1. Service Continuity of Enhanced-MBS Document Number: IEEE C802.16m-08/1011r2 Date Submitted: 2008-9-15 Source: Chun-Yen Wang, Chun-Yuan Chiu, Fang-Ching (Frank) Ren, Richard Li, Wern-Ho Sheen Voice: ITRI E-mail: {ChunYen, ccy, frank_ren, richard929, whsheen} Information and Communications Research Laboratories, @itri.org.tw 195 Chung Hsing Rd., Sec.4 Chu Tung, Hsin Chu, Taiwan 310, R.O.C. * http://standards.ieee.org/faqs/affiliationFAQ.html Re : IEEE 802.16m-08/033 - Call for Contributions on Project 802.16m System Description Document (SDD), on the topic of “MAC aspects of enhanced MBS” Venue: Kobe, JP Base Contribution: N/A Purpose: For discussion and approval by TGM Notice: This document does not represent the agreed views of the IEEE 802.16 Working Group or any of its subgroups. It represents only the views of the participants listed in the “Source(s)” field above. It is offered as a basis for discussion. It is not binding on the contributor(s), who reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.16. Patent Policy: The contributor is familiar with the IEEE-SA Patent Policy and Procedures: and.http://standards.ieee.org/guides/bylaws/sect6-7.html#6http://standards.ieee.org/guides/opman/sect6.html#6.3 Further information is located at and.http://standards.ieee.org/board/pat/pat-material.htmlhttp://standards.ieee.org/board/pat

2. Outline Scenario description Service continuity of E-MBS: –Inter-EMBS Zone transition of a connected-state MS –Inter-EMBS Zone transition of an idle-state MS From multi-BS transmission mode to single-BS transmission mode From single-BS transmission mode to single-BS (multi-BS) transmission mode From multi-BS transmission mode to multi-BS transmission mode 1

3. Scenario Description (1) Assumptions: –An E-MBS service area is the coverage of a set of BSs where some E- MBS service(s) is announced and available to be received –A BS within the service area is responsible to forward the associated E- MBS data from gateway by using single-BS transmission mode or multi-BS transmission mode –Each BS capable of providing E-MBS service belongs to a certain E- MBS Zone, identified by a unique MBS_Zone ID –The same CID and same Security Association (SA) is used for transmitting the content of certain E-MBS service(s) in a E-MBS Zone –Different CIDs or different SAs may be used in different E-MBS Zones for the same E-MBS service 2

4. Scenario Description (2) –A BS is allowed to turn off the transmission of an E-MBS service if there is no subscriber interesting for this service –A MS can continue to receive E-MBS data within the service area regardless of the MS operation mode (i.e., connected state/idle state) E-MBS service area single-BS transmission mode multi-BS transmission mode Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 3

5. E-MBS Service Continuity of a Connected-State MS Target BS decision: –Serving BS criteria for recommendation of target BS may include factors such as expected MS performance at potential target BS, BS and network loading conditions, MS QoS requirements, and E-MBS service availability. E-MBS HO decision: –An E-MBS service needs HO if the target BS does not belong to the associated E-MBS Zone MBS HO optimization: –A MS may be able to obtain the CID and the scheduling information used in the target BS during the HO preparation phase to improve service continuity –If the target BS had turned off the transmission of the E-MBS service, the target BS may be noticed to resume transmitting the E-MBS service during the HO preparation phase 4 MSSBSTBS Unicast HO REQ E-MBS HO decision HO preparation phase CID and scheduling information forwarding … GW E-MBS service resumption HO pre-notification Unicast HO RSP …

6. E-MBS Service Continuity of an Idle-State MS During idle state, a MS may have following methods to achieve E-MBS service continuity –Method 1: perform location update procedure to update CIDs when the MS detects a change in E-MBS Zone –Method 2: perform location update procedure when the MS detects a change in E- MBS Zone, unless the MS already has the CID mappings through a CID pre-allocation scheme [1] –Method 3: transit to connected state by network reentry procedure when the MS awakes to a possible inter-MBS Zone transition 5

7. Method 1 If the MS reselects a preferred BS during MS paging unavailable interval, and then detects the change of E-MBS Zone by monitoring the MBS zone identifier list which is transmitted by the new preferred BS in the downlink broadcast message, it can update its CIDs and resume content reception through location- update procedure Original preferred BS MS Reselects a preferred BS during MS paging unavailable interval New preferred BS E-MBS HO decision Location-update procedure for CID updating GW E-MBS service resumption perform location update procedure to update CIDs when the MS detects a change in E-MBS Zone… 6

8. Original preferred BS MS Reselects a preferred BS during MS paging unavailable interval New preferred BS E-MBS HO decision GW Location-update procedure for E-MBS service resumption The CID pre-allocation scheme informs MSs within a certain E-MBS Zone regarding the mapping of CIDs used in the current E-MBS Zone to new CID within a neighboring E- MBS Zone When a MS moves to a new zone, it can immediately (and internally) update its CIDs and resume content reception without the need to perform CID update through location-update Method 2 perform location update procedure when the MS detects a change in E-MBS Zone, unless the MS already has the CID mappings through a CID pre-allocation scheme[1]… 7

9. preferred BS (SBS) MS TBS GW E-MBS service continuity procedure of a connected-state MS When the MS awakes to a possible inter-MBS Zone transition by some measurements, it transits to connected state by network reentry procedure Method 3 transit to connected state by network reentry procedure when the MS awakes to a possible inter-MBS Zone transition… some measurements trigger network reentry procedure 8

10. CID Updating Method of an Idle-State MS: from Multi-BS Transmission Mode to single-BS Transmission Mode For a E-MBS service using multi-BS transmission mode, gateway is responsible to schedule resource and decides a MCID for the service Since this resource can not be reused in a guard range due to co-channel interference, the scheduling information should be forwarded to all BSs within the guard range If a BS within the guard range provides same E-MBS service by using single-BS transmission mode, it should be able to aware of the MCID used in the neighboring E-MBS Zone Therefore, the BS can provide the mapping of MCID used in the neighboring E-MBS Zone to the CID used in current E-MBS Zone Besides, we propose that the timing of transmitting E-MBS data in single- BS transmission mode is always later than the timing in multi-BS transmission mode to relieve packet loss multi-BS Tx mode single-BS TX mode Guard range gateway 9

11. CID Updating Method of an Idle-State MS: from single-BS Transmission Mode to single-BS (Multi-BS) Transmission Mode For a E-MBS service using single-BS transmission mode, BS is responsible to schedule resource and decides a CID for the service Therefore, its neighboring BSs are not aware of the CID used by itself for the service unless the CID pre-allocation scheme proposed in [1] is used In order to avoid the overhead of the CID pre-allocation, we propose to adopt the method 3 to achieve E-MBS service continuity for this case (an Idle-State MS may transit to connected state by network reentry procedure when the MS awakes to a possible inter-MBS Zone transition) In idle mode, a MS may reselect a preferred BS during MS paging unavailable interval according to some measurements. A stricter threshold of these measurements may be used for awaking to a possible inter-MBS Zone transition 10

12. CID Updating Method of an Idle-State MS: from Multi-BS Transmission Mode to Multi-BS Transmission Mode It seems like there is no reason to use different resource and CIDs in two neighboring MBS Zones for the same MBS service, instead of combining them to a bigger MBS Zone. –a MS transiting from multi-BS transmission mode to multi-BS transmission mode is an impossible case. If there is some rare reasons resulting in this situation, but the two neighboring MBS Zones always adopt same CID allocated by the gateway, –there is no need to update CID. If there is some rare reasons resulting in different resource and CIDs used in two neighboring MBS Zones for the same MBS service, –we propose to adopt the method 1 for this case. (an Idle-State MS update its CIDs and resume content reception through location-update procedure after detecting the change of MBS Zone) 11

13. MS Operation Idle mode? Unicast HO? MBS HO decision & HO procedure YES NO Single BS? YES Using threshold 1 (stricter) Monitor RSSI during MS paging unavailable interval over T1? Network reentry procedure YES NO Using threshold 2 (looser) over T2? Change preferred BS & update CIDs internally YES NO 12

14. Proposed Text for SDD 15.1: General Concepts Add the assumptions described in page 2-3 15.x: Service Continuity of Enhanced-MBS 15.x.1: E-MBS Service Continuity of a Connected-State MS Add the discussion described in page 4 15.x.2: E-MBS Service Continuity of an Idle-State MS Add the discussion described in page 5-12 13

15. Reference 1.IEEE C802.16maint-08/171r9, “Improvement in MBS in 802.16REV2 ” 14