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Hi Shoukang, Hoang, and all, Thank you for the initiating discussion on the path management. I am not clear when/how MS selects alternative path. Thus, can anyone explain it? Best Regards, Eunkyung Kim Electronics & Telecommunications Research Institute (ETRI) From: Zheng Shoukang [mailto:skzheng@I2R.A-STAR.EDU.SG] Hi All, Probably we can discuss on the difference between two approaches, either BS or MS determining the alternative path. If the advantage/disadvantage is clear, we may be able to see which approach is better. Regards, Shoukang From: Hoang Vinh Dien [mailto:hvdien@NICT.COM.SG] Hi All, Apology if you receive multiple copy of this email. I'm re-sending using 802.16 email reflector. Please let me initiate the discussion for Path management topic. We have total 6 contributions (In ascending order) as follow (Each contribution was assigned with specific color) 1. C802.16n-rg-11/0027 2. C802.16n-11/0028r3 3. C802.16n-rg-11/0029 4. C802.16n-rg-11/0036 5. C802.16n-rg-11/0039r1 6. C802.16n-11/0050r3 From these 6 contributions, I had consolidated the table of content and combined contributions together under the table of content as below. 17.2.7 Path Discovery and Management (C802.16n-rg-11/0027,C802.16n-rg-11/0036) 17.2.7.1 Alternative Path Definition (C802.16n-rg-11/0039r1) 17.2.7.2 Alternative Path Establishment Algorithm in a tree topology (C802.16n-rg-11/0029) 17.2.7.3 Alternative Path Establishment (C802.16n-11/0050r3, C802.16n-rg-11/0029) 17.2.7.4 Alternative Path Establishment with Multi-mode (C802.16n-rg-11/0039r1) 17.2.7.5 Alternative Path Maintenance at FS (C802.16n-rg-11/0039r1, C802.16n-11/0028r3) 17.2.7.6 Maintenance of Alternative Path(C802.16n-11/0050r3, C802.16n-rg-11/0029) 17.2.7.7 Handover to Alternative Path(C802.16n-rg-11/0029) 17.2.7.8 Failure Detection(C802.16n-11/0050r3) 17.2.7.9 Fast network re-entry after SPOF(C802.16n-11/0050r3,C802.16n-11/0028r3) Sessions 17.2.7, 17.2.7.3, 17.2.7.5, 17.2.7.6, 17.2.7.9 have two contributions each and may have conflicts. I would like to initiate one point of conflict between contribution 0029 and others: - Contribution 0029 state that alternative path could be decided by BS or MS. Other contributions mainly state that alternative path should be decided by BS only. Please have a view on this. With my best regards, Hoang PS: Below is the consolidated documents. Please note that text with same color comes from same contribution. ***** BEGIN: PATH MNG ***** 17.2.7 Path Discovery and Management [Begin of Text Proposal: From C802.16n-rg-11/0027] [HR-Network shall support neighbor and path discovery between HR-MSs as well as between HR-MS and HR-Network infrastructure stations. Path discovery can be accomplished with or without network support. HR-Network shall support path management and establishment, removal ,updating of alternative paths to support fast neighbor and path recovery in the event of disruption; for example, encountering intermediate HR-MS failure or movement. HR-Network shall provide the capability to choose the most reliable or the least latency path. The path information could be included and passed in the signaling.] [End of Text Proposal: From C802.16n-rg-11/0027] [Begin of Text Proposal: From C802.16n-rg-11/0036] [An HR-BS changing its role as HR-RS may select alternative path for subordinate HR-MS in the event of disruption. The HR-BS transmits MAC context information of the HR-MS during establishing relay link to neighbor HR-BS to allow HR-MS to select alternative path during performing handover to the neighbor HR-BS. The HR-BS may store MAC context information of the HR-MS to allow HR-MS to reselect reliable path after performing network reentry when returning back to the HR-BS upon its recovery. When an HR-MS changes its role as RS or returns to HR-MS from RS mode, alternative path may be selected for subordinate HR-MS. The superordinate HR-BS may transmit MAC context information of the subordinate HR-MS after establishing relay link to allow the HR-MS to select alternative path.] [End of Text Proposal: From C802.16n-rg-11/0036] 17.2.7.1 Alternative Path Definition [Begin of Text Proposal: From C802.16n-rg-11/0039r1] An alternative path is a link or a list of continuous links (through HR-RS or HR-MSs) between a HR-MS and the HR-network. There are no active connections on alternative paths in normal operation. The alternative path will only be activated when a single point of failure is detected. 17.2.7.2 Alternative Path Establishment Algorithm in a tree topology [Begin of Text Proposal: From C802.16n-rg-11/0029] In a tree topology, A backup tree could be calculated as follow:
17.2.7.3 Alternative Path Establishment [Begin of Text Proposal: From C802.16n-11/0050r3] [The alternative path shall be determined by the serving HR-BS. The decision shall be based on the measurement report on the links among the stations.] [End of Text Proposal: From C802.16n-11/0050r3] [Begin of Text Proposal: From C802.16n-rg-11/0029] HR-BS determines the tree topology of the network. From this tree topology, backup path for HR-MS will be determined according to session 17.2.7.2. HR-BS will have higher priority in backup path calculation. 17.2.7.4 Alternative Path Establishment with Multi-mode [Begin of Text Proposal: From C802.16n-rg-11/0039r1] The super-ordinate HR-BS shall determine alternative paths for every subordinate stations to prepare in advance for SPOF events. The stations along an alternative path shall include HR-MS or HR-BS that changes mode to relay or base-station modes if the alternative path is a better path (e.g. more reliable) than others. 17.2.7.5 Alternative Path Maintenance at FS [Begin of Text Proposal: From C802.16n-rg-11/0039r1] HR-BS shall maintain alternative paths of its subordinate stations. It shall update the stations with the alternative path information and network information to facilitate fast network re-entry for those paths. It shall inform HR-MS which changes mode (to HR-RS or HR-BS) of its subordinate HR-MSs and network information to facilitate fast network re-entry of those HR-MSs.] [End of Text Proposal: From C802.16n-rg-11/0039r1] [Begin of Text Proposal: From C802.16n-11/0028r3] The serving HR-BS shall maintain alternative paths of its subordinate stations through FSs. It shall periodically update FSs with a TBD message containing a list of SS it is responsible for network re-entry after SPOF, and configuration information to facilitate fast network re-entry. The serving HR-BS shall periodically update its SSs with a TBD message containing their respective FS and configuration information to facilitate fast network re-entry to that FS.] [End of Text Proposal: From C802.16n-11/0028r3] 17.2.7.6 Maintenance of Alternative Path [Begin of Text Proposal: From C802.16n-11/0050r3] HR-BS and HR-MS shall store the information of alternative path as the backup in the event of failure of intermediate station. The information of alternative path is TBD. The HR-MS and the access station of the alternative path shall store pre-negotiated information for fast network re-entry after SPOF.] [End of Text Proposal: From C802.16n-11/0050r3] [Begin of Text Proposal: From C802.16n-rg-11/0029] When the topology is changed, backup path should be recalculated to maintain its up to date status and efficiency. Both HR-BS and HR-MS can decide HR-MS’s current backup path is still relevant or not. If it’s not, HR-BS or HR-MS shall construct a new backup path according to session 17.2.7.2. 17.2.7.7 Handover to Alternative Path [Begin of Text Proposal: From C802.16n-rg-11/0029] When HR-MS’s timeout with its current superordinate node exceed the TIME_OUT threshold, it shall inform HR-BS of this disruption through DSD-REQ message. This DSD-REQ message is sent through the backup path. This message also serves as the trigger for nodes in backup path. Intermediate nodes on the backup path will then mark the corresponding backup entry in their routing table as currently active and shall use this entry to relay data from/to HR-BS. The intermediate nodes in the backup path should reply the DSD-REQ received from its subordinate node with DSD-RSP message to confirm that switching to backup path has been carried out. After receiving DSD-RSP message from its superordinate, HR-MS shall transmit data to HR-BS through the backup path normally. Once HR-BS receives the DSD-REQ from HR-MS, it shall refresh its topology information and inform affected HR-MS about the new topology changes.] [End of Text Proposal: From C802.16n-rg-11/0029] 17.2.7.8 Failure Detection [Begin of Text Proposal: From C802.16n-11/0050r3] The failure detection can be performed by the stations around the point of failure and the reports from the stations around the point of failure may be used for HR-BS’s decision to establish the path using alternative path information. The detection procedure and reporting messages is TBD. 17.2.7.9 Fast network re-entry after SPOF [Begin of Text Proposal: From C802.16n-11/0050r3] Optimized network re-entry shall be used for accelerating path recovery. Pre-allocated ranging codes shall be used to achieve contention-free ranging at network re-entry. The details are TBD. The path recovery could be either initiated by the serving HR-BS or the HR-MS lost of the connection with HR-network. When the HR-BS initiate the path recovery, it sends out the control messages to establish the path for the HR-MS lost of the connection with HR-network, and the access station along the alternative path prepares for the network re-entry for this HR-MS.] [End of Text Proposal: From C802.16n-11/0050r3] [Begin of Text Proposal: From C802.16n-11/0028r3] Upon detection of a failure at the serving BS, FSs shall switch mode and perform network entry using the most recent configuration information. It shall facilitate fast network re-entry for SSs obtained from the most recent configuration information.] [End of Text Proposal: From C802.16n-11/0028r3] ***** END: PATH MNG ***** |