the light of the foregoing discussion, there is a need for fragmenting the MAC PDU on the access link.

Embodiments of the present disclosure described herein provide a method and system for data transmission on an access link.

An example of a method for data transmission on an access link includes receiving a media access control (MAC) packet data unit (PDU) from a base station (BS) using a relay link. The method also includes fragmenting the MAC PDU into two or more fragments by a relay station (RS) if available bandwidth in the RS is lesser than size of the received MAC PDU. Further, the method includes adding a fragmented MAC PDU MAC header (FMMH) to each of the two or more fragments. Moreover, the method includes transmitting each of the two or more fragments to a mobile station (MS) on the access link.

Another example of a method for data transmission on an access link includes receiving a media access control (MAC) packet data unit (PDU) from a base station (BS) on a relay link. The method also includes fragmenting a payload in the received MAC PDU into two or more fragments by a relay station (RS) if required bandwidth in the RS is lesser than size of the received MAC PDU. The method further includes adding the payload specific extended headers unit to a first fragment of the two or more fragments. Further, the method includes adding a MAC PDU fragment extended header (MFEH) to each of the two or more fragments. Moreover, the method includes transmitting each of the two or more fragments along with a generic MAC header (GMH) to a mobile station (MS) on the access link.

Another example of a method for data transmission on an access link includes receiving a media access control (MAC) packet data from a base station (BS) on a relay link. The method also includes fragmenting a payload in the received MAC PDU into two or more fragments by a relay station (RS) if available bandwidth in the RS is lesser than size of the MAC PDU. The method further includesadding a security extended header (SEH) to each of the two or more fragments of the MAC PDU. Further, the method includes adding a payload specific extended headers unit to each of the two or more fragments. Moreover, the method includes transmitting each of the two or more fragments along with a generic MAC header (GMH) to a mobile station (MS) on the access link.

An example of a system for data transmission on an access link includes a base station (BS) that transmits a media access control (MAC) packet data unit (PDU) for a mobile station (MS) using a relay link. The system also includes a relay station (RS) that receives the MAC PDU to fragment the MAC PDU into two or more fragments if available bandwidth in the RS is lesser than size of the received MAC PDU, to add a fragmented MAC PDU MAC header (FMMH) to each of the two or more fragments, and to transmit each of the two or more fragments to the MS using the access link. Further the system includes the MS that receives the two or more fragments from the RS to assemble the two or more fragments to generate the MAC PDU if each of the two or more fragments are associated with the FMMH, and to decrypt the generated MAC PDU.

The present invention can provide method and system for fragmenting the MAC PDU on the access link.

The accompanying figure, similar reference numerals may refer to identical or functionally similar elements. These reference numerals are used in the detailed description to illustrate various embodiments and to explain various aspects and advantages of the present disclosure.

FIG. 1 is a block diagram of an environment, in accordance with which various embodiments can be implemented

FIG. 2 illustrates a fragmentation processon an access link, in accordance with one embodiment;

FIG. 3 illustrates format of a fragmented media access control packet data unit (MAC PDU)MAC header (FMMH) format, in accordance with one embodiment;

FIG. 4 is a flowchart illustrating a method for data transmission on an access link, in accordance with one embodiment;

FIG. 5 is a flowchart illustrating a method for receiving data at a mobile station (MS), in accordance with one embodiment;

FIG. 6 illustrates a fragmentation process on an access link, in accordance with another embodiment;

FIG. 7 illustrates format of a MAC PDU fragment extended header (MFEH) format, in accordance with another embodiment;

FIG. 8 is a flowchart illustrating a method for data transmission on an access link, in accordance with another embodiment;

FIG. 9 is a flowchart illustrating a method for receiving data at a mobile station (MS), in accordance with another embodiment;

FIG. 10 illustrates a fragmentation process on an access link, in accordance with yet another embodiment;

FIG. 11 illustrates format of a security extended header (SEH) format, in accordance with yet another embodiment;

FIG. 12 is a flowchart illustrating a method for data transmission on an access link, in accordance with yet another embodiment; and

FIG. 13 is a flowchart illustrating a method for receiving data at a mobile station (MS), in accordance with another embodiment.

Persons skilledin the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present disclosure.

It should be observed the method steps and system components have been represented by conventional symbols in the figure, showing only specific details which are relevant for an understanding of the present disclosure. Further, details may be readily apparent to person ordinarily skilled in the art may not have been disclosed. In the present disclosure, relational terms such as first and second, and the like, may be used to distinguish one entity from another entity, without necessarily implying any actual relationship or order between such entities.

FIG. 1 is a block diagram of an environment 100,for example a wireless communication system,in accordance with which various embodiments can be implemented. The environment 100 includes a base station, for example a base station (BS) 105, one or more relay stations, for example a relay station 110A, a relay station (RS) 110B, a relay station 110C, and a relay station 110D. The environment 100 also includes one or more mobile stations, for example a mobile station (MS) 115A, a mobile station 115B, a mobile station 115C, and a mobile station 115D. The BS 105 can provide services to the mobile stations within a cell coverage area 120.

The mobile stations communicate with the BS 105 via the relay stations when placed in one or more areas. Examples of the areas include, but are not limited to, a coverage hole area 125, a building area 130, a cell edge area 135, and an out of coverage area 140. The coverage hole area 125, for example a subway and a passage between buildings, is an area where radio frequency signal level is below a certain threshold. The MS 115A, located in the coverage hole area 125, can communicate with the BS 105 via the RS 110A and the RS 110B. The MS 115B, located within the building area 130, can communicate with the BS 105 via the RS 110C. The MS 115C, located in the cell edge area 135, can communicate with the BS 105 via the RS 110D. The MS 115D, located in the out of coverage area 140, can communicate with the BS 105 via the RS 110D.

The BS 105 communicates with each RS via a relay link. For example, the BS 105 communicates with the RS 110A via the relay link. Similarly, each RS communicates with each MS via an access link. For example, the RS 110C communicates with the MS 115B via the access link.

In some embodiments, the RS 110A, the RS 110B, the RS 110C, and the RS 110D can be the mobile stations that enable communication between the BS 105 and the each MS.

FIG. 2 illustrates a fragmentation process on an access link, in accordance with one embodiment. A media access control (MAC) packet data unit (PDU) 205 is to be transmitted by a base station (BS), for example a base station 105, to a relay station (RS), for example the RS 110C, using a relay link. The MAC PDU 205 includes an encrypted payload which is destined for the MS 115B. The encrypted payload can be decrypted by the MS 115B as the encrypted payload cannot be decrypted by the RS 110C. The encrypted payload in the MAC PDU 205 includes a packet number (PN) field, a data field, and an integrity check value (ICV) field. The PN and ICV fields are used to decrypt the encrypted payload. The encrypted payload can include other fields depending on a security algorithm used to encrypt the payload. The MAC PDU 205 is then transmitted as a payload 205 by the BS 105 to the RS 110C using the relay link along with a generic MAC header (GMH) 210 and an optional extended header (EH) 215. The GMH 210 includes information related to connection, indication of presence and absence of the EH 215 in the MAC PDU 205 and length of the MAC PDU 205. The EH 215 includes information relating to the payload 205 and other signaling information. The GMH 210, the EH 215 and the payload 205 is combined to form a payload 220. The BS 105 further adds a relay MAC header (RMH) 225 and the EH 215 to the payload 220 which is transmitted to the RS 110C using the relay link. The payload 220 forms a fragmentable unit that can be fragmented on the access link. The RS 110C fragments the fragmentable unit 220, into two or more fragments, for example a first fragment and a second fragment. The first fragment includes a fragment 230A and a fragmented MAC PDU MAC header (FMMH) 235A. Similarly, the second fragment includes a fragment 230B and a FMMH 235B. Each FMMH includes a fragmentation control (FC) field and a sequence number (SN) field. The information in each FMMH is used by the mobile station (MS) to identify the fragments and to reassemble the fragments in a sequence.

FIG. 3 illustrates format of the FMMH, for example the FMMH 235A, in accordance with one embodiment. The format of the FMMH 235A includes a flow identifier (ID) field 305, a length field 310, a fragmentation control (FC) field 315, and a sequence number (SN) field 320. The flow ID field 305 identifies the FMMH 235A and distinguishes the FMMH 235A from the GMH210. One flow ID is reserved for the FMMH 235A. The length field 310 provides length of the fragment, for example the length of the fragment 230A, sent by the RS 110C. The fragmentation control (FC) field 315 identifies a first fragment, a middle fragment and a last fragment. The sequence number (SN) field 320 identifies the sequence of the first fragment, the middle fragment and the last fragment. The SN 320 is necessary for assembling the first fragment, the middle fragment and the last fragment in a sequence. The RS 110C maintains a sequence number for each MS independently. The sequence number is initialized to zero when the MS 115B connects to the RS 110C at a first instance. The sequence number is assigned to each transmitted MAC PDU using the MAC PDU format including the FMMH 235A. The sequence number is incremented by one for every transmitted MAC PDUfragment including the FMMH 235A.

FIG. 4 is a flowchart illustrating a method for data transmission on an access link, in accordance with one embodiment. The method starts at step 405. At step 410, a relay station (RS) receives a media access control (MAC) packet data unit (PDU) from a base station (BS) using a relay link. At step 415, the RS analyzes bandwidth available on the access link. If the bandwidth available on the access link is insufficient to transmit the received MAC PDU,the RS fragments the MAC PDU as shown in step 420. At step 425, the RS prepares and attaches a fragmented MAC PDU MAC header (FMMH) to each fragment. The RS sets the fragmentation control (FC) field and the sequence number (SN) field in the FMMH. At step 430, the RS transmits the fragmented MAC PDU with the FMMH on the access link. At step 445, the RS checks if the MAC PDU is completely transmitted. If the MAC PDU is not completely transmitted, then the method goes to step 425 else the method stops at step 450.

If bandwidth in the access is link is sufficient to transmit the MAC PDU sent by the BS, then the RS directly transmits the MAC PDU received from the BS to a mobile station (MS) using the access link as shown in step 455. The method stops at step 450.

FIG. 5 is a flowchart illustrating a method for receiving data at the MS, in accordance with one embodiment. The method starts at step 505. At step 510, the MS receives the MAC PDU on a physical link. At step 515, the MS checks if the FMMH is present. If the FMMH is present, the MS processes the received MAC PDU with the FMMH at step 520 else step 525 is performed. At step 525,the MS parses the FMMH and determines a fragmentation control bit (FC) and a sequence number (SN). At step 530, the MS extracts the MAC PDU fragment present in the received MAC PDU and waits until other MAC PDU fragments arrive. At step 535, receipt of the fragments is checked. If yes, step 540 is performed else step 530 is performed. At step 540, the MS assembles the MAC PDU fragments using the FC and SN fields. The MS further processes and decrypts the assembled MAC PDU. The method stops at 545.

FIG. 6 illustrates a fragmentation process on an access link, in accordance with another embodiment. A media access control (MAC) packet data unit (PDU) 305 is to be transmitted by a base station (BS), for example a base station 105, to a relay station (RS), for example the RS 110C, using a relay link. The MAC PDU 305 includes an encrypted payload which is destined for the MS 115B. The encrypted payload can be decrypted by the MS 115B as the encrypted payload cannot be decrypted by the RS 110C. The encrypted payload in the MAC PDU 305 includes a packet number (PN) field, a data field, and anintegrity check value (ICV) field. The PN and ICV fields are used to decrypt the encrypted payload. The encrypted payload can include other fields depending on a security algorithm used to encrypt the payload. The MAC PDU 305 is then transmitted as a payload 305 by the BS 105 to the RS 110C using the relay link along with a generic MAC header (GMH) 310, an optional extended header (EH) 315, and a payload specific extended headers unit 605. The GMH 310 includes the information related to connection, indication of presence and absence of the EH 315 in the MAC PDU 305 and length of the MAC PDU 305. The EH 315 includes information relating to the payload 305 and other signaling information. The payload specific extended headers unit 605 isassociated with a specific payload and is used by a mobile station (MS) for parsing data units in the payload 305. The GMH 310, the EH 315, the payload specific extended headers unit 605, and the payload 305 is combined to form a payload 610. The BS 105 further adds a relay MAC header (RMH) 325 and the EH 315 to the payload 610 which is transmitted to the RS 110C using the relay link. The payload 305forms a fragmentable unit that can be fragmented on the access link. The payload specific extended headers unit 605 is attached to the fragmentable unit 305. The RS 110C fragments the fragmentable unit 305, into two or more fragments, for example a first fragment and a second fragment. The first fragment includes the GMH 310, a MAC PDU fragment extended header (MFEH) 615, other extended headers 620, and a fragment 625. Similarly, the second fragment includes the GMH 310, the MAC PDU fragment extended header (MFEH) 615, other extended headers 620, and a fragment 630. Each MFEH includes a fragmentation control (FC) field and a sequence number (SN) field. The information in each MFEH is used by the mobile station (MS) to identify the fragmentation process and to reassemble the fragments in a sequence.

FIG. 7 illustrates format of the MFEH, for example the MFEH 615 in accordance with one embodiment. The format of the MFEH 615 includes a type field 705, a fragmentation control (FC) field 710, and a sequence number (SN) field 715. The type field 705 identifies type of the extended header. The FC field 710 identifies a first fragment, a middle fragment and a last fragment. The SN field 715identifies the sequence number of the fragment. The SN field 715 is necessary for assembling the first fragment, the middle fragment and the last fragment in a sequence. The SN is assigned in sequence to each fragment transmitted in the MAC PDU 305 that includes the MFEH 615. The sequence number is incremented by one for every transmitted MAC PDU that includes the MFEH 615.

FIG. 8 is a flowchart illustrating a method for data transmission on an access link, in accordance with another embodiment. The method starts at step 805. At step 810, a relay station (RS) receives a media access control (MAC) packet data unit (PDU) from a base station (BS) using a relay link. At step 815 the RS extracts a payload specific extended header that is associated with the MAC PDU. At step 825, the RS analyzes bandwidth available on the access link. If the bandwidth available on the access link is sufficient to transmit the MAC PDU, the MAC PDU is transmitted on the access link as in step 820. If the bandwidth available on the access link is insufficient to transmit the MAC PDU, the RS fragments the payload received in the MAC PDU as shown in step 830. At step 835, the RS attaches a MAC PDU fragment extended Header (MFEH) to each fragmentalong with the generic MAC header (GMH), other extended headers, and payload specific extended header. The payload specific extended header is attached only to a first fragment. The RS sets the fragmentation control (FC) field and the sequence number (SN) field in the MFEH. At step 840,the RS transmits the MAC PDU including the fragment and the MFEH on the access link. At step 845, the RS checks if the MAC PDU is completely transmitted. If the MAC PDU is not completely transmitted, then the method goes to step 835 else the method stops at step 850.

FIG. 9 is a flowchart illustrating a method for receiving data at the MS, in accordance with another embodiment. The method starts at step 905. At step 910, the MS receives the MAC PDU on a physical link. At step 920, the MS checks if the MFEH is present. If the MFEH is not present, the MAC PDU is processed at step 915. If the MFEH is present and a first payload fragment is present, the MS extracts a payload specific extended header from the MAC PDU and stores the payload specific extended header at step 925. At step 930, the MS parses the MFEH and determines afragmentation control bit (FC) and a sequence number (SN). At step 935, the MS extracts a payload fragment from the MAC PDU and waits until the fragments arrive. At step 940, receipt of the fragments is checked. If yes, step 945 is performed else step 910 is performed. At step 945, the MS assembles the fragments using the FC and SN fields. The MS further processes and decrypts the assembled fragments. The method stops at 950.

FIG. 10 illustrates a fragmentation process on an access link, in accordance with yet another embodiment. A media access control (MAC) packet data unit (PDU) 305 is to be transmitted by a base station (BS), for example a base station 105, to a relay station (RS), for example the RS 110C, using a relay link. The MAC PDU 305 includes an encrypted payload which is destined for an MS 115B. The encrypted payload can be decrypted by the MS 115B as the encrypted payload cannot be decrypted by the RS 110C. The encrypted payload in the MAC PDU 305 includes a packet number (PN) field, a data field, and an integrity check value (ICV) field. The PN and ICV fields are used to decrypt the encrypted payload. The encrypted payload can include other fields depending on a security algorithm used to encrypt the payload. The MAC PDU 305 is then transmitted as a payload 305 by the BS 105 to the RS 110C using the relay link along with a generic MAC header (GMH) 310, an optional extended header (EH) 315, and a payload specific extended headers unit 1005. The GMH 310 includes the information related to connection, indication of presence and absence of the EH 315 in the MAC PDU 305 and length of the MAC PDU 305. The EH 315 includes information relating to the payload 305 and other signaling information The payload specific extended headers unit 1005 is associated with a specific payload and is used by a mobile station (MS) for parsing data units carried in the payload 305. The GMH 310, the EH 315, the payload specific extended headers unit 1005, and the payload 305 is combined to form a payload 1010. The BS 105 further adds a relay MAC header (RMH) 325 and the EH 315 to the payload 1010 which is transmitted to the RS 110C using the relay link. The payload 305 forms a fragmentable unit that can be fragmented on the access link. The RS 110C fragments the fragmentable unit 305, into two or more fragments, for example a first fragment and a second fragment. The first fragment includes the GMH 310, a security extended header (SEH) 1015, other extended headers 1020, the payload specific extended headers unit 1005,and a fragment 1025. Similarly, the second fragment includes the GMH 310, the security extended header (SEH) 1015, other extended headers 1020, the payload specific extended headers unit 1005, and a fragment 1030. Each SEH includes a fragmentation control (FC) field. The SN is included in the payload specific extended headers unit 1005 to identify the fragment of the payload 305. The information in each SEH and the payload specific extended headers unit 1005 is used by the mobile station (MS)to identify the fragmentation process and to reassemble the fragments in a sequence.

FIG. 11 illustrates format of the SEH, for example the SEH 1015, in accordance with one embodiment. The format of the SEH 1015 includes a type field 1105, a fragmentation control (FC) field 1110, and a reserved field 1115. The type field 1105 identifies type of the header. The FC field 1110 identifies a first fragment, a middle fragment and a last fragment. The reserved field 1115 is reserved for later use.

FIG 12 is a flow chart illustrating a method for data transmission on an access link, in accordance with yet another embodiment. The method starts at step 1205. At step 1210, a relay station (RS) receives a media access control (MAC) packet data unit (PDU) from a base station (BS) using a relay link. At step 1220, the RS analyzes bandwidth available on the access link. If the bandwidth available on the access link is sufficientto transmit the received MAC PDU, the MAC PDU is transmitted on the access link as in step 1215. If the bandwidth available on the access link is insufficient to transmit the MAC PDU, the RS checks if the payload is encrypted at step 1225. If the payload is encrypted the MAC PDU that includes security information is fragmented at step 1230. At step 1235, the RS attaches a security extended header (SEH) to each fragment along with the generic MAC header (GMH), other extended headers, and payload specific extended header. The RS sets the fragmentation control (FC) field in the SEH. At step 1240, the RS transmits the MAC PDU including the fragments and the SEH on the access link. At step 1245, the RS checks if the MAC PDU is completely transmitted. If the MAC PDU is not completely transmitted, then the method goes to step 1235 else the method stops at step 1250.

FIG. 13 is a flowchart illustrating a method for receiving data at the MS, in accordance with yet another embodiment. The method starts at step 1305. At step 1310 the MS receives a MAC PDU on a physical link. At step 1320, the MS checks if the SEH is present. If the SEH is not present, the MAC PDU is processed and decrypted at step 1315. If the SEH is present, the MS parses the SEH and determines the fragmentation control (FC)at step 1325. At step 1330, the MS extracts a payload specific extended header from the MAC PDU. At step 1335, the MS extracts the payload and waits until the fragments arrive. At step 1340, receipt of the fragments is checked. If yes, step 1345 is performed else step 1310 is performed. At step 1345, the MS assembles the fragments using the SN field in payload specific extended header and the FC in the SEH. The MS further processes and decrypts the assembled fragments. The method stops at 1350.

In the preceding specification, the present disclosure and its advantages have been described with reference to specific embodiments. However, it will be apparent to a person of ordinary skill in the art that various modifications and changes can be made, without departing from the scope of the present disclosure, as set forth in the claims below. Accordingly, the specification and figures are to be regarded as illustrative examples of the present disclosure, rather than in restrictive sense. All such possible modifications are intended to be included within the scope of the present disclosure.

Claims

A method of data transmission on an access link, the method comprising:

receiving a media access control (MAC) packet data unit (PDU) from a base station (BS) using a relay link;

fragmenting the MAC PDU into two or more fragments by a relay station (RS) if available bandwidth in the RS is lesser than size of the received MAC PDU;

adding a fragmented MAC PDU MAC header (FMMH) to each of the two or more fragments; and

transmitting each of the two or more fragments to a mobile station (MS) on the access link.
The method of claim 1, further comprising:

receiving the MAC PDU from the BS on the relay link; and

transmitting the received MAC PDU with a generic MAC header (GMH) from the RS to the MS on the access link, if available bandwidth in the RS is greater than the size of the received MAC PDU.
The method of claim 1, wherein the FMMH comprises a flow identifier field, a length field, a fragmentation control field, and a sequence number field.
The method of claim 1, further comprising:

receiving each of the two or more fragments in the MAC PDU along with the FMMH by the MS on the access link;

assembling the two or more fragments received in the MAC PDU with the FMMH to generate the MAC PDU; and

decrypting a payload in the generated MAC PDU.
The method of claim 4, further comprising:

receiving the MAC PDU by the MS on the access link; and

decrypting a payload in the received MAC PDU if the received MAC PDU is associated with a generic MAC header (GMH).
A method of data transmission on an access link, the method comprising:

receiving a media access control (MAC) packet data unit (PDU) from a base station (BS) on a relay link;

fragmenting a payload in the received MAC PDU into two or more fragments by a relay station (RS), if required bandwidth in the RS is lesser than size of the received MAC PDU;

adding the payload specific extended headers unit to a first fragment of the two or more fragments;

adding a MAC PDU fragment extended header (MFEH) to each of the two or more fragments; and

transmitting each of the two or more fragments along with a generic MAC header (GMH) to a mobile station (MS) on the access link.
The method of claim 6, further comprising:

receiving the MAC PDU from the BS on the relay link; and

transmitting the MAC PDU from the RS to the MS on the access link, if available bandwidth in the RS is greater than the size of the received MAC PDU.
The method of claim 6, wherein the MFEH comprises a type field, a fragmentation control field, and a sequence number field.
The method of claim 6, further comprising:

receiving each of the two or more fragments by the MS in the MAC PDU with the MFEH on the access link;

assembling the two or more fragments received in the MAC PDU with the MFEH to generate the MAC PDU payload; and

decrypting the payload in the generated MAC PDU to parse the payload using the payload specific extended headers, wherein the payload specific extended headers is extracted from the MAC PDU carrying the first fragment of the generated MAC PDU.
The method of claim 9, further comprising:

receiving the MAC PDU by the MS on the access link; and

decrypting the payload in the received MAC PDU if the MFEH is lacking in the MAC PDU to parse the payload using the payload specific extended headers in the received MAC PDU.
A method of data transmission on an access link, the method comprising:

receiving a media access control (MAC) packet data unit (PDU) from a base station (BS) on a relay link;

fragmenting a payload in the received MAC PDU into two or more fragments by a relay station (RS) if available bandwidth in the RS is lesser than size of the MAC PDU;

adding a security extended header (SEH) to each of the two or more fragments of the MAC PDU;

adding a payload specific extended headers unit to each of the two or more fragments; and

transmitting each of the two or more fragments along with a generic MAC header (GMH) in a sequence to a mobile station (MS) on the access link.
The method of claim 11, further comprising:

receiving the MAC PDU from the BS on the relay link; and

transmitting the MAC PDU from the RS to the MS on the access link if the required bandwidth in the RS is greater than the size of the received MAC PDU.
The method of claim 11, wherein the SEH comprises a type field, a fragmentation control field, and a reserved field.
The method of claim 11, further comprising:

receiving the two or more fragments in the MAC PDU along with the SEH by the MS on the access link;

assembling the two or more fragments to generate the MAC PDU; and

decrypting the payload in the generated MAC PDU to parse each of the two or more fragments using the payload specific extended headers in the MAC PDU.
The method of claim 14, further comprising:

receiving the MAC PDU by the MS on the access link; and

decrypting the payload of the MAC PDU if the SEH is lacking in the received MAC PDU to parse the payload using the payload specific extended headers in the received MAC PDU.
A system for data transmission on an access link, the system comprising:

a base station (BS) that transmits a media access control (MAC) packet data unit (PDU) for a mobile station (MS) using a relay link;

a relay station (RS) that receives the MAC PDU to

fragment the MAC PDU into two or more fragments if required bandwidth in the RS is lesser than size of the received MAC PDU,

add a fragmented MAC PDU MAC header (FMMH) to each of the two or more fragments, and

transmit each of the two or more fragments to the MS using the access link; and

the MS that receives the two or more fragments from the RS to

assemble the two or more fragments to generate the MAC PDU if each of the two or more fragments are associated with the FMMH, and

decrypt the generated MAC PDU.
The system of claim 16, wherein the RS receives the MAC PDU to

fragment a payload of the MAC PDU into two or more fragments if the required bandwidth in the RS is lesser than the size of the received MAC PDU,

add the payload specific extended headers unit to the first fragment in the MAC PDU,

add a MAC PDU fragment extended header (MFEH) to the two or more fragments, and

transmit the two or more fragments along with a generic MAC header (GMH) to the MS using the access link.
The system of claim 17, wherein the MS receives the two or more fragments to

assemble the two or more fragments to generate the MAC PDU if the two or more fragments are associated with the MFEH, and

decrypt the payload of the generated MAC PDU to parse the payload using the payload specific extended headers extracted from the MAC PDU carrying the first fragment of the generated MAC PDU.
The system of claim 16, wherein the RS receives the MAC PDU to

fragment the MAC PDU payload into the two or more fragments if the required bandwidth in the RS is lesser than the size of the received MAC PDU,

add a security extended header (SEH) to each of the two or more fragments of the MAC PDU,

add a payload specific extended headers unit to each of the two or more fragments, and

transmit the two or more fragments along with a generic MAC header (GMH) to the MS using the access link.
The system of claim 19, wherein the MS receives the two or more fragments to

assemble the two or more fragments to generate the MAC PDU payload if the two or more fragments are associated with the SEH, and

decrypt the payload of the generated MAC PDU to parse each of the two or more fragments using the payload specific extended headers in the MAC PDU.