Samsung Mobile WiMAX Outdoor RAS SPI-2331, System Description

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CHAPTER 4. Message Flow
4-16 © SAMSUNG Electronics Co., Ltd.
Classification Description
(1)~(3) The MS transmits the MOB_MSHO-REQ message including the Neighbor BS
(RAS) ID and the parameter related to handover to the current Serving RAS
(S-RAS) to request handover. The S-RAS transmits the HO-Request message
including the received MOB_MSHO-REQ parameter and the context information to
the ACR, and the ACR forwards the HO-Request message to the Target RAS(T-RAS).
(4)~(8) The T-RAS transmits the HO-Response message including its own capability
information to the ACR, and the S-RAS transmits the MOB_BSHO-RSP message
including the Recommended Neighbor BS-IDs, the HO-ID and the parameter result
value to the MS.
(9)~(11) The MS transmits the MOB_HO-IND message including the HO-IND Type and the
Target BS-ID to the S-RAS to notify handover finally, and the S-RAS transmits the
HO-Confirm message including the context information and the Data Integrity
information(e.g., Buffered SDU SN) of the MS to the T-RAS.
(12)~(15) The T-RAS transmits the Context-Request message to the ACR(Authenticator) to
request the AK Context information, and the ACR responds by using the Context-
Response message including the AK context information.
(16)~(21) The path pre-registration is executed to set a new data path between the ACR and
the T-RAS. In addition, a forwarding path is set to send to the T-RAS the traffics that
the S-RAS has not yet transmitted to the MS, and the traffics are sent to the T-RAS.
(22) If T-RAS allows the request of an MS, the T-RAS notifies UL_MAP IE to enable the
MS to transmit HO Ranging Request via uplink.
(23) The MS transmits to the T-RAS the RNG-REQ message that contains the MAC
address, Serving BS-ID, HO indication, and HO-ID.
(24)~(25) The path registration procedure is executed to exchange the SF information that is
mapped with the data path created between the ACR and the T-RAS through the
steps (16)~(18).
(26) The T-RAS replies with the RNG-RSP message along with HO Optimization Flag,
CID_Update, and SA-TEK_Update.
(27)~(30) If the S-RAS transmits all the traffic to the T-RAS, the forwarding path is removed.
(31) If an MS successfully receives the RNG-RAS message, the MS transmits Bandwidth
Request(BR) MAC PDU to RAS to inform the reception of the message.
(32)~(33) The T-RAS transmits the HO-Complete message to S-RAS to notify the completion
of handover.
(34)~(35) The RAS notifies the new CMAC_KEY_COUNT value updated by MS to the ACR,
which is an authenticator.
(36)~(38) When the handover procedure is completed, the old path between the S-RAS and
the ACR is removed.
Inter-ACR Handover
Inter-ACR handover within the same ASN considers the path extension via the R6 interface.
The inter-ACR handover procedure is the same with the inter-RAS handover procedure,
but data forwarding between the serving RAS and the target RAS is not supported.